• Ultraviolet Photography

Inexpensive 35/3.5 Faceoff: Asahi vs. Komine (Soligor)

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#1 OlDoinyo


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Posted 01 May 2021 - 01:05

There are many 35mm full-frame lenses more or less suitable for UV photography, but the best of them can be pricey and often difficult to obtain. For those who are engaged in UVB or other demanding technical work, the maximum bandpass and other optimum characteristics of these optics is often absolutely necessary; but for those more casual photographers doing miscellaneous general photography with cameras whose sensitivities do not extend much below 340 nanometers, one can obtain results almost as good with less costly and easier-to-find gear, and often the residual differences between images obtained with such gear and those obtained with the costlier optics is small enough that routine image manipulation in post-processing may largely mask the difference. Herein are presented two 35mm f/3.5 lenses which were obtained for under USD $100 each, the Asahi 35/3.5 and the Komine (Soligor) 35/3.5:

Attached Image: 35-3.jpg

The first of these will be familiar to some readers and has been used by this writer for several years. The second was made by Komine Seisakujyo, a Tokyo optical firm which mainly contracted to make lenses sold under the Vivitar and Soligor brand names in the 1960s and 1970s, although a few rare natively badged pieces have been found by collectors and historians; it sports a strange double-ring control for the aperture and takes 43mm filters on its front thread, and is identified as a Komine by the H6 prefix on the serial number.

The first step in the comparison is the obligatory pinhole test, with sunlight, an aluminum target, and the Baader filter. The Sony A900 was used and display intent is BGR:

Attached Image: Pinhole Tests.jpg

Both these lenses show a pale orange color through the lens, indicating bandpass which is OK but not outstanding for this focal length range. Detailed bandpass information for a lens very like the Asahi has in fact been posted elsewhere on this site; transmission peaks at 550nm and is down 1 stop at 362nm, 2 stops at 347nm and 3 stops at 343nm. For the Komine there is no published spectrum, but the slightly greyer and less clear color of the test may hint at bandpass just a whisker more than the Asahi's. But that is just a guess.

Image quality tests were performed with the Baader U2 filter wide-open and fully stopped-down. The Asahi only goes to f/16 whereas the Komine goes to f/22.

Attached Image: IQ.jpg

The light changed somewhat between these two sets of test photos, which somewhat complicates interpretation, and the filter had to be taped on the front of the Komine because a proper stepper ring was not to hand and there may have been a bit of IR leakage in the second set of photos. But chromaticity seems broadly similar between these two lenses. The Asahi seems a bit more contrasty with less veiling and more "snap."

Next we examine center and edge sharpness wide-open and stepped down:

Attached Image: Details.jpg

Wide-open, both show softness probably due to focus shift, although the Komine has substantially more of this as it is blurrier wide-open across the image. Neither lens has a really large focus shift; stopping both lenses down makes them quite sharp in the center. To my eye, the Komine is sharper in the center but the Asahi has less softening at the corners and is thus more consistent.

Foreground and background bokeh are evaluated next:

Attached Image: Bokeh Tests.jpg

In all but the wide-open position, the Asahi has markedly pentagonal bokeh with a strong tendency to radial elongation when off-center. Foreground is nearly neutral whereas background looks weakly negative. The Komine has more octagonal/circular bokeh with somewhat less tendency to elongation; the foreground is basically neutral whereas the background may be weakly positive.

In summary, these are two lenses which, for a reasonable price, can provide adequate long-wide-angle service for many ultraviolet use cases. I find the Asahi a bit preferable overall due to the more consistent image quality and smaller focus shift, but those wishing more classically appealing bokeh or a hair more bandpass may come to the reverse conclusion.

#2 Andrea B.

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Posted 02 May 2021 - 17:48

Clark, thank you for this analysis of the two lenses. When I next update the Sticky List, links to this topic will be included.
Andrea G. Blum
Often found hanging out with flowers & bees.