Tamron 90mm F/2.8 Macro Aperture issue?

[pgenon]

Hello all,

On the basis of good press reviews I recently bought the above lens to work on my D300.

I have encoutered two issues:

The first one, I am not really sure whether it is a real problem. The lens is supposed to range from F/2.8 to F/22 apertures but according to my D300 reader it goes from F/3.2 to F/32. I amnot sure if it is real, whether it is a lens issue or a camera issue?

The second thing is that there is quite a lot of blue fringing in contrasted scenes, generally a blue fringe at the end of anything bright white. I find that quite disappointing but is it an issue with the model or my particular lens?

I would be interested to hear from fellow users?

[nikonian]

I may be incorrect but I think the write up on PHOTOZONE for this lens states that there is a blue fringe with this lens

[flake]

The Tamron AF 90mm f/2.8 Di SP is a superb lens without any significant flaws and it's easily as good as the corresponding (classic) Micro-Nikkor - the resolution figures are extremely high, vignetting is marginal, CAs are low and distortions are non-existent. The build quality may be slightly inferior in comparison to the Nikkor but then the price tag is also substantially lower so the verdict can only be - HIGHLY recommended!

Conclusion from Photozone, you can force virtually any lens into CA's with extreme contrast, you might just want to check with the vendor that your copy is performing properly.

[pgenon]

Fair enough for the colour fringing, but I switched immediately to my (much cheaper) Nikon DX 18-70 and there was no colour fringing (on the same scene).

Any ideas on the aperture issue?

[F11]

I've had this lens for quite a while now and am really pleased with the results considering the price I paid. I can't say that I've noticed any blue fringing and I do achieve F2.8 many times on my old Canon 350D and later Canon 40 D. The only thing I have found recently is that sometimes the manual to auto push pull ring can sometimes get lodged in one position and I have to switch the camera off and sometimes remove the lens and refit for it to become active at the appropriate setting. I don't know why this sometimes happens. I did source my lens from Hong Kong but I don't think this should make any difference>

[F11]

F11 here again, check out my macro album to see what you think as I've added a few shots taken with this lens to my photo pages.

[PaulMontgomery]

I'm not familiar with this particular lens, but with a lot of macros, the amount of light entering the lens reduces when you focus close. Can you achieve f/2.8 when focused at infinity?

[pgenon]

Originally Posted by PaulMontgomery

I'm not familiar with this particular lens, but with a lot of macros, the amount of light entering the lens reduces when you focus close. Can you achieve f/2.8 when focused at infinity?

Ah yes, that is correct, I can achieve f/2.8 at about 4m focus distance and beyond. I have now learned why as well.

Many thanks for pointing me the right way!