From: "Milton Aupperle" <milton@outcastsoft.com>
Date: November 8, 2008 12:18:12 PM MST
To: Astro_IIDC@yahoogroups.com
Subject: Re: Moray
It could also be electrical interference (bad or poorly shielded
FireWire cable or Bad Mac FireWire port) or a camera defect too. The
iRez cameras were notoriously bad for this sort of noise showing up,
due to electrical coupling on the data out lines. That's one of the
main reasons I don't support them.
The easiest way to tell the difference is to have the defocussed
(assuming it has a lens) camera pointed at a blank wall, uniformly lit
with either natural or incandescent light (florescent lights will
cause strobe patterns at even multiple exposures of 50 or 60 hz
frequencies). Also make sure your analog monitor isn't lighting the
wall either, as the refresh rate can show up as strobing. Then adjust
the exposure time to make the image uniformly gray and see if the
pattern shows up or not.
If the pattern does show up, it's definitely a camera issue.
Hope that helps..
Milton Aupperle
--- In Astro_IIDC@yahoogroups.com, Alan Friedman <alan@...> wrote:
Hi Dean,
The dreaded moire pattern... it is coming from an interference between
surfaces in the optical path - with the glass in front of the CCD chip
most likely being one. Have you tried rotating the barlow or blocking
filter or camera? Does it remain unchanged at different effective
focal lengths?
I encountered this using a Nikon D1X with my Coronado solarmax 90
years ago and I couldn't eliminate it. I have not had a problem with
either of my DMK cameras, but others have. Strangely, I did notice the
pattern just the other day for the first time using my DMK 41AF02
camera with a Baader FFC. I tried using a long extension tube for
higher power and saw it on the screen during capture for the first
time in years. The magnification was too much for the seeing so I quit
for the day. Yesterday, back to my usual settings with the FFC (3.5x)
and all was fine.
I hope you are able to eliminate it. It is a nuisance to try and
remove it in Photoshop.
Alan
On Nov 7, 2008, at 6:34 PM, dean_drumheller wrote:
Using DKF 31AF03.AS, I'm getting curved lines in all images and not
sure how to deal with
them. I've tried many different focus, exposure and image controls
and not making any
progress. Appreciate a starting point, any input on fixing the
image. Thanks -Dean
Link: http://collegeofsanmateo.edu/astronomy/Image%20Post.asp