FROM: photo@gentletouch.com (Stuart Burden)
SUBJECT: Re: Kodak Infrared Puzzler...
DATE: Fri, 07 Jun 1996 22:41:19 -0700
ORGANIZATION: Gentle Touch Photographics

Thanks for all the suggestions.  The closest to the answer was Sandor with
the  hole in the pressure plate for the databack.

The problem is not that there is a databack on my 9xi (which there isn't),
in fact with or without the databack the problem would be the same.

What Minolta did to cut cost was put the databack pressure plate on all
the earlier 9xi's (I believe that they do not do this now because of
complaints.. unfortunately as an early adoptor of the product I now get
dinged for the cost of replacing it).  The underexposure I was seeing on
the negative was not the result of film fogging, IR sensor systems, or
light leaks through the pressure plates, but was the result of a
differential in the pressure plate reflectivness of IR (essentially zero
in that spot).  Remember Koday IR has no antihalation layer and gets it's
extra pop from the IR that bounces back off the pressure plate (not having
this in one region would explain why it was under exposed).

Thanks for all the great thoughts and comments.

Regards.

Stuart Burden.
Gentle Touch Photographics
--
photo@gentletouch.com    ----    http://www.gentletouch.com
--
Water is best. But gold shines like fire blazing in the night, supreme of
lordly wealth.
                                                                    Pindar
                                                    Olympian Odes, I, l. 1

Date sent:        Wed, 12 Jun 1996 23:23:57 -0400
From:             rlynch@cais.cais.com (Robert A. Lynch)
Subject:          IR film & 700si (was: IR film & 9xi)
To:               minolta-l@osfmail.isc.rit.edu
Send reply to:    minolta-l@listserver.isc.rit.edu

I tried a roll of Kodak HIE in my 700si and the results were mixed.  The 
flip side of my Kodak grey card is 90% white.  I took several pictures of 
this under bright lighting bracketing over a 7 stop range through a #25 
red filter.  The (relatively) underexposed frames clearly show the 
rectangular outlines of the two holes in the pressure plate used by the 
optional date back (which I do not have).  The rectangles are not visible 
in the denser frames.  I also shot a bunch of frames outdoors of subjects 
with a broader contrast range than a 90% white card (trees, buildings, 
etc.).  There were no visible areas of differing exposure in those frames 
and I was able to make a couple of prints tonight that look perfect.

I will try some more tests over the next few weeks with HIE.  I also have 
a few rolls of Konica and Ilford IR film that I will try but I suspect 
that only HIE will have any problems.

My rush to premature judgement so far:  The holes on the pressure plate 
affect exposure for underexposed, low contrast images, but YMMV.

RAL

Date sent:        Sun, 22 Sep 1996 15:46:29 -0400
From:             BruceP7341@aol.com
Subject:          IR/700si helpful hint
To:               minolta-l@osfmail.isc.rit.edu
Send reply to:    minolta-l@listserver.isc.rit.edu

For those using the 700si to shoot Kodak B&W IR film, here's a helpful hint.
 As you may know from previous postings, the 700si has two holes in the
pressure plate which cause the IR film to underexpose in those areas.  The
result can be two underexposed rectangles on the negative and print.  Minolta
sells a special pressure plate for the 700si without the cutouts.  (You can
get it by calling the parts department at Minolta).

A less expensive alternative is to stick some silver mylar photographer's
tape on the back side of the pressure plate over the holes.  This solution
works beautifully, and as long as you are very careful when placing the tape
in position, the results will be great.  I've just gotten a couple of Kodak
IR rolls back, and none of them has those underexposed areas on the negative.

Bruce

Date sent:        Thu, 21 Aug 1997 11:59:20 +0000
From:             Willem-Jan Markerink 
Subject:          Re: Infrared
To:               minolta-l@listserver.isc.rit.edu
Copies to:        infrared@a1.nl
Send reply to:    minolta-l@listserver.isc.rit.edu

(originally from Minolta list, CC'd to the IR list)

On 20 Aug 97 at 17:32, Jim Williams wrote:

> >Many moons ago I asked more than once which Minolta bodies use an 
> >IR-LED counter. Never got any reaction from this list, the only 
> >IR-affecting detail was the data-back prepared film pressure plate 
> >(has a rectangular cut out, affecting the image, as Kodak HIE relies 
> >on light passing through the film and being reflected for a secondary 
> >('foggy' highlight) image). 
> >
> >Sooo....could someone please state *which* Minolta bodies use an 
> >IR-LED counter? Or deny it completely?
> 
> Here's a response straight out of the August (British) 'Practical 
> Photography' magazine:
> 
> Q: Can I use infrared film in the Minolta Dynax 700si or does it have an 
> infrared counter like the 500si that causes fogging?
> A: The Dynax 700si is perfectly safe and won't fog your infrared film. 
> Among the Minolta Dynax range it's just the 500si, 500si Super and 300si 
> that use an infrared sensor in the film advance system that fogs infrared 
> film.
> 
> Translate that from British to U.S. model designations and you should 
> have your answer.

