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09-15-2011, 12:44 PM   #1
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Subject matter for test shots-lens comparison?

What would bee a good subject matter to photograph to test out and compare lenses for weakness and strengths? Lenses will be zooms in the 28-300mm range, and range from very old manual focus lenses to much more recent but still full frame AF lenses? I would thing outdoor shots would be best (especially to expose flair on older lenses) but limited time and bad weather has made that difficult. Some indoor testing would be helpfull and much easier to accomplish. I have done some general shooting comparisons but I'm looking for something easily repeatable for the same shot (perhaps even at different times for different lenses). One point to mention, a few of the super zooms have terrible close focus so if its going to test all lenses it may need to be a goot 8 feet away or more.

Does anyone have any recommendations?

09-15-2011, 12:58 PM   #2
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I would suggest something like a printed poster - preferably with good amount of colours. Then you could tack it up in a room with good lighting, and set yourself wherever you require. A flat poster means you can always check that your focus is spot on, instead of having to wonder if it's on a closer or further away object.
09-15-2011, 01:30 PM - 1 Like   #3
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Sharpness is all about controlling technical variables. A subject with details and contrast in the center and corners is good. Lighting should be consistent for maybe 30 minutes to an hour. My house is brick so I've used that, and we get a lot of days with no clouds at all. Bricks are supposed to reveal distortion but it's hard to see. At 300mm I used a house about 4 houses away. I try to get something about the same distance as where you'd use the lens. If you are at the minimum focus distance, field curvature is more significant and can make lenses with a lot of curvature look bad in the corners.

Recently I tested some 24mm lenses in a garage, taping some newspapers up like this:



The lighting is clearly not even, but that's not a big problem. It's consistent. It was very handy to use the post-it note to identify the lens. The results were useful. My wife ran over my tripod, though.

For sharpness, focus is all-important. I mount a lens, focus as well as I can, run through several apertures, then do the next lens. I repeat the whole test three times. If I'm careful, I can get focus right for most lenses for two out of three tests. But I always have one or more series that is clearly worse.

I try to establish one exposure for a "middle" aperture with one of the lenses, then shoot them all based on calculations from that. For example, I pick a lens and put it at f8, then find a shutter speed that gives an "exposed to the right" histogram. If the shutter speed is 1/250, then I shoot every lens at f8@1/250, f5.6@1/500, f4@1/1000, etc. That avoids metering and differences in mounts.

What I like to test is sharpness like this, flare with a strong light source on the edge of the frame, and colors and contrast by going to a botanical garden. With a group of lenses, that's a lot of shooting.
09-15-2011, 01:40 PM   #4
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For sharpness results, I like to use Adobe Camera RAW to set the white balance to the same color temperature and tint for each shot. I look at the focus for each test with one lens and pick the best-focused series of shots. Then I find a spot to take samples from. I make two composite images with 100% crops from the center and one corner, with different apertures left and right, different lenses up and down. That puts the samples right next to other apertures and other lenses. For posting here, I will break them up into smaller bits to get a more reasonable size, like this:



09-15-2011, 02:09 PM   #5
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Thanks a bunch for the recommendations. Something like that should be easy enough to set up.
09-15-2011, 09:08 PM   #6
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Such a test tells you about flatfield sharpness. If you intend to shoot many flat subjects, it is informative. It might not be so useful in showing real-world performance of other than macro and enlarger lenses. It doesn't tell you much about bokeh, rendering, that sort of fluffy stuff. Shoot flatfield sharpness tests, sure; but also shoot some rounded subjects with receding backgrounds, and see if you LIKE the lens.
09-16-2011, 03:02 AM   #7
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QuoteOriginally posted by ripit Quote
What would bee a good subject matter to photograph to test out and compare lenses for weakness and strengths? Lenses will be zooms in the 28-300mm range, and range from very old manual focus lenses to much more recent but still full frame AF lenses? I would thing outdoor shots would be best (especially to expose flair on older lenses) but limited time and bad weather has made that difficult. Some indoor testing would be helpfull and much easier to accomplish. I have done some general shooting comparisons but I'm looking for something easily repeatable for the same shot (perhaps even at different times for different lenses). One point to mention, a few of the super zooms have terrible close focus so if its going to test all lenses it may need to be a goot 8 feet away or more.

