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Thread: Sigma 35mm F1.4

  1. #51
    Senior Subscriber Member Steen's Avatar
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    Sigma 35mm F1.4


    Quote Originally Posted by Jan Brittenson View Post

    Yes. Unfortunately, neither Nikon or apparently Sigma agree, which is at the root of the problem. Nikon should for any 'pro' product give it a critical QC pass, then service or tweak it as needed until it passes. This would include critical inspection of files produced on a real-world, actual live camera like a D800E and focus performance on a D4. 1-3 AF tune clicks is fine (the value should be on the test certificate) on most lenses, 15 is not. A zoom that can only be tuned to one end is not. If this adds $100 to the cost of each lens sold (about two-three hours of bench work for a competent technician, averaged) - so be it. Pass it on. This is not the place to cut product cost.

    Well spoken, Jan, I fully agree

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    Re: Sigma 35mm F1.4

    Quote Originally Posted by Jan Brittenson View Post
    Yes. Unfortunately, neither Nikon or apparently Sigma agree, which is at the root of the problem. Nikon should for any 'pro' product give it a critical QC pass, then service or tweak it as needed until it passes. This would include critical inspection of files produced on a real-world, actual live camera like a D800E and focus performance on a D4. 1-3 AF tune clicks is fine (the value should be on the test certificate) on most lenses, 15 is not. A zoom that can only be tuned to one end is not. If this adds $100 to the cost of each lens sold (about two-three hours of bench work for a competent technician, averaged) - so be it. Pass it on. This is not the place to cut product cost.
    Test certificate??? Nikon does not issue test certificates. It would add a lot more to the cost than $100, unless you are thinking of minimum wage employees doing this. But then who can afford Leica S prices if you are going to do this?

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    Subscriber Member tashley's Avatar
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    Re: Sigma 35mm F1.4

    Quote Originally Posted by Steen View Post



    + 1 more

    Another firm yes to that question, I actually think you are far too tolerant when you are willing to downsize to 50 % before judging the sharpness at the left and right side and expecting them to be equal. I always judge such matters at 100 % no less.

    I can only judge from the Nikon 4/24-120mm and now the Sigma 1.4/35mm sample pictures you have shown, but I can at least say with certainty that I wouldn't accept such an asymmetry (or I would find myself spending far too much time looking for it).
    Phew, you come to my rescue again Steen: I was keen to pass on the crown of 'most critical person on GetDPI for optics'...

    But I do of course always check at 100%. However, 50% is my 'no brainer for return' procedure otherwise I would be returning 90% rather than 70% and that would just wear me down...

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    Re: Sigma 35mm F1.4

    tashley, I did not mean that as an insult. I hope you don't take it that way.

  5. #55
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    Re: Sigma 35mm F1.4

    Quote Originally Posted by tashley View Post
    Just so's you know Guy, Lloyd Chambers' copy has a slight decentering too... It may be that the design is prone to it.
    I hope I don't come across as a Sigma apologist - really I'm not - but it seems to me that most copies of all lenses are more likely than not to have a slight decentering. A quick look at SLRGear blur plots for various lenses indicates as much. That said, I haven't noticed any decentering with my copy of the Sigma 35/1.4.

    Quote Originally Posted by Jack View Post
    I have come to the ultimate conclusion that buying glass for ANY high-resolution camera requires a "shoppers" mentality: try on several to find the one that looks and fits you -- or in this case your camera -- the best...

    Short conclusion: my advice is to moderate ones expectations -- and then get back to creating images
    I agree, Jack. I don't have much time or patience for exchanging, so I've lowered my expectations accordingly. I'm fine with an average amount of decentering, a certain amount of AF issues, etc.

    So far with the Nikon system I've been very lucky - very good copies of several complex lenses on the first go.

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    Re: Sigma 35mm F1.4

    Quote Originally Posted by Shashin View Post
    Test certificate??? Nikon does not issue test certificates. It would add a lot more to the cost than $100, unless you are thinking of minimum wage employees doing this.
    Zeiss manages to... and their lenses are priced at or near Nikon's. At Nikon volumes it should be doable. Leica is pretty extreme, no need to go quite that far...

