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

[Ray Butler <ray.butler@nuigalway.ie>]

So putting it all together, Ilford Delta 400 (& 3200?) seems to be the 
B&W winner on red sensitivity - if you can hyper away its reciprocity 
problems.

Ray

georgea@cam.org wrote:

> 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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> 
> 
> 
> 
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-- 
Dr. Ray Butler (ray.butler@nuigalway.ie || ray@physics.nuigalway.ie)
Lecturer, Dept. of Physics || Computational Astrophysics Laboratory
National University of Ireland, Galway, University Road, Galway, Ireland.
Tel: +353-91-524411 ext. 3788   FAX: +353-91-525700

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