Setting Up An Enlarger For 16mm and Minox

xkaes

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It helps to clarify which Minolta 30mm lens being used -- Minolta made three. The first was f4.5, and then two f2.8 -- one was with the ENLAUNIT, and the other the C.E. model (which came with three versions -- Rokkor, Rokkor-X, and Minolta). They also made a 25mm f3.5.

And there are lots of other enlarging lenses and ENLAHEADS for 16mm and 8x11mm negatives:

http://www.subclub.org/darkroom/lenses.htm
 
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ic-racer

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That should be 32.5mm. I've never seen one with a 30mm thread.
Click to expand...


Yes, something like that. It is mounted in a SAE 1 and 1/4" washer which technically is a little bigger than 30mm.
 
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ic-racer

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Looking back, I see I don't have a picture of the lens, I'll have to post one. But it is a beautiful 30mm Rokkor CE that came in the original plastic case. I did have to get a lenscap for the front and a tiny one for the back.
It is a unique design with an exaggerated flange-focal distance.
If one pulls down on the illuminated aperture ring a red band appears on the aperture scale and the detends are defeated.
 
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ic-racer

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Reading back through the thread I can comment that I have only used the Omegaron 25mm on the Omega D5500 and it was extremely difficult to have the little Minox negative perfectly centered on the 'sharp' portion of the lens field. Very tedious.

The 30mm Rokkor CE, on the other hand, has a lot of leeway to centering the negative, even at f2.8.

I'll have to post a picture of the negative carrier. I have modified the masking blades by reversing them so they close down to just about 8x11mm. Perhaps that is the most important feature of this enlarger to make it Minox friendly.
 

Ian C

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In Post #28, IC mentions the unique design of the Rokker 30 mm CE lens with “exaggerated flange-focal distance.”

That, of course, would make positioning the lens at the appropriate distance to the negative much easier than with a standard short-focal-length enlarging lens.

This idea was apparently also used in the design of the Computar 30 mm f/2.8 lens intended as a wide-angle enlarging lens for the 35 mm format. At 30 mm focal length, it would also certainly work with smaller negatives, provided that sufficient projection distance was available.

It apparently was also equipped with an integral radially graduated neutral-density filter coated onto one of the lens elements.

Time-Life Photography Year 1979 Edition, page 160​

“Two unique lenses, adaptable to a number of enlargers, came from Computar. A wide-angle 30mm f/2.8 lens for 35mm gives large magnifications without requiring that the enlarger head be raised a great distance from the easel: it can make a 20 by 30 inch print on an average 35mm enlarger. The lens is designed to be placed the same distance from the film as normal lenses, allowing its use with condenser or diffusion enlargers. The falloff of light at the edges, common with wide-angle lenses, is reduced by coating one of the elements to even out the illumination.

The other Computar lens, the 55mm, is exceptionally fast—f/1.9—for sharp, large prints made from negatives that would otherwise require long exposure times. It uses an unusual solution to a problem that affects large-aperture lenses—the difficulty of providing a “flat field” of maximum sharpness from edge to edge at all magnification settings. Computar made one of the elements inside the lens “float” so that it could shift slightly backward or forward with a dial. This adjustment is needed only when the lens is used wide open. After the desired magnification is set and the lens is focused for sharpness at the center of the image, the floating element is shifted until the edges of the image are as sharp as the center.”

http://125px.com/docs/manuals/darkroom/computar/computar_lenses.pdf
 
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ic-racer

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Philips glass negative carrier with masks modified to close down around a Minox negative.


 
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ic-racer

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Yashica Atoron Electro; HP5; Ilford MG FB:

 

xkaes

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The Minolta 30mm C.E. lenses have a recessed design -- as seen in the above photo. Usually, this means a recessed lens board is not needed.
 
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ic-racer

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My Rodenstock Omegaron 25mm f4 is not a six element lens (4/3), so I don't think it is in the same league as a Rodagon 28mm with it's six elements. After obtaining the six element 30mm Rokkor-X CE, I stopped seeking the Rodagon 28mm.

Again, the drawback of the 4 element Omegaron is its limited sharp image circle, making centering the Minox negative on a large format glass negative carrier tedious.
 
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ic-racer

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xkaes said:
The Minolta 30mm C.E. lenses have a recessed design -- as seen in the above photo. Usually, this means a recessed lens board is not needed.
Click to expand...

