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Stopping Down Enlarger Lens Focus Question Newbie
I'm a beginner. So go easy. I'm printing B&W (first prints done this week in
fact). When I stop down my enlarger lens (exposure around 20secs. at f22) does focusing becoming less critical, ie. is it similar to a camera in that I'm increasing depth of field therefore I can be out a bit? What are the advantages to stopping down as opposed to using lower f-stop values (f5.6). Am I losing contrast or sharpness in the print? Any grain issues? Does leaving the light on that long change any of the characteristics of tone distribution? Thx. |
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Stopping Down Enlarger Lens Focus Question Newbie
On 4/17/2004 12:10 PM SofaKing spake thus:
I'm a beginner. So go easy. OK. I'm printing B&W (first prints done this week in fact). When I stop down my enlarger lens (exposure around 20secs. at f22) does focusing becoming less critical, ie. is it similar to a camera in that I'm increasing depth of field therefore I can be out a bit? Yes; it increases the depth of field of the projected image in exactly the same way as with a camera taking a picture. Smaller aperture = greater depth of field = more latitude in misfocusing. What are the advantages to stopping down as opposed to using lower f-stop values (f5.6). Just what was described above: increased overall sharpness. Am I losing contrast or sharpness in the print? Nope. Any grain issues? Only that what grain is visible will be more sharply in focus. That could be good or bad, depending. Does leaving the light on that long change any of the characteristics of tone distribution? Nope; you're apparently thinking of reciprocity failure characteristics. I don't think this becomes a problem with photo paper until your exposures are into the range of several minutes or more. -- I was quickly apprised that an "RSS feed" was not, as I had naively imagined, some new and unspeakable form of sexual debauchery practised by young persons of dubious morality, but a way of providing news articles to the cybernetic publishing moguls of the World Wide Wait so they can fill the airwaves with even more useless drivel. - Cynical shop talk from comp.publish.prepress |
#3
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Stopping Down Enlarger Lens Focus Question Newbie
So maybe other than being slower to print no real disadvantages mostly
advantages, good. I also like stopping down because it's a little bit more forgiving when I want to increase or descrease exposure too. Thx. "David Nebenzahl" wrote in message ... On 4/17/2004 12:10 PM SofaKing spake thus: I'm a beginner. So go easy. OK. I'm printing B&W (first prints done this week in fact). When I stop down my enlarger lens (exposure around 20secs. at f22) does focusing becoming less critical, ie. is it similar to a camera in that I'm increasing depth of field therefore I can be out a bit? Yes; it increases the depth of field of the projected image in exactly the same way as with a camera taking a picture. Smaller aperture = greater depth of field = more latitude in misfocusing. What are the advantages to stopping down as opposed to using lower f-stop values (f5.6). Just what was described above: increased overall sharpness. Am I losing contrast or sharpness in the print? Nope. Any grain issues? Only that what grain is visible will be more sharply in focus. That could be good or bad, depending. Does leaving the light on that long change any of the characteristics of tone distribution? Nope; you're apparently thinking of reciprocity failure characteristics. I don't think this becomes a problem with photo paper until your exposures are into the range of several minutes or more. -- I was quickly apprised that an "RSS feed" was not, as I had naively imagined, some new and unspeakable form of sexual debauchery practised by young persons of dubious morality, but a way of providing news articles to the cybernetic publishing moguls of the World Wide Wait so they can fill the airwaves with even more useless drivel. - Cynical shop talk from comp.publish.prepress |
#4
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Stopping Down Enlarger Lens Focus Question Newbie
When I stop down my enlarger lens (exposure around 20secs. at f22)
does focusing becoming less critical, No, all the image focus is in the negative, your enlarger will not make focus where there is none. Oft time a grain focuser is used to focus on the grain of the negative which has nothing to do with image focus. If you missed focus at the camera stage you will not get it back of come close at the printing stage. In the darkroom all you can do focuse the negative to sharpness and let the image fall where it will. What are the advantages to stopping down as opposed to using lower f-stop values (f5.6). Every lens has a "sweet spot". It is usually mid way between max and min apature, maybe 5.6 or 8. Enlarging lenses are flat focus lenses in that they project a flat negative image onto a flat piece of paper, unlike camera lenses.. All the DOF the image has in in the negative, closing the apature will not increase image DOF. It will lengthen exposure time which is a good thing. I personally like exposures of more than 30 seconds and if burning or dodging is involved I will stop down as much as possible to insure enough time for burning or dodging. _________________ Ready, Fire, AIM. Bruce Brooklyn, N.Y. |
#5
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Stopping Down Enlarger Lens Focus Question Newbie
In article , David Nebenzahl
wrote: Just what was described above: increased overall sharpness. Am I losing contrast or sharpness in the print? Nope. Any grain issues? Only that what grain is visible will be more sharply in focus. That could be good or bad, depending. With my 35mm printing (on a focomat), stopping down to F22 decreases sharpness and blurs grain. |
#6
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Stopping Down Enlarger Lens Focus Question Newbie
On 4/17/2004 4:05 PM Bruce spake thus:
