Re: [APML] A small print film test...

[georgea@cam.org]

Hi Bill

What you are saying is the same as what I have heard and have been following. 
Recently I have seen some discussion about using T-Max 400 for astro work and 
having some red response. I figured that for the cost of a couple rolls of film 
I would give it a shot at hypering.
But if the film is red dead out of the box, then there is no point in bothering 
with it. The spectrograph for the film on the Kodak datasheet shows it starting 
the classic nosedive at 640nm but it looked like it may still be useable at 
660nm.
And I have learned that just because a film is good in daylight doesn't mean 
that it is any good hypered. SFX-200 is a prime teacher of that one. In full 
daylight it records reds very nicely, when hypered (different levels of fog 
from 0.10 to 0.50) it is still just as useless. It may be good for solar H-
Alpha recording.

George Anderson
Montreal Canada

Clear skies and good health


Quoting "William R. Mattil" <wrmattil@ix.netcom.com>:

> George Anderson wrote:
> 
> >
> >I have a couple of rolls of 400TMax TMY that I will try hypering unless
> >someone has already been down that road.
> >
> >
> >  
> >
> George,
> 
> My understanding of the hypering process is this. That *if* the film is 
> good to begin with it can possibly decrease reciprocity failure to a 
> manageable level. Now all of the films that I have shot hypered, were 
> good unhypered ..... good reds, blues and greens. Hypering made them 
> better. Particularly for long exposures.
> 
> Is this, in fact, accurate ? Can anyone point to a relatively current 
> film that had horrible red response that hypering improved ?
> 
> Unhypered TP is quite useable for short exposures.
> 
> T-Max in all the varieties that I have shot had horrible red response. 
> Therefore my guess is that hypering will gain nothing. I used this film 
> to focus test my prime focus set-up and my schmidt camera. Never saw any 
> red in any of it (realising it *is* a B&W film mind you.) :)
> 
> 
> I guess what I am trying to say is that unless someone can state that my 
> assumption is wrong, trying short exposures with the film and 
> determining the overall color response makes more sense than hypering a 
> bad film to start with. My understanding is that hypering does not 
> change the sensitivity at a given wavelength. It just reduces reciprocity.
> 
> Regards
> 
> Bill
> 
> -- 
> 
> William R. Mattil  :  http://www.celestial-images.com
> 
> 
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