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    Member nikonf's Avatar
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    Re: Sigma 35mm F1.4

    When it comes to quality control, I have found Leica, Zeiss, Rodenstock and Schneider typically can deliver a manufactured optic which is closer to the original design.
    I have encountered some exceptions and yet I am much more confident when I decide to purchase from the aforementioned optics manufacturers.
    I am been photographing for more than 40 years and I have only had to return one Rodenstock and one Schneider lens due to defects in manufacture.
    Zeiss lenses were much more reliable before they allowed Sony to become involved with the Alpha series of lenses. I had a 24-70 Zeiss Sony Alpha which came brand new in the box with a terrible wobble in the zoom mechanism. The certificate which was packed with the lens was signed by a technician. I can not seriously believe he actually ever looked at the lens. This is NOT acceptable for a $2000 lens!
    Manufacturers are taking shortcuts with quality control and we are experiencing more lens problems than we should be at this point in time.
    It's all about "doing more with less". This has led to disastrous consequences in Information Technology and I fear the same in the manufacture of optics.
    Read some of the horror stories Joseph Holmes has posted on his web site regarding finding optics which pass his tests.
    He is a world class photographer and his images speak for themselves.
    Good luck!

  8. #58
    Subscriber Member tashley's Avatar
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    Re: Sigma 35mm F1.4

    DXOmark on the rx-1 lens
    "With excellent image quality at maximum aperture becoming outstanding at f/2.8 and on, the Zeiss Sonnar T* 2/35 is likely to become a classic, against which all others are judged."

    This is what I hoped for from the Siggy but I will try getting mine tweaked to perfection and report back!

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    Senior Subscriber Member Steen's Avatar
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    Re: Sigma 35mm F1.4


    Quote Originally Posted by D&A View Post

    (...) It's a USB dock where the lens mounts onto the dock and it's cord plugs into a CPU's USB. I guess with supplied software, one is not only supposed to be able to update firmware of the lens, but also change or re-set the Af fine tune. I presume a lens that say needs -18...could be "nulled" and re-set to zero. I'm not exactly sure if that how it works or not, as Sigma hasn't apparently said much about it. (...)

    Quote Originally Posted by tashley View Post

    (...) I got news from Sigma: the dock will be available to end-users but price and date not confirmed...

    Imagine what a revolution such a dock would be if it really enables the end-user to AF-fine-tune the lenses and why not at a later stage also cameras ?

    A Do-It-Yourself AF-fine-tune kit. That would be awesome.

    In theory it has the potential to save the manufacturer a lot of money and the customers a lot of frustration, good reasons why it ought not to be all that expensive.

    Just for once the rather worn out Win-Win Situation phrase would make a lot of sense.

    Think about it, Nikon

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    Re: Sigma 35mm F1.4

    I had only positive experiences with the Sony ZA lenses and think they were outstanding... The Planar 85/1.4 T* clearly was an old design, and more mojo than laser, but I think it compared reasonably to the Summilux-R 80/1.4. More of a Zeiss look though (= high contrast, none of those classic Leica pastels). The only thing I didn't like was that the AF turned the focusing ring, but it lived up to its promise nicely in terms of optics. I think Sony's SLR/SLT lens QC overall is much better than Nikon's though, so it's not just a Zeiss thing.

    I still have the A850 (with grip even) since I can't use my M42 collection with Nikon...

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    Re: Sigma 35mm F1.4

    Quote Originally Posted by nikonf View Post
    The certificate which was packed with the lens was signed by a technician. I can not seriously believe he actually ever looked at the lens.
    I don't think anyone is under the illusion that a test certificate means there is never anything wrong with a lens when you get it. It could get banged up in transit, be dropped by a dealer, or have a manufacturing defect that manifests itself sometime later - like from thermal stress during transit. But at least you know it was good at some point. It also means when you exchange it as defective your chances of getting another defective unit are way, way lower.

  12. #62
    Senior Member Amin's Avatar
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    Re: Sigma 35mm F1.4

    I'm posting a few D800 and D600 samples I took today across the street from my nephew's birthday party. Again, I don't use this lens for landscapes, only for people photography, but I'm sharing these in case they may be helpful. These were handheld, but I don't think handshake was an issue.

    After staring at them a bit, I've come to the conclusion that the lens has fairly strong field curvature. Ie, the two shots of the trees show pretty good edge sharpness while the central area is backfocused, while the third photo (parking lot) shows great central sharpness and edges which are less optimal.

    D800 f/2.8: https://www.dropbox.com/s/9iobcz7yh7o8nf9/D800-F2.8.nef


    D800 f/4: https://www.dropbox.com/s/q60sx72h3rsz7ql/D800-F4.nef


    D600 f/5.6: https://www.dropbox.com/s/12q6le4u4agz0b4/D600-F5.6.nef

  13. #63
    Member nikonf's Avatar
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    Re: Sigma 35mm F1.4

