RE: [APML] Another one from New Mexico

["Jon Kolb" <jkolb@datawest.net>]

Hi John,

>     I have this same region shot on Provia 400F using my 
> Schmidt, and I also found it difficult to nail colour balance 
> on this field. It looks to me like there may be differences 
> in the rate of reciprocity failure between the 3 colour 
> layers with 400F. The darker bits always seem to need a 
> different balance than the brighter bits. I don't plan to 
> continue using 400F. Your shot came out much nicer, probably 
> due to the longer FL and large format. No tinkering required! 

Thanks very much.  I haven't noticed the problem with P400F you mention.
If it's there, it's probably masked by my processing stumbles.  I'm
going to keep shooting it, along with E200.  I'd especially like to get
a shot of the Cone region, IC405, and the Seagull with this film, but I
was clouded out on those targets this winter.  So far, I find that with
my equipment anyway, 400F seems to excel at targets that have both red
and blue components - the M8-M20 I posted recently, the Antares region,
and a couple of others.

> I have a "close-up" version of B86 at 
> http://members.shaw.ca/astrophoto/n6520.htm > which shows a bit 
> more detail taken with an 8" f6 - no colour balance problems 
> with this shot. :-)  Tough to shoot, as I live so close to 
> the north pole!

That's good resolution in 6520!  Interestingly, Uranometria shows a
globular cluster, E456-38, that's just west of B86 and is about as large
as the combined field of 6520 and B86.  I can't see it in either of our
shots, so I'm wondering if I'm just missing it amongst the star cloud,
or if it's a background object that can't be readily distinguished from
the cloud with amateur instruments.  Any thoughts on that one?

Sincerely,
Jon Kolb
Adventures in Astrophotography
http://home.datawest.net/jkolb/
jkolb@datawest.net




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