[weverka]

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I just purchased a used Pentax Takumar/Super-Multi-Coated Takumar 500mm F4.5 lens from a PF member. I paid $200 for it. It's a nice clean copy.


A few months ago I purchased a Kalimar MC 500mm F8 mirror lens. I also paid around $200 for it.


Today I took them both out and shot some photos with them on my Pentax K-1 to see which one I prefer the IQ on.


Obviously, the bokeh balls produced by a mirror lens are an acquired taste. I happen to like the little donuts for certain scenes.
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Thank you for this contribution. I've been meaning to do a long lens comparison, but I am still expanding my collection in preparation. I had a 500mm CAT that was messed up and replaced it with a solid CAT. When I get around to it, I also want to compare performance with the AF adapter. I have had some success getting final focus with F4 lenses and the 1.7x AF adapter with good light.

Here is another fundamental question I hope to answer with some experimentation. Under what conditions is the atmosphere itself the limiting factor in resolving detail? When astronomers look straight up through the atmosphere, an aperture larger than 4 inches is likely to have atmospheric distortions blurring the image, unless conditions are really good. So when we look horizontally through the atmosphere, over hot ground, or over a lake, the atmosphere may be giving us a limit.

thanks again for your comparison,
Teddy

SMC Takumar 6x7 600mm F4
SMC Pentax 500mm F4.5
Perkin-Elmer 600mm/f8 Solid Cat
Meyer OPTIK Gorlitz Telemegor 400mm F5.5
Celestron 9.25" edge (2350mm focal length)

SMC Pentax-F 1.7x AF Adapter

[barondla]

Thank you for this contribution. I've been meaning to do a long lens comparison, but I am still expanding my collection in preparation. I had a 500mm CAT that was messed up and replaced it with a solid CAT. When I get around to it, I also want to compare performance with the AF adapter. I have had some success getting final focus with F4 lenses and the 1.7x AF adapter with good light.

Here is another fundamental question I hope to answer with some experimentation. Under what conditions is the atmosphere itself the limiting factor in resolving detail? When astronomers look straight up through the atmosphere, an aperture larger than 4 inches is likely to have atmospheric distortions blurring the image, unless conditions are really good. So when we look horizontally through the atmosphere, over hot ground, or over a lake, the atmosphere may be giving us a limit.

thanks again for your comparison,
Teddy

SMC Takumar 6x7 600mm F4
SMC Pentax 500mm F4.5
Perkin-Elmer 600mm/f8 Solid Cat
Meyer OPTIK Gorlitz Telemegor 400mm F5.5
Celestron 9.25" edge (2350mm focal length)

SMC Pentax-F 1.7x AF Adapter

There are days the atmosphere is so bad any long lens will be incapable of taking sharp distant images. The closer a subject is the better, just like underwater photography.

Curious to know how well the 6x7 600 f4 performs on APS-C or full frame?
Thanks,
barondla

[weverka]

There are days the atmosphere is so bad any long lens will be incapable of taking sharp distant images. The closer a subject is the better, just like underwater photography.

Curious to know how well the 6x7 600 f4 performs on APS-C or full frame?
Thanks,
barondla

(standard warnings about difficulty of focus and shake for large aperture long lens apply. These used live view zoom to focus, a tripod, and a timer to wait for oscillations to damp out.)
Shot at f4, 1/200 s ISO100, SMC Takumar 6x7 600mm F4 with adaptor for a Pentax K1.

So far I have only shot it on full frame and I like the results. here is the NCAR building in Boulder from the high school across the way, full frame and crop. I have also shot it with the 1.7 AF adapter. I am looking at getting a Pentax 67 so I can compare the film. It seems such a waste to capture only 24x35 mm out of 60x70 mm (90mm image circle).

cheers,
Teddy

[barondla]

(standard warnings about difficulty of focus and shake for large aperture long lens apply. These used live view zoom to focus, a tripod, and a timer to wait for oscillations to damp out.)
Shot at f4, 1/200 s ISO100, SMC Takumar 6x7 600mm F4 with adaptor for a Pentax K1.