    I absolutely agree with you. That said, I can confirm the Sony/Zeiss ZA 135mm f1.8 lives up to it's sterling reputation. The Sony 135mm STF is also quite remarkable. This lens offers some of the most beautiful BOKEH of any lens!
    Remember the 'Old Days" when cameras were so affordable you could cherry pick the optics you wanted and buy a body after the lens?
    I had great lenses by Leica, Zeiss, Canon, Nikon, Olympus, Pentax and Minolta. They all had a unique look which I could take advantage of for certain aspects of my photography.
    When I ran a Photo Lab unit in the US Army Signal Corp, I used to take images with lenses from Leica, Nikon, Zeiss and view them on the enlarging lens magnifier and I could instantly see the difference in the optical characteristics.
    Quite often, the Leitz lenses would look vastly superior, and yet there were some noticeable surprises.
    The Leitz lenses were almost always better at the 2 maximum apertures.
    The 75mm Zeiss Planar on the Rolleiflex was generally better than the Hasselblad 80mm Zeiss Planar. Mirror slap could also have been a reason for the differences.
    Quote Originally Posted by Jan Brittenson View Post
    I don't think anyone is under the illusion that a test certificate means there is never anything wrong with a lens when you get it. It could get banged up in transit, be dropped by a dealer, or have a manufacturing defect that manifests itself sometime later - like from thermal stress during transit. But at least you know it was good at some point. It also means when you exchange it as defective your chances of getting another defective unit are way, way lower.

  14. #64
    Senior Member Amin's Avatar
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    Re: Sigma 35mm F1.4

    Quote Originally Posted by Amin View Post
    I'm posting a few D800 and D600 samples I took today across the street from my nephew's birthday party. Again, I don't use this lens for landscapes, only for people photography, but I'm sharing these in case they may be helpful. These were handheld, but I don't think handshake was an issue.

    After staring at them a bit, I've come to the conclusion that the lens has fairly strong field curvature. Ie, the two shots of the trees show pretty good edge sharpness while the central area is backfocused, while the third photo (parking lot) shows great central sharpness and edges which are less optimal.

    D800 f/2.8: https://www.dropbox.com/s/9iobcz7yh7o8nf9/D800-F2.8.nef


    D800 f/4: https://www.dropbox.com/s/q60sx72h3rsz7ql/D800-F4.nef


    D600 f/5.6: https://www.dropbox.com/s/12q6le4u4agz0b4/D600-F5.6.nef
    For anyone who'd prefer to view processed JPEGs to downloading the NEFs, here you go. Click through to view full-res versions:






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    Senior Subscriber Member Steen's Avatar
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    Sigma 35mm F1.4


    at the moment your processed jpegs are not directly accessible, Amin, I get prompted by a Yahoo login when clicking the images

    but thanks a lot for providing the NEF files to play with, much appreciated, I'm downloading them as I write this

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    Subscriber Member tashley's Avatar
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    Re: Sigma 35mm F1.4

    Ditto Amin, but we also need to know how and where you focussed.

    Shots I made with my replacement today confirm very strong field curvature despite claims to the contrary from Sigma and from many reviewers: it is to me quite reminiscent of the Nikkor 28mm f1.8G, a lens which is about equally sharp if slightly lagging the lovely look of the Sigma... but then the Nikkor is also a lot cheaper and a lot lighter...

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    Senior Subscriber Member Steen's Avatar
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    Sigma 35mm F1.4


    I looked up the focus points in Capture NX2.
    Here they are, in the same order.











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    Senior Member Amin's Avatar
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    Re: Sigma 35mm F1.4

    Steen, those were all autofocused and recomposed, so the point you indicated are not the actual focus points even though NX shows them to be. Those three are well in front of the focus point.

    For the first two shots, I focused on the center of the row of trees across the top. Interestingly the trees at the edges are sharper than the center, where the focus appears to be best behind the trees.

    For the third, I focused on the green "Pay to Park" sign near the middle of the frame, and that came out very sharp indeed.

  19. #69
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    Re: Sigma 35mm F1.4

    Just a general comment as to why we're seeing a lot more curvature in recently released lenses. It's a way for manufacturers to design a fairly fast lens with increased sharpness at a somewhat lower price point (and associated costs). In other words, unless the manufaturer intended to also correct for this curvature and pass along the costs with a very expensive lens, this now is becoming an acceptable alternative, There are many other factors to consider and it's somewhat of an oversimplification, but compared to flat field general use lenses, these lenses have excellent sharpness but exhibit a fair amount of curvature, some more than others.

    Some recent lenses that illustrate this point are the Sigma 35mm f1.4, the Nikon 16-35mm f4 VR, the Voigtlander M mount 35mm f1.2and the Samyang 14mm f2.8. In the past, I think manufacturers were afraid to release such lenses for fear that there was no easy way to correct in the film only era....but with the advent of a relatively easy fix in software post processing, most users are more receptive to these compromises. You generally can't make a lens sharper than it is, in post processing, but you can generally correct curvature with use of software.

