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Asahi 35mm f/3.5 Super-Takumar

Lens
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#1 UlfW

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Posted 30 March 2021 - 14:17

Last Update: 03 April 2021 agb/label
Finalized: Work in progress.


Asahi 35mm f/3.5 Super-Takumar

Manufacturer: Asahi Opt. Co.
Lens Label: Asahi Opt. Co. Lens made in Japan Super Takumar 1:3.5/35 <serial number>
Currently manufactured: No

Lens type: Manual focus, Prime, Wide Angle
Design: 5 elements in 4 groups
Focal length: 35mm
Aperture range: f/3.5 – f/16, Preset Manual, 5 blades
Optimal magnification *: ?
Sensor format/coverage: up to 24 mm x 36 mm
Mount: M42 x 1 thread**, others. The mount is internally mounted on a T2 mount structure that can be exchanged between lenses
Helicoid: Yes
Flange Focus distance: M42/45.46 mm,
Front filter: 49 mm x 0.75 mm
Introduction year: 1959 as Auto-Takumar. With the same optical design for three versions named Super-Takumar, between 1962 and 1971
This lens produced: between 1964 and 1966 (version 2)
S/N of test object: 33858

More info, on the web: https://www.pentaxfo...-35mm-F3.5.html


Image of test object:

Attached Image: IMG_2700.jpg Attached Image: IMG_2701.jpg Attached Image: IMG_2702.jpg


Transmittance Summary

Definitions of the parameters below
  • Range: This Super-Takumar 1:3.5/35 lens transmits from 1-71% in an increasing slope from 333nm to 400nm.
  • TVISmax (%) = 87%
  • T400nm (%) = 71%
  • T365nm (%) = 47%
    This high percentage is an indicator for reasonably short exposure time under typical UV-pass filtration peaking around 360 nm or when using 365 nm UV-LED illumination.
  • λUV HMvis(nm) = 363nm
  • λUV HM400(nm) = 356nm
  • λUV Zero(nm) = 333nm
  • These three values indicate that the lens is working well for upper UV-A photography with suitable filters.

Spectral Transmission Graphs

UV-NIR, Super-Takumar 1:3.5/35
Attached Image: Screen Shot 2021-03-18 at 08.55.29 (1).png
The transmission measurement accuracy into the end of NIR range is less good due to limitations in the light source.

UV, Super-Takumar 1:3.5/35
Attached Image: Screen Shot 2021-03-18 at 08.56.29 (1).png

UV-Log, Super-Takumar 1:3.5/35
Attached Image: Screen Shot 2021-03-18 at 08.57.05 (1).png
Numerical Spectra Data available: Pending

General comments about the UV-reach:
This lens do not have a great UV-reach, but in the most common cases it still can be good enough.
If the sharpness is superior compared to other lenses, that might be a reason to use this lens instead of a less sharp lens with better UV-reach.

Filters and how to use them on this lens:
The front filter thread is 46mm standard filter thread.

It is also possible to use rear mounted filters, either in lens mount adapters for mirrorless cameras like Sony A-series etc, or placed directly in the camera.

An alternative, if space in the camera allows, is to putty-mount a filter directly against the lenses rear element mount ring. The rear lens element is recessed and thus safe and the ring provides a good reference plane for orienting the filter normal to the optic axis.


Handling and focussing:
TBD

Flare and sun-stars:
TBD

Sharpness:
High according to sources on the web

Lens distortion:
TBD

Chromatic Aberration in UV:
TBD
Ulf Wilhelmson
Curious and trying to see the invisible.

#2 Andy Perrin

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Posted 30 March 2021 - 15:59

I have the infamous 50mm/1.4 Super-Takumar with the radiation-yellowed glass. I take it this variant doesn’t have that issue.

#3 Andrea B.

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Posted 30 March 2021 - 18:12

Well, this one surprised me a bit! I'm thinking that because it is an older Takumar 35/3.5, it probably does not have the stronger UV blocking coatings of the Pentax SMC versions.
Andrea G. Blum
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#4 UlfW

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Posted 31 March 2021 - 04:21

View PostAndy Perrin, on 30 March 2021 - 15:59, said:

I have the infamous 50mm/1.4 Super-Takumar with the radiation-yellowed glass. I take it this variant doesn’t have that issue.
I don't think so.

I recently got a geiger counter so I can check.
Beside my Canon FD 35/2.0 SSC I have not found any significantly radioactive lens
Ulf Wilhelmson
Curious and trying to see the invisible.

#5 UlfW

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Posted 31 March 2021 - 04:28

View PostAndrea B., on 30 March 2021 - 18:12, said:

Well, this one surprised me a bit! I'm thinking that because it is an older Takumar 35/3.5, it probably does not have the stronger UV blocking coatings of the Pentax SMC versions.
It could be the glass types used that creates the cutoff, or possibly the cement in the cemented pair.
The very first version named Auto Takumar might be better. They can be found on eBay.
I can measure if someone pays for the lens. After the test I can forward it to the buyer.

For the moment I feel that my own need for more 35/3.5 is saturated.
There is no space left, not even for a thin slice of mint.
Ulf Wilhelmson
Curious and trying to see the invisible.

#6 OlDoinyo

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Posted 03 April 2021 - 16:54

I think you may have posted the wrong graphs above.

I have been using this lens for a while in the UV, even though I did not originally purchase it for this purpose. It may not have bandpass equal to the best performers in this class, but it is very sharp and seems to have minimal focus shift or chromatic aberration. It is also very compact and takes modestly-sized 49mm filters. IR and visible performance are also surprisingly respectable.

#7 UlfW

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Posted 03 April 2021 - 19:44

View PostOlDoinyo, on 03 April 2021 - 16:54, said:

I think you may have posted the wrong graphs above.

I have been using this lens for a while in the UV, even though I did not originally purchase it for this purpose. It may not have bandpass equal to the best performers in this class, but it is very sharp and seems to have minimal focus shift or chromatic aberration. It is also very compact and takes modestly-sized 49mm filters. IR and visible performance are also surprisingly respectable.
Thanks.
Corrected now

Originally it was the correct graphs.
When I later added indication lines at 365nm and 400nm to improve readability, I messed up.
All posts in the "normal" group should now have such lines, if I haven't made more mistakes.

That is nice to hear and what I hoped for when getting this lens.

Edited by UlfW, 03 April 2021 - 19:46.

Ulf Wilhelmson
Curious and trying to see the invisible.