Does anyone have any recommendations?
There can be very good reasons to do - also - some indoor tests, as this is where you can secure reasonable uniform test conditions. (Outdoor results with, say, a 300 mm lens may vary quite wildly with atmospheric conditions).

So, for resolution, sharpness, flatness etc. tests I would go for a standard test chart solution such as this one:



You cannot use the low-resolution picture I have inserted here, but I found mine as a high-resolution TIFF file by searching on the internet and I am confident that you may find something similar too.
09-16-2011, 04:32 AM   #8
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I had no problems finding a lens test chart for printing on A3. I printed on the stiffest paper I had, stuck it to the window and put the camera on a tripod. I also found that lens test shots are not as easy as you think they are going to be...

09-16-2011, 05:16 AM   #9
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I actually have a test chart I printed on photo paper to test resolution on some manual primes. Turns out they all had better resolution than my 6MP ist-ds. I'll probably do something in stages just to get a ball park idea of how they compare. For instance, I could shoot them all wide open at a few focal distances and or all at the same aperture (whatever the fastest aperture they can all do is) for a first test. Then something stopped down a little in a similar manner at a different time.

I'm also aware of the difficulty of taking that many shots and keeping them all organized and comparing them and dealing with out of focus and other shooter errors. I have tried before with other lenses and got some useful results though I must admit I got pictures mixed up a few times.

I did some outdoor testing with these lenses and got a rough idea on a couple of the lenses but found that some could not be compared as the subject matter didn't give meaningful or compatible results (I wasn't shooting the same subjects plus some subjects are hard to judge like a waterfall with no distinct lines.

I'm thinking the hardest part will be all the focal ranges (lenses are 28-200, 28-210, 35-200, 70-210, 28-200AF, 70-200AF, 70-300AF, 100-300AF, 90-230, 100-300), and that is if I exclude wider zooms like 28-90.
09-16-2011, 04:47 PM   #10
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For me a tele lens is all about shooting wild life. If you really want to test the lens set up a dummy subject in a tree with twigs before and behind the subject and test with both dark or neutral background and against a brighter sky. Look for lenses that exhibit extreme purple fringing with the bright sky and both lateral and longitudinal CA in the out of focus detail

Lateral CA will have out of focus twigs green on one side purple on the other. Longitudinal CA will have purple surrounding out of focus before the subject and green surrounding out of focus behind the subject

Twigs are the worst thing possible (or best depending on what you want to demonstrate) for CA in the oOF regions
09-16-2011, 07:23 PM   #11
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QuoteOriginally posted by Lowell Goudge Quote
For me a tele lens is all about shooting wild life. If you really want to test the lens set up a dummy subject in a tree with twigs before and behind the subject and test with both dark or neutral background and against a brighter sky. Look for lenses that exhibit extreme purple fringing with the bright sky and both lateral and longitudinal CA in the out of focus detail

Lateral CA will have out of focus twigs green on one side purple on the other. Longitudinal CA will have purple surrounding out of focus before the subject and green surrounding out of focus behind the subject

Twigs are the worst thing possible (or best depending on what you want to demonstrate) for CA in the oOF regions
I have tried many times to get squirrels out front but by the time I get back with a camera they are gone. Maybe a fake would work.
09-16-2011, 11:38 PM   #12
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QuoteOriginally posted by ripit Quote
I have tried many times to get squirrels out front but by the time I get back with a camera they are gone. Maybe a fake would work.
Try bribery maybe? Nice juicy acorn pie, peanut-butter cookies, sunflower-seed polenta?
09-17-2011, 03:16 PM   #13
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I use the ISO 12233 test chart. It's pretty good for resolution testing, and CA testing too if you put a lot of light on it.

A PDF is downloadable here (211kb):
http://www.graphics.cornell.edu/~westin/misc/ISO_12233-reschart.pdf
09-17-2011, 06:40 PM   #14
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I go out and take pictures.
Most of the time, this proves the equipment is good enough.
09-17-2011, 10:19 PM   #15
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Honestly I think both chart testing and real world shooting compliment each other when trying to test a lens but I'll know better when I finally get some more shooting done.

QuoteOriginally posted by RioRico Quote
Try bribery maybe? Nice juicy acorn pie, peanut-butter cookies, sunflower-seed polenta?
I think there must be lots of food for them to steal. I have tried leaving food and all it attracted was ants (and the right time of year I can get birds).
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