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Thread: Experience Counts-SK LS Blue Ring lens optimal f-stops

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    Experience Counts-SK LS Blue Ring lens optimal f-stops

    For landscape using an XF+100MP system intended for 24x36" images where near/far in focus is important, but focus stacking is an option:

    Any suggestions from real experiences as to what are the optimal f stops for 35,55,110,120,150,240 SK LS lenses?

    I am trying to reduce the learning curve for use of above system before going on long and time consuming travel where dialing in this new kit from others experiences will greatly help.

    If for no other reason I would think about f8.0 or f9.0, but then again I could be way off base. Any help appreciated. TIA

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    Senior Member DougDolde's Avatar
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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    f/11
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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    Thanks Doug and you are so very lucky to be so close to such a lovely NP.

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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    There isn't one answer to this question.

    Diffraction will start to take effect as early as f/5.6, but at that point the effect is extremely small. By f/22 diffraction will be very strong. Where, in between those two values, you personally feel the amount of diffraction is unacceptable is up to you.

    I'd suggest you download one of our IQ3 100mp raw file diffraction ramps, or capture your own, and judge based on your actual desired output medium (print of a certain size? 100% pixel view? web?).

    My personal rule of thumb is that f/9 is a good trade off between practical (gaining depth of field) and softening due to diffraction. But I'll gladly stop down to f/16 if I need depth of field over extreme per-pixel detail; doing so will result in files that are definitely a tad soft at 100% but still can print with great detail pretty dang bit (just not quite as big as a file shot at f/9.

    The new focus stacking tool changes this math a bit as well, since in some cases (not strong wind, subject conducive to stacking) a quick 2 or 3 shot focus stack can replace using a more strongly diffracted aperture.
    Doug Peterson , Digital Transitions | Email
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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    Like Doug mentioned, there's no magic bullet.

    Your answer will come down to a combination of things including final print size, type of scene, composition,etc.

    For me, I switch between f/8 and f/11 regularly for my landscape work with f/16 only used when I absolutely have to get more DOF. For most of the BR lineup with high res backs, diffraction is noticeable at f/16 and beyond. F/8 tends to be the sharpest in general, but f/11 is certainly not far behind. From my experience, I'd recommend trying f/11 on most of the wide angles for the best DOF/sharpness balance.
    Zac Henderson- Technical Sales and 24/7 Support: Mega Pixels Digital - Colorado www.megapixelsdigital.com
    Phase One Mamiya Leaf Profoto Eizo 334-728-1465 [email protected]
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    Senior Member Bill Caulfeild-Browne's Avatar
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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    I agree with Zac. My "go to" aperture is f8 unless I need the DOF. I generally hesitate to go beyond f11.
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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    The resolution limit of the system is dictated by the Nyquist frequency, which is half the sampling rate of the signal to be resolved. For example (and please forgive my rudimentary explanation - I struggled but ultimately did pass college physics many decades ago), to resolve two points 10 microns apart without aliasing artifacts requires sampling at 5 micron intervals or less. The IQ3 100's pixel pitch of 4.6 microns dictates that with a perfect (i.e., truly diffraction limited) lens it can resolve down to around 9 microns. Assuming those blue ring lenses are diffraction limited (I imagine they are), consider the diameter of the Airy disk at various apertures*:

    f/5.6: 7.5 microns
    f/8: 10.7 microns
    f/11: 14.7 microns
    f/16: 21.3 microns

    So, in term of resolution only, as Doug mentions diffraction will start degrading your image somewhere between f/5.6 and f/8. But having objects in reasonable focus at non-pixel-peeping distances counts, too! The specific situation combined with your own tolerance for "suboptimal" resolution will dictate what compromises you're willing to make. When shooting with my IQ160 back (6 micron pixel pitch) I don't see much if any degradation between f/8 and f/11, but do see a noticeable loss of resolution when stopping down to f/16 - not too surprising given the above. I generally try to avoid stopping down beyond f/11, but sometimes do so to increase depth of field. All else equal (which, by the way, it rarely is), the smaller pixel pitch/higher resolution of the 100 Mp sensor probably shifts these limits back by a stop. But again, none of this really matters if the critical elements in an image are out of focus. YMMV, of course.

    -John

    * using the calculator found at: Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks.
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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    Thanks all. I see I have opened up pandoras box to some extent. I will check your files Doug. John that is a nice site. Bill I see many real world results you post so I must assume you are in the f8-11 range with what I see.

