Casual lens test

[donald_a]

Can anyone help me with ideas for a "real-world" lens test. I'm not interested in taking pictures of lens charts or

even using a tripod because that's not how my pictures will be taken. I just want to have a couple of go to tests that

I can use to quantify the overall performance of a lens. I'm thinking of things like:

 

1.) Resolution - Picture of a sign that's relatively small in frame (use text on sign for res test)

2.) Distortion - Picture of building like a church from close range. Churches usually have towers that show distortion

well, at least that's what I've experienced so far.

 

I just bought a Tamron 17-50mm and want to compare it with my Canon 18-55mm IS and Canon 50mm f/1.8

because if it doesn't provide much visible improvement over the combination of the other two (besides the

convenience of not having to switch lenses) I can return the Tamron within 14 days and save my 400 bucks for

another lens.

 

Thanks for any help you can provide.

[bobatkins]

Well, you're not testing the lens, you're testing you!

 

If you want to test lens resolution, use a tripod. If you want to test how steady you can hold the camera, shoot handheld.

 

Distortion has to be measured using a flat target with the lens axis perpenticular to the target. If you shoot a church and tilt the camera up, you'll get "distortion", but it's not caused by the lens, it's caused by the way you are using it. If you tilt a lens up, you get "keystone" distortion (converging verticals) simply due to the geometric optics of the system. A perfect lens will show this effect.

 

See http://www.bobatkins.com/photography/technical/testing.html for suggestions on what and how to test lenses

 

"I just bought a Tamron 17-50mm and want to compare it with my Canon 18-55mm IS and Canon 50mm f/1.8 because if it doesn't provide much visible improvement over the combination of the other two" That could be because you're not using a tripod and you're misinterpreting distortion. In simple casual viewing of images I doubt you will see a huge amount of difference anyway.

[phule]

If you're not willing to test rigorously, as Bob points out, then your "tests" have no real value. Just use your lens. There's very little chance there's anything wrong with it. If you notice something significant over time that cannot be explained by user error (as most problems can be) then you sit down and do a real test. Don't get caught up in this testing nonsense. It's just not worth it.

 

If you purchased a lens and you're not convinced you should have, then perhaps that's as telling as any test you could perform.

[apetty]

The use of a tripod in any test would be better whether or not you use it in real life.

 

The tripod will eliminate the shooter as the variable. If you hand hold for the test, you could have a moment when your Wheaties kick in and you hold the camera better then you did a few moments ago. If its on the tripod, then it doesn't matter if you just held 100lbs of camera gear 2 minutes before you did the test and in the middle of the shot you get your arm strength back. Even if the tripod is just sitting the camera on a ledge, you should make it as steady as possible

 

 

You should have the camera on a solid surface/support with a remote shutter release to prove beyond doubt the lens meets your expectation.

 

just my 2¢

[g dan mitchell]

<p>Unless you eliminate variables like camera shake, different AF, and so forth you'll be testing so many things at once

that the amount of info you'll get about the lens/camera will be quite limited.

 

<p>If you want to know what your lenses are capable of do something like this:

 

<ol>

<li>Put the camera on a tripod. Use mirror lockup and a remote release. (A second-best substitute might be to use the

timer to take the photo.)

<li>Place the camera in aV mode.

<li>Set the lens to largest aperture and some focal length. Let the lens AF on your subject.*

<li>Switch AF off.

<li>Make an exposure.

<li>Manually close down one stop. (aV mode will automatically compensate by altering shutter speed.) Make another

exposure. Close down one more stop, repeat until you have gone through all whole f/stops.

<li>If you are testing a zoom repeat the process at a few other focal lengths in its zoom range.

</ol>

 

<p>This might take 5 minutes or so for a zoom lens.

 

<p>*Subject could be any typical subject of the type you like to shoot, though it is better if most elements of the scene

are more or less in a place parallel to the sensor.

 

<p>My preference is to shoot RAW mode and then do at least default sharpening and so forth - this gives me a better

idea of what real world performance will be like when I follow my typical work flow.

 

<p>Some things you'll learn from this:

 

<ol>

<li>How the lens performs at various focal lengths.

<li>How aperture affects IQ on your lens.

<li>What the lens is capable of in ideal situations.

</ol>

 

<p>Why do this? Not to find out if you have a "bad copy." Instead, the main value of this process is to fairly quickly

learn the personalities of your lenses, so that you can apply what you learn to making good choices among your lenses

and among the settings available on a given lens.