When I stop down my enlarger lens (exposure around 20secs. at f22) does focusing becoming less critical, No, all the image focus is in the negative, your enlarger will not make focus where there is none. Oft time a grain focuser is used to focus on the grain of the negative which has nothing to do with image focus. If you missed focus at the camera stage you will not get it back of come close at the printing stage. In the darkroom all you can do focuse the negative to sharpness and let the image fall where it will. You missed my point, or maybe I didn't state it clearly enough: I'm not claiming that greater depth-of-field at the enlargement state can make up for poor focus in the picture-taking stage. (That would be quite a feat, with metaphysical and quantum-mechanics implications.) What I meant is that stopping down an enlarging lens gives greater depth of field so far as the negative being projected is concerned, and will allow more focusing errors to still result in a sharp image of the negative (which may well be out of focus, but that's another story). -- I was quickly apprised that an "RSS feed" was not, as I had naively imagined, some new and unspeakable form of sexual debauchery practised by young persons of dubious morality, but a way of providing news articles to the cybernetic publishing moguls of the World Wide Wait so they can fill the airwaves with even more useless drivel. - Cynical shop talk from comp.publish.prepress |
#7
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Stopping Down Enlarger Lens Focus Question Newbie
On 4/17/2004 4:38 PM David Nebenzahl spake thus:
On 4/17/2004 4:05 PM Bruce spake thus: When I stop down my enlarger lens (exposure around 20secs. at f22) does focusing becoming less critical, No, all the image focus is in the negative, your enlarger will not make focus where there is none. Oft time a grain focuser is used to focus on the grain of the negative which has nothing to do with image focus. If you missed focus at the camera stage you will not get it back of come close at the printing stage. In the darkroom all you can do focuse the negative to sharpness and let the image fall where it will. You missed my point, or maybe I didn't state it clearly enough: I'm not claiming that greater depth-of-field at the enlargement state can make up for poor focus in the picture-taking stage. Whoops: realized too late that you weren't replying to *my* reply. But the point remains, since I don't believe the O.P. was asking whether stopping down an enlarging lens could increase depth of field *in the original negative*. (At least I hope they weren't.) In other words, when he asked "does focusing become less critical?", he was referring to focusing the enlarging lens, not the camera lens. -- I was quickly apprised that an "RSS feed" was not, as I had naively imagined, some new and unspeakable form of sexual debauchery practised by young persons of dubious morality, but a way of providing news articles to the cybernetic publishing moguls of the World Wide Wait so they can fill the airwaves with even more useless drivel. - Cynical shop talk from comp.publish.prepress |
#8
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Stopping Down Enlarger Lens Focus Question Newbie
On 4/17/2004 4:23 PM jjs spake thus:
In article , David Nebenzahl wrote: Just what was described above: increased overall sharpness. Am I losing contrast or sharpness in the print? Nope. Any grain issues? Only that what grain is visible will be more sharply in focus. That could be good or bad, depending. With my 35mm printing (on a focomat), stopping down to F22 decreases sharpness and blurs grain. So you're encountering diffraction effects, right? Or focus shift, one. -- I was quickly apprised that an "RSS feed" was not, as I had naively imagined, some new and unspeakable form of sexual debauchery practised by young persons of dubious morality, but a way of providing news articles to the cybernetic publishing moguls of the World Wide Wait so they can fill the airwaves with even more useless drivel. - Cynical shop talk from comp.publish.prepress |
#9
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Stopping Down Enlarger Lens Focus Question Newbie
"SofaKing" wrote in message news:Tifgc.147080$Pk3.126052@pd7tw1no... I'm a beginner. So go easy. I'm printing B&W (first prints done this week in fact). Your questions are very good. Some of the replies are not. When I stop down my enlarger lens (exposure around 20secs. at f22) does focusing becoming less critical, ie. is it similar to a camera in that I'm increasing depth of field therefore I can be out a bit? Small aperature will increase depth of field, but not enough to overcome poor initial focus. What are the advantages to stopping down as opposed to using lower f-stop values (f5.6). None, as to the resulting image. Am I losing contrast or sharpness in the print? You are loosing sharpness because of optical defraction when you use your lens much below f8.0. This a matter of light itself, not lens design or construction. The only way a close comparision would not clearly show this for you would be if you were using a very low quality lens or were out of focus. Any grain issues? No. Does leaving the light on that long change any of the characteristics of tone distribution? No. If you want longer print times, which can be useful, use a lower output bulb or insert neutral density filtration above the negative, and [assuming 35mm printing with a 50mm lens] keep the lens aperature in the 5.6 - 8.0 range. |
#10
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Stopping Down Enlarger Lens Focus Question Newbie
In article , David Nebenzahl
wrote: On 4/17/2004 4:23 PM jjs spake thus: With my 35mm printing (on a focomat), stopping down to F22 decreases sharpness and blurs grain. So you're encountering diffraction effects, right? Or focus shift, one. Yes, diffraction. I can watch the grain go soft through the focusing scope. Refocusing has no effect. So I always print stopped down two from wide open. If the exposure is too short to comfortably dodge and burn, I use an ND filter. |
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