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  1. #11

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    Pentaxuser, how big is that enlarger and what focal length lens do you have on it? My Omega B66 does 35mm and medium format (square) although I have never shot medium format. My prints are also usually 10x8. I have a 50mm f4 EL Nikkor on it. Way back when I was first taught the rule of thumb was to stop down 2 tops from wide open, which gives me f8, and that's how I printed for a long time, mostly using Plus-X when I first started. But some years ago when I switched to Delta 100 I started noticing the prints were not uniformly sharp, due to what appears to be a slight waviness in the negatives as I described above. The older films curled more, but uniformly so, and flattened nicely in the glassless carrier. So I now find myself printing at f11, which makes for long printing times on this enlarger. Sometimes the grain appears slightly less sharp to my eye at f11, which I first thought must be diffraction, but when I thought about it further diffraction shouldn't be that noticeable moving from f8 to f11. I can't focus well with the grain magnifier at f11, that's for sure. I have to focus at f8 and then stop down to f11. So I then thought maybe there was some focus shift going on, but that can't really be happening on this lens between f8 and f11, can it? Anyway even at f11 sometimes the print is not uniformly sharp, so I thought maybe a glass carrier might flatten the negative better. Now I'm even more curious to try it since you say it didn't make much of a difference for you.

    The other thing is, when you load a new negative, do you leave it in the enlarger for a few minutes to heat up before focusing and printing? I've always done that but was never sure if it actually helps. Do 35mm negatives actually buckle?

  2. #12
    ic-racer's Avatar
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    That lack of sharpness at f11 is diffraction. If you notice it at your normal viewing distance then you need to use f8 for what you are doing. That Nikkor lens is a 4 element lens and may not have a good of flatness of field or coverage as the f2.8 lens with 6 elements.

    A diffusion head will blurr out dust on the top and bottom glass surfaces. Dust between the glass will show up, so you need to dust off the inner glass well and make sure no dust is on either side of the negative.

    If I were you, I'd get that 6x6 Glass carrier (I think that is the only one made for your enlarger) and a 6 element lens.

  3. #13

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    If I can't find a glass carrier for my enlarger that has anti-newton glass, do those sprays work? Do they do any damage to the negative?

    Incidentally, are glass carriers made from high quality optical glass (like the glass used in high quality lens filters)? Otherwise I've never been clear on why a glass carrier doesn't reduce image quality as the light passes through another piece of glass after going through the negative. It's probably not anything large format users need to worry about, but given the relatively high magnification in 35mm printing I would have thought even the slightest impurity or other flaw in the glass would adversely affect the print.

  4. #14
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    Leitz Valoy enlargers had a unique (?) carrier where the bottom of the condenser forms the top pressure plate. Some of the Leitz enlargers had an anti-newton surface on the condenser. I don't remember dust being a really big problem with Valoys, but the 'glass' part of the carrier never left the enlarger. In the old days, when glass carriers were more common, it wasn't unusual to only have glass on the top surface - the glass acted like the pressure plate in a camera. I think a glass bottom plate for 35mm or normal 120 would have little effect.
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  5. #15
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    Quote Originally Posted by Michael R 1974 View Post
    If I can't find a glass carrier for my enlarger that has anti-newton glass, do those sprays work? Do they do any damage to the negative?

    Incidentally, are glass carriers made from high quality optical glass (like the glass used in high quality lens filters)? Otherwise I've never been clear on why a glass carrier doesn't reduce image quality as the light passes through another piece of glass after going through the negative. It's probably not anything large format users need to worry about, but given the relatively high magnification in 35mm printing I would have thought even the slightest impurity or other flaw in the glass would adversely affect the print.
    It needs to be optical glass.

    You probably only need it on the top for 35mm as Nicholas pointed out, but those carrieres are not as common as the usual glass sandwich.

    I'm not sure how wide your enlarger opens up to accept the negative holder, but on my Minolta enlarger (for which the glass carrier is extremely rare) I taped together two pieces of negative carrier glass and it works perfectly.
    Last edited by ic-racer; 07-06-2010 at 12:14 PM. Click to view previous post history.

  6. #16

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    Michael It's a Durst m605 which does up to 6x6 negs but I do very few of these. My reference was to 35mm negs. It may be that the Durst glassless neg carriers do a particularly good job of holding the negs flat. By the time I am ready to expose for the print the lamp has been on for a good number of seconds i.e centering the neg, focusing at f2.8 with grain focuser, stopping down to usually f8, measuring exposure for the equivalent of zone VII and analysing the grade via a Philips analyser. Then switching off while I locate the paper into the easel - not more than a few seconds - then exposing.

    It may just be my Durst enlarger but at f8 most exposures even with dual filtration are about 10 secs. In fact if a bit of dodging and burning is required I often go to f11 to give me the kind of time I feel I need. I even have substituted the 100W standard bulb for a 75W one. This was really a means of getting my colour neg exposure into the range that a Paterson colour analyser could register but it serves to show that long exposures are not an issue. The reverse if anything is true.

    Equally it may be that Durst dichroic head enlargers prevent enough heat getting to the negs to distort them and the time to do the above with the lamp switched on is irrelevant. I don't know.

    One day I will do the best print I can glassless then do the same print with double glass and do a close examination of both to be sure but I have a feeling that my conclusion will be that any slight improvement in sharpness is offset by the chore of cleaning the glass and risking the occasional Newton ring.

    pentaxuser

  7. #17
    Nicholas Lindan's Avatar
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    I think glass carriers only make an appreciable difference with APO lenses that are used at f4.0 - f5.6. Although I can see them being an advantage with films that can curl themselves into a drinking straw.
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  8. #18

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    Quote Originally Posted by ralnphot View Post
    How about putting the 35mm negs in slide mounts and using the matching 35mm slide carrier in your enlarger.
    Well, you'd need glass slide mounts to keep the film flat. Have you ever noticed just how un-flat many slide mounts hold the film? It's not insignificant. It can be so pronounced that there are projector lenses with curved fields tailored for slides in cardboard mounts with, and others with flat fields for slides in glass mounts. No joke. So once you've got the negative in a glass slide mount, you're back to square one dealing with the dust problem. I don't use glass negative carriers for anything and I can't say that I've had the problem the OP is experiencing either. Only if I'm trying to enlarge a negative made on very thin graphic arts film, do I have a bowing problem, but this is unusual. I get around the problem by keeping some tension on the film and taping the corners down with some low tack masking tape. I'm using an Omega D series enlarger and the negative carriers are big and heavy, so maybe that's why it holds the film flat enough.
    Frank Schifano

  9. #19

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    Yes heavy would help. The head on the B66 is pretty light weight and so doesn't clamp down on the carrier with much force. I have a smaller 35mm Durst enlarger that is in pretty rough shape (picked it up recently for free) that I use for flashing, but I've noticed on the Durst, the way the negative carrier slides tightly into the fixed head (instead of the head opening like a clamshell on the Omega), the Durst way seems like a better system for small enlargers where gravity doesn't work as hard for you.

  10. #20

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    My LPL 4500 has a top glass only carrier for 35mm. I believe the LPL holders fit some Omega enlargers. I'm not familiar with the B66.

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