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