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01-20-2010, 02:09 PM   #1
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Tips for shooting lens comparison shots you like to share?

Does anyone have any words of wisdom (or pointers to articles/tutorials) on best practices for shooting lens comparison shots?

I realize that it is important to tripod mount the camera and not move anything between lens takes. Seems like the lens reviews I've seen shoot a scene full of detail/color from corner to corner, etc.

I'm planning on using a little white board to label the lens/exposures before each shot.

I've got a whole list of fun MF lens comparisons I'd like to do including:

Comparison of SMC K 50mm f1.4 and Super Takumar 50mm f1.4

Comparison of SMC K 50mm f1.2 and SMC K 50mm f1.4

Comparison of FA 35mm f2.0 and Super Takumar 35mm f3.5

Comparison of Quantaray 28mm f2.8 (m42) and Pentax-M 28mm f2.8 (and Super Takumar 28mm f3.5?)

Comparison of Sears 55mm f1.4, Pentacon 55mm f1.8 and Super Takumar 55mm f2.0

Comparison of Pentax-M 100mm f2.8 and Takumar 100mm f3.5 preset (1957)

Comparison of Super Takumar 135mm f3.5 and Pentax-M 135mm f3.5

Any pointers you'd care to share?

01-20-2010, 02:16 PM   #2
Ash
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Norman Koren has a decent guide starting from here:
Understanding resolution and MTF and then discusses lens sharpness specifically here: Lens testing

Here is another good tutorial on lens testing:
How To Test A Lens

Finally a practical yet simple and not so scientific test guide is described here:
Lens Testing
01-20-2010, 04:20 PM   #3
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Ash's links were interesting, but I don't go as far into science. I think even the most rigorous testing proves something for one lens, maybe not every copy of that lens. Mostly I test out of curiosity, because I buy out of curiosity. I often need to thin out lenses at a particular focal length. Line pairs per millimeter aren't really necessary.

I use the brick wall of my garage for indications of sharpness, vignetting and distortion. I try to choose an appropriate working distance, keeping in mind the use of the lens. I wait for a clear day and get the test done quickly with similar light. For these shots, I use RAW and adjust each color temperature to the same numbers. I shoot a series of apertures three times with each lens, refocusing each time. I shoot a few more shots wide open at slightly different focus settings to see if a lens has extreme field curvature. Later, I choose the sharpest image for 100% crops from the center and one corner. I crop the same bricks so the crops all look the same. I assemble a large composite image of the different apertures and crops.

Sharpness isn't everything. I try to invent setups to test for flare resistance, with a bright light in the frame. I take the lenses to a botanical garden and try to compare the bokeh and colors in the real world.
01-20-2010, 04:52 PM   #4
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I am with Dave. While objective tests are a good thing, they don't tell the whole story. The most useful thing for me is to actually compare using identical real world subjects under identical lighting.

Resolution:
I use the backs of cereal and other food boxes at 20X the focal length distance. It works best if there is mostly print in various size fonts. Newsprint mounted on a board also works well. I also use a small pewter jewelry box.

Bokeh:
My daughter has a human hair china doll. I stage the doll in the foreground with some fake flowers and such behind. In winter, I also use a bare-branched bush in the backyard and focus on branches toward the center of the bush. Lately, I have been testing against lawn and coarse gravel as well to bring out "busy" or "nervous" bokeh. For some reason, I have never done the specular highlight test. I guess that aspect is less important to me.

Purple Fringing:
Tree branches/foliage against a bright sky, sunlit chrome tubing

Chromatic Aberration:
Bright/dark transitions; in focus, out-of-focus (front), out-of-focus (back).

General:
A variety of subjects:
  • low/high contrast
  • bright/muted colors
  • Strongly backlit and/or specular light sources (coma and flare)
Steve

01-20-2010, 04:55 PM   #5
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My only advice is that if you're impatient don't try to be comprehensive--just focus on one aspect. You'll end up making errors, otherwise. I don't think there's anything wrong with "measurbating," as long as it's done right. BTW, I'm too impatient to do any good measurbating.
01-21-2010, 05:55 AM   #6
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And please, by all means, post your work. I'd love to see comparison shots from ALL of these lenses.
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