this is pretty much the info I was expecting to hear. good to clarify this. so basically I need a lens of supreme focal length. what's the deal with any ol' 300mm lens mounted in a lens board and rammed forcefully into a cheapo ebay besler?
idk if your "ebay cheapo beseler" will accomodate a 12" lens. Besides, if you use a 12" lens vs a 150MM(a "normal FL enlarging lens for 4x5), then you'll be needing even MORE room
-Dan
In terms of lens, when I do that I use a 'standard' 210mm lens. My enlarger's lens is about 100" from the wall and that focal length works just about right when I have the head flipped to horizontal.
David, I fear that you have misunderstood the important points that several contributors above have tried to make.
Allen in Montreal discussed two excellent recent lens options, the 120mm Rodagon WA and the 150mm Rodagon G. Both of these lenses are optimized for higher magnifications than are typical enlarging lenses and I presume that this is why he focused on these. He seemed to settle on the 150 Rodagon G because of its superior performance at the highest magnifications you mentioned, while I focused on the practical advantages of the shorter, wide angle design. You seem to have taken the message instead to be that longer is better.
A longer lens has a direct negative consequence. For a print magnification equal to M, the paper to negative distance is (2 + M + 1/M) x Focal Length. So for a 300mm lens you would need about 14 feet so you are definitely talking about projecting horizontally. Most 300mm enlarging lenses are likely to be optimized for a fairly modest magnification such as 3X to 4X and would not be as good for your purposes as either the 150 or 120mm lenses that Allen mentioned above.
Consider also the often repeated advice that the negative, the lens and the easel will need to be very accurately aligned for best results and that you will need to use a glass negative carrier for best sharpness.
You need one of these (But I may be a bit biased)
One thing to consider is the lamp wattage in which ever enlarger that you decide upon. Most 4X5 enlargers are going to result in incredibly long exposure times for the enlargements that you are aiming to do.
Everything is going to be more critical at this degree of enlargement...minor misalignments are going to become very apparent.
One extreme to the other, there is middle ground!
http://www.ebay.com/itm/320749884691...84.m1423.l2649
http://www.ebay.com/itm/310309656905...84.m1423.l2649
For what it's worth, 40x50 (from 4x5) is not 10x. 64x80 would only be 5x. In addition to what others have said, just be aware that at some point, light falloff becomes an issue when making very large prints (this is why using an 8x10 or bigger enlarger makes a lot of sense). Good luck!
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