    I guess it does not really matter if the lens has an f 2.8-22 or an f 4.5-32 range. I have generally tired to go up from wide open around 3 stops as a guesstimate, but as many have said if the situation calls for more DOF then going beyond that benchmark is occasionally done. I do believe I will try more focus stacking if I can figure it out. Saw Doug's webinar and I like the filtering of a sequence idea very much. Perhaps the 20 focus points I initially tried was too many even when shooting from 6' to infinity with either the 35, 55 or 80.

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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    A few thoughts from a landscape perspective, 35SK LS, 55LS, 28LS, 75-150 non LS 80mm LS.

    I regularly go to F16, try to stay @ F8 to F11, but large DOF and MF don't go together well (without movements).

    IMO what is lost from F12 to F16, is very easily gained by with a good sharpening tool like Picture +, excellent tool, a bit slow, but amazing results, or Focus Magic.

    You are losing resolution just to the Bayer interpolation on the back. Just look at a multishot vs non multishot image, it's a bit shocking as to what can be gained by defeating the Bayer pattern interpolation. Diffraction will add to that, but to my eyes, the issue is just not that much up to F16, with the lenses you have mentioned.

    As to focus stacking, alas, it's extremely limited in the field at least from my testing due to wind/movement. Kudos to P1 for the implementation in the XF, but the software involved, Helicon or Zerene stacker, can handle any movement, period. The results will always show hazy spots, or massive non aligned parts of a file due to wind movement. So if you are shooting in the field and your subject is moving, Focus stacking may be a waste of space. I was surprised that just the slightest movement can't be accounted for with Focus stacking. What needs to be done is some form of alignment process but so far none of the tools out there seem to handle this. For a studio, subject, the focus stacking solution is great, as all the videos show. So if you are shooting the Grand Canyon, or Bryce, or Monument Valley type subjects, focus stacking with the XF is great way to gain DOF, but if you are working subjects with trees, flowers, bushes, etc, really check for movement before you stack and take up a ton of space on your card as testing, just the slightest amount of movement due to wind will give you a non stackable solution if there are a lot of trees close up or near by. Way off in the distance you more than likely can handle it.

    Paul C
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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    Doug
    P27-017 @f14 I like the focus better than f10 in another image od the same Model with MacBeth on her head. I was surprised at my liking that f stop. At 200% her eye lashes are considerably sharper than the f10 image. Maybe it's the focus itself, but I doube it. That 120 is a phenomenal lens.

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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    Paul
    Thanks for your comments. Agree re focus stacking for landscapes. I found myself taking too many in a sequence where the clouds moved a bit too much to my liking from say #1 to #15. No trees in that example luckily.

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    Senior Member DougDolde's Avatar
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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    Quote Originally Posted by algrove View Post
    Thanks Doug and you are so very lucky to be so close to such a lovely NP.
    Yes but its too damn hot in the summer to enjoy

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    Senior Member Steve Hendrix's Avatar
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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    Quote Originally Posted by algrove View Post
    For landscape using an XF+100MP system intended for 24x36" images where near/far in focus is important, but focus stacking is an option:

    Any suggestions from real experiences as to what are the optimal f stops for 35,55,110,120,150,240 SK LS lenses?

    I am trying to reduce the learning curve for use of above system before going on long and time consuming travel where dialing in this new kit from others experiences will greatly help.

    If for no other reason I would think about f8.0 or f9.0, but then again I could be way off base. Any help appreciated. TIA

    Another important factor - perhaps the most important - if it wasn't already mentioned, was you, and what you like to see in your 36x24 prints, what level of sharpness, detail, etc. The obvious answer might be well, the most possible, but in a print, the most possible would probably not please very many, so the subjectivity is important.

    While some may prefer not shooting at f/16 or even f/11, you may find the result - shot through your lenses, shot with your sensor, printed on your printer, with your media - uniquely preferred by your eyes over other settings. The f/8 - f/11, etc, are good guidelines, but I would encourage you to do some experimentation. Surprises often result!


    Steve Hendrix/CI
    Steve Hendrix, Sales Manager, www.captureintegration.com (e-mail Me)
    Digital Cam: Phase One | Leaf | Leica | Sinar Authorized Reseller
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    Re: Experience Counts-SK LS Blue Ring lens optimal f-stops

    Thanks Steve. I have now looked at many images and for some strange reason I most often tend to like the sharpness with many different lenses at f13. Do not know why, but every time I like a shot which is crisp throughout it seems that's the f-stop. I even took some up to 200% (not what I would normally do) and they hold together very well throughout the image. Now I will print a few to see if I still like what I see in print form.

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