Yes, this is a great design feature. I measured the Flange-Focal distance on the Minolta 30mm and got a little over 40mm (similar to many 50mm enlarging lenses), whereas the Rodagon 28mm has a Flange-Focal distance of only 23mm!

 
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xkaes

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My mistake. I was referring to the Rodenstock 25mm f4, not the 28mm -- but the 25mm is more suited to Minox use. I use my Roddy 25mm for 16mm (10x14mm) images, but I'd use it for my Minox negs if I didn't have my 21mm Yashinon-DX.
 
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ic-racer

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xkaes said:
My mistake. I was referring to the Rodenstock 25mm f4, not the 28mm -- but the 25mm is more suited to Minox use. I use my Roddy 25mm for 16mm (10x14mm) images, but I'd use it for my Minox negs if I didn't have my 21mm Yashinon-DX.
Click to expand...
You have one of these? Very nice!!!

 

xkaes

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I found one several years ago at an unbelievable price -- fortunately with the film holder.
 

eli griggs

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Has anyone setup a Leitz Valloy II, using Leitz/Leica extension tubes.

I have a set and, IIRC, it has at least one smaller than the tube used to mount the 50mm it wears now, but I would like to see experienced Valloy II users, whom have used their enlarger with 25mm focal length and ex. tubes.
 

Bronson Dugnutt

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ic-racer said:
Here is my Rokkor-X CE 30mm 2.8
Click to expand...

I've mostly used mine for cropped enlargements from half-frame and 35mm, so far. I haven't been enlarging much lately but have been futzing with adapters, so I slapped my copy onto a F mount adapter then onto a FTZ for a snapshot. It vignettes on a 35mm frame as expected but is quite a nice taking lens @ f/8.

Pictured: a different 30mm f2.8
 

xkaes

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I've heard/read that the Minolta 30mm C.E. f2.8 does not quite cover half-frame, so I've never tried it. I use a Schneider 28mm f4 for that.
 
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ic-racer

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So I have removed the red filter (and safely stored it within the enlarger for safe keeping). As expected, the image for lith printing is much brighter. Had to go to work, so did not get a chance to measure the difference.

I also discovered my Philips PCS 150 enlarger "secretly" (no mention in Philips literature) uses a light pipe mixer just like the Vivitar enlarger in this ad below. Vivitar makes a big deal of the light pipe while Philips conceals its presence.

The Philips arrangement is different from the Vivitar. Philips is additive, so 3 lamps & 3 fixed flters, then a horizontal 'light pipe' before the mirror. After the mirror, light passes to the condensers.

 
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ic-racer

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I'll post some pictures of the disassembled light source to see the light pipe, but curiously I cannot detect it in this promotional ad. The light pipe is where the artist is showing some yellow, red and blue, just behind the circular diffuser. There is no blue, yellow or red in there, just the light pipe. Perhaps they were trying to keep it a secret.

 
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ic-racer

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So removing the red filter, going from two lamps (paper I use is not sensitive to red) to thee lamps increased the light output 2.5 stops for lith printing without any negative affect on multigrade printing.
 

Hilo

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Yes, I use the Valoy II. Mostly using a Focotar-2 50mm for 35mm negs, and an Olympus 38mm for half frame.

For the 50mm, I use the standard Leitz extension tube 17675 (or DOORX) of 10mm (I think). With the 38mm, I use
a smaller (probably 5mm) non Leitz extension tube.

I have attached my Valoy II to a Focomat Ic column, bringing the lens further from the column and making it possible to go up to 50x60cm prints (20x24in.). Using the 38mm for half frame negatives, I have printed 40x50cm, but I can probably still go up more than that.
The reason for this modification of the Valoy II is its non-automatic nature, which I prefer over the automatic focus of the Focomat Ic. The Valoy II's large helicoid (that holds the lens) is great when focusing.

I have had no need for other lenses, but intend to use a Leitz 13x17mm negative mask to find out what happens using the 50mm and the 38mm with a normal 35mm negative. I think this would be a simulation of printing 13x17mm, but I am not sure of this as I am not good in theoretical reasoning. I must see what happens in reality, using different or no extension tubes in combination with being able to go up high. I have found my non automatic focusing enlargers (Valoy II and a Durst L1000) more flexible than my enlargers with automatic focusing (Focomats Ic and IIc).

attached a picture of said negative mask


 
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