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"X-ray" lenses for 1x-5x
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Lou Jost



Joined: 04 Sep 2015
Posts: 1798
Location: Ecuador

PostPosted: Wed Nov 01, 2017 8:48 am    Post subject: Reply with quote

I should add a note about the sellers of these lenses. The best seller, with a fantastic selection, good prices, and accurate descriptions, is
http://stores.ebay.com/Lens-Camera?_trksid=p2047675.l2563
Note their cosmetics and optics rating for each lens. If a lens is fungus-free, they will say it, and then you are protected by eBay if it turns out to have fungus. MANY of these fast lenses have fungus and it does not show up in typical eBay photos of the lens (you need dark-field illumination to see it). Some sellers may honestly be unaware of it. About half the ultra-fast "x-ray" lenses I bought have had fungus!! So always look for a statement that the lens is fungus-free.
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Choronzon



Joined: 21 Feb 2010
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Location: Chicago USA

PostPosted: Wed Nov 01, 2017 1:02 pm    Post subject: Reply with quote

Lou Jost wrote:
Interesting! I note the working distance is as bad as that of these x-ray lenses though.


We, yea, of course it would be since its a multi immersion objective with only 3.5 mm wd.
There is no market for this thing. Customers are far better off using a 10x plan apo multi immersion 0.50 na objective with a 5mm wd and stitching for large field.
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Chris S.
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Joined: 05 Apr 2009
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Location: Ohio, USA

PostPosted: Thu Nov 02, 2017 12:47 am    Post subject: Reply with quote

Lou, I really appreciate the information you're sharing in this thread!

Years ago, a friend gave me a lens of this type, a Kowa 1:0.75 /65 . He serviced medical imaging equipment, and took the lens from a machine that was about to be scrapped. He told me the lens was used to image small CRT screens.

I never could figure out how they used this lens for such a purpose. I did try some "free lensing" (hand-holding the lens in front of the camera), and got shots reminiscent of Haris' images--a style I'm not inclined to pursue further.

Until reading your post, I had no idea these lenses were meant to be used as pairs. Paired, reversed orientation makes a very different ballgame.

It seems clear how such a pair, oriented with wide ends inward, would act as a beam expander and beam concentrator, respectively. This seems to make sense in the case where a beam splitter is put in the space between them.

Yet you seem to be implying that such a pair of lenses may have additional desirable characteristics even when no beam splitter is used.This isn't so apparent to me. Could you explain? Do very large apertures still apply--and deliver high resolution--even though the nominally-rear opening used to take the picture is rather small? If you are focused very close, does this small opening still act like a large aperture?

Cheers,

--Chris S.
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Lou Jost



Joined: 04 Sep 2015
Posts: 1798
Location: Ecuador

PostPosted: Thu Nov 02, 2017 5:14 am    Post subject: Reply with quote

Quote:
Until reading your post, I had no idea these lenses were meant to be used as pairs. Paired, reversed orientation makes a very different ballgame.


This information was a game-changer for me too. I am a big fan of coupled lenses for use at m around 1 to 4, because of their significantly lower EA than the same lenses used alone with pure extension: EA= mf instead of m(f+1), which makes a big difference at low m.

The problem is that most lenses we normally use for macro aren't designed for this use. So I am always searching for combinations where the lenses ARE designed for this. These "x-ray" lenses are examples. (Other examples are the Zeiss stepper lenses for photolithography; they are really two beam expanders facing each other, in a single tube, hence their huge size in spite of small rear elements. Such an arrangement apparently permits better correction of lens aberrations, according to Zeiss.)

Quote:
If you are focused very close, does this small opening still act like a large aperture?


Yes Chris, think about it in terms of numerical aperture, which is the angle of the entrance cone of the light. For these lenses the numerical aperture is huge because they are so close.
https://www.microscopyu.com/microscopy-basics/numerical-aperture
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Andy Davies



Joined: 09 Dec 2014
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PostPosted: Thu Nov 02, 2017 5:39 pm    Post subject: Reply with quote

Has anyone looked at the lenses used by drum scanners?
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enricosavazzi



Joined: 21 Nov 2009
Posts: 854
Location: Stockholm, Sweden

PostPosted: Mon Nov 13, 2017 6:44 am    Post subject: Reply with quote

Andy Davies wrote:
Has anyone looked at the lenses used by drum scanners?

I should expect that they are extremely sharp on a minuscule image circle. Supposedly they just focus a small dot on the original onto a single-pixel sensor.

If the image circle is sufficiently large to cover Micro 4/3, then these lenses might be among the few potentially capable to outresolve the 50/80 Mpixel high-res mode of top-of-the-line Micro 4/3 cameras. However, more likely, they are only designed with a sub-mm sized subject and sensor area in mind. They might even have built-in baffles to cut out all the image circle except from the very center.
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kds315*



Joined: 02 Feb 2009
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PostPosted: Mon Nov 20, 2017 8:54 am    Post subject: Reply with quote

I have many of these lenses Xray and micro-litho, most of them unfortunately just great as paperweight or better, door stops. Soem are useful and I use(d) them. Some may be seen in my online collection, along with some data I could find (select "Special Lenses"): http://www.macrolenses.de/
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Klaus

http://www.macrolenses.de for macro and special lens info
http://www.pbase.com/kds315/uv_photos for UV Images and lens/filter info
http://photographyoftheinvisibleworld.blogspot.com/ my UV diary
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Lou Jost



Joined: 04 Sep 2015
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PostPosted: Mon Nov 20, 2017 9:32 am    Post subject: Reply with quote

I had read your posts about these. Sure, they are garbage if used far from their design point. But they are superb lenses when used properly. Granted, not everyone has an application where they will be useful.

