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An 85mm f1.2\f1 Lens Made for work with Laser equipment
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PostPosted: Wed Jan 04, 2012 9:43 am    Post subject: An 85mm f1.2\f1 Lens Made for work with Laser equipment Reply with quote
I dont know nothing about this one, only that i have adaped it so i can use it on my canon 60d.]

Got it in a junk store witch sells electronics by weight..
The lens cannot reach infinity on 60d, only if used on NEX type with closer register distance.

I would very like some help in understanding the optical formula of this lens, and comparing it to a known optical design.

Also in comparing its aperture number, i figured its gotta be more than f1.4 because it is so bright, but any instructions or tips in figuring out its brightness would be very much appreciated, and ill test it here.

I HAVE ALOT OF PICS ONCE AGAIN, so, sorry for that Very Happy

here it is compared in size to Jupiter 9, and 50mm Tak:





Here Im removing the retaining ring for the BACK element/cemented elements group

this is the element


Now its side by side with the Front element group, its a huge piece of glass very thick and heavy



This is the way they are aligned inside the barrel


now i have returned all the elements back into the barrel and i want to show how i adapter this for mt EOS mount

M42 to EOS Adapter

Ready for shooting!!

I can make with no problem a Focusing Helicoid for this one, and i already have a very good idea how



Now for a few shots with this beast, i doesnt flare at all good coatings and overall good colors.







These are with shot under a mere 20W fluorescent light bulb!






Another Cyclops?!




Laughing


PostPosted: Wed Jan 04, 2012 10:04 am    Post subject: Reply with quote
Looks like a f-theta scan lens to me, which has a different projection that normal taking lenses.
Usually those are not color corrected, so only useful around the designed wavelength (esp. for
lasers), so they have massive CA is used with white light.

You pictures show both effects btw.


PostPosted: Wed Jan 04, 2012 10:05 am    Post subject: Reply with quote
Wow, what a beautiful lens and stunning results, this is perhaps the smoothest bokeh I have seen, and it is certainly sharp in centre. Reminds me of Petzval type projector lens I have in how it renders.

I think it is a Petzval type lens, front and read cemented doublets. With the huge size, you could fit an aperture in there between the elements with some work.



PostPosted: Wed Jan 04, 2012 12:14 pm    Post subject: Reply with quote
Yes very silimar design to what you have posted Ian, and i looked up F-theta scanning lenses, and they look almost identical to this lens.

man do i wish for nex camera right now or what....

klaus about the CA, there is slight a slight hint but honestly i didnt see massive amounts and i cant see something that stands out in the pictures.
but the projection does seems unusual to normal taking lenses. i wish i could test it with further subjects....


PostPosted: Wed Jan 04, 2012 3:03 pm    Post subject: Reply with quote
Holy Cyclop .... 85mm f/1 ??? ... Woww .... and it looks quite OK too.

How far is the focus distance using 60D ?

Thanks a lot for sharing ...


PostPosted: Wed Jan 04, 2012 3:20 pm    Post subject: Reply with quote
Nice experiments... I somehow like the slight surreal look of the results.


PostPosted: Wed Jan 04, 2012 4:16 pm    Post subject: Reply with quote
about 1 meter Sad
Maybe you know some trick i can do to make it focus further and them build a helicoid for it? like those adapters with glass elements?


PostPosted: Wed Jan 04, 2012 6:31 pm    Post subject: Reply with quote
Smoli4 wrote:
Yes very silimar design to what you have posted Ian, and i looked up F-theta scanning lenses, and they look almost identical to this lens.

man do i wish for nex camera right now or what....

klaus about the CA, there is slight a slight hint but honestly i didnt see massive amounts and i cant see something that stands out in the pictures.
but the projection does seems unusual to normal taking lenses. i wish i could test it with further subjects....


You picture of the spring is quite a dead giveaway for CA. It gets all green on top.
Same on the cats whiskers in cat image #2. Bit actually you are right, it is not as
bad as I had expected.

