Difference between revisions of "Talk:Diaphragm"
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<br/>[[User:Steevithak|Steevithak]] 13:57, 7 January 2012 (PST) | <br/>[[User:Steevithak|Steevithak]] 13:57, 7 January 2012 (PST) | ||
:My recollection is that "preset" always referred the two-ring style of aperture control: one ring without detents that actually closes the diaphragm; the second with detents but unconnected to the diaphragm—just providing a stop, as you twisted the first ring to close down to shooting aperture. --[[User:Voxphoto|Vox]] 14:32, 7 January 2012 (PST) | :My recollection is that "preset" always referred the two-ring style of aperture control: one ring without detents that actually closes the diaphragm; the second with detents but unconnected to the diaphragm—just providing a stop, as you twisted the first ring to close down to shooting aperture. --[[User:Voxphoto|Vox]] 14:32, 7 January 2012 (PST) | ||
+ | ::So, if you're correct, that means "2 Ring Preset" is a redundant phrase? I'll have some fix ups to do if that turns out to be the case. I'm having a hard time finding anything definitive. I've found one source so far, a 1961 Popular Science with a couple of paragraphs on the history of lenses. Seems to support your understanding (e.g. manual has detents, preset is manual + preview ring). [http://books.google.com/books?id=4SADAAAAMBAJ&lpg=PA162&dq=%22preset%20diaphragm%22&pg=PA162#v=onepage&q=%22preset%20diaphragm%22&f=false Pop Sci Aug 1962]<br/>[[User:Steevithak|Steevithak]] 16:02, 7 January 2012 (PST) | ||
+ | :::Good reference, as that predates my adolescent perusing of PopPhoto mags, etc. by a decade. I don't think I've ever seen the phrase "2-ring preset," though. It's the second ring that "pre-sets" the desired shooting aperture. | ||
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+ | :::The only really oddball alternative I know about is the early [[Canonflex]] lenses: They had a full auto diaphragm, but added a second ring for depth of field preview (I believe—never handled one in person)--[[User:Voxphoto|Vox]] 20:36, 7 January 2012 (PST) |
Latest revision as of 04:36, 8 January 2012
Need better sourcing
We need to find some references for this page. I see the definitions I original posted have drifted and the first two now seem to conflict (or at least the distinction is no longer clear).
My understanding (which is very possibly flawed!) is that a manual diaphragm is one that is continuously adjustable and does not have detents (presets). A preset diaphragm is a like a manual except that is has detents (presets). Also a preset may optionally have a 2nd ring for preview purposes and the preview ring operates like a manual diaphragm (i.e. continuously variable). I don't have any good authoritative sources to back this up at the moment. If anyone can source this, please do so and correct the definitions if needed.
Steevithak 13:57, 7 January 2012 (PST)
- My recollection is that "preset" always referred the two-ring style of aperture control: one ring without detents that actually closes the diaphragm; the second with detents but unconnected to the diaphragm—just providing a stop, as you twisted the first ring to close down to shooting aperture. --Vox 14:32, 7 January 2012 (PST)
- So, if you're correct, that means "2 Ring Preset" is a redundant phrase? I'll have some fix ups to do if that turns out to be the case. I'm having a hard time finding anything definitive. I've found one source so far, a 1961 Popular Science with a couple of paragraphs on the history of lenses. Seems to support your understanding (e.g. manual has detents, preset is manual + preview ring). Pop Sci Aug 1962
Steevithak 16:02, 7 January 2012 (PST)- Good reference, as that predates my adolescent perusing of PopPhoto mags, etc. by a decade. I don't think I've ever seen the phrase "2-ring preset," though. It's the second ring that "pre-sets" the desired shooting aperture.
- So, if you're correct, that means "2 Ring Preset" is a redundant phrase? I'll have some fix ups to do if that turns out to be the case. I'm having a hard time finding anything definitive. I've found one source so far, a 1961 Popular Science with a couple of paragraphs on the history of lenses. Seems to support your understanding (e.g. manual has detents, preset is manual + preview ring). Pop Sci Aug 1962