    Dave (D&A)
    Last edited by D&A; 25th February 2013 at 06:02.

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    Senior Subscriber Member Steen's Avatar
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    Re: Sigma 35mm F1.4


    Quote Originally Posted by Amin View Post

    Steen, those were all autofocused and recomposed, so the point you indicated are not the actual focus points even though NX shows them to be. Those three are well in front of the focus point.

    For the first two shots, I focused on the center of the row of trees across the top. Interestingly the trees at the edges are sharper than the center, where the focus appears to be best behind the trees.

    For the third, I focused on the green "Pay to Park" sign near the middle of the frame, and that came out very sharp indeed.
    Oh sorry, Amin
    I have now removed the misleading focus point illustrations
    I apologize for the confusion caused
    And once again, thanks a lot for providing the NEF files !

  21. #71
    Subscriber Member tashley's Avatar
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    Re: Sigma 35mm F1.4

    Quote Originally Posted by D&A View Post
    Just a general comment as to why we're seeing a lot more curvature in recently released lenses. It's a way for manufacturers to design a fairly fast lens with increased sharpness at a somewhat lower price point (and associated costs). In other words, unless the manufaturer intended to also correct for this curvature and pass along the costs with a very expensive lens, this now is becoming an acceptable alternative, There are many other factors to consider and it's somewhat of an oversimplification, but compared to flat field general use lenses, these lenses have excellent sharpness but exhibit a fair amount of curvature, some more than others.

    Some recent lenses that illustrate this point are the Sigma 35mm f1.4, the Nikon 16-35mm f4 VR, the Voigtlander M mount 35mm f1.2and the Samyang 14mm f2.8. In the past, I think manufacturers were afraid to release such lenses for fear that there was no easy way to correct in the film only era....but with the advent of a relatively easy fix in software post processing, most users are more receptive to these compromises. You generally can't make a lens sharper than it is, in post processing, but you can generally correct curvature in with use of software.

    Dave (D&A)
    Dave, I think that field curvature (being a curved rather than planar field of focus) and distortion (being the inability of a lens to project straight subject lines onto the film/sensor) are related in lens design but that whilst software in post can correct distortion usually at relatively minimal cost to IQ, it can only correct the curved field of focus by cropping, which is usually a much bigger cost.

    So while I get that digital is something that changes the balance of lens design so as to allow more distortion (a quotidian notion today but look at the horror that greeted Hasselbald's first being explicitly public about this a few years back!) I don't get that field curvature becomes any more acceptable other than as an economic decision.

    What is also very clear is that manufacturers are wise to the ways in which labs test resolution, and are very good at designing cost-effective glass with great charts and great central sharpness, but which in real-world use have really soft edges. Of course, the edges aren't really soft: they are just sharp at a different distance from the camera than the central target. Consequently, given the rarity of planar targets in the real world, this often goes unnoticed by the photographer due to the varying shapes of the subject field.

    It astonishes me that one routinely reads reviews of lenses that say 'there is no significant field curvature' when in real use it is so strong as to ruin any images that need planar focus abilities. Of course lens design is a lot more complex than this: lenses natural tendencies are to create a curved field of focus because of the fact that the photographer sits at the centre of a virtual sphere, and the equal distances to the centre of his target and the edges describe a circle (the radius) rather than the unequal focus distances that planar focus at different subject ranges present. But we know it can be done, beautifully, as per the Zeiss lens on the RX-1...

  22. #72
    Senior Member johnnygoesdigital's Avatar
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    Re: Sigma 35mm F1.4

    Please just get the RX-1 already
    Likes 1 Member(s) liked this post

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    Subscriber Member tashley's Avatar
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    Re: Sigma 35mm F1.4

    Quote Originally Posted by johnnygoesdigital View Post
    Please just get the RX-1 already
    I have! It's brilliant! But I would like for some uses to be able to use the resolution of the D800 sensor with a lens that can cope with it. A not unreasonable wish, given the marketing claims made and the prices involved, I think.

  24. #74
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    Re: Sigma 35mm F1.4

    Quote Originally Posted by tashley View Post
    Dave, I think that field curvature (being a curved rather than planar field of focus) and distortion (being the inability of a lens to project straight subject lines onto the film/sensor) are related in lens design but that whilst software in post can correct distortion usually at relatively minimal cost to IQ, it can only correct the curved field of focus by cropping, which is usually a much bigger cost.

    So while I get that digital is something that changes the balance of lens design so as to allow more distortion (a quotidian notion today but look at the horror that greeted Hasselbald's first being explicitly public about this a few years back!) I don't get that field curvature becomes any more acceptable other than as an economic decision.