Last edited by kds315* on Wed Jan 04, 2012 6:38 pm; edited 1 time in total


PostPosted: Wed Jan 04, 2012 6:34 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
Wow, what a beautiful lens and stunning results, this is perhaps the smoothest bokeh I have seen, and it is certainly sharp in centre. Reminds me of Petzval type projector lens I have in how it renders.

I think it is a Petzval type lens, front and read cemented doublets. With the huge size, you could fit an aperture in there between the elements with some work.


Ian, take a look at the lens scheme before you type: the rear elements of a Petzval lens are NOT cemented.

I honestly doubt that this laser lens is a Petzval design, it looks like a 3e/2g design to me


PostPosted: Wed Jan 04, 2012 7:42 pm    Post subject: Reply with quote
Klaus, read what I wrote carefully before you condescend.

I wrote 'Petzval type' not 'Petzval'. I have quite a few 'Petzval type' lenses and I've had most of them apart for cleaning, most had both groups cemented.

The Petzval type isn't one specific design, it has been slightly modified by many makers, hence I used 'type' to designate this family of modifications based on the original Petzval design.

This is all rather pedantic though, n'est pa?

smoli can clarify whether there are one or two elements in the rear of his lens.


PostPosted: Wed Jan 04, 2012 8:18 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:

I wrote 'Petzval type' not 'Petzval'. I have quite a few 'Petzval type' lenses and I've had most of them apart for cleaning, most had both groups cemented.


But then it is no Petzval type - the air space is necessary for the design, dropping it does result in a lens with quite different characteristics. Even if some ebay sellers would like to extend the definition to every coke bottle bottom in their drawers, only Petzvals are in fact Petzvals. You may want to re-check whether your double-cemented "Petzvals" aren't really of the (much more widespread) RR/Aplanat type.


PostPosted: Wed Jan 04, 2012 8:22 pm    Post subject: Reply with quote
nixland wrote:
Holy Cyclop .... 85mm f/1 ???


Field lenses almost always are f/1, due to the way they are typically used (where their aperture must be bigger than either image or object). They are the opposite of a flat field lens - their purpose is to counteract the curvature of some optical system.


PostPosted: Wed Jan 04, 2012 9:25 pm    Post subject: Reply with quote
About this lens optical design.
I cant really tell if the rear element\s is a one piece or a cemented group.

correct me if im wrong, but most of the time when 2 lenses are cemented you could see under some angle and light, a round Circle reflecting inside the glass. ?

well if this should happen every single time with all cemented elements, then its not happening with this rear group.
But if it shouldn't happen every single time, then the rear element looks like its constructed from 2 slightly different diameter lenses and both will have to be concave elements.

Last edited by Smoli4 on Wed Jan 04, 2012 10:10 pm; edited 1 time in total


PostPosted: Wed Jan 04, 2012 10:05 pm    Post subject: Reply with quote
http://www.antiquecameras.net/petzvallens.html


Quote:
The next Petzval variation was in 1878 by Voigtlander. This design basically eliminated the air space in the rear group of Petzval's original design. Removing the air space was to help improve contrast and reduce flare, over Petzval's original design, but from actual accounts, the improvements appeared minimal and the lens wasnt quite as sharp as other Petzval lenses.

Hermann Wilhelm Vogel wrote in his book, The Progress of Photography Since the Year 1879;

"Voigtlander's new Portrait Lens.—This has a front combination similar to the old Petzval. But the back combination consists of two single lenses cemented, by which the reflection of light occurring in the old form with separated lenses is avoided. The focus of these lenses is relatively shorter than that of the old form with similar opening. For instance, Voigtlander's C lens, by substituting the new back combination, has its focus shortened from 10 inches to 7 1/2 inches, thus increasing the illumination in the proportion 9:16. The new back combinations may be bought separately, so as to be used with any lenses by the same maker. We thus have the power to shorten or lengthen the focus, and correspondingly increase or lessen the light at will, by using the new form of back combination."
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