I think they get a bad rap.
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kds315*



Joined: 02 Feb 2009
Posts: 174

PostPosted: Mon Nov 20, 2017 9:42 am    Post subject: Reply with quote

Lou Jost wrote:
I had read your posts about these. Sure, they are garbage if used far from their design point. But they are superb lenses when used properly. Granted, not everyone has an application where they will be useful.

I think they get a bad rap.


Agreed, most people are just getting nuts about their speed and try to use them for normal photography, with a high rate of disappointment. Well used,
those can work quite nicely... even just for effect at times (Carl Zeiss Jena 0.75/50mm):



Here a few of teh ones I have/had (rather old pic):

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Klaus

http://www.macrolenses.de for macro and special lens info
http://www.pbase.com/kds315/uv_photos for UV Images and lens/filter info
http://photographyoftheinvisibleworld.blogspot.com/ my UV diary


Last edited by kds315* on Mon Nov 20, 2017 9:51 am; edited 1 time in total
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Lou Jost



Joined: 04 Sep 2015
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Location: Ecuador

PostPosted: Mon Nov 20, 2017 9:50 am    Post subject: Reply with quote

My collection looks similar....but I really can use them for what they were intended. Even the fact that they are made to shoot through thick glass (4+mm) works to my advantage, since I need to shoot specimens through a few mm of liquid.
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kds315*



Joined: 02 Feb 2009
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PostPosted: Mon Nov 20, 2017 9:52 am    Post subject: Reply with quote

Lou Jost wrote:
My collection looks similar....but I really can use them for what they were intended. Even the fact that they are made to shoot through thick glass (4+mm) works to my advantage, since I need to shoot specimens through a few mm of liquid.


Great if that works for you!!
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Klaus

http://www.macrolenses.de for macro and special lens info
http://www.pbase.com/kds315/uv_photos for UV Images and lens/filter info
http://photographyoftheinvisibleworld.blogspot.com/ my UV diary
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kds315*



Joined: 02 Feb 2009
Posts: 174

PostPosted: Tue Nov 21, 2017 3:14 am    Post subject: Reply with quote

I have some collection of older RODENSTOCK XRAY Lens datasheets (Heligon, Rotelar etc. about 40MB) which I would be willing to share. I would upload them, if there is an interest....
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Klaus

http://www.macrolenses.de for macro and special lens info
http://www.pbase.com/kds315/uv_photos for UV Images and lens/filter info
http://photographyoftheinvisibleworld.blogspot.com/ my UV diary
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kds315*



Joined: 02 Feb 2009
Posts: 174

PostPosted: Tue Nov 21, 2017 3:40 am    Post subject: Reply with quote

Lou Jost wrote:
Quote:
Until reading your post, I had no idea these lenses were meant to be used as pairs. Paired, reversed orientation makes a very different ballgame.


This information was a game-changer for me too. I am a big fan of coupled lenses for use at m around 1 to 4, because of their significantly lower EA than the same lenses used alone with pure extension: EA= mf instead of m(f+1), which makes a big difference at low m.

The problem is that most lenses we normally use for macro aren't designed for this use. So I am always searching for combinations where the lenses ARE designed for this. These "x-ray" lenses are examples. (Other examples are the Zeiss stepper lenses for photolithography; they are really two beam expanders facing each other, in a single tube, hence their huge size in spite of small rear elements. Such an arrangement apparently permits better correction of lens aberrations, according to Zeiss.)

Quote:
If you are focused very close, does this small opening still act like a large aperture?


Yes Chris, think about it in terms of numerical aperture, which is the angle of the entrance cone of the light. For these lenses the numerical aperture is huge because they are so close.
https://www.microscopyu.com/microscopy-basics/numerical-aperture


Here the schematics for this so called "tandem" lens arrangement ...


C) Rodenstock


(C) Sydney F Ray

and here for a stepper lens:


(C) Shafer
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Klaus

http://www.macrolenses.de for macro and special lens info
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Lou Jost



Joined: 04 Sep 2015
Posts: 1798
Location: Ecuador

PostPosted: Tue Nov 21, 2017 4:48 am    Post subject: Reply with quote

Klaus, thanks for adding those. I wonder, what did the stepper lens designer mean when he said "on the fast end"? I assume he is talking about the wafer side (mask side would have an image circle of 4*27=108mm).

Note that stepper lenses such as the one shown in the diagram are not the ones appearing on eBay. The eBay ones belong to an earlier generation; they are optimized for longer wavelengths and have NA around 0.20-0.30.
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kds315*



Joined: 02 Feb 2009
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PostPosted: Tue Nov 21, 2017 6:20 am    Post subject: Reply with quote

Yes, my good friend Marco Cavina has researched and written about them, those older ones look like that (left/rightmost normal lenses for comparison), both S-Planar 436nm resp. 405nm:



and inside like that:



and in more detail:



all (C) Marco Cavina
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Klaus

http://www.macrolenses.de for macro and special lens info
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http://photographyoftheinvisibleworld.blogspot.com/ my UV diary
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