Archived posting to the Leica Users Group, 2005/06/17[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]
Another solution is using a Cold Light enlarger head. You will never have to woory about heat and negative "popping". You will also have less dust and scratch retouching issues. Mike ----- Original Message ----- From: "Robert Browne" <firstname.lastname@example.org> To: "Leica digest" <LUG@leica-users.org> Sent: Thursday, June 16, 2005 1:55 AM Subject: Re: [Leica] darkroom focusing > Feli, > > Aside from the lens focus shift issue, it may also depend on what type of > enlarger you are using. If there is enough heat from the light source and > you are not using a glass negative carrier, your negative will "pop" > during the exposure and go out of focus. One way to test for this is to > turn on the enlarger for a minute or so, focus your negative and then turn > off the enlarger. Wait a couple of minutes and then turn it back on while > viewing the negative through the focuser. If it is out of focus when you > turn the focus switch on and then pops into focus after several seconds > then you know that there will be a short duration of your exposure when > the negative is out of focus. > > Remedies are either to use a glass negative carrier (with four extra > surfaces to clean - forget it), heat absorbing glass between the condenser > and negative, or compensate by turning on the enlarger for the duration > necessary to pop the negative into focus (while the paper is covered), > then exposing your paper for the specified time. > > One thing to check is that your paper is perfectly flat. I used to use a > vacuum easel. Another is that if you stop your lens down too far, > diffraction can result, which will reduce sharpness. Test to find the > optimal aperture. > > In my experience I've also found that fiber base paper looks sharper than > RC paper. Make some contact sheets on Azo paper, for example, and you'll > see a big difference. > > Maybe you already know all this stuff. If not, I hope it is useful. > > Robert Browne > > Feli wrote: > > See that's exactly what has me rethinking my methodology. I focus wide > open, > stop down and the grain in the print is not as sharp as I would expect > it to be. > I'm using a good lens, a Schneider Rodagon 2.8/50, but I'm starting to > suspect that > there may be a certain amount of focus shift at work. Just goes to show > you, you shouldn't > believe everything you learned in school... ;-) > > > _______________________________________________ > 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!