 

<p>Once you have this baseline, go ahead and do some informal hand held tests with and without IS to see how your technique affects

your photos.

 

<p>Dan

[tim_klimowicz]

I know part of the fun is doing it yourself, but if you want to take yourself (and the human error that includes) out of the equation

and not reinvent the wheel, there are some good tests already out there at photozone.de.<br>

<br>

In particular, their tests cover very measurable things (distortion, vignetting, resolution, and chromatic aberations), as well as

more subjective things like build, feel, etc.<br>

<br>

Tamron 17-50: <a href="http://www.photozone.de/canon-eos/289-tamron-af-17-50mm-f28-sp-xr-di-ii-ld-aspherical-if-canon-test-report--

review">http://www.photozone.de/canon-eos/289-tamron-af-17-50mm-f28-sp-xr-di-ii-ld-aspherical-if-canon-test-report--

review</a><br>

Canon 18-55 IS (not the II, but that's there as well): <a href="http://www.photozone.de/canon-eos/181-canon-ef-s-18-55mm-f35-56-is-test-

report--

review">http://www.photozone.de/canon-eos/181-canon-ef-s-18-55mm-f35-56-is-test-report--review</a><br>

Canon 50mm 1.8: <a href="http://www.photozone.de/canon-eos/160-canon-ef-50mm-f18-ii-test-report--

review">http://www.photozone.de/canon-eos/160-canon-ef-50mm-f18-ii-test-report--review</a><br>

<br>

All reviews:<br>

<a href="http://www.photozone.de/reviews">http://www.photozone.de/reviews</a><br>

[bobatkins]

However those tests are on one sample of each lens, and that one sample isn't your lens. They're a good data point, but you can't always assume that the lens you have will be exactly the same as they lens someone else tested. You also can't be sure all published tests are accurate. I don't think anyone out there is doing strictly controlled "optics lab" quality testing (though Popular Photography does have a professional lab quality professional testing system)

[jason_hall5]

It seems to me the words "Casual" and "Test" do not go together.

 

If you like you can go out for a casual shoot and see if you like the results. That is real world.

 

If you want to Test the lens, all other variables must be removed. Testing requires that only one varible exist at any one time. All else must be controlled.

 

Jason

[jason_hall5]

I image you are saying to your self..."boy these guys are up tight about this". Well...yes we are. Casual testing is how so many products get bad reviews from folks who have no buisness doing reviews.

 

I realize you are not looking to do a review for others to hinge a decision on, but the idea is the same.

 

Jason

[tdigi]

Focus on the eyes and shoot making sure your exposed properly and if it looks good its good. Its just like testing audio, if

it sounds good it sounds good. Not much else to it. To much pixel peeping just messes you up. Well it does for me.

[donald_a]

OK, maybe casual wasn't the right word. G Dan Mitchell's test procedure seems to be pretty straightforward and would give results of what to expect if taken of my typical subjects. I'll give that a try. But I would think that even handheld with enough care (high enough shutter speed, careful focus, etc.) the lens would be the dominant contributor to image quality, but maybe I'm wrong. I can try a shot-to-shot test also to see how much contribution I'm causing to image quality.

[www.philwinterphotography.]

I used to obsess about testing lenses too. Then I found for me that it was a waste of time. What's more important to me is does the lens produce a quality image in the real world? A few years ago, I bought an EF 20 f2.8. I tested the first copy and it didn't look as good as my EF 28-135. So I sent that one back and got another. This one looked a little better than the previous one, but still not so great (being a prime) compared to my 28-135, but I kept it. The more I used the lens the more I liked it. Sharp, contrasty. Sure, open it up to f2.8 and the edges are soft. Big deal.

 

I just took delivery of an 17-40 L. A jewel of a lens. I haven't - and won't - "test it." I shot a bunch of random shots on the back deck to find out that it works, focuses like greased lightning, and produces sharp contrasty images. Yes, the edges at f4 close up are a bit soft, but not at f8.

 

If you like the feel, build quality, and real world images you get from the 17-55, keep it. If not, the world is full of other lenses.

 

Chasing lens sharpness is about as wasteful as chasing megapixels.

[SteveH]

Here's a casual test: photograph the funny pages. I was curious to see the difference between using a 1.4 and 2x extender

on various lenses. So I waited 'til Sunday, taped the funny pages on a wall, put the camera on a tripod square to the wall

and tried a variety of lens/extender combinations at various apertures. Put all that in the computer and was easily able to

tell the difference in performance. Not too scientific, but good enough to tell me which lenses on which to avoid the doubler

and/or the 1.4.