[MSL]

When you buy a lens (whether new or used) do you have a standard set of tests you put it through? For example, do you run a set of shots at a fixed ISO and range of apertures to check its sharpness? Do you test how much it flares, fringes or shows chromatic aberation? And do you find you use these results to influence how you might use the lens in the future? Or do you just buy, use when you feel like and then examine the results as you go along? (Note that in asking this question I'm excluding the idea of trying to do a rigorous test of lens as one might do from an engineering perspective or to write a detailed review).

[Adam]

I usually go out and shoot with the lens, as a whole day's use should reveal any problems it might have (unscientifically)

[northcoastgreg]

I usually go out and take some pics of my house. That will give me a rough idea of what the lens is capable of. The I simply put it through normal usuage. After a few weeks use I can get a pretty good idea of what the lens is capable of and what are it's weaknesses. I don't really believe in "testing" a lens becuase tests tend to be rather artificial and emphasize easily testable aspects of the lens at the expense of the more subtle qualities.

[JinDesu]

I'll usually take my new lens out to give it a full range test - wide open, stopped down 1-2 stops, and stopped to F8, at each focal length if it's a zoom, against evenly lit and unevenly lit subjects.

Usually it tells me how nice the bokeh is, where I get bad fringing, where my lens performs sharpest, etc. Then I use that information to determine if I keep it or return it, but rarely will it change what I use it for since I buy my lenses for specific purposes.

[Lowell Goudge]

Aside from running out and shooting as much as possible, the only thing I do as a relitive standard (although I am a little behind) is to check exposure on each of my bodies.

My test is to use a block wall, and check the exposure at each aperture increment in Av mode (for A lenses), and M42 lenses, and in M mode with the green button for Manual aperture lenses.

It is important to me to know how the lens meters and otherwise performs with each body. For example, some lenses may have slight errors in exposure at maximum or minimum aperture, some may have a uniform offset, of perhaps 0.5 stops, Manual lenses have all sorts of different behavior depending on body, M42 lenses have offsets due to whether they short out pin 7 on the lens mount or not, and others may have a linear but increasing error between wide open and stopped down to minimum.

As examples of each,

Error at minimum aperturewhen discussing exposure issues with manual lenses, one member (Bendie8) sent me a set of shots with his A50/1.2 in A mode. exposure was dead on, and consistent until F22 where it was about +1/3 of a stop, probably due to the aperture not really being accurate at minimum

Gradually increasing error when stopped downmy Tamron 28-75/2.8 has a slight but ever increasing exopsure error as you stop down, it is dead on at F2.8 but as you stop down to minimum aperture the error increases linearly to about a 1 stop over exposure

Exposure offset when I use my Sigma 70-200/2.8 EX with a teleconverter, on my K10D specifically, the metering is off because the TC does not report the true aperture to the camera, but only feeds lens data directly. with a 1.4x TC i need -0.7 stops of EV comp and with a 2X I need _1.3 stops EV comp but aside from the offset metering is absolutly flat at all apertures.

Manual aperture lenses and errors this is somewhat body dependant with the K10D and K20 D being the worst offenders, but my K50/1.4 under exposes by abut 1 stop wide open, by F5.6 it is spot on, but by F11 it is +2 stops, and by F22 it is back to about +1. The same lens on my *istD is spot on wide open and drifts up to about +1 stop by F22.

M42 lenses and metering on some cameras, if the Data pin is not shorted to the lens mount, there is an exposure offset of perhaps 2 stops. Many people use tinfoil to make this connection to remove the offset, because they would wish to use EV comp for its true purpose as opposed to switching to manual exposure.

The bottom line is that exposure variations are the biggest issue I see that requires a specific test, just so you know your kit. it takes about 10 minutes per lens/ body combination to do, and is really the only thing that needs a controled test, otherwise, if the lens you have produces images that please you, and that you do not have issue with, shooting is the best approach, How a lens handles, focuses, (or perhaps not) and the other subjective qualities like bokeh and color rendition are only things you will get from shooting. Even sharpness and focusing is best evaluated on real subjects and not targets.

[audiobomber]

I usually test a lens against other lenses to see how it stacks up for sharpness, CA, flare, vignetting.
I always test auto-focus lenses for AF accuracy using a chart.

[pinholecam]

Just take more photos

[wombat2go]

I like to do a quick "fence test" and scan thru the results in picasa
For example a member on Saturday mentioned he had a Rikenon p zoom 35~70mm.
So I ran a check on it (no filter):
The following 3000 by 2000 jpgs are at f/16, f/8 and f/3.4 respectively.
The metering is OK.
Particularly where the white shed is behind the fence, we can see this old lens is happier around f/8 !

https://www.box.com/s/5ab4922ece40bb7ce83e
https://www.box.com/s/e77bec47b98caa833c68
https://www.box.com/s/640dcd5ff233e5a239e1

[MSL]

I usually test a lens against other lenses to see how it stacks up for sharpness, CA, flare, vignetting.

Do you have a standard target you use for this sort of testing. One issue that prompted my question was wondering whether I should test my lenses for sharpness just to see how much I'd need to stop down each lens from its minimum aperture to something that might be considered sharp.

[mikeSF]

i do a mix of technical and practical tests. first i do AF testing and dial in a compensation if needed. then use a newspaper or brick wall test for decentering and field curvature at 3 or 4 aperture settings. after this, i take it around to my familiar subjects (rusty hay rake) to look at bokeh, flaring, CA. finally, just shoot with it for a week or so and look for anything in the photos that bugs me.
once i know where the lens excels, i make a mental note in my mind of when to best use it.

[lightbulb]

I shoot fishes in the tank for AF, color , and also brick wall at various aperture.

[audiobomber]

Do you have a standard target you use for this sort of testing. One issue that prompted my question was wondering whether I should test my lenses for sharpness just to see how much I'd need to stop down each lens from its minimum aperture to something that might be considered sharp.

I set up a cereal box so that it covers a portion of the frame. I use a tripod and 2s lockup, usually Av mode at lowest ISO. I crop to 100% or even 200% to test for shapness. I find that print is most telling for resolution tests. You can look at PF and bokeh around the box.

This example is tighter than usual, but it's one I had handy. I usually set it up so that the box only covers half or a third of the frame.

[abacus07]

I check a lens to make sure that something horrible isn't wrong with it but other than that I just use it. Of course I have plans to someday take all of my similar focal length lenses out and do some formal testing before I sell some. But I would rather take interesting photos instead this 'work'.

[luftfluss]

I shoot into the woods behind my house to make sure the sharpness and focusing are what I expected. After that, I'm ready to go.

[NaClH2O]

I'm more like abacus07 and Adam. I just go out and shoot with it under "normal" shooting conditions. I'll try to get it to CA by shooting some tree branches against the sky; check flare resistance by shooting near bright light sources (sun) check bokeh by shooting something wide open etc. But nothing particularly formal. I try to get a variety of colors, lighting conditions etc, but I'm not obsessive about it. I try to use a variety of apertures and if it's a zoom a variety of focal lenghts within the zoom range; but mostly I just go out and shoot with it.

NaCl(any real flaws will show up in that first outing but I do nothing "scientific" )H2O