Archived posting to the Leica Users Group, 2005/06/17[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]
Hi Henning, In your experience, how do the Leitz Focotars compare with their German cousins and the infamous Apo-Nikkor enlarging lenses? Thanks, Mike ----- Original Message ----- From: "Henning Wulff" <firstname.lastname@example.org> To: "Leica Users Group" <email@example.com>; <firstname.lastname@example.org> Sent: Thursday, June 16, 2005 2:38 AM Subject: [Leica] Re: darkroom focusing > At 7:18 PM -0700 6/15/05, Herbert Kanner wrote: >>I think focus shift is a myth. If the focus were to shift when stopping >>down, this would indicate that spherical aberration is so poorly corrected >>that the portion (a ring) of the lens that is active between say f/8 (the >>enlarging aperture)and say f/2,8, the focusing aperture, has a marked;y >>different focus distance than the portion (a circle) from the center to >>the periphery at f/2.8. If this were true, the lens would suck; it would >>be noticeably fuzzy at f/2.8. >> >>Herb >>-- >>Herbert Kanner >>email@example.com >>650-326-8204 > > It's no myth. Check it out; most enlarging lenses, especially the f/2.8 > ones and older 4 and 3 element ones, suffer from it to a noticeable > degree. I use a Micromega focusser that I bought in the 70's, and it has > no trouble detecting the difference in focal plane if I don't have a sheet > of paper in the easel. It corresponds with the results I get from > printing, so it's accurate enough. > > Anyway, print one picture after focussing on the grain stopped down, and > then open it up and print again. Then print the picture with the lens > focussed wide open. Do this for a 16x print. You'll probably see the > difference, unless your lens is one of those few that really doesn't have > any focus shift. > > Some lenses I've had or used that have had focus shift problems: > Various 50mm f/2.8 Rodagons of different eras (all) > 50mm f/2.8 Componons - same > 40mm Focotar > 240 Componon > 150 Rodagons and Componons of various ages > 75 Nikkor > 50/2.8 Nikkor > 105 Rodagon (slight) > WA Componon 60 > > > Lenses that have negligible or no focus shift: > Nikkor 80/5.6 > Nikkor 63 > Focotar 50 (second) > S-Orthoplanar 60 > > There were others, but I can't recall, because they were all good lenses > and I focussed them stopped down, so it doesn't matter. > > On 8x10's, it rarely matters. On 16x20's, it almost always makes a > difference, just like aligning your enlarger. > > For many pictures, it doesn't matter very much if the grain is crisp; on > others it does make a difference. YMMV :-) > > -- > * Henning J. Wulff > /|\ Wulff Photography & Design > /###\ mailto:firstname.lastname@example.org > |[ ]| http://www.archiphoto.com > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information > -- I am using the free version of SPAMfighter for private users. It has removed 371 spam emails to date. Paying users do not have this message in their emails. Try www.SPAMfighter.com for free now!