Re: [APML] Pushing & Mars

[astropix@att.net]

 Gary writes:
> 2.  What would be a good film speed to use for pics of Mars?

 Hey Gary... hopefully the other responses have cued you in on push-
processing slide films. As for Mars, *do not* push your film... too 
inexact... too iffy. Remember, Mars is illuminated by the Sun... even with a 
projection set-up yielding f/32, your exposure time on ISO 50 film is only 
about 1/4 second!

 Unlike deep-sky with shorter focal lengths, successful planetary imaging 
with film requires excellent 'seeing' conditions... in fact, a modest level 
of haze is acceptable *if* you adjust your exposure times accordingly. There 
is simply no substitute for seeing conditions when shooting effective focal 
lengths of 7000mm at f/32 on film... this is why I have a campsite reserved 
at Bahia Honda Park in the FL Keys during 'Mars Week'. Southern latitude 
*and* some of the best seeing conditions east of Hawaii!

 Under ideal conditions, slow speed, fine grained, *high saturation* slide 
films such as Fuji Velvia and Agfa Ultra 50 will yield best results on a 
bright object such as Mars. If your skies don't permit it, work your way up 
the film speeds from there. Kodak's 'Extra Color' slide film should be good 
for 100 speed... Fuji's Provias - 100 and 400, might be winners as well. 
While your at it, shoot some various print films, too... couldn't hurt!

 When gathering the exposures, bracket exposure times a stop or two beyond 
your calculations... *BUT*... shoot at least three or more shots at the same 
exposure as quickly as possible... this gives you a better chance of catching 
a sequence you can stack to further inhance the image. Also, use mirror lock-
up or pre-fire and check focus each time you change exposure times.

 Good Luck !!!

 

--
 Geoff

http://home.att.net/~astropix/


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