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05-19-2010, 06:38 AM   #1
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Are user lens 'tests' useful? what are the basic requirements.

How many here appreciate lens 'tests' done by amatures ?, how many think they are useless.

What are some basic requriements?......Tripod, 2-sec MLU timer, MF or AF (is AF ok if the lens is calibrated) etc? is there any other basic requirements without which the test is a dud ? (I mean the very basics, not what you would wish would be there...)

What needs to be posted ? a center 100% crop, one corner, bokeh?, test distant subjects at infinity focus?, what aperture (wide open and what others ?).....lack of any of these, IMO will not make the test useless, but still would like to know what you think are some basic requirements.

I would like to hear what others think about this.

Thanks.


Last edited by pcarfan; 05-19-2010 at 06:43 AM.
05-19-2010, 07:03 AM   #2
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QuoteOriginally posted by pcarfan Quote
How many here appreciate lens 'tests' done by amatures ?, how many think they are useless.

What are some basic requriements?......Tripod, 2-sec MLU timer, MF or AF (is AF ok if the lens is calibrated) etc? is there any other basic requirements without which the test is a dud ? (I mean the very basics, not what you would wish would be there...)

What needs to be posted ? a center 100% crop, one corner, bokeh?, test distant subjects at infinity focus?, what aperture (wide open and what others ?).....lack of any of these, IMO will not make the test useless, but still would like to know what you think are some basic requirements.

I would like to hear what others think about this.

Thanks.
Great question.

In my mind the biggest fault of most demo shots I've seen is a lack of detail RE post processing. I usually have no idea if the OP applied noise reduction, sharpening, curves, etc etc...

The most basic requirement is out-of-the-camera, unadjusted data.
Dave
05-19-2010, 07:19 AM   #3
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That is true. I assumed everyone does that...I shoot in RAW, open in LR and save as a jpeg (So, only the default processing). PP definitely ruins a test (but the default PP which cannot be removed, done to a minimum to all images is fine IMO)
05-19-2010, 07:23 AM   #4
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I have killed a few brain cells trying this myself ... you definitely need a tripod and a well printed focus/lens-test chart, with decent lighting (so that good light/low light issues don't overlap with pure focus issues). And patience to set it all up well, and minimize user errors.

I used an IR remote and the 2-sec MLU to be super careful with any random shake.

MF/AF depends on whether you are testing the focus ability for the lens+body combination (then AF to show hits/misses) or you are testing for other lens issues ... I used AF since I was particularly testing for FF/BF issues ...

For focus testing, you need the lens wide open so that the DOF does not mask any FF/BF issues... but this means that at certain focal length, subject distance and aperture combinations, the margin of error is minimal, and you need to be patient and careful (like some science experiment, which it probably is).

My suggestion would be to post images as-is from the camera and not do any PP at all ... this ways, you have not 'destroyed any evidence' ...

05-19-2010, 07:27 AM   #5
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Personally, I think lens tests are pretty useless no matter who does them.
05-19-2010, 07:30 AM   #6
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The main use is for the tester, what he/she (though, let's not kid: it's usually a he) sees between his lenses.

There are so many variables involved that any testing is merely indicative, and usually the tests don't tell us what we really need to know: which lens in the tested circumstances allows you to make a photo that makes sense, hangs together better, seems more holistic.
05-19-2010, 07:48 AM   #7
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Just to clarify a few things here.

The tests I am talking of are not tests to see whether a lens is defective per se. But to show the IQ of a lens, or to even compare IQ of two lenses. This requires tests done to a lens to be sure it's not defective - I usually do a BF/FF test at varying distances, and a rough test to see any edge issues.

Also, I very much believe that a lens test no matter how well done can never reveal the whole picture, however this does'nt necessarily mean tests are useless. I think they are useful, but they are useful in a limited way if done correctly.

I test all my lenses and actually enjoy the experience. My tests are both critcal tests like on a tripod etc. but also include hand held shots of hundrads and hundrads of images with varying light conditions and distances and only some of these are critically evaluated at 100%. Then if they are adequate take real life shots and then come to a conclusion. It is impossible to post such a test. What is the bare minimum that would make it useful.

I would have a chance to test my FA*28-70/2.8 with a Tamron 28-75/2.8. I will do my run of tests which will satisfy me. I find posting even a handful of test shots in the forum highly vexing. But, I can do the bare minumium if it would be helpful. What is this bare minimum?

Last edited by pcarfan; 05-19-2010 at 07:55 AM.
05-19-2010, 07:51 AM   #8
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QuoteOriginally posted by Nesster Quote
The main use is for the tester, what he/she (though, let's not kid: it's usually a he) sees between his lenses.

There are so many variables involved that any testing is merely indicative, and usually the tests don't tell us what we really need to know: which lens in the tested circumstances allows you to make a photo that makes sense, hangs together better, seems more holistic.

