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
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
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.
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.
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.
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.
Last edited by aduncanson; 9-Sep-2010 at 13:41. Reason: Deleted comments addressed previously by OP
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
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.
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.
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
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