Pentax Quartz Takumar f3.5 85mm in use

kds315* · Expire: 2021-03-09

Today on some astonishingly sunny day, I took the Quartz Takumar f3.5 85mm out of my "lens vault" and made a few shots with it.

The questions was, how the image quality would turn out, knowing that such type of lenses can usually only be used for a quite
narrow wavelength band (literature states between 10nm and 20nm depending on source), as these lenses are not chromatically
corrected. All shots were done stopped down to f8, which is a usual working aperture to get enough DOF and sharpness.

Here some results:

visible light image using UV/IR cut filter:

multispectral image (i.e. unfiltered) and sunlight:

UV image using Baader-U filter and sunlight:

UV image using Baader-U filter and sunlight + 365nm UV LED:

Findings:
1) There is a substantial focusing difference, here 5mm between the UV (95mm) and the VIS image (100mm between front and
camera mount), resulting in a 5% different image size when focused both (UV image is smaller). Distance orchid - camera was
700mm.

2) When white light is being used for visible photography, the 400-750nm band is quite broad, i.e. 350nm, which leads to quite
visible CA (around edges), soft image and loss of contrast.

3) When white light is being used for multispectral (i.e. unfiltered ca 300-1100nm) photography, that band is even broader,
leading to even softer images and loss of contrast.

4) Also the UV image taken in sunlight using a Baader-U filter (320-395nm i.e. 75nm bandwith) leads to rather soft images,
but a bit better as the band is narrower, only 75nm wide.

5) The UV image taken in UV LED light at 365nm (ca 20nm bandwith) using a Baader-U filter leads to the best image, as here
only the narrow 20nm bandwith of the UV LED around 365nm plays a role. The image is crisp, sharp (see structures on petals)
and has a rather high contrast.

Conclusion is, that only if quasi monochromatic photography is being done (either using narrowband UV filters or narrowband UV
light), acceptable results can be expected. For broadband UV photography, chromatically corrected UV lenses are required, such
as quartz fluorite lenses.

Spotmatic · Joined: 18 Aug 2008 Posts: 4045 Location: Netherlands

Thanks for sharing, again I have learned something new from you.

So to sum up this lens is not suitable for normal photography but the Ultra-Achromatic Takumar is? Someone should tell that to the director of "You Only Live Twice", a James Bond movie from 1967... (Here it's installed in a Toyota 2000 GT to show off the Japanese car, electronics and photography industry):

kds315* · Expire: 2021-03-09

Since I'm sure this question will come up, here the link to my lens from my macrolenses database:
http://macrolenses.de/ml_detail_sl.php?ObjektiveNr=238