Thanks a bunch Jim, I knew I read this somewhere a long time ago, but couldn't
remember/find which model this applies to!

I'll copy this message 1:1 to my homepage, with full credentials of 
course!....:-))


-- 
Bye,

Willem-Jan Markerink


      The desire to understand 
is sometimes far less intelligent than
     the inability to understand



[note: 'a-one' & 'en-el'!]

Date sent:        Mon, 05 Oct 1998 11:56:43 -0500
To:               infrared@a1.nl
From:             "David J. Carlyon" 
Subject:          Re: IR-LED film counter on Hassy X-Pan
Send reply to:    infrared@a1.nl

>Dan, can you put a full-size scan on the web?
>Seems as if Hasselblad hasn't done a better job technically, but they 
>just avoided the unnecessary precaution that Canon, Minolta and 
>Contax apply in their manual. 

With my Minolta 500si, HIE is fogged horribly along the bottom of the negs,
well into the image area. It appears in the form of vignetting. (There are
some examples in the infrared page of my photo gallery.) I took a piece of
electrical tape, and covered about half of the IR film counter, and the
fogging still occurs on about half the sprocket holes - a negligible amount
of fogging might still occur in the image area, but it's no longer
noticable (maybe it's simply not there, or the graininess of the film
disguises it anyway). I don't think I have any scans uploaded with the
reduced fogging - maybe I'll do that later.

Hasselblad probably just minimized the fogging, by maybe making the thing
smaller, or positioning it further from the image area.

David
http://scc.net/~david/Photography/

Date sent:        Sat, 09 Oct 1999 16:08:17 -0500
To:               infrared@a1.nl
From:             "David J. Carlyon" 
Subject:          Holes in film back
Send reply to:    infrared@a1.nl

I have an 800si, and the part of the back that springs forward to keep the
film flat has a couple of rectangular holes in it - I believe they're for
the time/date option, though I don't have that option. The result, when I
use Kodak HIE, is 2 rectangles in the prints, slightly darker than the rest of
the image. 

There's an example of the effect in
http://scc.net/~david/Photography/Ellee/sky.jpg - look over her left
shoulder (right side of the image, behind her neck).

I believe the effect is probably because the light isn't bouncing back to
the film there, but just going on through. Is there any particular tape or
something I could cover that up with? The rest of the back piece is a shiny
black.

David

Date sent:        Sat, 10 Oct 1998 13:58:49 +0100
From:             Eckhard Stephan 
To:               infrared@a1.nl
Subject:          Re: Holes in film back
Send reply to:    infrared@a1.nl

"David J. Carlyon" wrote:

> I have an 800si, and the part of the back that springs forward to keep the
> film flat has a couple of rectangular holes in it - I believe they're for the
> time/date option, though I don't have that option. The result, when I use
> Kodak HIE, is 2 rectangles in the prints, slightly darker than the rest of the
> image.
>
> There's an example of the effect in
> http://scc.net/~david/Photography/Ellee/sky.jpg - look over her left
> shoulder (right side of the image, behind her neck).
>
> I believe the effect is probably because the light isn't bouncing back to the
> film there, but just going on through. Is there any particular tape or
> something I could cover that up with? The rest of the back piece is a shiny
> black.
>
> David
>

Hello David,

I recently bought a Minolta 600si Classic, which has a similar backplate.
Therefore I had exactly the same problem with HIE (BTW: the holes do not seem to
matter when using EIR). I simply got myself a piece of black self-adhesive
plastic foil at a local department store. After I had put the foil over the
backplate, I got perfect HIE-pictures [at least in a technical sense ;-) ].
Normally the foil is used to put a cover on furniture, working plates and the
like. It is available in different colours. There are shiny versions as well as
dull ones (I use a shiny one that resembles the backplate's colour). The foil is
called "dc-fix". I do not know, whether it is sold outside Germany (where I
live), but I am quite sure you could get something similar, too.

Hope, this will help you,

Eckhard Stephan

eckhard.stephan@writeme.com
http://www.eckhards-photobox.de

If you have any question, remark, comment, want to share some philosophy or just want to express your opinion about these pages, feel free to send email to: w.j.markerink @ a1.nl