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  #11  
Old 1st November 2021, 07:42 PM
snusmumriken snusmumriken is offline
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Quote:
Originally Posted by Mike O'Pray View Post
Thanks Alex That was what I had assumed, namely set to infinity and held there with a click stop

Mike
I don't understand the optics of that arrangement, I must admit. The back focus of a camera lens (its focal length) is the distance between the optical centre of the lens and the film. If a camera lens is mounted on the enlarger facing outwards, as if in the camera, the negative would be in focus when the distance between the lens and the negative is equal to the focal length, wouldn't it? It's that distance that the bellows alters. So then we are assuming that the enlarger baseboard, which is maybe 25 cm away, is actually at infinity?

I really hope someone wise out there can explain this!
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  #12  
Old 1st November 2021, 07:43 PM
Michael Michael is offline
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When my Valoy 2 arrived in April, I did try a 5cm Elmar in it out of interest. I couldn't get focus on any projection larger than about 6x4, as I recall. Fortunately a kind friend from here had sent me three 50mm enlarger lenses (the Valoy came with a poor Focotar copying lens), which took my mind off further Elmar experiments.
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  #13  
Old 1st November 2021, 09:10 PM
egrabczewski egrabczewski is offline
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Wow! what fascinating replies. You've certainly answered my question. Thanks everyone!

Eddy
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  #14  
Old 1st November 2021, 10:16 PM
John King John King is offline
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Default Enlarging lenses.

One point that has been missed and it was one pressed home to me in the early days when I was learning the trade was the heat from an enlarger lamp during long exposures could in some cases de-laminate elements that were cemented together.

I have never tried it, but reversing a lens so the rear element was the front element was reputed to make a very good macro lens, so apart from the point I made at the start of this post it was suggested that a camera optic could successfully be used as a enlarging lens.
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  #15  
Old 2nd November 2021, 08:18 AM
Lostlabours Lostlabours is offline
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Originally Posted by John King View Post
I have never tried it, but reversing a lens so the rear element was the front element was reputed to make a very good macro lens, so apart from the point I made at the start of this post it was suggested that a camera optic could successfully be used as a enlarging lens.
Whileat shcool I did a lot of Macro work reversing the 58mm Helios on bellows with my Zenit E and the results were OK, later I used an enlarger lens which was better still. I used the enlarger lens for slide copying as well.

I seem to remember books and AP articles saying the best 35mm standard lenses lenses to reverse for Macro work were Tessars but I didn't have one.

Ian
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  #16  
Old 8th December 2022, 09:50 PM
JOReynolds JOReynolds is offline
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Quote:
Originally Posted by Mike O'Pray View Post
Thanks Alex That was what I had assumed, namely set to infinity and held there with a click stop

Mike
a typical camera lens has a helical focussing mechanism that moves the entire assembly back and forth with respect to the film plane. There is no click stop. In the enlarger the helical screw is not used.
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  #17  
Old 8th December 2022, 10:25 PM
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Petrochemist Petrochemist is offline
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Quote:
Originally Posted by snusmumriken View Post
I've always understood that it is because the design constraints for enlarger lenses require both image plane and object plane to be very flat. For a camera lens, other considerations like maximum aperture may be more important than a flat object plane.

The famous Soviet Zenit suitcase enlarger did indeed function with their Industar or Helios camera lenses. I never had one of those enlargers, but I wasn't very impressed with the Industar lens even on the camera.
This flat field of focus is indeed one of the features of enlarger lens design & helps explain why enlarger lenses are effective for shooting macro.