    What is also very clear is that manufacturers are wise to the ways in which labs test resolution, and are very good at designing cost-effective glass with great charts and great central sharpness, but which in real-world use have really soft edges. Of course, the edges aren't really soft: they are just sharp at a different distance from the camera than the central target. Consequently, given the rarity of planar targets in the real world, this often goes unnoticed by the photographer due to the varying shapes of the subject field.

    It astonishes me that one routinely reads reviews of lenses that say 'there is no significant field curvature' when in real use it is so strong as to ruin any images that need planar focus abilities. Of course lens design is a lot more complex than this: lenses natural tendencies are to create a curved field of focus because of the fact that the photographer sits at the centre of a virtual sphere, and the equal distances to the centre of his target and the edges describe a circle (the radius) rather than the unequal focus distances that planar focus at different subject ranges present. But we know it can be done, beautifully, as per the Zeiss lens on the RX-1...
    HI Tim,

    Just two small points. It's not that I'm implying that correction of field curvature through software is an a completely acceptable alternative to designing a plannar like lens. On the contrary...it's that with the advent of digital and farily recent advances with programs like PTLens and the like, that more are seemingly willing to accept the "often times" tradeoffs of applying such software to their images in order to obtain somewhat more affordable but highly sharp lens, once all is said and done.

    This was generally not the case in the film only era....and it's not just field curvature where some are willing to make compromises in image quality where in the past, it might have not been acceptable. It reminds me of the phrase 'It's the new norm"...where certain standards of acceptability are often compromised for gainging other things.

    You're correct, designing a plannar lens in a spherical world isn't easy nor inexpensive but it seems the manufaturers feel out their intended customers base and determine what will be acceptable and sell at a certain price point...espcially when quite a few feel there is at least some way they can address these image anomolies...as opposed to spending hundreds or even a few thousand more on a similarly designed lens albeit without the curvature. Just some personal thoughts of mine.

    Dave (D&A)

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    Re: Sigma 35mm F1.4

    I am not a landscape photographer, and my experience in this field is really
    quite limited. It seems that is very difficult to find a lens, expecially for 35 mm format, that is up to the performance required at least for a certain type of landscape. Having in practice only Leica lenses (just a few Nikon zooms for autofocus) I don't have the possibility to make comparisons. So I would like to have your opinions regarding the usability of the elmarit r 28 in that field.
    A test shot with D800 (I apologize for the subject)focused on the gray wall, with the full size version available on flickr.


    _DSC1322 by sergio lovisolo, on Flickr

    link to full size
    All sizes | _DSC1322 | Flickr - Photo Sharing!

    Thanks.
    Sergio

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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: Sigma 35mm F1.4

    My lens has been repaired. Need to go pick it up later today.
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com
    Likes 1 Member(s) liked this post

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    Re: Sigma 35mm F1.4

    Quote Originally Posted by Guy Mancuso View Post
    My lens has been repaired. Need to go pick it up later today.
    Guy:

    Sightly OT, but let us know what you think of the Sigma repair facility after you get your lens back. I'm assuming it's Cris Camera Services in Chandler. While I've only taken a few shots with my Sigma 35 f1.4 and it seems good, I do have the relatively new Sigma 150mm macro that seems to have auto focus issues and I was planning on sending it the same facility. It would be great to hear what you think of their work.

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    Subscriber Member tashley's Avatar
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    Re: Sigma 35mm F1.4

    also really interested to hear back Guy - mine is off to Sigma UK tomorrow and I must say that by email they couldn't be more friendly and helpful.. but the proof of the pudding will be in the snapping not the chatting!

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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: Sigma 35mm F1.4

    Okay I'm here at shop. First off Nikon has a bug in the firmware. Bob brought this up the other day and just found it too. Apparently putting the lens back on at its saved value was worthless than going back to zero as well. So do this reset back to zero turn camera off than back on than turn AF back in and the values are much better. Weird but it seems so and at first lens seemed like nothing fixed until I did that. But it was still around -15 which is better and a lot of shots looked good in close range but still a little off so I left the lens for the tech to double check it again in the morning. Now most would walk away and say its fine but not me and also we are talking AF here which frankly has been always suspect to me. I still can manually focus better than any AF machine but I'm slower . Lol

    The folks here are great and it was a fast turn around also but it's more me here. It felt a little hit and miss. I did find out they where talking to Japan on this lens as well and did do firmware and adjustments as well. To me it's like a doctor never aggressive enough with meds to kill off something but conservative enough to fight something off. I'm a go for it person. So maybe they took baby steps here.
    Photography is all about experimentation and without it you will never learn art.

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  30. #80
    Subscriber Member tashley's Avatar
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    Re: Sigma 35mm F1.4

    Hey Guy, that sounds really useful, thank you! But I am not sure I quite understand the process for getting around the bug. Does the bug only affect this lens? And what exactly is the sequence you used? Sorry to ask for it again but am being thick!

