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Thread: best DB for lens cast

  1. #1
    aitc
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    best DB for lens cast

    looking on the best DB for minimal lens cast... what do folks think?

    thanks

  2. #2
    Administrator, Instructor Guy Mancuso's Avatar
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    Re: best DB for lens cast

    Dalsa sensors in general are the best at lens cast. So that would include Sinar not sure of the models though. Leaf they are all Dalsa. Hassy has the new 60 and than Phase p40,65 and all the new IQ backs as well. Need to avoid ones with micro lenses like the P30 and H31. Now the least amount of lens cast will be the crop sensors since they are cropped you simply won't see casts as bad. Now with LCC corrections almost any lens cast can be corrected. Now there are some Kodak sensors that are fine from both Phase and Hassy like the P45 P25 and if course the Hassy 39 and 50. I think that is the run of the backs you can use best on a tech cam. Now it really depends on what your looking for and what is the best software to correct that. I'm a C1 fan so that is Leaf and Phase for me.

    What are you looking for as far as mpx and feature sets. The P45 will do a hour exposure but most Dalsa if not all will go 2 minutes max I believe. Maybe the Hassy 60 does 4 need to check that

    BTW welcome to the forum
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    Senior Member yaya's Avatar
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    Re: best DB for lens cast

    Quote Originally Posted by aitc View Post
    looking on the best DB for minimal lens cast... what do folks think?

    thanks
    If you are not after the highest resolution sensor then a 22MP or 33MP Leaf back will give you the cleanest images, cast wise.

    If you go for an Aptus-II 5 or Aptus-II 7 you can also use the new feature that allows you to have the cast corrected in the back. You can read more about it here and here

    HTH

    Yair
    Yair Shahar | Product Manager | Phase One | Mamiya Leaf
    e: [email protected] | m: +44(0)77 8992 8199 | yaya's blog

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    Re: best DB for lens cast

    P45? No micro lenses like the modern backs, right?

  5. #5
    rpb
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    Re: best DB for lens cast

    If you go for an Aptus-II 5 or Aptus-II 7 you can also use the new feature that allows you to have the cast corrected in the back. You can read more about it here and here
    that's a fantastic development, is it only a matter of time before we communication between tech cameras and backs? So LCC becomes a thing of the past. I know that these cameras are completely manual but add a few sensors running of the backs battery???

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    Subscriber Member tashley's Avatar
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    Re: best DB for lens cast

    Quote Originally Posted by Guy Mancuso View Post
    Dalsa sensors in general are the best at lens cast. So that would include Sinar not sure of the models though. Leaf they are all Dalsa. Hassy has the new 60 and than Phase p40,65 and all the new IQ backs as well. Need to avoid ones with micro lenses like the P30 and H31. Now the least amount of lens cast will be the crop sensors since they are cropped you simply won't see casts as bad. Now with LCC corrections almost any lens cast can be corrected. Now there are some Kodak sensors that are fine from both Phase and Hassy like the P45 P25 and if course the Hassy 39 and 50. I think that is the run of the backs you can use best on a tech cam. Now it really depends on what your looking for and what is the best software to correct that. I'm a C1 fan so that is Leaf and Phase for me.

    What are you looking for as far as mpx and feature sets. The P45 will do a hour exposure but most Dalsa if not all will go 2 minutes max I believe. Maybe the Hassy 60 does 4 need to check that

    BTW welcome to the forum
    Hi Guy,

    Any news yet from the tests you and Doug were running on the various tech lenses on the IQ180?

    Best
    Tim

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    Re: best DB for lens cast

    Tim not yet but we specially did shoot the 35mm lens with you in mind. From just what we can tell given the software , hardware today you will lose about 5- 10 percent more than your P65+. But I would not do anything until he has those final results posted. The 28 and 35 look from the previews to be a little limited on movements but I'm being cautious here as well as Phase maybe working on something with C1. I'm a little afraid to commit fully to a yes or no on it without seeing those final results.

    I know your sitting there playing russian roulette on this. Totally understand and I don't want you to panic or mislead you but it most likely will be more limited than your P65+

    BTW the 35mm is a nice lens compared to my 35D which I have the new version and is pretty good. I know Doug took a few days off for the weekend but should be back in full swing starting today.
    Photography is all about experimentation and without it you will never learn art.

