A Photography forum. PhotoBanter.com

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.

Go Back   Home » PhotoBanter.com forum » Digital Photography » Digital SLR Cameras
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

"film" and "digital" lenses



 
 
Thread Tools Display Modes
  #1  
Old May 29th 05, 10:08 PM
Mr. Mark
external usenet poster
 
Posts: n/a
Default "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  
Old May 29th 05, 10:44 PM
Alan Browne
external usenet poster
 
Posts: n/a
Default

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  
Old May 29th 05, 10:51 PM
Martin Francis
external usenet poster
 
Posts: n/a
Default


"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  
Old May 30th 05, 04:19 AM
Paul Furman
external usenet poster
 
Posts: n/a
Default

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  
Old May 30th 05, 04:38 AM
Stacey
external usenet poster
 
Posts: n/a
Default

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  
Old May 30th 05, 05:25 AM
Darrell
external usenet poster
 
Posts: n/a
Default

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  
Old May 30th 05, 12:52 PM
Alan Browne
external usenet poster
 
Posts: n/a
Default

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  
Old May 30th 05, 02:54 PM
Alan Browne
external usenet poster
 
Posts: n/a
Default

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  
Old May 30th 05, 06:06 PM
Mr. Mark
external usenet poster
 
Posts: n/a
Default

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  
Old May 30th 05, 06:07 PM
Mr. Mark
external usenet poster
 
Posts: n/a
Default

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

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

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


All times are GMT +1. The time now is 06:17 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 PhotoBanter.com.
The comments are property of their posters.