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    Re: Sigma 35mm F1.4

    Quote Originally Posted by tashley View Post
    Hey Guy, that sounds really useful, thank you! But I am not sure I quite understand the process for getting around the bug. Does the bug only affect this lens? And what exactly is the sequence you used? Sorry to ask for it again but am being thick!
    I'll second that, please clarify more about this bug and the workaround when you get a minute, thanks!

    BTW, I focus calibrated my 35 f1.4 using the Focal software and it came out at with an AF tune of -4.

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    Re: Sigma 35mm F1.4

    Will do tonight basically turn AF fine tune off than turn camera off than turn AF back on and start from scratch at zero
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    Re: Sigma 35mm F1.4

    Alright if you want to recalibrate a lens you already done. Start by setting AF back to zero on that lens. Than turn AF fine tune off. Than turn camera off. Now turn camera on than AF fine tune back on than calibrate lens again. I did this and it jumped to -15 from -20 and looked pretty good. But I still want my number like -5 so had him look at it one more time.
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    Re: Sigma 35mm F1.4

    Quote Originally Posted by drb View Post
    Guy:

    Sightly OT, but let us know what you think of the Sigma repair facility after you get your lens back. I'm assuming it's Cris Camera Services in Chandler. While I've only taken a few shots with my Sigma 35 f1.4 and it seems good, I do have the relatively new Sigma 150mm macro that seems to have auto focus issues and I was planning on sending it the same facility. It would be great to hear what you think of their work.
    Hi drb,

    Earlier in this thread I posted some comments regarding CRIS which I thought might be helpful and partly address your question.

    Dave (D&A)

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    Re: Sigma 35mm F1.4

    Quote Originally Posted by Guy Mancuso View Post
    Alright if you want to recalibrate a lens you already done. Start by setting AF back to zero on that lens. Than turn AF fine tune off. Than turn camera off. Now turn camera on than AF fine tune back on than calibrate lens again. I did this and it jumped to -15 from -20 and looked pretty good. But I still want my number like -5 so had him look at it one more time.
    Extremely useful Guy thanks...but ultimately the question is whether the softness seen on the right side with your lens has been address (corrected) even though Af fine tune has been reset to -15 from it's original -20.

    Should I wait up till 4am in the morning for your announcing the results or have all the CRIS techs gone home for the night and they'll look at your lens again in the morning...LOL!

    Dave (D&A)

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    Re: Sigma 35mm F1.4

    I sent them home to see there kids but they got till 9 am to fix it. I'm a nice guy but not that nice. Lol
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    Re: Sigma 35mm F1.4

    Seriously I'm going to fully test it out and redo a wall to check this skew issue I had. My bet is that was the mechanical adjustment. They did say they where worried they would have to send to Sigma but I think they got the firmware from Japan. I want the techs ear and see what he has done
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    Re: Sigma 35mm F1.4

    Quote Originally Posted by D&A View Post
    Hi drb,

    Earlier in this thread I posted some comments regarding CRIS which I thought might be helpful and partly address your question.

    Dave (D&A)
    Thanks Dave, I saw your posts afterwards. I'm guessing that it's easier to get top service from Cris Camera if you are in a position to walk in there and "break some glass" if things aren't done quite right

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    Re: Sigma 35mm F1.4

    Quote Originally Posted by Guy Mancuso View Post
    Seriously I'm going to fully test it out and redo a wall to check this skew issue I had. My bet is that was the mechanical adjustment. They did say they where worried they would have to send to Sigma but I think they got the firmware from Japan. I want the techs ear and see what he has done
    Guy,

    I can see where an update in firmware can help in recalibrating a lens whereby it no longer extends beyond the -20 (or + 20 for that matter) with regards to the AF fine tune adjustment in a particular body. Yet when there is asymmetry and optical misalignment causing causing softness on one side of a image, I can't imagine anything helping except an actual physical adjusment of the lens.

    Dave (D&A)
    Last edited by D&A; 25th February 2013 at 23:18.

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    Re: Sigma 35mm F1.4

    My thoughts as well.
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    Re: Sigma 35mm F1.4

    Quote Originally Posted by D&A View Post
    Guy,

    I can see where an update in firmware can help in recalibrating a lens whereby it no longer extends beyond the -20 (or + 20 for that matter) with regards to the AF fine tune adjustment in a particular body. Yet when there is asymmetry and optical misalignment causing causing softness on one side of a image, I can't imagine anything helping except an actual physical adjusment of the lens.