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    Re: best DB for lens cast

    Quote Originally Posted by yaya View Post
    If you are not after the highest resolution sensor then a 22MP or 33MP Leaf back will give you the cleanest images, cast wise.

    If you go for an Aptus-II 5 or Aptus-II 7 you can also use the new feature that allows you to have the cast corrected in the back. You can read more about it here and here

    HTH

    Yair
    Very interesting indeed .
    Where can I find a detailed description of how to use the "LCC" set up ? ? ?

    @ YAIR

    When will you be at PHOTO UNIVERSAL in Stuttgart again ? ? ?
    I am thinking of an APTUS II-7 .
    Regards . Jürgen .
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  9. #9
    Administrator, Instructor Guy Mancuso's Avatar
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    Re: best DB for lens cast

    Love to see those auto corrections on the Phase backs and folks my opinion maybe the smartest purchase Phase made was buy Leaf and the shared technology they can do together. Hopefully good times ahead for tech shooters in both camps.
    Photography is all about experimentation and without it you will never learn art.

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    Re: best DB for lens cast

    Quote Originally Posted by tashley View Post
    Any news yet from the tests you and Doug were running on the various tech lenses on the IQ180?
    Will post within 72 hours.

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    Re: best DB for lens cast

    Thanks Doug
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com

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    Re: best DB for lens cast

    Quote Originally Posted by aitc View Post
    looking on the best DB for minimal lens cast... what do folks think?

    thanks
    I strongly believe this is a largely moot question.

    Other than some very specific lenses and the 5.2 micron backs (IQ180 / Aptus II 12) there is only very modest impact on the final image of the color cast after correction - and often the level of impact is offset by generally higher quality anyway.

    In other words if you compare a P25 and P45 the P25 will generally have less visible cast before correction, and the shadows/colors of the P45 will require modestly more correction, but the P45 has a bit more reserve dynamic range anyway so the end result is essentially the same.

    There is no [tech camera + digital back + wide angle] combination that I suggest be shot without applying an LCC to every shot (even the combinations where the uncorrected images has very little visible cast it's often clear after correction that there was some cast to start with). So if you have to correct it anyway it's moot how much you see before correction.

    The exception being very wide lenses on the very small micron backs

    And of course you must avoid at all costs the backs that use strongly micro-lensed sensors such as the P30, H3D-31, H4D-40. Also the P21 which has modest micro lenses and is not the best choice.

    But yes generally speaking (and echoing most posts above):
    - Dalsa show less cast than Kodak
    - Larger pixels show less cast than smaller pixels
    - Microlensed pixels are to be avoided if at all possible

    Doug Peterson (e-mail Me)
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    Re: best DB for lens cast

    Quote Originally Posted by dougpetersonci View Post

    . . . . .
    But yes generally speaking (and echoing most posts above):
    - Dalsa show less cast than Kodak
    - Larger pixels show less cast than smaller pixels
    - Microlensed pixels are to be avoided if at all possible

    Doug Peterson (e-mail Me)
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    Doug

    I think it should also be mentioned that :
    Symetrical designed WA lenses , I use to say BIOGON type lenses ,
    produce more CC than Retro-Focus type lenses .
    The HASSELBLAD DISTAGON 4/40 CFE/IF , for example , produces very little CC . That is a retrofocus type lens , while my APO-SIRONAR digital 35mm produces strong CC (not only that) .
    Also many Schneider lenses show a strong CC .
    Regards . Jürgen .
    -----------------------------------------------------------------------------------

  14. #14
    aitc
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    Re: best DB for lens cast

    thanks to all for all the great input, and thanks Guy for the welcome.

    I've heard great things about all the backs mentioned on this forum and have tried to learn about the subject from the other threads... that combined with some very quick testing on the Aptus II 10 and the CFV-50 (I believe the former having special cast-friendly micro lenses and the latter no microlenses?) have shown me that some form of correction always needs to be part of the work flow and the results are sometimes spectacular, sometimes adequate - as I plan to stitch 2x2s using full frame horizontal and vertical shifts using a 90mm lens, I'd say I'm pushing the limits about the same as single shot with a 45mm.

