Completely agree Bob. Glass carriers all the way, in all formats!
I tend to use MGWT, which is pretty slow. This means preferring to use my enlarger lenses at a stop down if I can, or two stops where I must. It took a while, but I now know that my 63mm f2.8 Nikkor makes a mean 16x12 at f4 (only possible with perfect alignment) but is appreciably better at F5.6 with larger prints. With the odd dense negative, I would prefer to enlarge at F4, at 20x16, to manage exposure times and this is the only reason I have for considering APO lenses. With my lenses for 35mm, they are not quite good enough at F4 for perfect prints at this size. With Adox MCC, enlargement times are much shorter and I can stop down.
For optimum resolution, don't stop down your enlarging lens at all - always use it wide open.
Is that an April Fools joke!?!
But not a joke. Highest res. will come from wide open. This fact really becomes readily apparent with condenser or point source and a high acutance neg.
Hmmm, on centre, maybe, but when you take overall performance into account (corners included), wide open is rarely the best aperture. Wide open works better with longer lenses with more coverage and when making small enlargements. Try making a 20x16 from a 35mm neg on a 50mm non-APO Nikkor/Rod/Schn at f2.8 and the resultant print will be dramatically worse than at two or three stops down. Not only will the corners be poor, but falloff will be more of an issue too.
I dont own any APO lenses, but I understand they are optimise for a stop of so down from wide open, whereas other lenses generally give best performance 2-3 stops down.
While best resolution may occur on centre wide open with many lenses, the improvement in resolution would not justify the reduction in performance in other areas in my experience. Where I have compared sharpness of enlarger lenses on centre at various apertures, the differences have been trivial and not worth considering. The corners, well, thats another matter!
Originally Posted by frotog
I don't have issues with fall-off or corner focus issues when enlarging wide open. But then again, I like to use a Nikkor 240mm 5.6 for both 4x5 and 5x7. If you've got the lumens to spare, might as well use a longer than standard lens for just this reason.
One can, but it means more extension and issues with large prints on some set ups. Arguably the resolution is lower on longer lenses too (according to Ctein and others) but whether this matters a lot I don't know.
With LF, I have often printed 5x4 wide open, or close to, with my 150 rodagon with no issues, but I would not do this will small formats. My 105 Rodagon is incredible wide open, but the same cannot be said for some of my others wide open! I guess 'it depends.'
FWIW, some years ago one of the photo magazines tested 50mm enlarging lenses from all the sources at that time. The best overall was the 50mm f/2.8 EL-Nikkor. Here are the results - f/stop; center; edge (line pairs): f/2.8 40 25; f/4 45 40; f/5.6 80 65; f/8 60 45; f/11 40 30; f/16 25 20. All of the lenses showed a similar progression with best results 2 to 3 stops down from open as is commonly accepted.
Some enlarging lenses can be used wide open IF they are exceptional quality and significantly longer than "normal" focal length per format size, so that you are using only the center of the lens, and IF your
carrier and paper plane are precisely aligned. I sometimes do this with a 150 Apo Rodagon and 67x7 or 6x9
film. But with more typical lenses and applications its a pretty bad idea. The manufacturers give general
recommendations, and for most enlarging lenses its one or more frequently two stops down from max.
I just answered this question late last night, got a mint copy of one after debating on buying it for over two weeks.
Originally Posted by PKM-25
On to finding a 150mm Apo-Rodagon N....