    Dave (D&A)
    That would seem intuitively correct but I wonder of sometimes it might work. These asymmetries can come and go according to really very slight changes of focus, or rather, be masked as the inclusion or exclusion of subject areas into areas of marginal DOF changes. We don't expect sharp edges on a lens like this until f4 for sharp-ish, f5.6 for sharp and f8 for really sharp, and so slight asymmetries can sometimes be largely veiled at wider apertures by general peripheral de-focus and largely hidden in DOF at f8 and possibly f5.6 so in my experience it is f4 and 5.6 that is the danger zone and even there, if the asymmetry is slight, there's a chance that an AFFT can deal with it.

    Do a Reikan test on some lenses and the top of the curve can be quite flat. F&R zooms, for example, you might find that the short end needs a plus 12 and the short end a plus 6, but that both of those values are at the apex of a flat-ish part of the curve, in which case a plus 9 might work for both ends. So it is with mild asymmetries. The joker here, of course, is that you can't easily use Reikan with this bug. However, there is some stuff on the Internet to the effect that specifically this bug affects only the second and subsequent sigma lenses you enter an AFFT for: so if you Delete Saved Value and then start again, you can make the camera forget that there was ever a previous sigma lens and think only about your current one.

    I am sure that most techs, when faced with a mild asymmetry, will try and tune it out with firmware and see if that makes the customer happy...

    EDIT: adding sample images after using Guy's technique for getting round the FW bug.

    Here are two shots that show pretty clearly what I mean. They are handheld at F4 and f5.6 and then a focus mask is added in Capture One. This camera is now accurately adjusted to +20 for my new copy of the Sigma, which was previously showing a very slight weakness on the left.




    Observations: firstly, ignore the tower, it isn't in great focus on either shot (better in F5.6). Focus was on the nameplate of the little monument, centre. The grass 'mask' is pretty accurate but at the very granular level, the lens focusses very slightly closer on the left. I have confirmed this somewhat with other tests but need to do some with extreme rigour. Nonetheless I am fairly confident.

    Note that the field of focus is croissant-shaped, as is very often the case. What this means is that there IS a line, parallel to the sensor, in a perfectly adjusted lens, at F4 and tighter, where everything is in pretty good focus in the same plane as the subject. But if your AF FIne Tune is off and the croissant is placed too far forward in the field, then the edges of that line will fall into the defocus area. getting AFFT just right has shifted the croissant backwards so that all of that parallel line is 'in the zone' but this is very very finely judged. For example, this lens now passes a brick wall test, just, because I have placed the croissant as far back as I safely can (the lens still focusses pretty well on centre wide open). However if I switch to Live View AF, the camera moves the croissant forwards and the edges of the wall, even at F5.6, are a little out of focus and slightly more so on the left because the slight decentering means that the croissant is twisted very slightly closer to the camera on the left.

    My conclusion, subject to further testing at other distances, is that this lens does need attention but more because the AFFT value required is +20. However, an adjustment to the slight decentering would mean that I could notch the fine tune forward a touch and get slightly more reliable results in overall use. For me this shows that careful AFFT can under certain circumstances 'hide' slight lens asymmetry and possibly even negate the need for a repair. Given that almost no lenses have perfect alignment of all elements and groups, it's a judgement call as to when the effect can be worked around and when it needs fixing. SO I will be interested to see what happens with Guy's.

    All this goes to show that to get the very best results from these systems requires quite an anal retentive approach, a lot of thought and quite some work! Luckily, few subject 'shapes' will show an effect like this noticeably. Regarding the fact that Live View tends to place the croissant too far forward, I will experiment with using magnified focus on a point half way to the edge: that should get a good compromise.
    Last edited by tashley; 26th February 2013 at 05:19.

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    Re: Sigma 35mm F1.4

    I always AF tune for the AF point to be in best focus, then compensate for field curvature and DoF when I shoot. But it's a matter of taste of course.

    I'm hard pressed to tell your lens focuses closer on the left side, especially given that you shot hand held and the ground isn't a perfect plane. It's neither level or flat on a hill like that. So I'd just stop down, shoot, check, adjust, reshoot and at some point further improvements are pointless.

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    Re: Sigma 35mm F1.4

    Tim Wrote--->>>"For me this shows that careful AFFT can under certain circumstances 'hide' slight lens asymmetry and possibly even negate the need for a repair."<<<

    That was basically the point I was trying to make. Sure certain aspects of asymmetry might be masked by adjusting/changing the AFFT through firmware and if it works, then all well and good. I too have experienced the changes you described by adjusting AFFT to somewhat ameliorate the affects of a slightly decentered lens. Of course the asymmetry is still there, just not as evident by the changing shift in the depth of field at a given f-stop.

    It's of course very subject dependent in terms of what fills the frame, especially towards the sides & edges and a whole host of other image related characteristics.

