Another lens candidate for UV macro

[bvf]

In another recent post there was a discussion about how some lenses perform in UV macro work. The discussion initially commented that the metal El Nikkor 105mm did not perform as well as the Cassar S 50mm because (a) it suffered from focal shift, and (b) even when re-focussed at 345nm it didn't seem able to produce a particularly sharp image at that wavelength.

 

Birna had been looking for a shorter focal length lens for macro and so was interested in the Cassar S, but in the end decided that the Ocean APO (I think it was) performed better.

 

It so happens that last year there was a discussion about lenses with a good UV reach, and in the data provided one of the best was the Soligor 35mm f/3.5 enlarging lens. I was keen to get one of these, but they are pretty rare - but the wonderful Timber took pity on me and generously gave me his copy. So I though I'd do a quick comparison of the Soligor with the Cassar S and El Nik 105 - results below. The main caveat to make is that because the Soligor is a short focal length lens it gives very little working space between lens and subject, so it's quite difficult to position the lighting. But for Birna, who needs a short focal length lens, this Soligor might be the answer.

 

Another comment to make is that I had to ramp up the contrast significantly for the Soligor and quite a lot for the Cassar to match that of the El Nik.

 

This first image is of the centre of a Forget-Me-Not, which is a flower about 5mm across. It was actually a bad choice for the test, because the centre renders very dark in UV. In this image I had the bellows at full extension. The images have been cropped to the same extent (to about 25% of the whole frame) so that you can see the relative image size produced by the three lenses.

 

 

In the second image the bellows extension has been adjusted for each lens so that they give the same magnification.

 

 

The third image is a full bellows extension comparison (like the first image) of printed text:

 

 

And ther last image is like image 2, i.e. bellows extension adjusted to give similar enlargements, but using the text as the subject:

 

 

The Soligor appears to be the best performer of the three lenses.