In the early days of enlargers it was quite normal to use the camera lens in the enlarger as well. I think I've also read of early LF cameras being used as enlargers something I might try myself further down the line as I can't afford a 5x4 enlarger. Rigging the negative into the rear standard should be simple enough, but finding a bright EVEN light source to work with it might prove more difficult...
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  #18  
Old 8th December 2022, 10:37 PM
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Quote:
Originally Posted by JOReynolds View Post
a typical camera lens has a helical focussing mechanism that moves the entire assembly back and forth with respect to the film plane. There is no click stop. In the enlarger the helical screw is not used.
Block focusing like that it typical for manual focus lenses, but autofocus tends to encourage lighter moving parts to reduce motor loading so internal focusing designs are more typical in modern lenses.
Click stops are common in enlarger apertures, but (like my bellows lenses for cameras) they don't usually have any form of focus control built into the lens. I think all the enlargers I've seen use a rack & pinion focus control, but no doubt there are exceptions!
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  #19  
Old 9th December 2022, 01:17 AM
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Reginald S Reginald S is offline
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Let's make this old thread more complicated

I wouldn't call lenses "typical camera" lenses because of their wide field of characteres and usages, but each lens could be used as a camera lens - or an enlarging lens. Even a simple meniscus lens:-)
It depends on personal recommandations (quality aspects) and of course on the lens design.
The image circle of the lens also may give restrictions to the projection if big enlargements are wanted.

The ancient Angulon (90mm) spreads his focus to a semi-sphere because of it's spherical miscorrection called "Kugelgestaltfehler" in german's optical physics.
So it is more difficult to bring in focus, but of great advantage if you want to focus a semi-spherical subject like interiours or let's say the inside of a watertank.
It is a fixfocus lens with a wide angel of view, and for focusing you have to use a bellows.
I wouldn't recommend lenses with lots of optical miscorrections but if there is no other lens on hand some light will shine onto the easel, yes.

Looking onto these old folder cameras they often come with a lens with helicoil focusing but fix bellows.
If you want to become insane please bring the lens to a camera (or an enlarger) with a moveable front standard.
So for such moveable cameras (RB67, LF cameras..) fixfocus lenses are typical.

All types of camera lenses are designed to bring a mostly large subject (portrait, landscape) to a small film plane or digital sensor (ratio) which the lens engeneer has to have in mind.
You will find best performance way beyond 1:1 ratio, I don't remember the typical numbers.
Looking for best enlargements here you generally will find the reason not to use those camera lenses as enlarging lenses.

But as said earlier in this thread (and concerning to that optical law that everything will also work to the other direction if the lens direction is changed) the 180 degree "retro" position of a camera lens should give good enough enlarging lense - except lenses with a symmetrical design of the lens cells in an optical sense. No direction's change necessary because of no physical effect there.

"Repro" (reproduction) lenses like the Ronar family are designed for best performance at 1:1 ratio but normally perform well as camera lenses, too.
Rodenstock has sold repro lenses as camera lenses, using a woodoo trick with bringing very thin chims between lens cells and shutter.

Since a reproduction typically is a kind of procection in the sense of starting from a twodimensional plane/bringing the image to a twodimensional plane I can't see repro lenses working bad as enlarging lenses.
Enlargements are projections.
But enlarging lenses are typically used for enlarging a smaller source (negative) which means the ratio design for giving best enlarging performance changes, too.

Repro lenses and projection lenses on the other hand are designed to bring the focus to a flat plane (called Flachzeichner in germany) which should cover your (not mine) needs while enlarging.

I have no experience with color enlargements but concerning chromatic abberations I would consider an Apo lens.

Last edited by Reginald S; 9th December 2022 at 01:26 AM.
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  #20  
Old 9th December 2022, 08:25 AM
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Quote:
Originally Posted by Reginald S View Post
Repro lenses and projection lenses on the other hand are designed to bring the focus to a flat plane (called Flachzeichner in germany) which should cover your (not mine) needs while enlarging.
I'd never considered trying a projection lens for enlarging. They are often quite fast so might make sourcing a suitable light source easier, but I suspect getting good enough focus might prove challenging.
You've given me another reason to get on with mounting my huge (2.2kg) TV projection lens, if it's 'Flachzeichner' it will be able to make interesting images in ways I hadn't considered. - Probably something any lens can do in all honesty, but the range of possibilities expands further.
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