Reflective enlarger

mvons · Jul 30, 2021

Hi,

I saw that it is possible to enlarge paper negatives. I also saw some thread here about that but due to fact that most of those threads were quite old the photos are lost.
I would like to try built reflective enlarger but here is a thing. I am really newbie with this. Does anybody have "blueprints" for that? What lens i should use to enlarge reflected image?
Could it be an old lens from camera?
Could anyone show their enlarger that I could inspire?

Thank you!

pentaxuser · Jul 30, 2021

That's a new one on me but very interesting. I have never heard of being able to make enlargements from paper negatives. Can you say where you saw this and remember anything more about it?

Thanks

pentaxuser

cramej · Jul 30, 2021

Look up designs for an opaque projector. There are new ones out there such as the Braun Paxiscope. I remember using an old one back in the early 90's to enlarge a map on to a poster.

Donald Qualls · Jul 30, 2021

We had opaque projectors when I was in grade school in the 1960s, and the one my school had was old then.

You need a big first surface mirror, a large lens (for enlarging, it would need to be of good quality, at least an actual projection lens), and an extremely bright light source (which with LED would at least require much less power and produce much less heat than it would have back when incandescent was the only practical choice). You'll most likely need a glass plate to keep the original flat under the light.

pentaxuser · Jul 30, 2021

cramej, can the Paxiscope in that sense perform the same function as an enlarger and successfully turn a paper negative of whatever size into a positive print on an easel to the same quality print as that achieved from a film negative in an enlarger?

Thanks

pentaxuser

cramej · Jul 30, 2021

pentaxuser said:
cramej, can the Paxiscope in that sense perform the same function as an enlarger and successfully turn a paper negative of whatever size into a positive print on an easel to the same quality print as that achieved from a film negative in an enlarger?

Thanks

pentaxuser

Same quality? Maybe not. I've not used a Paxiscope but I believe Braun is the same Braun that makes some film scanners and other optical devices. The lens is probably decent but not up to the quality of an enlarging lens.

Donald Qualls · Jul 30, 2021

Generally, projection lenses don't need to be as sharp as either film exposure lenses or enlarging lenses, because although there's a lot of magnification involved, those viewing the image will see it from a considerable distance -- the apparent size is comparable to an 8x10 or so print at a comfortable viewing distance (far enough the older ones of us wouldn't need our bifocals). Still, it'll be better than, say, a condenser lens or quizzing glass type magnifier; it's probably a two to four element lens with minimal chromatic aberration (as that's very visible in projection) and somewhat controls spherical aberration and coma -- offset by being much faster than optimum for the formula used.

cramej · Jul 30, 2021

Donald Qualls said:
Generally, projection lenses don't need to be as sharp as either film exposure lenses or enlarging lenses, because although there's a lot of magnification involved, those viewing the image will see it from a considerable distance -- the apparent size is comparable to an 8x10 or so print at a comfortable viewing distance (far enough the older ones of us wouldn't need our bifocals). Still, it'll be better than, say, a condenser lens or quizzing glass type magnifier; it's probably a two to four element lens with minimal chromatic aberration (as that's very visible in projection) and somewhat controls spherical aberration and coma -- offset by being much faster than optimum for the formula used.

Hmm, I wonder if the sharpness could be improved on one by fabricating a smaller aperture to place behind the lens?

AgX · Jul 30, 2021

A reflective enlarger, in classic built, thus no episcope, is no new idea. After WWII when films were scarce in Europe and standard camera-film emulsion was coated on cardboard, to make enlargements from this a dedicated reflective enlarger was used.

Doremus Scudder · Jul 30, 2021

Seems to me that it would be easier, and likely of better quality, to simply make a contact internegative and then enlarge that conventionally.

Doremus

Bill Burk · Jul 30, 2021

Have you seen the street cameras? The solution is to put a copy board on your camera and take a picture of your paper negative.

AgX · Jul 30, 2021

cramej said:
I believe Braun is the same Braun that makes some film scanners and other optical devices. The lens is probably decent but not up to the quality of an enlarging lens.

There were two Braun companies in Germany: the "design" Braun, with an elecronic tube in their name, started with audio-electronics and later made electronic flashlights too and acquired the cine-camera manufacturer Niezold. The other Braun company, with an achromat as icon, started with cameras. Both firms made projectors too. Here the latter Braun is referred to.

cullah · Jul 30, 2021

I once had a job using a Cruse or cruze camera It was a wonderous machine. It enlarged whatever you put onto the table directly onto a piece of color paper. You could make a print 4x8 foot enlargement or any size, for that matter. This was back in the early 90's. Since there was no interneg, it was sharp as a tack. The place I worked with it was Charrett. I wish I still had access to one. Good luck.

AgX · Jul 31, 2021

Basically there are 2 types of reflective projectors:

-) Episcope
a closed stage and and horizontal projection
triplet lens in proprietary mount and no aperture
there is however a model that could be mounted on a vertical collumn to achieve vertical projection

-) reflective enlarger
Built as a photographic enlarger with the feature of having a stage made for reflective illumination

removed account4 · Jul 31, 2021

here are a few links on building and using a reflective enlarger
https://www.photrio.com/forum/threads/paper-negative-enlarger-prototype.122382/#post-1620173
https://www.photrio.com/forum/group...aper-negatives.13415/discussion#m-13415

have fuN!
John

Nicholas Lindan · Aug 13, 2021

You could try a process camera. Vertical ones are reasonably compact (as compared to horizontal ones) - about the size of a large appliance.

geirtbr · May 28, 2025

I once did this with an Braun Paxiscope XL! I remember i enlarged some instax photos on black and white paper. Got it to work, but I had to dim down the bulb maximum with an ikea dimmer, and also make a custom diafragm (cardboard with a hole) that i placed in front or behind the lens (dont remember). The light would be much too strong without dimming.

Reflective enlarger

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