[rollei_list] Re: RPA, Efke 25, fixer with hardener?

  • From: Laurence Cuffe <cuffe@xxxxxxx>
  • To: rollei_list@xxxxxxxxxxxxx
  • Date: Fri, 03 Apr 2009 18:12:02 -0400

 
On Friday, April 03, 2009, at 02:52PM, "Richard Knoppow" 
<dickburk@xxxxxxxxxxxxx> wrote:
>
>----- Original Message ----- 
>From: "Robert Lilley" <54moggie@xxxxxxxxxxxxxx>
>To: <rollei_list@xxxxxxxxxxxxx>
>Sent: Thursday, April 02, 2009 4:37 PM
>Subject: [rollei_list] Re: RPA, Efke 25, fixer with 
>hardener?
>
>
>>I imagine you could rig a sheet film holder to take a glass 
>>plate -  just dremel out the additional depth and don't use 
>>the other side.
>>
>> Rob
>> On Apr 2, 2009, at 6:44 PM, Mark Rabiner wrote:
>
>     Plate holders were available on the used market until 
>not too long ago, perhaps a search would find some. Plate 
>holders have a spring inside which presses the plate against 
>the front of the holder.
>     Kodak made plates coated with T-Max emulsion until 
>about ten years ago. These were made mostly for scientific 
>photography but electronic imaging has take over there. 
>Astro photography has relyed on electronic sensors for 
>decades now. The glass plates mentioned earlier sound like 
>someone's home made jobs and might be based on very old 
>technology.
>
>--
>Richard Knoppow
>Los Angeles, CA, USA
>dickburk@xxxxxxxxxxxxx 
Richard
The plates I mentioned seemed to be an Agfa product, one which it appears Dr 
Biggler has had some experience of from what I read on a french photo groups 
web site, A cursory google reveals at least two manufactures of glass 
photographic plates for holography still in buisness. Details are available on 
the following web sites
http://www.holokits.com/holographic_film_plates.htm#hologram_film_plates
and
http://www.townetech.com/holoplat.htm,
Plates on the second site appear to be spin coated, which is probably an 
appropriate modern method of achieving an even coating. Holographic emulsions 
tend to have a rather uniform distribution of photosensitive crystals, and as 
such would tend to be inherently high contrast materials. Because of the high 
resolution necessary for good holographic results, they will also be fine 
grained and thus slow. Incidentally spin coating was the technique used by Mrs 
Thatcher (nee Roberts) in her research into Langmuir Bloddget films when she 
was a scientist before she went into politics. (H.H.G.Jellinek and M.H.Roberts, 
J. Sci. Food Agric., 2 (1951) 391.) 
All the best
Larry Cuffe
>
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