180mm f/1.4 - homemade focal reducer

[ZoneV]

Today I finalized my first good working focal reducer prototype.
My aim was to get a super fast telephoto lens with big blur. The actual lens speed in terms of T-stop is not that interesting for me.

I made different tests with several projection lenses (like the Visionar 183/1.9) and photographic taking lenses.
It was very fast clear, that Canon FD super tele lenses are ideal. With their easy replaceable back end it was possible to make a new back with my lathe and other tools. In this I could mount the focal reducer lens.
There I tried very different lenses, but the single lens and achromatic lenses did´t work well for my plan- image quality was bad. Even the triplet lenses did not get me the quality I want. So I tried more and more lenses, to get both a acceptable quality and enough working distance.
Cause I want to get a very fast lens for wideopen use, the simple focal reducer lens setups don´t work.

With my current setup the maximum working distance is low, about 2.5-3 meter. Fore some of my ideas this is sufficient.
It seems easy to update the back for Sony E mount, the Alpha 7 would get infinity! But I do not have this camera at the moment - first time I wish I would have it.

With an earlier setup and the Canon FD 300mm/2.8L as main lens I got something like a 135/1.4 or a bit faster. But with heavy IQ loss to the border, and curved image plane.

Now I use the FD 400mm/2.8L and get a 180mm lens with f/1.4 or even f/1.2. The image quality is much better - but yes, it is far away from a Canon EF 200/2 - but my lens is a full f-stop faster

The lens with focal reducer:


The focal reducer assembly:



Test - with 180mm/1.4


And with Nikkor AI-S 180mm/2.8 wideopen as comparison:


And some first images with it - made with Canon EOS 5D:





More images with full EOS 5D resolution here:
Homemade Focal Reducer

[SonicScot]

Very interesting

Good job

[Alex H]

Great work, Markus!

[kds315*]

Sorry, but I'm not impressed - sharpness even in the very center is lacking. Looks like there is some haze all over the image.
I made such experiments myself and those results would have not satisfied me.

[ZoneV]

[kds315*]

Maybe you could use flash to remove the noise that usually masks the results.
And it would clearly show how much CA was introduced - at least my findings.

[ZoneV]

Yes, I have to make few more test images - and use the lens for my real life photography.
The latter is what really tells me wheter I am statisfied or not.
Its huge and heavy, I did not want to carry this ~5.5 kg lens for mediocre results for example in flower or nude photography. At least I have dual use - I only need one/two minutes to change it back to original FD 400/2.8.

[LucisPictor]

Better light will show the real quality. It is an impressive project after all - and some clever thinking!

[ZoneV]

Made some images with flash - and now I am totally impressed


Full EOS 5D resolution test image


Full EOS 5D resolution test image

This speed booster / focal reducer / Shapley lens works much better than I thought. Even on the border the image quality is good enough for my images I think.
Probably I could manage to get a larger maximum focus distance even with the EOS 5D, or I need the Sony Alpha 7.

At least these images show that those Canon FD 400/2.8L (and 300/2.8L) have a much larger image circle with good quality.
I need to build my planned Kiev 60 adapter - this should be absolutly no problem for the FD 400 and 300/2.8. Probably even 60x90mm medium format could be used with this lens for 24x36mm

[kds315*]

Indeed, looks much better (as expected) as the noise is much less prominent now.

[ZoneV]

Thanks all!
Probably I make a comparison with my Rokkor 58/1.2 to wheter the DOF is f/1.2 or f/1.4.
From calculation I get clear f/1.2, from exposure time about f/1.4.
From back illumination through the camera, my first test illuminates the hole front diameter, which also leed to f/1.2. Probably I make a Laser beam test, to be sure nothing from front input diameter is lost on its way to the camera - want to be sure about the f-stop

[ZoneV]

I made the laser test: The DIY focal reducer transmitts all rays, even from the front lens edge. So the lens has f/1.2 at about 180mm focal length, and works fine on fullformat 24x36mm

Some other pre-testing with another lens got me ~135mm focal length. But the laser beam, and image DOF shows that I do not get the ~f/1.0, but only f/1.2 or f/1.4. I am working on it.

