Sigma and Takumar Macro Lenses in UV

[bvf]

I do a lot of UV macro photography, using various known UV-friendly vintage lenses and bellows. I've got a couple of specialised macro lenses, but haven't used these for UV because they're not on the list of UV-friendly lenses. So I thought I'd give them a try - perhaps I've been doing them an injustice and they could be giving me better results.

 

The macro lenses are:

1. A modern Sigma 105mm f/2.8 macro lens. A quick sense-check showed it could make images through a Baader U, but couldn't squeeze anythoing out of a 345BP25 filter.
    
   
2. A vintage SMC Macro-Takumar, 100mm f/4. Actually Pentax are a bit naughty calling this a Macro lens, as its maximum magnification is 1:2. The sense-check showed this could make images through a Baader U and the 345BP25, but failed to produce anything through a 315BP20 filter.
   

So these lenses could be used with the Baader U, but clearly have less UV reach than UV-friendly lenses which can get images at 320nm or even 315nm. However, this might not be a problem with a broad bandpass filter like the Baader U, because even with a UV-friendly lens the image is formed mainly by the longer-wavelength end of UVA because of the nosedive in sensor sensitivity and lens transmission with shorter wavelengths. Cue for a test ....

 

The images below compare these lenses with the UV-friendly El Nikkor 105mm (metal). All exposures were at an indicated f/8, ISO 100, flash lighting, and a Baader U. The images are all focus-stacked using Zerene.

 

Both of the macro lenses made good images, but there is definitely something missing compared to the ElNik - especially with the Sigma. In terms of image quality there is no obvious benefits of the macro lenses over the ElNik. So my conclusion is that there's no point using these specialised macro lenses and to continue using the UV-friendly lenses with bellows. (Actually, it might be worthwhile using the Macro-Takumar on the odd occasion when it's not practical - or I can't be bothered - to use the bellows and magnification of 1:2 is adequate).

 

Here is the reference image using the ElNik 105. Magnification is about 1:1:

 

 

Here is the Macro-Takumar image, using the ElNik white-balancing. Bellows were used to get a magnification of about 1:1 :

 

 

And this is the Sigma Macro image. Magnification 1:1, using the ElNik white-balancing:

 

 

Here are some cropped/enlarged images to judge image quality. First the ElNik:

 

 

The Macro Takumar, using bellows to get 1:1 magnification:

 

 

Now the Macro Takumar again, but from an image at the lens's maximum magnification of 1:2 without the use of bellows:

 

 

And finally the Sigma Macro:

 

[Andy Perrin]

I think I agree the ElNik is winning this? My ranking would be ElNik > SIgma Macro > Macro Takumar

[bvf]

I think I agree the ElNik is winning this? My ranking would be ElNik > SIgma Macro > Macro Takumar

 

I'd probably agree for image quality, but the Macro Takumar transmission is closer to the ElNik.

[dabateman]

Yes the blue of the Sigma implies that your mostly above 380nm.