I made a vacuum easel at work last week. Not for photographic printing purposes though. It was so we could place a printed sheet (screen printed conductive silver on polyester) under a high resolution video camera to view it on a large screen to look for print defects. The sheet had to be flat because there was minimal depth of field. It works very well.
If it was me having this problem, once I determined if one of the magnifiers was correct, then I'd use
the same target system to correctly shim or shave all the others to match. In the past I used my
good one mainly for critical work and had merely OK ones avail for garden-variety work like typical
black and white printing. Now I use only the best one and hope that my progressively arthritic fingers
don't drop it like the cheaper ones! (Knowing it was expensive does make me a lot more careful!!)
If purchasing new, I always assume correction is needed unless a test determines otherwise. The
fine focus on a 138 can slip, but there's an adjustment feature for the tension which can be checked
during maintenance intervals. For super-critical work a helical-focus lens mount could always be added, of course.
Steve- thanks for the link, I had a chance to read through the manufacturer's rep's replies. It seemed like they didnt really do any testing of it though (or atleast didnt state that they tested it), and seemed that their conclusions were drawn from their own experiences. I shall try it one day when I have a bit of time, and a very sharp contrasty neg to do it with as I dont have any test pattern negatives.
Drew has a good point with the film, which brings up an interesting question. If you were to use a film with a totally clear base, maybe a lithographic arts film, and were to print emulsion side down, the image would not be as sharp as emulsion side up, with only a tiny difference of the height that the image was exposed at. Unless the totally clear base would effect the light path? But we use glass neg carriers that light has to travel though as well. or maybe I have had too long of a day. lol
Drew, It's been my experience, with the few Kodak color papers I've evaluated for this, that they exceeded my needs for detail by a LARGE margin. Way beyond what a 6X loupe could show.
Originally Posted by DREW WILEY
So I'm skeptical about your comment about "ordinary paper" not being able to pick up enough detail. Can you elaborate? Is this from testing, or is it just an assumption?
Marco, in the following post (#40), "Michael R 1974" explains things.
Originally Posted by Marco Buonocore
Let me try to be a bit more blunt. It is possible that your paper can be exposed by UV light, which you cannot see. The (invisible) UV image is probably out-of-focus. I suggest exposing through a UV filter, which will block the UV light, eliminating this possibility. This simple (if you own a UV filter) test can eliminate any need to hypothesize about whether or not UV light might be causing a fuzzy image.
I mention this possibility because the photographer/printer/writer Ctein reports that it has happened to him, and I do not take Ctein lightly. I don't have evidence that it IS your problem, only that it is a possibility that can be easily tested.
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Bill - I don't guess at anything. I do tests and tests upon tests - but normally only on problems which affect me personally. I'm not interested in argument for argument's sake. Having done many
years of large format printing onto high-resolution materials like Cibachrome I have had the opportunity to isolate and fine-tune a lot of variables, and am simply making this info avail to others
from time to time, to save them similar heaches. When I speak of using a loupe, it's not just for the
groundglass or film. I want you to be able to walk up to a 30x40 print, spot a water drop a mm wide
on the actual print, and take a loupe to that!! Of course, not every original chrome or neg will be
that sharp to begin with, but sometimes they are, at least in key areas.
Fix a line to it, with the other end fixed to the peak of the enlarger collumn and add some line enough to have it move around freely on the baseboard. Thus it cannot fall deep, if at all, if it is by accident wiped off the baseboard. Fix a box near the collumn as a savehaven for it.
Originally Posted by DREW WILEY
Thanks. That's exactly what I do with the groundglass back to my view camera - a bit of lightwt
shock cord. But usually I don't lift expensive glass things in the lab very far off a surface. And once
I get away from computers awhile my fingers seem to get much better (get to retire from these
damn torture keyboards in a couple of years - but for now, got to use it all day!)
These may be stupid questions, but what the hell:
Is it possible to callibrate the mirror on a grain scope? Or, perhaps can the enlarger be calibrated to the grain scope?
The only adjustment on the Peak 1 is the viewfinder diopter adjustment. If it is not set correctly and you have presbyopia (inability to alter the focus of your eye), then your prints will be blurry.
Originally Posted by sbattert
The optical components are easy to disassemble and there is always the possibility that someone took it apart and buggered it up by not putting the focusing reticle in the correct location.