So far I have only shot it on full frame and I like the results. here is the NCAR building in Boulder from the high school across the way, full frame and crop. I have also shot it with the 1.7 AF adapter. I am looking at getting a Pentax 67 so I can compare the film. It seems such a waste to capture only 24x35 mm out of 60x70 mm (90mm image circle).

cheers,
Teddy

Results look promising. It is a huge lens to photograph with. Pics with 6x7 would be interesting. Might be more difficult to focus without live view.You might consider a Pentax 645 digital body. It would use more of the lens than full frame, but less the 6x7.

Thanks for the info & example,
barondla

[Fenwoodian]

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Here's a photo I took of a gentleman next to a stream using the above mirror lens. While not this mirror lens is not quite as sharp as the Pentax 500/4.5 lens, it's not too bad. So, if one can live with the bokeh ball "donuts", maybe the mirror lens is an option worth considering (especially when you consider the difference in weight)?

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[weverka]

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I just purchased a used Pentax Takumar/Super-Multi-Coated Takumar 500mm F4.5 lens from a PF member. I paid $200 for it. It's a nice clean copy.
A few months ago I purchased a Kalimar MC 500mm F8 mirror lens. I also paid around $200 for it.
Today I took them both out and shot some photos with them on my Pentax K-1 to see which one I prefer the IQ on ....


So, my conclusion is, if you've only got a couple of hundred to spend on an extreme telephoto, as long as you are OK with manual focus and the huge size/weight of the Takumar, the Takumar definitely produces the better images.
[/SIZE]

Thanks for this. This inspired me to compare my Takumar/Super-Multi-Coated Takumar 500mm F4.5 lens to my Perkin Elmer 600mm solid Cat. I got comparable photos from both. I'm still processing the results, but I found I am pretty happy with the solid Cat, and I'll keep them both.

The Takumar shakes more because it sticks out. The Rear Converter-A 2x-L fits on the Takumar and does a nice job. I'll post tonight's moon photo in the astro pages.


For kicks, I also compared my pentax FA 70-200 and zoomed in post and also tried the 1.7x AF with it. The

[ZombieArmy]

You can also find pretty sharp mirror lenses. I use my mirror lens mainly for astro stuff.

[MalcS]

Mirror lenses are quite similar to some astronomical telescopes, namely Schmidt Cassegrains, and Maksutovs.

The first ‘problem’ they have is they are quite obstructed. The central obstruction is maybe 35-40%, and causes a reduction in contrast.
The second problem is that their aperture to focal length ratio is usually quite high, as in F8 or worse, which makes focusing difficult, and results in longer exposure times, which can be problematic due to long focal length (ie vibration/shake). The aperture is also fixed.
The third problem is that for economy of manufacture, the mirrors are made with a spherical figure, rather than parabolic, which leads to spherical abberations. The front glass element is supposed to correct for that, but...with varying success.
Lastly, in camera lens configuration there are additional lenses in the construction that don’t appear in telescopes at all, to make the image is right side up and correct left to right as well, and hopefully bringing the image to focus over the entire area of the film or image sensor (flat field).

As an aside, a photographic Schmidt cassegrain telescope known as a Schmidt camera had an image plane so curved that the film (back in the day) had to be fitted to a curved film holder in order that the entire image be in focus.

At the end of the day, mirror lenses are a compromise in many ways, and the price is generally very low, so you know something has to give. I would expect the takumar to be superior in almost every way, though it will be prone to chromatic aberration (color fringing) due to the age of its design and no ED elements, and it’s length makes it susceptible to vibration/shake unless well supported.

Just my $0.02...

[weverka]

Mirror lenses are quite similar to some astronomical telescopes, namely Schmidt Cassegrains, and Maksutovs.
...
As an aside, a photographic Schmidt cassegrain telescope known as a Schmidt camera had an image plane so curved that the film (back in the day) had to be fitted to a curved film holder in order that the entire image be in focus.
...
Just my $0.02...

A curved focal plane is still a good solution. NASA - Kepler Focal Plane Array

[Wasp]

The thing is, an astronomical telescope doesn't need to have a focusing mechanism. The celestial bodies are pretty much at infinity. A camera lens need extra glass to focus. This messes up the elegant simplicity of the Schmidt Cassegrain design.

[MalcS]

A curved focal plane is still a good solution. NASA - Kepler Focal Plane Array

Indeed, keeps it simple and no need for a hyper expensive image degrading optical solution.