Absolutley, 100% agree with this.....but, will a test be partially useful, if so what is the bare mimimum that can be done and still be helpful?


Last edited by pcarfan; 05-19-2010 at 07:56 AM.
05-19-2010, 07:55 AM   #9
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QuoteOriginally posted by Wheatfield Quote
Personally, I think lens tests are pretty useless no matter who does them.
I agree. If someone is going to post one though, take a Real picture, no charts, brick walls, newspapers, etc, and describe in some detail what they like or dislike about the result it gives them.

05-19-2010, 08:02 AM   #10
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pcarfan I guess I understand what you are aiming at.

Nevertheless one precondition for me is the realm of photography you personally are into and therefore want to do the tests in that same realm.

Having said this, my totally amateur style of testing is simply to take some snaps from my open kitchen window of a distant church spire on a tripod. Center and all four corners through the aperture range could indicate a misaligned lens and a broad guess of how good the resolution of that lens might be. If in doubt I do some focus bracketing, too (I do manual focus anyway).

I think a comparison between lenses under the same conditions is always interesting and can be as amateurish as anything as long as you apply the same conditions.

Crappy but OK for me: Righthand lens not in focus (center crops only)


I prefer personal style reviews though (like in our very Pentax lensbase) but I guess that's not what you have been looking for in this case.
Cheers, Georg

Last edited by georgweb; 05-19-2010 at 08:17 AM.
05-19-2010, 08:09 AM   #11
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QuoteOriginally posted by JeffJS Quote
I agree. If someone is going to post one though, take a Real picture, no charts, brick walls, newspapers, etc, and describe in some detail what they like or dislike about the result it gives them.

These would be useful in 'user reviews' after getting familiar with the lens. So, the image posted just shows what is possible.

But, I think one image as a 'test' would'nt be useful in gauging how good a lens is, as it would be full of varying parameters that it would be virtually impossible to compare to another lens.

Last edited by pcarfan; 05-19-2010 at 08:38 AM.
05-19-2010, 08:20 AM   #12
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QuoteOriginally posted by georgweb Quote
pcarfan ..............I think a comparison between lenses under the same conditions is always interesting and can be as amateurish as anything as long as you apply the same conditions.

I prefer personal style reviews though (like in our very Pentax lensbase) but I guess that's not what you have been looking for in this case.
Cheers, Georg
I tend to agree with this.

Pentax lens base is very useful and usually it takes me at least 6 months before I can post a review there, but usually it takes even longer (Like almost a year for the FA77). It takes that long to form a definite opinion on a lens before posting it there.

But, I am wondering whether a test could reveal differnet stuff (center sharpness, corner quality, show bokeh etc.) that a typical lens review in the data bast doesn't dwell into. Especially if it is directly compared to another lens.

Last edited by pcarfan; 05-19-2010 at 08:37 AM.
05-19-2010, 08:32 AM   #13
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I think user reports are extremely useful because they report the experience of someone... using the lens/camera/tool.

Measurebating is all very fine, but I prefer a comment like "I've never noticed CA issues" than a comment like "CA is visible at 0.64 pixels width in the extreme corner". So for me, user reports are key to evaluating.

How can a test chart evaluate the "pixie dust" of the FA limiteds, or the 3D effect of the DA limiteds? How can a test chart realize that the Sigma 17-70 has different colours than a Pentax lens, but is a great jack of all trades?

I think formal tests are also useful, but they are a different type of information than user reports.
05-19-2010, 08:36 AM   #14
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QuoteOriginally posted by bdery Quote
I think user reports are extremely useful because they report the experience of someone... using the lens/camera/tool.

Measurebating is all very fine, but I prefer a comment like "I've never noticed CA issues" than a comment like "CA is visible at 0.64 pixels width in the extreme corner". So for me, user reports are key to evaluating.

How can a test chart evaluate the "pixie dust" of the FA limiteds, or the 3D effect of the DA limiteds? How can a test chart realize that the Sigma 17-70 has different colours than a Pentax lens, but is a great jack of all trades?

I think formal tests are also useful, but they are a different type of information than user reports.

I completely agree with this....
05-19-2010, 08:39 AM   #15
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Some posted guidelines would be helpful. I agree that people should be asked to gain some experience with a new lens for at least 6 months or so. There are plenty of ways to share your new lens with members (posting pictures for example), but the review database should not be one of those areas.

A basic list of things to look for (CA for example), and how to check for them, might be useful. I wouldn't want to the the database turned into a pixel peeping exercise however....we have enough of those. Real pictures under realistic conditions are important to me, not some aspect that goes beyond what the human eye can normally pick up.

There are a number of qualities that can be hard to itemize, so the database will always be subjective.
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