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#21
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Nikon 50mm f4.0 vs. 50mm f2.8
depend on the film, processing, quality of the camera and enlarger and lens.
Tri-X I think does best for small prints but then I usually don't over 8x10 anyway. Anyway some people like grainy blurry photographs. Sheldon Strauss www.shel.focalfix.com |
#22
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Aligning enlargers
O.K. I got it. "The hall of mirror" idea took to me to back to high school
physics days.... I also have a Schneider 80mm WA lens which I can use for 35mm enlargement. The problem is that I can't raise my enlarger to it maximum hight due to a low ceiling in my darkroom. Anyway, thank you all for all your help.. Regards Shawn.. "David Nebenzahl" wrote in message ... On 2/25/2004 9:48 AM Mike spake thus: O.K. I can hear the sighs from here, but how do I align an Omega DII enlarger? Is a glass carrier required as well in 35mm format? Glass carrier isn't necessary for 35mm IMHO. If you enlarger isn't aligned perfectly, just stop down to f11 or higher. The DII has 4 sets of rollers on which the head slides on. There is a bar connecting each set, and this bar has a hole in the center. By loosening the screws, and sticking a screwdriver in the hole, you can change the alignment. Do your best...with just the negative carrier you should get a perfect rectangle (not a trapezoid) So you can use the extremely simple and extremely accurate alignment method I used for my Beseler 23C. I adapted the method given by Conrad Hoffman (http://members.rpa.net/~choffman/beseler01.htm), which uses two mirrors to set the negative stage and baseboard plane-parallel to each other. Basically, you cut one large piece of mirror and put it on the baseboard. The other piece is cut in a narrow strip that gets clamped in the negative carrier. This piece extends out the side of the enlarger and has a hole in it through which you can view the other mirror. (My modification to his method was to simply scratch the reflective coating of the mirror off in a small spot, rather than going to the trouble of drilling a hole in the mirror. Worked fine.) You shine a light up at the upper mirror and view through the hole. The idea is to make the "hall of mirrors" effect--multiple receding reflections--collapse to a single reflection (in both X and Y axes), at which point you can be sure that both mirrors, and therfore the enlarger parts, are in perfect alignment. Forget the Zigalign and its vaunted 0.00000000005" alignment claims. -- It's fun to demonize the neo-cons and rejoice in their discomfiture, but don't make the mistake of thinking US foreign policy was set by Norman Podhoretz or William Kristol. They're the clowns capering about in front of the donkey and the elephant. The donkey says the UN should clean up after them, and the elephant now says the donkey may have a point. Somebody has come out with a dustpan and broom. - Alexander Cockburn, _CounterPunch_ (http://www.counterpunch.org), 9/17/03 |
#23
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Nikon 50mm f4.0 vs. 50mm f2.8
On Fri, 27 Feb 2004 20:04:31 -0500, "Sheldon Strauss"
wrote: Anyway some people like grainy blurry photographs. Sometimes it works. My favorite such image I photographed a couple walking along the Atlantic City surf holding hands using a Soligor 80~180 /3.8 zoom with two cheap 2X converters on it. Film was Kodak Gold 1600 which I exposed with the lens wide open. Perhaps a little over-exposed but then that film was very low in saturation anyway. Regards, John S. Douglas, Photographer - http://www.darkroompro.com Please remove the "_" when replying via email |
#24
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Aligning enlargers
"Shawn H"
The shape of the projected image must be the same as the negative being projected AND the image must be in focus at all points. The only equipment needed is a ruler and a square and an easel will do for the square. The proof of a good alignment is the projected image. Am I making myself clear? Dan |
#25
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Aligning enlargers
On 2/28/2004 2:29 PM Dan Quinn spake thus:
"Shawn H" The shape of the projected image must be the same as the negative being projected AND the image must be in focus at all points. The only equipment needed is a ruler and a square and an easel will do for the square. The proof of a good alignment is the projected image. Am I making myself clear? Dan That method will work; however, I think the two-mirrors method is even more accurate, as it can detect extremely minute angular shifts from parallel. But certainly the is-the-image-square? method is a lot better than nothing. -- It's fun to demonize the neo-cons and rejoice in their discomfiture, but don't make the mistake of thinking US foreign policy was set by Norman Podhoretz or William Kristol. They're the clowns capering about in front of the donkey and the elephant. The donkey says the UN should clean up after them, and the elephant now says the donkey may have a point. Somebody has come out with a dustpan and broom. - Alexander Cockburn, _CounterPunch_ (http://www.counterpunch.org), 9/17/03 |
#26
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Aligning enlargers
David Nebenzahl wrote
