RE: [APML] IC 410 uploaded and IC 405 adjusted

[John Mirtle <spampit@shaw.ca>]

Alan,
	Sorry about jumping in late, I was out of town this weekend.
Something isn't right here. Both of your images are badly clipped at the
dark end which I find very odd. This would imply that your scanner can't get
deeply into the black part of the negative but what is odd here is that with
your gargantuan exposure times, the background shouldn't be very dark! To
see what I mean, look back a week or so for a posting from Jon Kolb. He
posted a set of exquisite images which were also taken on E200. The optics
were an f7.9 refractor - only marginally faster than yours at f8.1. Jon's
shots were in the 70 minute range and yet they went plenty deep. For sky fog
and nebula, f-ratio matters - not diameter! Your shots should be recording
much more. Much, much more! 
	By using the same exposure times as Jon and pushing 1 stop, the
results should be the same except for a smaller image scale and fewer stars.
The fact that you are exposing much longer and getting less would imply that
you have a problem somewhere. Are you sure that the shutter is remaining
open the entire time? Does a roll of "normal" daytime shots from your
photofinisher look normal? Are there spiders living in your optical tube? It
looks like something is stealing your photons. I recently heard something
about Tak refractors with 2.7" focusers that was a bit disturbing that might
explain some of this. Apparently, at the objective end of the focuser
drawtube, the drawtube is bottlenecked to 48mm aperture. The 4" versions and
the FSQ do not have this problem, I am wondering if you are being affected
by this. This would certainly slow down the effective f-ratio or increase
vignetting. Not many others are shooting prime with an FS-102 which makes it
hard to do a direct comparison. Are your slides as dark as the web images
imply? With your excellent focus, guiding and long exposures, your images
should be giving a bit more "punch".

John Mirtle
Calgary, Ab. Canada

-----Original Message-----
From: astro-photo-bounces@seds.org [mailto:astro-photo-bounces@seds.org] On
Behalf Of Alan Voetsch
Sent: Sunday, October 31, 2004 11:26 AM
To: APML; SOS
Subject: [APML] IC 410 uploaded and IC 405 adjusted

Hey all,

Following Rob Gendler's advice, I backed off on the saturation just a
bit in the IC 405 shot. I have also added the shot info below the
picture. http://www.pbase.com/avoetsch12952/image/35699620

Also, I just uploaded a weak shot of IC 410. It could benefit from much
more exposure time, but that's not an option now. Info below the shot:
http://www.pbase.com/avoetsc12952/image/35749434

Thanks,
Alan



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