Author Topic: Tamron 90/2.5 macro, manual focus version (Read 9098 times)

Airy · « **Reply #15 on:** May 17, 2016, 22:11:17 »

Around noon in Paris. f/5.6. Full pic and 100% crop.

Airy · « **Reply #16 on:** May 17, 2016, 22:21:48 »

Note : I got the impression that in the publishing process, the picture contrast gets increased (edit: or maybe it's the wb browser). I had to remove comments saying that the contrast was on the low side because these comments would sound silly, but in reality I'd categorize the Tamron in the "mild contrast / high sharpness" category, a bit like the Tamron 45/1.8 or the Nikon 300/4 PF.

Airy · « **Reply #17 on:** May 21, 2016, 09:35:11 »

I had some reading on internet. The later 52BB design reportedly benefitted from slight recalculation of the optical formula, with the effect of higher homogeneity, and higher contrast wide open. In any case the lens (8/6) is a double Gauss with two additional elements behind to improve field flatness.

The rear element is nearly plane on its outer side, and according to one commenter this could be teh cause for contrast loss with digital cameras (see my somewhat extreme example when shooting directly into a lit bulb). I do not know if that explanation belongs to urban legends or not. Did sb group lenses into two families, one with plane rear elements and another one with curved ones, and test the hypothesis "contrast loss with in-axis light source" ? not that I knew. This is a plausible explanation, but no more.

Otherwise the older 52B is reported to have somewhat lower CA. In any case, either of them are very good value for money.

Airy · « **Reply #18 on:** May 21, 2016, 11:00:45 »

... colors : rather cold. See for instance my picture of the bridge in Paris, above.
Diffraction : at mid-distances, f/4 is clearly better than f/11 because of diffraction onset. Here is an example (first one is f/11; both are 100% crops. Difference is more striking locally than when examining via the browser). In practice, on Df, I'd advise against going beyond f/8 for general photography purposes.

Airy · « **Reply #19 on:** May 26, 2016, 22:54:33 »

Shooting against the light : with honours. Here at f/4.

Airy · « **Reply #20 on:** May 26, 2016, 23:08:08 »

As you may see on these crops, the background bokeh is pretty nervous; here the 105/2.5 is definitely better. Shot at f/4 and f/2.5 respectively. Of course, these are worst conditions (high contrast subject).