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12-23-2010, 11:19 AM   #16
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Pentax FA and "F" 50mm f2,8 Macro has the highest resolution even at small apertures.

12-23-2010, 11:34 AM   #17
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QuoteOriginally posted by yperion Quote
Thank you all for your respond.
Well, Iím thinking that the wide lenses, like 24mm or 28mm, will produce more sharpness but also more distortion. The 100mm or 135mm at the other side, will produce less distortion but also less sharpness and I have to shoot from some distance.

I believe that 35mm or 50mm are the lenses for this job.
  • As macTak mentioned, a 50mm slow lens and macro, will have his optimum performance at smaller apertures.
  • RioRico, I would like, someday, to own a 645D, until thenÖ
  • d.bradley, tilt/shift lens is for perspective control, I donít think that will offer anything here.
  • As for stacking a multi focus shoe, as omega leader and RioRico advice, I had it on my mind, but I would like to do less work.
Generally my thoughts matching the suggestions of macTak and I think that a M-50mm f/4 macro will help.
So at 35mm and 50mm are there any other suggestions?
I think, you did not consider the above posts seriously enough. Diffraction will set in somewhere between f/8 and f/11. If you use a smaller aperture, the resolution loss, due to diffraction will be more serious, than any gain in resolution the one or the other lens may provide.

One help would be a tilt-lens
(ofcourse, the pure shift lens, will not do any good for your kind of work). But there are not many tilt lenses available in K-mount and you need some luck, to find one.

Shooting from a distance with a longer lens is always a good idea for product shots, as this reduces the distortion introduced by perspective (i.e. being too near to the subject with your camera, because you use a wide angle lens or similar). The residual optical distortion (barrel or cushion) could be corrected easily in post-processing, but with many images it is not obvious anyway, especially if you leave some white space around your subject.

Ben
12-23-2010, 11:56 AM - 1 Like   #18
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DOF is certainly NOT independent of focal length! DOF is a complex function of photography, presentation, and perception. The factors under the control of the photographer are focal length, aperture size, and subject distance. Holding all other factors constant:

* a longer focal length lens will have thinner DOF than a shorter lens;
* an open aperture will have thinner DOF than a stopped-down aperture;
* a closer shooting distance will have thinner DOF than a further distance.

Various online DOF calculators allow anyone to plug in some numbers and verify this. In fact, such calculators may help decide on a lens selection. Try this:

* With a kit zoom, try focal lengths of various candidate prime lenses: 28-31-35-40-50mm.
* Establish the shooting distance for each FL, that captures the largest-size subject (shoes).
* Measure the depth of those largest shoes, to establish the maximum DOF necessary.
* Plug in the numbers to see what f-stop satisfies each FL's parameters; don't pass f/11.

This method should provide lens guidelines. While you're at it, try a diffraction calculator too. Good luck.

Last edited by RioRico; 12-23-2010 at 12:02 PM.
12-23-2010, 12:18 PM   #19
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QuoteOriginally posted by Ben_Edict Quote
I think, you did not consider the above posts seriously enough. Diffraction will set in somewhere between f/8 and f/11. If you use a smaller aperture, the resolution loss, due to diffraction will be more serious, than any gain in resolution the one or the other lens may provide.
Ben, I must disagree with you somewhat--all lenses will lose sharpness from diffraction, but how much sharpness they lose at small apertures can vary by a surprising amount. Look at photozone's Pentax macro lens tests--at f22, the Cosina 100mm is 1706/1683, the Pentax D-FA 100mm is 1189/1097. This is quite the difference. In other words, the gain in resolution we are looking at here is not the peak resolution (which may indeed be different, the D-FA is actually better at its best aperture than the Cosina).

QuoteOriginally posted by eigelb Quote
Pentax FA and "F" 50mm f2,8 Macro has the highest resolution even at small apertures.
Do you have any test results you can point me to that back this up--I'd actually be really interested to see them.

