Re: [APML]: Planetary Photography on Hypered Tech Pan?

["Bobby Middleton" <bobbym@unicomp.net>]

The Astro-Photography Mailing List
------------------------------------

Thanks for passing on the info Chuck.
A speed of 800 would be exactly what I am looking for. I realize 
you are talking about this with D-19, but too much contrast
might be a decent trade-off for faster exposure times. 
Perhaps the speed gains 
would apply for the HC110 developer as well.
I guess I will just have to try it and see how they look. 

At ISO 200, I was looking at 3 sec green exposures at only f/32.
f/64 is really minimum at my scope's focal length and f/94 
is much better as far as the desired image scale needed. 
New calculations using ISO 800 speed give me a 2 sec ex. at 
f/64 for green on Jupiter; 5 sec at f/94.  
Chuck do you know if Lumicon's hypered TP is done in a high 
vacuum? My chamber is not set up for high vacuum. 

Bobby Middleton

astropics at: http://home.unicomp.net/~bobbym/astro1.htm


----------
> From: Chuck Vaughn <aa6g@aa6g.org>

> 
> In the process of running tests to try to figure out how to properly
> combine my B&W images into a tricolor photo, I ran across something
> that might be of interest to those doing planetary photography.
> 
> Over the weekend I photographed a Kodak grayscale chart on unhypered
> TP and metered the exposure for ISO 200 for development in D19. The
> results were right on with mid gray being in the center of the film's
> dynamic range.
> 
> Yesterday I photographed the chart again but with my high vacuum
> hypered TP. To my amazement the film was two stops overexposed!
> This means I needed to meter the exposure at ISO 800. I going
> to re-photograph the chart and meter for ISO 800.
> 
> I don't know how this applies to TP hypered by less extreme methods
> or developed in lower contrast developers but there must be some
> effect.
> 
> The standard advice has always been use non-hypered TP for planetary
> photography but if you can get two stops more speed by using it
> hypered then why not? Maybe this would be fast enough for Bobby M.
> to do his tricolor planetary photography.
> 
> Chuck <aa6g@aa6g.org>