If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
"film" and "digital" lenses
Someone said in alt.photography that "film" lenses are designed to focus the
different color wavelengths differently to make up for the layered emulsion in film. That sounds like non-sense to me. Opinions? -- Mark Photos, Ideas & Opinions http://www.marklauter.com |
#2
|
|||
|
|||
Mr. Mark wrote:
Someone said in alt.photography that "film" lenses are designed to focus the different color wavelengths differently to make up for the layered emulsion in film. That sounds like non-sense to me. I believe you're right. The 'layers' of film emulsions are so thin as to escape correction in the optics. Film thickness variance, optics variances, film transport variances and so on, combined, are huge compared to the thin-ness of the film emulsion. Further, the film companies have differing emulsion build up designs, including Fuji "4th layer" in some negative films. I never heard of needing special lenses for that... Opinions? The only 'issue' I know of, and don't pay much attention to, is whether UV filters are necessary anymore. A flat piece of optical glass as a sacrificial filter (or better: none at all) is all that is needed. This does apply to CCD (lower UV sensitivity than film), I don't know about CMOS. OTOH I've seen another claim that lack of UV filtering may lead to 'blooming' when photosites are close to saturation. (May apply to CMOS and not CCD, I don't know). All the lenses, unless designed to filter specifically, pass a range of light far larger than the visible range we're interested in but are centered in the visual spectrum where focus on the film plane is concerned. The sensors have filtering (to greater or lesser degrees) in their covers to block IR and possibly UV. Cheers, Alan. -- -- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. |
#3
|
|||
|
|||
"Alan Browne" wrote in message ... Mr. Mark wrote: Someone said in alt.photography that "film" lenses are designed to focus the different color wavelengths differently to make up for the layered emulsion in film. That sounds like non-sense to me. I believe you're right. The 'layers' of film emulsions are so thin as to escape correction in the optics. Film thickness variance, optics variances, film transport variances and so on, combined, are huge compared to the thin-ness of the film emulsion. Further, the film companies have differing emulsion build up designs, including Fuji "4th layer" in some negative films. I never heard of needing special lenses for that... Or special lenses for black and white... |
#4
|
|||
|
|||
Mr. Mark wrote:
Someone said in alt.photography that "film" lenses are designed to focus the different color wavelengths differently to make up for the layered emulsion in film. That sounds like non-sense to me. Opinions? I heard there is a coating on the rear element to prevent reflections off the sensor for digital lenses though I've not seen any example of these reflections so I assume it's quite a minor issue. -- Paul Furman http://www.edgehill.net/1 san francisco native plants |
#5
|
|||
|
|||
Mr. Mark wrote:
Someone said in alt.photography that "film" lenses are designed to focus the different color wavelengths differently to make up for the layered emulsion in film. Thats BS.. -- Stacey |
#6
|
|||
|
|||
Mr. Mark wrote:
Someone said in alt.photography that "film" lenses are designed to focus the different color wavelengths differently to make up for the layered emulsion in film. Like George Preddy claiming Lateral Chromatic Aberration was a Sigma feature... |
#7
|
|||
|
|||
Martin Francis wrote:
Further, the film companies have differing emulsion build up designs, including Fuji "4th layer" in some negative films. I never heard of needing special lenses for that... Or special lenses for black and white... Good point. Cheers, Alan -- -- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. |
#8
|
|||
|
|||
Paul Furman wrote:
Mr. Mark wrote: Someone said in alt.photography that "film" lenses are designed to focus the different color wavelengths differently to make up for the layered emulsion in film. That sounds like non-sense to me. Opinions? I heard there is a coating on the rear element to prevent reflections off the sensor for digital lenses though I've not seen any example of these reflections so I assume it's quite a minor issue. So minor that DSLR's cannot do OTF TTL metering. Any need for coatings to help in this regard sounds like the cry of the marketeers. Cheers, Alan. -- -- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. |
#9
|
|||
|
|||
Further, the film companies have differing emulsion build up designs,
including Fuji "4th layer" in some negative films. I never heard of needing special lenses for that... Or special lenses for black and white... That was the first thing I considered. I even asked the poster about that and several folks have replied that he's full of $#@!, but he has apparently disappeared. -- Mark Photos, Ideas & Opinions http://www.marklauter.com |
#10
|
|||
|
|||
I heard there is a coating on the rear element to prevent reflections
off the sensor for digital lenses though I've not seen any example of these reflections so I assume it's quite a minor issue. Wouldn't film do the same thing? It's shiny plasticy stuff after all. -- Mark Photos, Ideas & Opinions http://www.marklauter.com |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
New Leica digital back info.... | Barney | 35mm Photo Equipment | 19 | June 30th 04 12:45 AM |
Digital Imaging vs. (Digital and Film) Photography | Bob Monaghan | Medium Format Photography Equipment | 9 | June 19th 04 05:48 PM |
The first film of the Digital Revolution is here.... | Todd Bailey | Film & Labs | 0 | May 27th 04 08:12 AM |
Which is better? digital cameras or older crappy cameras thatuse film? | Michael Weinstein, M.D. | In The Darkroom | 13 | January 24th 04 10:51 PM |