From: Milton Aupperle <milton@outcastsoft.com>

Date: March 23, 2006 10:11:46 AM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: iRez Stealth Fire work with Astro IIDC


Hi Randy;


On 22-Mar-06, at 7:50 PM, kjtest wrote:


Yes, that did it - Thanks.


I just purchased a Meade 200LXR and am considering getting a Canon 350D for

astrophotography.  I had been using an ETX-105 with a Quickcam 4000 and a sony digital

camera.  I had this StealthFire lying around and found your software -- not sure if it will fit

in somehow.  I'm wondering if the Quckcam or iRez can be used for autoguiding?  Any

other suggestions for how I could use it?


Astro IIDC only supports IIDC cameras - it won't support USB ones like the Quickcam.



The iRez Stealthfire has always had something wrong with it -- after it is on for a while

there is a vertical "band" in the image (not always in the same place).  The image within the

band is slightly darker than the remainder of the image.  It does this with all video

software so it must be something in the sensor / circuits.


The Stealth cameras suffers from bad EM noise, worse than the other inexpensive cameras and of two noise types.


The first type is what you have describe above and is called  vertical bar "step noise" that is caused by EM coupling. The faster you run the frame rate, the further it shifts to the right. If you run the camera at about 3.75 frames per second - the bar basically goes away. At higher frame rates this can be partially compensated for by using Astro IDC's live Dark Frame subtraction (cover the optical path, take the dark frames, uncover the optical path). However you have to make sure that you don't change the brightness, black point or gains afterwards or you have to repeat the cover - take darks - uncover steps.


The other noise is something you may or may not have seen. It is a variably oriented wavy noise that is tied to the temperature of a component on the camera. When it hits steady state, the pattern pretty well stabilizes and it stops changing orientation, but it's still present. If you look at this image


http://www.outcastsoft.com/AstroImages/MVMJS_04_03_28.jpg


you can see a diagonal pattern on Jupiter, which is the second EM noise I'm talking about. The orientation varies a lot depending on the camera temperature.


Both of these issues can be compensated for by running the camera at slower frame rates (3.75 frames per second) and to boost the brightness use the Monochrome 2x2 mode. You need to be careful in how you adjust your Exposure and Black Point as they will amplify noise rather than signal.


The only ones who have solved all of the above are "The Imaging Source", which have spent the money and time to fix all the coupling issues in their 21F04 series of cameras. But they are a lot more expensive than the iRez and if all your doing is guiding, I would not bother with them.


HTH..


Milton J. Aupperle

President

ASC - Aupperle Services and Contracting

Mac Software (Drivers, Components and Application) Specialist

#1005 - 815 14th Avenue. S.W.

Calgary Alberta Canada T2R0N5

1-(403)-229-9456

milton@outcastsoft.com

www.outcastsoft.com