    From what I'm reading, based on folks experience here, it sounds like either of the backs I've tested are probably going to be good as long as I use very sound and rigorous technique? Or is there still a clear choice for this very specific application? and not to complicate matters, but would the choice of lens, or the use of non-digital lenses (which may be needed for coverage), make one back better than the other.

    Thanks

    reposting in hopes of getting back to the original question

    thanks
    Last edited by aitc; 13th June 2011 at 08:38. Reason: reposting in hopes of getting back to the original question

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    Re: best DB for lens cast

    Quote Originally Posted by dougpetersonci View Post
    Will post within 72 hours.
    Doug, is there any chance to see a comparison between the new Schneider 28mm Super Digitar and the 32mm or other wide ones?

    My 28mm lost a lot of it's shifting ability due to extreme color cast resulting in serious light fall off.

    Word has it that Schneider is releasing a 1.5 Centre Filter which could help but that is still to be seen.

    thanks

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    Re: best DB for lens cast

    Quote Originally Posted by tashley View Post
    Hi Guy,

    Any news yet from the tests you and Doug were running on the various tech lenses on the IQ180?

    Best
    Tim
    Tim - I got my back on Friday. So, far I'm pleasantly surprised at how good the LCC's are working to correct the images. I'm only shooting the 43 and I know you are interested in the 35. I really was expecting much worse. Still waiting to see Doug's test.

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    Re: best DB for lens cast

    When visiting Arca Swiss we did some quick snaps with the 28vs32 and in would say the 32 is a LOT better regarding lens cast. I don't have the files, but can try to get some.

  18. #18
    aitc
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    Re: best DB for lens cast

    reposting in hopes of getting back to the original question

    thanks

    thanks to all for all the great input, and thanks Guy for the welcome.

    I've heard great things about all the backs mentioned on this forum and have tried to learn about the subject from the other threads... that combined with some very quick testing on the Aptus II 10 and the CFV-50 (I believe the former having special cast-friendly micro lenses and the latter no microlenses?) have shown me that some form of correction always needs to be part of the work flow and the results are sometimes spectacular, sometimes adequate - as I plan to stitch 2x2s using full frame horizontal and vertical shifts using a 90mm lens, I'd say I'm pushing the limits about the same as single shot with a 45mm.

    From what I'm reading, based on folks experience here, it sounds like either of the backs I've tested are probably going to be good as long as I use very sound and rigorous technique? Or is there still a clear choice for this very specific application? and not to complicate matters, but would the choice of lens, or the use of non-digital lenses (which may be needed for coverage), make one back better than the other.

    Thanks

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    Re: best DB for lens cast

    The problem I think is the backs you've specifically mentioned are not very common, and I don't think many folks here are actually using them on a tech camera, so nobody wants to say for certain yes or no. Nor are they similar, and that's creating some confusion, at least for me: the Hassy back is a Kodak sensor, the Leaf a Dalsa; the Leaf you mention is a full-width 2:3 aspect, not the more common 3:4, and the Hassy 50 is a cropped sensor at 36x48mm IIRC?

    To repeat: Dalsa sensors tend to be easier on corrections than Kodak, but either will work if you actually perform the LCC. The bigger the pixel the less sensitive to color casts, all else equal. Given what you want to accomplish -- stitching -- any back with NO microlenses is going to be fine if you follow the appropriate LCC protocol. Does this help?
    Jack
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  20. #20
    aitc
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    Re: best DB for lens cast

    thanks Jack, very helpful

    I think you are right, the CFV-50 is smaller than the 10R (49mm vs 56mm in wdth), but pixel density/pitch should be the same.

    the sensors are very different, and that's why I'm asking for preferences based on experience, but understand there is a very limited audience for this specific application.

    tc

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    Subscriber Member tashley's Avatar
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    Re: best DB for lens cast

    Thanks Guy, much appreciated!

    Quote Originally Posted by Guy Mancuso View Post
    Tim not yet but we specially did shoot the 35mm lens with you in mind. From just what we can tell given the software , hardware today you will lose about 5- 10 percent more than your P65+. But I would not do anything until he has those final results posted. The 28 and 35 look from the previews to be a little limited on movements but I'm being cautious here as well as Phase maybe working on something with C1. I'm a little afraid to commit fully to a yes or no on it without seeing those final results.

