Lens For High Acutance Large Prints

ChrisW · May 4, 2006

I commonly print images up to 40 inches using a Besseler 23 IIIC condenser and Rodagon 80mm off b+w 120 25 iso films. The distance form lens to floor easel is 76 inches. The acutance is good, but at these enlargements should I get a different lens? 4x5 format would help, but for mobility I must shoot 120.

Also, am I correct in assuming an aperture of f11 will produce the sharpest image? Film flatness in not an issue as I use a double glass carrier.

rbarker · May 4, 2006

Assuming you have the f/4 80mm Rodagon, it's a 6-element lens with 4 groups - one of the better "standard" designs, optimized for 2x-10x (6x optimum) magnification (manufacturer specs). You might get improved results with one of the APO enlarging lenses. The 80mm f4 APO Rodagon, for example, has a (stated) magnification range of 2x-15x (10x optimum).

As to the sharpest f-stop, that's usually 2 or 3 stops down from wide open, but running your own tests will show what your optimum f-stop is.

Claire Senft · May 4, 2006

I would expect a first class enlarging lens for the 120 formats to be at optimum by f8 perhaps by f5.6

ChrisW · May 4, 2006

Ralph, thanks for the advice. I will get an APO lens. Any thoughts on Rodenstock versus Schneider?

jeroldharter · May 4, 2006

I have a Schneider Apo-Componon 90 mm lens that I use for 6x7 negatives. It is extremely sharp up to my maximum print size of 20 x 24.

ChrisW · May 4, 2006

Ms. Thrope:

Thanks for the guidance. In my infinite wisdom I only tested f4, f11, and f22. Perhaps I should have listened during my physics class.

df cardwell · May 4, 2006

Each lens is DESIGNED for a specific job. Hunt down a Rodagon G, designed for really big prints, unlike the apo componons and Rodagon n

If you come upon a 105 apo el nikkor, get it.

For getting the most from the lens you have,
lay a mirror on the edge of the print and stop down until you see a clear aperture. It may be a stop or stop and a half from wide open.

Go no further.

ChrisW · May 4, 2006

Will the 105mm focal length work with 6x6? Is the Nikkor better than either Rodenstock or Schneider? Will Speed marry Trixie?

df cardwell · May 4, 2006

Even though you'll need to stop down to f/8, the 105 Apo El Nikkor will be fine. It is head and shoulders above anything. And priced accordingly. But some turn up when color sep houses close, or top labs unload stuff. The downside is the cost. Some are available, still, new. Slightly under $3k.

Speed would be a fool to let Trixie go.

.

ChrisW · May 4, 2006

df cardwell said:
For getting the most from the lens you have,
lay a mirror on the edge of the print and stop down until you see a clear aperture. It may be a stop or stop and a half from wide open.

Go no further.

Neat trick with the mirror. I assume a clear aperture is when all leaves are showing. This is a different aperture depending on the magnification. Hence the range of 5.6 to 8 as proffered by Ralph and Claire. All these years I thought f11 to be the optimal due to my flawed logic. Thanks.

rbarker · May 4, 2006

The Schneider APO Componon HM lenses are also said to be made for high magnification (the HM part), but I haven't seen manufacturer specs for their optimum magnification factor.

ChrisW · May 4, 2006

Three thousand clams. Wow. I'll have to think about that. I will look for a used one in the meantime.

You're right about Trixie. She's a good sheila, and not at all stuck up.

df cardwell · May 4, 2006

ChrisW said:
Three thousand clams. Wow. I'll have to think about that. I will look for a used one in the meantime.

A LOT of clams. I got mine at an auction. A table full of lenses, and nobody saw but my pal Les. It was sold in a lot with a couple of El Nikkor 105s. A lunatic wouldn't stop bidding .... it took every penny in my pocket. A once-in-a-lifetime buy, but still, I'd have lost it had the guy had gone $5 higher.

Then I sold the guy the other two.

But take a look around. You never know.

Have you made an adjustable lens board to fine tune the alignment ?

