Asahi-Kogaku Tele-Takumar 135mm F3.5 Lens Test
I made a series of tests using a DSLR to judge the performance of the Asahi-Kogaku Takumar 135 mm f/3.5 lens that came with my Asahiflex IIa (more about that kit here: link). I compare it with a Super Multi Coated Takumar 135 mm f/3.5 lens and an Opticam Auto 135 mm f/2.8 lens. The Asahiflex lens has an m37 mount, the others have m42 mounts. The Super Multi Coated Takumar and Opticam lenses are the only other m42 lenses that I own with the same focal length as the Asahiflex lens. The Super Multi Coated Takumar is well known among the vintage lens fraternity so provides a useful baseline for comparison. The Opticam is poorly known, is not the preset model and the Korean manufacturer is a mystery. So, you can consider this a test of the Opticam too, if you like.
I followed the same methods used for the 58mm f2.4 lens that came with the Asahiflex, which I posted here. I will repeat some of the information below so that this post is a stand-alone review. My tests use a full frame Canon DSLR (5Dii) with a m37>m42 adapter inside a m42>EOS adapter. The EOS adapter flange prevents light leaks that are found with some other DSLR adapters. However, with this adapter combination the lens focuses beyond infinity (better than not focusing to infinity, so I am OK with that). Also, when mounted the inscription on the lens showing aperture, focal distance and depth of field is on the underside of the camera. However, on this lens when the focus ring is turned, the whole barrel rotates and the markings can be read, and set, when it is at near focus distances. This is a nuisance but a lot better than having to turn the camera upside down as with the 58/2.4.
Click on any image below to see it enlarged, and navigate in the gallery with the arrows.
The 135/3.5 came with the Asahiflex in a leather case with both end caps; the front cap and leather case are embossed with the Asahiflex Optical Company (AOCo) logo. It also has an original lens hood in an embossed leather case (pictured in the 58/2.4 post here and here). The hood separates in the middle so that filters can be inserted.
The initial tests were taken indoors – less than ideal, but it was raining pretty hard and I was impatient. I hope these tests are adequate to show the capabilities of the three lenses, at least in near focus conditions (the subject was about 230 cm (90 inches) from the camera. I added some more tests at a longer distance with two of the lenses to explore a question about the Tele-Takumar contrast.
The camera was mounted on a tripod and used full magnification in live view at f/3.5 to focus. In the pictures below the focus was on the red tulip in the upper left corner, on the veins in the middle petal. I used a 2 second shutter delay indoors and a 10 second delay for the outdoor tests to steady vibrations, the camera was set to 100 ISO and aperture priority. All shots were RAW with a Neutral setting so no in-camera settings influence the images. No filters or lens hoods were used on the lenses. Three pictures were taken with each lens – at f/16, f/8 and f/3.5. The f/3.5 setting on the Opticam is approximate – the lens is marked with click stops for f/2.8 and f/4 so I placed it half way between.
The f/16 indoor exposures range from 8 to 4 seconds. The f/8 exposures were all 1.3 second. The f/3.5 exposures were 1/8 and 1/6 seconds. The exposures were not all even in appearance (even those shots with the same lens), probably due to one of the m42>EOS chip adapters not having a programmed focal length which I have noticed can confuse the camera. Therefore, I changed the exposures in Lightroom to have a similar appearance (as judged by eye) at the centre of the image. I forgot to cancel the automatic sharpening on import into Lightroom (value of 25) that was applied to all the images equally. I had already exported and renamed all the images when I realised this mistake and do not have the energy to correct it. Otherwise there are no clarity or other changes made except to crop details. The original images are 5616 x 3744, all the crops to show image detail were at 1501 x 1001 and are placed in precisely the same parts of the frame – differences in view are due to minor focal length differences and possibly tiny adjustments of the camera on the tripod during lens changes. Some of the outdoor shots also require a small amount of exposure calibration (maximum was 0.27 E.V.).
The Super Multi Coated Takumar and Tele-Takumar have good reputations while the Opticam has no particular reputation. These tests show the Super Multi Coated Takumar to be the sharpest lens at most f-stops across the field of view, though at f/5.6 there is little or nothing to choose between the two lenses (see bottom gallery). At f/16 the two Takumars are very similar in the corners but the Super Multi Coated Takumar appears sharper in the middle (this might be related to loss of contrast in the Tele-Takumar). At f/8 the Tele-Takumar might be a touch sharper in the very far corners and very similar to the newer Takumar just inside the corners, but again the middle appears quite soft in the Tele-Takumar. At f3.5 there is little to choose between the three lenses in the corners (not surprising that the Opticam might be better here since as an f/2.8 lens it is not yet wide open), but again the center of the Super Multi Coated Takumar is the clearest. The Tele-Takumar has less chromatic aberration when wide open than the other Takumar. The Opticam is generally less sharp in all situations than the other lenses but is not a disaster, especially for the few dollars I paid ($5? or $2, can’t remember now).
The main problem with the Tele-Takumar is that at f/16 and f/8 it has a marked drop off in contrast, especially in the centre of the image. I also shot the tulips at f/5.6 (not shown here) and both 5.6 and 3.5 do not suffer from this problem in that series of tests. I asked a question on PentaxForums about this and one person volunteered that they had noticed a similar drop in contrast with their Tele-Takumar 135/3.5 when shooting against a bright background. So, I thought I had better run some more tests, this time with the “sun” behind me, and no really bright areas in view. For this second test I only compared with the Super Multi Coated Takumar. The cemetery shots below are the results of this testing. You can see that in fact with a darker area in the middle of the view that the contrast is lower for all tested f-stops in the Tele-Takumar than the more modern lens (hardly surprising given the more modern coatings). I think that in these lighting conditions the Tele-Takumar works just fine, and a choice of a contrasty film would render this difference negligible. High contrast lighting would probably help as well. Even so, on balance, the Super Multi Coated Takumar comes out well ahead of the Tele Takumar for this contrast “issue” and overall sharpness, if nothing else.
In the next few days I will conduct and publish similar tests for the Fujitar P.C 35/2.5 that also came with my kit (see here).
The three lenses at F/16
Each group below is organised by full frame image then cropped details from lower left corner, center left and upper right corner. The SMC abbreviation for Super Multi Coated is my doing, it is not an “SMC Takumar” model of this lens.
Click on any image below for larger view and navigate with the arrows.
The three lenses at F/8
Secondary testing in Ross Bay Cemetery:
The three lenses at F/3.5
Secondary testing in Ross Bay Cemetery:
The extreme crops below were made at 400 x 267 in Lightroom (though they reproduce larger here) – they show that the Super Multi Coated Takumar has a lot more chromatic aberrations at f/3.5 than the Tele-Takumar, though one has to do some serious pixel peeping to see these differences. Since I noticed it when looking at sharpness, I thought I would share.
Two Lenses at F/5.6
While exploring the issue with contrast for the Tele-Takumar I also took images at f/5.6. This aperture turns out to be the sweet spot for the Tele-Takumar for both contrast and sharpness. In these tests there is barely noticeable less contrast in the Tele-Takumar than the Super Multi Coated Takumar, and otherwise at f/5.6 there is little to choose between the two lenses in terms of sharpness, with the former having a very slight edge in the corners, and both lacking chromatic aberrations in this kind of light.