    I know your sitting there playing russian roulette on this. Totally understand and I don't want you to panic or mislead you but it most likely will be more limited than your P65+

    BTW the 35mm is a nice lens compared to my 35D which I have the new version and is pretty good. I know Doug took a few days off for the weekend but should be back in full swing starting today.

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    Subscriber Member tashley's Avatar
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    Re: best DB for lens cast

    Quote Originally Posted by dougpetersonci View Post
    Will post within 72 hours.
    Thanks Doug, really appreciate it!

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    Re: best DB for lens cast

    Quote Originally Posted by TEBnewyork View Post
    Tim - I got my back on Friday. So, far I'm pleasantly surprised at how good the LCC's are working to correct the images. I'm only shooting the 43 and I know you are interested in the 35. I really was expecting much worse. Still waiting to see Doug's test.
    Good to know Terry, thank you for the feedback!

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    Re: best DB for lens cast

    At a given level of sensor construction technology the issue is made apparently worse if the pixel pitch is smaller and the sensor is larger and if the filter layer is thicker. In addition some lcc algorithmic adjustment needs to be made for such things as periodic polysilicon conductors that are spaced every so often across the sensor surface.
    Most ccd sensor makers are pretty much at the same technology level give or take a little, so it mostly boilds down to the quality of the lcc software algorithms that your raw converter ustilizes and if it has been tweaked for your specific sensor.
    All things considered:
    Noise is worse as the sensor data is "pushed", so physical center filters needed for the best quality in terms of noise (but worse flare characteristics)
    chromatic shifts due to the diffraction gradient effect caused by pixel pitch causes some colors to need more boost than others.
    Bottom line, is that given a decent center filter to handle the lens fall-off and good algorithms for cosine law and diffraction color contamination, no wide will have the same noise and DR in the corners as they do in the center.
    YMMYV so it is pretty much up to you how much you can take.
    -bob

    p.s.
    there is a universal constant relation of angle of impingement, pixel pitch, filter thickness, and sensor size, that can predict the amount of misbehavior, but it is the quality of the correction and the loss of noise margin an dr that is the real limiting factor.

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    Re: best DB for lens cast

    Hi Bob,

    I'm not an engineer so I'm trying to apply what you said to how I shoot.

    1. If I have a 35mm, using a center filter and LCC will give me better results than LCC alone?

    2. If I use left and right shift and then stitch the images together (essentially putting more of the center of the lens toward the edges of the center shot of the image, will it still be better to use a center filter? Is that true whether or not I crop the final stitch?

    Thanks for helping me understand,
    Nontechnical Bob


    Quote Originally Posted by Bob View Post
    At a given level of sensor construction technology the issue is made apparently worse if the pixel pitch is smaller and the sensor is larger and if the filter layer is thicker. In addition some lcc algorithmic adjustment needs to be made for such things as periodic polysilicon conductors that are spaced every so often across the sensor surface.
    Most ccd sensor makers are pretty much at the same technology level give or take a little, so it mostly boilds down to the quality of the lcc software algorithms that your raw converter ustilizes and if it has been tweaked for your specific sensor.
    All things considered:
    Noise is worse as the sensor data is "pushed", so physical center filters needed for the best quality in terms of noise (but worse flare characteristics)
    chromatic shifts due to the diffraction gradient effect caused by pixel pitch causes some colors to need more boost than others.
    Bottom line, is that given a decent center filter to handle the lens fall-off and good algorithms for cosine law and diffraction color contamination, no wide will have the same noise and DR in the corners as they do in the center.
    YMMYV so it is pretty much up to you how much you can take.
    -bob

    p.s.
    there is a universal constant relation of angle of impingement, pixel pitch, filter thickness, and sensor size, that can predict the amount of misbehavior, but it is the quality of the correction and the loss of noise margin an dr that is the real limiting factor.

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    Re: best DB for lens cast

    Simple answer is YES -- using a physical CF makes it easier on the LCC file. The associated algorithm does not have to work as hard to correct the entire frame because the physical filter has done a lot of the heavy lifting re falloff.
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    Re: best DB for lens cast

    Quote Originally Posted by rga View Post
    Hi Bob,

    I'm not an engineer so I'm trying to apply what you said to how I shoot.