ChrisW · May 4, 2006

df cardwell said:
Have you made an adjustable lens board to fine tune the alignment ?

Alas, ignorance rears its familiar head. I have never heard of an adjustable lens board. I will proffer the following: I insert a sheet of glass in the carrier slot and use a common spirit level to check carrier alignment. I also check and adjust the surface and easel. When focusing an image, the grain magnifier is used on all four corners as well as the center. Of course the grain is difficult to pull out of Tech Pan negatives, but I try.

df cardwell · May 4, 2006

Fred Picker made these famous many years back. The idea is to be able to make fine adjustments with machine screws, to critically set the lens plane. They are easy to make. You can use three or four holes, probably three are better. Mine uses four because Steve Grimes was telling me a funny story while I was laying out the work and I was listening instead of working.

The sketch is conceptual.... meaning I THINK it's pretty close. Check to see that the screws and holes fit the opening of the enlarger.... helpful.

The foam should offer enough springiness to hold the boards apart. If not, add... springs !

Sometimes it's handy to make an adjustable bed for the easel as well.

ChrisW · May 4, 2006

Many thanks for the diagram. Being a perfectionist, I will cut and tap some 6061 T6 sheet this week end. Wait. Not this week end. Lacrosse, baseball, then another lacrosse. Next week end.

ChrisW · May 4, 2006

Thanks to everyone for responding. And for responding so quickly. Until I close my next business deal I will procure Schneider's 90MM APO Componon High Modulation lens. This, of coarse, is merely a costly folly in my pursuit of a mint and boxed 105 EI.

df cardwell · May 4, 2006

Don't be LAX when it's time for pictures.

Lame, yes. But I'm going out for a bike ride.

-- have fun with the HM.... it'll be a beaut

d

davetravis · May 4, 2006

I'll have to ditto on the 80 mm APO Rodagon. I moved up from 16x20 to 20x24 and could really tell the difference! Sharper and richer color.
Got a perfect one on Ebay for around $300.
Good luck.
Long live Ciba!!!

ChrisW · May 4, 2006

davetravis said:
I'll have to ditto on the 80 mm APO Rodagon. I moved up from 16x20 to 20x24 and could really tell the difference! Sharper and richer color.
Got a perfect one on Ebay for around $300.
Good luck.
Long live Ciba!!!

Who is Ciba, and does she any designs on Speed?

Jim Jones · May 4, 2006

ChrisW said:
Many thanks for the diagram. Being a perfectionist, I will cut and tap some 6061 T6 sheet this week end. Wait. Not this week end. Lacrosse, baseball, then another lacrosse. Next week end.

Then you won't want to shim lens boards or film carriers with tape like I do. Litho tape or clear Scotch tape doesn't compress like some other tapes. Really, it does work, and it doesn't get out of alignment easily. As for optimum aperture, a quick check with your grain focuser will tell you more than theory or your physics class would have. Sharp fine grain can get a bit fuzzy in the center of the image when a fine lens is stopped down to f/8. In theory any lens can resolve only about 200 lp/mm at f/8.

df cardwell · May 4, 2006

Amen, Jim.

The bigger the picture, the better the lens, and the nicer the image, the more demands on the enlarger.

Beseler is really good, and part of that goodness means it's not too hard to make simple mechanical improvements ( replacing screws, fussing with the lens board fittings, and so on ) to make it as good an enlarger as possible. Without it, there is a little play in the lensboard that won't go away withour shimming. Tying the enlarger column to the wall or rafters is essential, and a tunable enlarging table is a gotta.

With a Beseler, make sure the focus rack is snug but secure with no backlash. Do you have the model with the motor rise ? That's good, because spinning the flywheel is your fine focus.

Have fun. Making big prints from 120 ... and 35mm ... is more than doable, it's beautiful and easy. Someday, you might trash the beseler for a Durst.... but in the meantime, make a bunch of cool pictures and have fun.

.

Lens For High Acutance Large Prints

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