12-23-2010, 12:23 PM   #20
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QuoteOriginally posted by yperion Quote
Stack photo. Grasshopper, from Tamron SP AF 90mm f/2.8 Di Macro, three shots, handheld.
DAMMIT don't get me started!!!
12-23-2010, 12:46 PM   #21
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QuoteOriginally posted by omega leader Quote
For this kind of work diffraction is a killer.
Would it make sense to choose a camera with fewer megapixels and a less aggressive AA filter, to reduce diffraction? I'm thinking of the K10D here. If I comprehend what I've read, the theory is correct, I just don't know if it makes enough difference in the real world to matter.
12-23-2010, 01:11 PM   #22
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QuoteOriginally posted by Just1MoreDave Quote
Would it make sense to choose a camera with fewer megapixels and a less aggressive AA filter, to reduce diffraction? I'm thinking of the K10D here. If I comprehend what I've read, the theory is correct, I just don't know if it makes enough difference in the real world to matter.
Not really, the diffraction limit has to do with the larger image size. As long as you reduce your 16mp images to 10mp size, then the sharpness will appear the same.
12-23-2010, 02:23 PM   #23
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QuoteOriginally posted by RioRico Quote
28mm is closest to 'normal' for APS-C (30mm is the diagonal of an APS-C frame) and should show no distortion from the distance at which you would be photographing shoes. Since sharpness is limited by diffraction and DOF, and the diffraction limit for APS-C is around f/8-11, then the greater DOF of a 28mm lens vs 35mm may be critical. Anything longer than 40mm may have DOF too thin for your needs without focus-stacking.

I like inexpensive approaches. A cheap approach would be an M42 bellows, with 28mm + 35mm + 50mm enlarger lenses, plus any needed cheap adapters. Some judicious eBaying should put that kit together for under US$75. I suggest that range of lenses because you could easily (and inexpensively) test to see what works best for you. At about US$10 each, 't'ain't no big thang, eh?
Well, bellows and enlarger lenses, hmm. If Iím not wrong, IĎll have more DOF in focus.
On K20D, are they gonna work? The resolution etc, are gonna be what Iím looking for?
Anyone who has that equipment can post his experience?

QuoteQuote:
I think, you did not consider the above posts seriously enough. Diffraction will set in somewhere between f/8 and f/11. If you use a smaller aperture, the resolution loss, due to diffraction will be more serious, than any gain in resolution the one or the other lens may provide.
Ben I consider the posts seriously, more than enough. Ok the f/11 is the limit, but if there are lenses which can produce very good results at smaller apertures, I want to know it.

Some days ago, I read an article where the DOF is thinner on lenses with longer focal length. I donít know, maybe the differences are minimal.
Anyway, I still consider, as best focal length the range between 35mm (and 28mm?) and 50mm (55mm even 70mm?). This way you are in a good distance and have less distortion

12-23-2010, 02:30 PM   #24
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QuoteOriginally posted by macTak Quote
No, DOF does not increase with working distance.
So for this sort of work, which would be better?

35mm Macro ltd or D FA 100mm Macro?
12-23-2010, 02:42 PM   #25
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DOF is directly related to "magnification" is it not? If your shoe fills a frame at 50mm or 500mm with different working distances, the DOF should be the same. FOV and perspective will be different, but not DOF.

The beauty of a tilt lens is your ability to orient the DOF to best align with your subject. It's the shift part of the lens that changes perspective. These lenses are often used for the work you're describing.

MC 35 mm Tilt & Shift M42 lens

Available in K or M42 mount.
12-23-2010, 04:46 PM   #26
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QuoteOriginally posted by d.bradley Quote
DOF is directly related to "magnification" is it not? If your shoe fills a frame at 50mm or 500mm with different working distances, the DOF should be the same. FOV and perspective will be different, but not DOF.
Thanks for clearing this one up.
12-23-2010, 07:11 PM   #27
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QuoteOriginally posted by d.bradley Quote
DOF is directly related to "magnification" is it not?
Well, sort of. DOF is a function of focal length, aperture size, subject distance, and format size or circle of confusion criteria. (See the Wikipedia entry.) Magnification is a function of focal length, total extension, and subject distance. Greater extension for greater magnification usually implies a closer subject distance and thus diminished DOF, but that's an effect, not a cause.