    1. If I have a 35mm, using a center filter and LCC will give me better results than LCC alone?


    Nontechnical Bob
    Another reason for the center filter is so the sensor can handle the dynamic range of the scene. Not an issue on many lenses but I find the 35mm schneider has a two stop difference between center and corners. Without the filter, there are scenes within the dynamic range of the sensor but with the added two stops push it too far. Personally I dislike my 35mm very much ... but I think that's reason why. Hoping the center filter will make it much more useful to me.
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    Re: best DB for lens cast

    Wayne,

    I'd love to hear more about how you get on with your 35XL. I just picked up one of these myself, without the center filter, and I've been seriously considering getting one to even out the light fall off prior to LCC post processing. I'm sure that for a crop sensor (44x33mm) it's much less of a consideration than a P65+ or IQ180/160 etc but I am tempted to get the optical filter just in case.
    Last edited by GrahamWelland; 13th June 2011 at 23:07.
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    Re: best DB for lens cast

    I've been using the 35xl on a p65+ for about a year now without cf and it has been fine, though looking possibly a little stretched with shifts over 10mm, but still pretty good. It has very little distortion and, at f16, gives good focus to infinity from about 3m if set to focus at 5m, though that may vary per sample. For me it is a lens with no character whatsoever, a very good thing for certain kinds of work. It simply reproduces reality - as long as you LCC it.

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    Re: best DB for lens cast

    I've not had the same issues as Wayne, though eventually I'd like to get a center filter. I've done several panos with the 35 doing 10mm shifts to either side.

    This one was pointed into the sun:
    http://www.rgaphoto.com/benches/cont...TER_large.html

    This was at mid-day on a beach in Florida:
    http://www.rgaphoto.com/FL/content/2...ano_large.html

    As was this:
    http://www.rgaphoto.com/FL/content/2...g_2_large.html

    However I do firmly believe that getting exposure right at the time of capture is much better than correcting in post processing.

    I am concerned about the loss of 2 stops, the possibility of vignetting when putting a polarizer in front of the center filter, and the high cost of the center filter. So for now I'll have to put it off. It does seem like a good idea.

    Bob

    Quote Originally Posted by GrahamWelland View Post
    Wayne,

    I'd love to hear more about how you get on with your 35XL. I just picked up one of these myself, without the center filter, and I've been seriously considering getting one to even out the light fall off prior to LCC post processing. I'm sure that for a crop sensor (44x33mm) it's much less of a consideration than a P65+ or IQ180/160 etc but I am tempted to get the optical fiter just in case.

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    Re: best DB for lens cast

    Quote Originally Posted by rga View Post
    Hi Bob,

    I'm not an engineer so I'm trying to apply what you said to how I shoot.

    1. If I have a 35mm, using a center filter and LCC will give me better results than LCC alone?

    2. If I use left and right shift and then stitch the images together (essentially putting more of the center of the lens toward the edges of the center shot of the image, will it still be better to use a center filter? Is that true whether or not I crop the final stitch?

    Thanks for helping me understand,
    Nontechnical Bob
    Yes, whatever can be corrected by center filter does not need a mathematical fix.
    and yes to Nr2
    -technical bob

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    Re: best DB for lens cast

    anytime you shift to the edges of the image circle you will pick up more extreme casts and vignetting.

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    Re: best DB for lens cast

    The 35mm XL needs a CF and attempting to shoot without one is an exercise in masochism. I even have a CF on order for my 43mm XL, even though some believe that a CF is not as essential for the 43mm as it is for the 35mm.

    I don't understand anyone who questions the need for a CF where one exists for a particular lens. CF's are notoriously difficult to manufacture, so they are not produced just for the sake of it. If Schneider/Rodenstock offer a CF then the default position should be to assume that it is necessary to obtain the best results from a given lens.

    Also, the specs for the 35mm XL's CF specifically state +2 compensation, so why the surprise that the lens has a 2-stop falloff at the edges?

    Two common complaints I hear about using CF's is the light loss and cost. The light loss can admittedly make life difficult in some situations, but the cost of a CF is negligible relative to the lens itself.

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    Re: best DB for lens cast

    I honestly would love to have one and will get one. Unfortunately I leave for a workshop Thursday morning and will not have it for that. Sure wish I could get one in time...
    Bob

    Quote Originally Posted by cng View Post
    The 35mm XL needs a CF and attempting to shoot without one is an exercise in masochism. I even have a CF on order for my 43mm XL, even though some believe that a CF is not as essential for the 43mm as it is for the 35mm.

