RE: [APML] Rho Ophiuchi Using Provia 100F

["Thomas W.Earle" <twade@bmi.net>]

Chris,

I'd definitely go with E200 for emmission nebula, especially HII regions.  It is 
awesome in its h-alpha response (i.e. you want find a better film).  It's a little 
more "nebulous" which to choose as you head towards the blue spectrum.  If you have 
very dark skies E200 will suffice; however, if you have less than ideal skies, you 
should likely go with Provia 400F.  I'll be posting some images over the next few 
weeks that show E200 can produce nice blues; however, the blue layer takes more 
time to build (i.e. it is less sensitive) so you must have a dark enough sky to 
allow the blue layer to register the nebula properly.  For example, I have another 
image of Rho Ophiuchi (wider view) and M20 (FSQ) that came out nicely.  The 
exposures were 45 minutes at F/4.0 and 75 minutes at F/5.0, repectively.

I hope this helps.  Let me know if you need more information.

Wade

P.S. I'd still recommend using Provia 100F with your Schmidt Camera.  With those 
short exposures, the reciprocity failure of the layer producing the yellow cast 
should have little effect (i.e. there should be very little or not yellow cast).  
More specifically, you should be fine as long as exposures are kept below 20 
minutes.
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