QuoteQuote:
If your shoe fills a frame at 50mm or 500mm with different working distances, the DOF should be the same. FOV and perspective will be different, but not DOF.
Not quite. At the same aperture, the 500mm lens will have thinner DOF than the 50mm. If you fill the frame with each lens, FOV will be the same but not DOF. And perspective is a function of subject distance only, so the frame-filling shots will indeed have different perspectives -- the 500mm shot will seem 'flattened'.

Nice device! A bit outside the budgets of some of us, alas.
12-23-2010, 10:06 PM - 1 Like   #28
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QuoteOriginally posted by RioRico Quote
Well, sort of. DOF is a function of focal length, aperture size, subject distance, and format size or circle of confusion criteria. (See the Wikipedia entry.) Magnification is a function of focal length, total extension, and subject distance. Greater extension for greater magnification usually implies a closer subject distance and thus diminished DOF, but that's an effect, not a cause.



Not quite. At the same aperture, the 500mm lens will have thinner DOF than the 50mm. If you fill the frame with each lens, FOV will be the same but not DOF. And perspective is a function of subject distance only, so the frame-filling shots will indeed have different perspectives -- the 500mm shot will seem 'flattened'.
(
I will not bother to correct all of the misstatements here. For anyone interested, I advise that you consult this white paper published on the subject by Carl Zeiss, which I consider the best reference:

http://www.zeiss.com/c12567a8003b8b6f/embedtitelintern/cln_35_bokeh_en/$file/cln35_bokeh_en.pdf

But in short, cf. page 11 ("the depth of field (almost) does not depend on the focal length at all but rather on the imaging scale"), and especially 16-17 and the chart therein--where you can see that the 50mm and 100mm macro lenses have almost exactly the same DOF at the same imaging scale. The only differences are working distance and the amount of exposure compensation needed for macro distances (the 50mm requiring less than the 100mm). Perspecive is of course another matter and does indeed change. Hence my two recommendations--no need for a wide angle enlarger lens on a bellows (unless you want to play with perspective)
12-24-2010, 12:56 AM   #29
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Conclusions so far

QuoteOriginally posted by stover98074 Quote
For product photos I use a bellows and enlarging lenses. You can also use tubes and M42 tubes are inexpensive. I have written an article on it at this post.
https://sites.google.com/site/inexpensivemacrophotography/
QuoteOriginally posted by RioRico Quote
I like inexpensive approaches. A cheap approach would be an M42 bellows, with 28mm + 35mm + 50mm enlarger lenses, plus any needed cheap adapters. Some judicious eBaying should put that kit together for under US$75. I suggest that range of lenses because you could easily (and inexpensively) test to see what works best for you. At about US$10 each, 't'ain't no big thang, eh?
QuoteOriginally posted by macTak Quote
I would recommend the Pentax M 50 mm f4 (or the optically identical K 50mm f4) or the Pentax M 100mm f4 (or again the K or A versions). These are both macro lens so they are designed to have the best sharpness as closer focusing distances as you will be using for studio work. Secondly, as they are both quite slow lenses (and macro lens to boot) they should have their optimum performance at smaller apertures (or at least hold their performance a little better) than regular fast lenses...
QuoteOriginally posted by d.bradley Quote
The beauty of a tilt lens is your ability to orient the DOF to best align with your subject. It's the shift part of the lens that changes perspective. These lenses are often used for the work you're describing.

MC 35 mm Tilt & Shift M42 lens

Available in K or M42 mount.
QuoteOriginally posted by omega leader Quote
For this kind of work diffraction is a killer. I think your best best for shooting stationary objects is to shoot as an ideal apature (f4 to f8) and then focus stack in post. A little more work, but far better results.
The Suggestions that we have here are:

1) Bellows and enlarging lenses
Can be found easily and at low price. Worth a try

2) Macro lenses (not fast)

3) Tilt/Sift lenses
I still donít think that will help me here. And the price is high! Thanks for the link d.bradley

4) Stack multifocus image
The inexpensive solution with guarandied results and of course more work. Especially when photographing a large number of items
12-24-2010, 06:13 AM   #30
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A tilt lens will do what you want for a shoe like shown in the first post; ie an 18" x 12" x 3" slab of space viewed at an angle of 45 degrees or so can be in focus at a reasonable f-stop.

Last edited by newarts; 12-24-2010 at 06:18 AM.
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