Dan Quinn spake The shape of the projected image must be the same as the negative being projected AND the image must be in focus at all points. The only equipment needed is a ruler and a square and an easel will do for the square. The proof of a good alignment is the projected image. Am I making myself clear? That method will work; however, I think the two-mirrors method is even more accurate, as it can detect extremely minute angular shifts from parallel. But certainly the is-the-image-square? method is a lot better than nothing. Personally I would'nt trust to a method other than one using a negative in the negative carrier or the carrier itself, and an image projected upon the paper holder in it's usuall position. My objection to other methods stems from an awarness of mechanical imperfection. Also, there's the simple matter of "more things that can go wrong". My instincts are for fewer moveing parts. But there again I'm the minimulist. I was only trying to make clear that a good alignment can be done without purchasing anything. Further more, nothing need be fabricated. I favor a No buy No build approach to wadeing into this and other endeavors. I think that approach should be at least mentioned, and more often, where it does apply. For example, when the subject is ventilation how often do you see someone suggest "do without". Case in point: I've an air leaky darkroom and use oderless, fumeless chemistry. That said, I and some others don't need a ventilation system. An in room HEPA air filter will do me. Dan |
#27
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Nikon 50mm f4.0 vs. 50mm f2.8
John,
I can't give you an NBS traceable test result on your diffraction question, but I can tell you what happens with my old f/4 50mm El Nikkor. Running the enlarger up to 12x and watching the grain with a 10x grain focuser, as the aperture gets down to f/8, the grain is still visually sharp. Somewhere between f/8 and f/11 it begins to get soft, and at f/16 it is mush. And that was in the print center. As for glass carriers -- in an enlargement to 11x14, the depth of field at the negative is just a couple of tenths of a millimeter. (A sheet of typing paper is roughly a tenth of a millimeter thick.) Hold a glassless negative carrier up to the room light so that the light is glancing off the back of the negative. You will be able to see the warp in the negative. Glass carriers are needed for enlarging 35mm negatives beyond 8x10. Bob p.s. Spammers should get the hell out of my e-mail. ----------------------- John wrote: On Wed, 25 Feb 2004 11:48:40 -0600, Mike wrote: Glass carrier isn't necessary for 35mm IMHO. If you enlarger isn't aligned perfectly, just stop down to f11 or higher. I wonder what the diffraction limit is on a 50mm enlarging lens ? Regards, John S. Douglas, Photographer - http://www.darkroompro.com Please remove the "_" when replying via email |
#28
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Nikon 50mm f4.0 vs. 50mm f2.8
Get POPFile - free and darned efficient!
Jorge HypoBob wrote in news:40464188.6030503 @pacbellhell.net: p.s. Spammers should get the hell out of my e-mail. ----------------------- |
#29
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Nikon 50mm f4.0 vs. 50mm f2.8
On 3/3/2004 12:35 PM HypoBob spake thus:
As for glass carriers -- in an enlargement to 11x14, the depth of field at the negative is just a couple of tenths of a millimeter. Small correction: you mean depth of focus, not depth of field. Similar but different animals. (Depth of field is on the subject side of the lens, in this case the print.) -- The Bush administration should restrain itself from its imperial arrogance that has so alienated countries around the world. Their contempt for the United Nations in the dash to war with Iraq; their support of the coup in Venezuela in April 2002, and the continuing hostility toward President Chavez; the pressure on nations of the world to exempt the US from the International Criminal Court, now joined by their contemptuous attitude toward President Aristide must be halted. It is time for the people of the USA to make this point clear even if the administration continues to walk around with wax in its collective ears, with eyes closed, and ranting about its version of the world as defined by Bush. - Excerpt from TransAfrica statement on the situation in Haiti, 2/17/04 (http://www.transafricaforum.org/) |
#30
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Nikon 50mm f4.0 vs. 50mm f2.8
David,
When enlarging, the negative is the subject and the focus limits around it are in the depth of field. The print acts like the film and is in the focal plane of the lens, so the terminology down there is the depth of focus. It sounded a little strange to me too, but I saw that nomenclature in a few references, one of which is on page 292 of Ralph Lambrecht's book "Way Beyond Monochrome". It is quite a good book, by the way; one of the few really good new photo books I have come across lately. Ralph used to contribute to this ng, but I haven't seen him on it lately. I am in complete agreement with the sentiments in your signature block, but I fear that The Little Moron has a huge supply of money and dirty tricks that will carry the day. I hope you live in a swing state where your vote will count for something. I live in California where our votes don't count, but TLM's energy buddies love our $2.25 a gallon gasoline. Bob ------------------------ David Nebenzahl wrote: On 3/3/2004 12:35 PM HypoBob spake thus: As for glass carriers -- in an enlargement to 11x14, the depth of field at the negative is just a couple of tenths of a millimeter. Small correction: you mean depth of focus, not depth of field. Similar but different animals. (Depth of field is on the subject side of the lens, in this case the print.) |
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