[jon.partsch]

Hello,

I am new here, so hi everyone!

I have read about some quality control issues with newer (especially zoom) lenses. I am coming from the universe of old-school metal-construction manual-focus prime lenses on my Minolta 35mm equipment, and I am migrating to Pentax so I can continue to use my Tamrom SP Adaptall-2 300mm f/2.8 lens that I love for wildlife photography. I created a test target, which I am attemping to attach to this post, for testing new lenses. I thought it might be helpful to some others on this forum. The target is not intended to measure absolute resolution but should prove usefull in determining if a lens does not focus evenly across the film plane (a common problem, as I understand it). Note that this target was made in Excel. It may be possible to do a better job in Illustrator or another software package, but I don't have the time or skill for that. However, if you have any suggestions on how this target might be improved, I'd be happy to hear them.

Incidentally, I am hoping to pick up Tamrons 17-50mm f/2.8 and 90mm f/2.8 macro in the near future. Are these good choices? Are there any older lenses which might do as good a job for less $$$?

Thanks,

Jon

Attached Images

LensTestTarget_v1.pdf (57.6 KB, 529 views)

[deadwolfbones]

Incidentally, I am hoping to pick up Tamrons 17-50mm f/2.8 and 90mm f/2.8 macro in the near future. Are these good choices? Are there any older lenses which might do as good a job for less $$$?

The Tamrons are excellent choices, particularly the macro.

[Dangermouse]

Thanks for posting that - I'd been wondering if there was a chart or something that I could use to test lenses. So far, I've been taking photos involving a lot of edges, corners, and grain (kitchen cupboard doors are good for this!) and then comparing them for sharpness.

[jon.partsch]

I found this online...

This target is cropped to be printed on 8.5x11 paper - do not "size to fit" when printing. On the hard copy, the top and bottom tick marks should be exactly 200mm apart.

To use this chart, frame the test picture exactly between the top an bottom tick marks (200 mm). Read the number where all the lines closest together can be seen and multiply by 100. This will give you the LW/PH (Line Widths/Picture Height) resolution.

dpreview has figures for the absolute and extinction resolutions for various DSLRs.

Note: I still think my chart would work better for determining focus across the film (sensor) plane.

~Jon

Attached Images

TestTaget_pro.pdf (153.9 KB, 544 views)