[KingRoach]

The DIYness of the project itself is impressive. Not that you would compare the results at this level to high-end prosumer products made by an industry with an army of opticians and everything at its disposal including hard to get materials to actually MAKE the glass rather than use something via an adapter...

I applaud the effort and thinking.

Could you tell more about the lenses you added and why you chose them? You said something about triplets. Your logic behind lens-choice could help others make something up as well. I've always wanted to do something like this. (and I already have an FD 400mm f2.8, I don't think this 5kg chuck of glass and metal is going anywhere outdoors soon, though!!)

I want to hear more details about your project please.

[ZoneV]

Thank you very much!
At the moment I do not want to tell the focal reducer lens setup, sorry. Need some time to have this fastest lens in this range for me

I want to show here that the usable image circle some lenses have is much more than stated - it is a full format lens now used with 95mm image circle (at closer distances). So the FD 400/2.8L is usable as a medium format lens with at least 6x6cm film with good results.

Furthermore it is possible to make a DIY focal reducer which gives good results in a extreme fast f/1.2 resulting lens for full format. And this even with a 0.45 factor - not only the 0.71 factor the Metabones Speed Booster has (they don´t need more).

Yesterday I was on a walk with the lens. During this I saw the moment hot glued mount was loose :-/
I have forgotten to glue it properly to the lens, how I did in the earlier prototype states. No big problem to fix, but not good for image capturing with this heavy lens.

I took this event to optimize the lens a bit, turning the lens some millimeters shorter.
I was a bit in as hurry because of my child which was with me in my workshop.
Now the lens was a bit more protruding into the camera, but this should still clear the mirror, no need to modify the lens housing there.

Afterwards during the test images I noticed that the mirror seems to get caught, even with extension tubes - strange. But I worked on.
Big Mistake!
At some point the camera quit to react - it is dead now!
It seems very much like I have blown a fuse :-/

Positive thing: It was not one short thing that blow the fuse, it has warned me. If I only have reacted and inspected the mount, it would most likely would still work.

Now I need to disassemble the camera, and measure the fuses. And then I need to get a new small fuse. And solder it in place. Not the work I like to do

[KingRoach]

Ooooh sorry to hear about your camera. Hope you've been able to sort it out by now. Please let us know what the problem has been and how you solved it (fuse? really?) and also take pictures of the repair to help others.

Looking forward to hearing more about this.

[ZoneV]

Found no time yet - I think I need at last 2-3 hours free time with no kids around. Don´t want to have a break between the disassembly and assembly of the camera
Got the fuse, its very small, in case I cant solder this a friend has offered to help

At the moment I use the camera my wife normally has, so no need to rush.

[araucaria]

Great job! How big is the change in focal distance?

[ZoneV]

Original 400mm now 180mm - 220mm difference - or more helpful factor 0.45 for focal length and f-stop.
Easy replaceable adapter, no modification on the Canon FD lens made for this.

[araucaria]

Nice, I actually wanted to mean the focus distance.

[ZoneV]

Ah, at the moment maximum object distance around 3 meter on EOS 5D. Not much for 180mm :-/
On a Sony Alpah 7 Infinity should be no problem, have ordered material for the mount, probably I get the possibility to get a Alpha 7 for some tests in few months.

I will try to get another combination, probably with less speed but infinity which works up to infinity on my 5D.
Much testing with different lenses needed, try to get some more lenses as possible better focal reducer - but this testing is a bit expensive.

[lensfan1]

Interesting project.
Would be interesting how its done.

[ZoneV]

[araucaria]

Good to hear you were able to fix your camera. You got a PM

[ZoneV]

[Blazer0ne]

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