    Dave (D&A)

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    Re: Sigma 35mm F1.4

    Okay the folks at C.R.I.S. are really nice . There head technician called me today and basically he has this thing just about perfect but still he was not happy. He ran it outside on a D700 and at distance at 1.4 was not getting good results which i noticed as well. The firmware that Sigma is speaking of is a left/right AF point issue with the D800/D800E he does not have that firmware and with talks in Japan they are working on it but that is not my issue with the lens. Now at 2.8 and smaller apertures the lens is awesome both close and at distance but he wants to hold it another day and talk to Sigma again and discuss what they feel could be the issue. He is also not surprised as i mentioned a big gap between the 1st batch out and the long delay in the second batch that is due out. Sounds like Tim may have got a second batch version on the replacement. Now most of us shoot at distance stopped down and he wanted me to know that at the wider apertures he was uncomfortable about giving it back right now. They worked on one other 35mm but in Canon mount and sort of the same issue that one went back toSigma. The problem he said is they are so new that all the repair shops have not been exposed to working on them as well but he ran a slope test and a resolution test and he did say this thing is very very good. Once again i seem to be in the guinea pig position but Im okay with that. The is not the repair shops fault and if anything they are being extremely good about getting this dead on for me. We talked for about 15 minutes so it was really nice to get to chat over this. Keep you posted more
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    Re: Sigma 35mm F1.4

    BTW nice review and NO focus shift. Im glad I bought it

    Sigma AF 35mm f/1.4 DG HSM (Nikon FX) - Review / Test Report
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    Re: Sigma 35mm F1.4

    Guy,

    Nice to hear this about C.R.I.S. I suspect a lot of this excellent service and interaction has to do with your personally being able to interact with them.

    I'm curious and would like to know more (as I'm sure others would too), about what this particular Sigma firmware for the lens with specific regards to the D800/e left side focus sensor issue, is all about?

    As well known, the left side focus point issue with D800/e bodies is random and not all bodies are effected and when they are, they vary greatly from body to body. Since a lens when sent in for adjustment or repair is generally done without a body, what does this 35mm f1.4 Sigma specific firmware accomplish when adjusting a 35mm f1.4 (the one that has to do with the D800/e left side sensor issue)? All I can think of is if someone sends in their D800/e along with a Sigma 35mm f 1.4 that needs adjusting, the firmware interacts with both the specific D800/e /lens combo and compensates for any left side sensor issue that particular body has.

    If no body is sent in and it's simply adjustment of the lens...not sure how being interactive with the D800/e sensor plays a role in adjustment of the lens alone. This is only a guess on my part. Maybe firmware that also allows compensation of a lens for a D800/e's left side sensor that's "off" is simply a optional feature of Sigma's latest firmware for the 35mm f1.4 lens? Sounds interesting though.

    Guy, I almost typed that we expect a 75 page detailed written report (double spaced of course) from you by morning...but then though that request might be grounds for being banned....LOL!

    Dave (D&A)
    Last edited by D&A; 26th February 2013 at 16:47.

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    Re: Sigma 35mm F1.4

    Quote Originally Posted by D&A View Post
    Guy,
    Guy, I almost typed that we expect a 75 page detailed written report (double spaced of course) from you by morning...but then though that request might be grounds for being banned....LOL!

    Dave (D&A)
    Are you trying to get us all killed ?


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    Re: Sigma 35mm F1.4

    Quote Originally Posted by Jan Brittenson View Post

    I'm hard pressed to tell your lens focuses closer on the left side, especially given that you shot hand held and the ground isn't a perfect plane. It's neither level or flat on a hill like that. So I'd just stop down, shoot, check, adjust, reshoot and at some point further improvements are pointless.
    "at the very granular level, the lens focusses very slightly closer on the left. I have confirmed this somewhat with other tests but need to do some with extreme rigour. Nonetheless I am fairly confident."

    Actually as a down and dirty indication, this is quite a good scene: the rising ground makes the 'croissant' easy to demonstrate in a rough way. Of course it's not lab-accurate! But then, all the lab-based reviews I have read of this lens say that it has very low field curvature whereas this test indicates, and other tests confirm, that in the field it can be significant.

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    Re: Sigma 35mm F1.4

    At repair shop brought my D800e and lens is off quite a bit . Testing both now and should be adjusting it. Running slope tests and resolution tests. These folks are really nice . Could not be more honest and helpful.
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    Re: Sigma 35mm F1.4

    Geez the tech came out with camera and lens along with a sledge hammer. Big smile on his face and Pronounced it all fixed just needed a big adjustment. ROTFLMAO
    Photography is all about experimentation and without it you will never learn art.

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