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LF_rookie_to_be
9-Sep-2010, 10:27
Can it be used?

Reverse-mounted on a home-made lensboard, stopped to f22.
Negative size: 6x7, shot with a Pentax, 55mm, f16, heavy tripod.
Enlargement ratio: 32x >> 70x88" print.
Dichroic head, Ultra Endura N, Fuji CPRA juice.
Sharpness/contrast requirements: considerable.

Any suggestions, advices, warnings - GREATLY APPRECIATED!

LFrtb

Daniel Stone
9-Sep-2010, 10:59
may I ask why a Grandagon? I'd imagine it COULD work, but I don't think you'll want a curved field lens(which I believe a Grandagon is, vs a FLAT-FIELD lens(macro and enlarging lenses))

and a 65mm is a little too short IMO to enlarge 6x7 with. The WA perspective throws things way out. I've found a 90mm-135mm the best for proper enlarging, even large enlargments from 6x7 negs.

-Dan

LF_rookie_to_be
9-Sep-2010, 11:14
Dan,

The reasons: size of the darkroom (8x8ft), the negatives which
I already have and the required print size. I do have a 105mm
Rodagon-G, which works beautifully, but can't move to a larger
darkroom any time soon. This Grandagon was offered to me for
a very good price (it has a slight mark on the rear glass) and
so this seems as a quick and dirty solution. Do you know of
a lens in the 60-70mm range that might be good for enlarging
to this size? I thought about using the 55mm lens that these
negatives were shot with, but mounting it to the enlarger
would require two expensive adapters - hence the idea for
reverse mounting using inexpensive filter holders.

Robert Ley
9-Sep-2010, 11:40
Really excellent enlarging lenses can be had very cheaply. The Grandagon lens is really not optimized for enlarging purposes and I suspect would not be as good as a dedicated enlarging lens.

I have used a Schneider Componon-S lens in 80mm f:5.6 for 6x7 and it works very well. Some would prefer a longer lens in the 90-100 mm range.

In any event, I would not go to the trouble of trying to use a LF lens, at least not that LF lens for this job.

Drew Wiley
9-Sep-2010, 13:30
I'd imagine a Grandagon would make a horrible enlarging lens. For 6x7 I personally
recommend an enlarging lens in the 105 to 135mm range, although a 90 would be OK.
What I actually use, however, is a 150 Apo-Rodagon.

aduncanson
9-Sep-2010, 13:37
60mm WA enlarging lenses from Schneider or Rodenstock are none too common and still fetch something of a premium, but they are what you want. Occasionally a 60mm WA enlarging lens from Bogen shows up on ebay, but I know nothing of its performance. The Grandagon is not what you want for the reasons given above, but in any case you do not want to reverse it - unless you are trying to make a print that is smaller than the negative.

LF_rookie_to_be
9-Sep-2010, 13:46
Drew,

The sizes are the problem here - the required size of the print and the size of my darkroom. The maximum distance from the lens to the wall easel I can work with
at present is around 7', and the 6x7 negative has to be enlarged to over 80" width.
I understand a camera lens might work well at very large enlargement ratios, such
as 30-35x. But how to keep it parallel to the negative with two or three adapters
needed to mount it on the enlarger?

LFrtb

boris
9-Sep-2010, 14:59
developing a print this big isn't easy either, unless you have a professional developing machine... you could avoid a lot of trouble by scanning the negativ and continue the digital path.

W K Longcor
9-Sep-2010, 15:08
One other "why is should not be done" that I do not think any one else mentioned --- illumination problems. That wide angle lens will be looking at light (or lack of it) coming from the edges of the light source -- behind the negative. I think you will be driving youself crazy trying to get even illumination across the print -- unless you have a large format enlarger with a really big light source -- and by the sound of your problem - you don't.

LF_rookie_to_be
9-Sep-2010, 15:23
W K,

Do you think the evenness of illumination would still be a problem with the
105mm Rodagon-G lens? Is it much more pronounced on colour print this large
than in a black & white print on 30x40" graded FB paper?

LFrtb

Drew Wiley
9-Sep-2010, 15:44
Rodagon G is corrected for high levels of magnification.

Bob Salomon
9-Sep-2010, 16:39
No, among other problems, listed above, you would be into diffraction at 22. Get an enlarging lens. The 60mm Rodagon-WA covers 6x7 as do all Rodagon and Apo Rodagon-N 80mm lenses.

jeroldharter
9-Sep-2010, 18:05
...although a 90 would be OK.
What I actually use, however, is a 150 Apo-Rodagon.

Drew,

I have been thinking about doing something similar for 6x7. I have a great Schneider Apo-Componon 90mm lens which is quite sharp, but the working distance for 8x10 prints is too close for comfort at times. I have a 150 mm Rodagon, 135 mm Nikkor, and a 150 mm Apo-Componon which I could use as alternative. Are there any drawbacks to using the longer lenses to get more "working distance" for dodging and burning?

W K Longcor
10-Sep-2010, 05:43
W K,

Do you think the evenness of illumination would still be a problem with the
105mm Rodagon-G lens? Is it much more pronounced on colour print this large
than in a black & white print on 30x40" graded FB paper?

LFrtb

This length lens should cause no illumination problems.