    I don't understand anyone who questions the need for a CF where one exists for a particular lens. CF's are notoriously difficult to manufacture, so they are not produced just for the sake of it. If Schneider/Rodenstock offer a CF then the default position should be to assume that it is necessary to obtain the best results from a given lens.

    Also, the specs for the 35mm XL's CF specifically state +2 compensation, so why the surprise that the lens has a 2-stop falloff at the edges?

    Two common complaints I hear about using CF's is the light loss and cost. The light loss can admittedly make life difficult in some situations, but the cost of a CF is negligible relative to the lens itself.

  35. #35
    Senior Member dchew's Avatar
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    Re: best DB for lens cast

    I got the following note from Schneider a few days ago regarding a CF for the 43mm:

    "Hi Dave,
    I heard back from our photo product manager in Germany and he informed me that calculations have been made for glass Center Filters for the new 28mm, 43mm and 60mm Apo-Digitar lenses and these should be in production soon. As soon as we have part numbers and pricing, we will post the information on our website."

    Ciao,
    Dave

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    Re: best DB for lens cast

    Quote Originally Posted by dchew View Post
    calculations have been made for glass Center Filters for the new 28mm, 43mm and 60mm Apo-Digitar lenses and these should be in production soon.
    Just adding to this, I got an email from Cambo about a week ago: "Center Filters for the 28XL as well as the 43XL will become available within the next few weeks, so meaning in July ready for sale."

    It's great that Schneider is planning to produce CF's for the 28mm and 60mm as well.

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    Re: best DB for lens cast

    Also from the list above to include Sinar 86H (48mp) (multishots) w/ Dalsa new generation micro lenses - allowing greater angle than the 1st gen micro lenses - 86H specially designed for tech-camera.

  38. #38
    Workshop Member Woody Campbell's Avatar
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    Re: best DB for lens cast

    Quote Originally Posted by tashley View Post
    I've been using the 35xl on a p65+ for about a year now without cf and it has been fine, though looking possibly a little stretched with shifts over 10mm, but still pretty good. It has very little distortion and, at f16, gives good focus to infinity from about 3m if set to focus at 5m, though that may vary per sample. For me it is a lens with no character whatsoever, a very good thing for certain kinds of work. It simply reproduces reality - as long as you LCC it.
    Thanks to Lance Shad at Digital Transitions I had the use of a loaner IQ 180 over the weekend. I tested three Schneider lenses on my Alpa Max: the 35 xl and the 47 xl (both in Alpa dress) and the 72 L. I plan on posting samples whenever I can get an hour of free time to assemble them.

    My observations on the 35 xl can be summarized as follows: The LCC correction files look like they have some fairly steep gradients but the LCC correction appears to work well. Ambient light has a strong effect on the LCC correction so it's a good idea to take one with each new situation - I found this out when I tried to use a shade LCC to correct a daylight image and the result was terrible. Properly corrected the unshifted images look very good, espically if you back off the vignetting correction - it will take a lot more experience for me to have a view on whether the LCC corrections for this lens are using up capacity to make further image adjustments but overall I was pleased.

    There is very little scope for shifts on the IQ 180 with this lens. Maybe 7mm max on the short axis, and none on the long axis. If you look at the lens's mtf curves the sweet spot for the lens barely covers the IQ 180's 67mm diagonal. This is consistent with Jack's observations that the really wides seem to hit the zone of blue death at about the same point that they run out of resolution. As to the 35 that's ok with me because I'm actually using this lens on my Alpa TC as a digital SWC - I really didn't expect to get any shiifts out of this focal length.

    The issue that I'm not clear on is whether the IQ 180 oversamples this lens - in other words the issue is whether the lens delivers enough resolution to meet the demands of an 80 meg sensor. It's fine with my 60 meg Blad. My experience varied on this subject but I did get a few images of outstanding clarity. If I end up owning an IQ 180 I'll sort this out - variables include the fact that this lens's perfromance peaks sharply at f 11 (not all of my images were at f11); based on the mtf curves the lens may be optimized for closer distances; Lance's Alpa adapter may or may not be optimally shimmed (which Alpa says is important for wides because of their short focus throw); and I need a bit more experience with focus masking to be sure that I'm getting it right.

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