From: Milton Aupperle <milton@outcastsoft.com>

Date: November 21, 2005 2:09:55 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: Having fun with my Fire-i, but what about better cameras?

Hi Steve;

On 21-Nov-05, at 1:09 PM, Milton Aupperle wrote:

--- In Astro_IIDC@yahoogroups.com, "Steve Bryson" <stevebeam@y...> wrote:

-----Snipped for brevity..

1) I am only interested in planetary/lunar photography with the webcam.

For deep sky I am content with my digital rebel. Does this mean I would

be happy with a camera without the extra trigger and I/O (like that on the

DMK 31BF03)? As far as I can tell I'm only losing the ability to do long

exposures (which I don't want) and to have very high frame rates (which

I might use but is not worth $200). Is this correct?

Both the 31BF03 or 31AF03 support exposures up to 30 seconds per frame. Since the trigger and IO pins will be of no use to you, you would be better off going with the 31AF03 and saving $200. They max out at 30 fps at 1024x768 sizes, which is 22.5 megabytes per second or 1.3 gigabytes per minute of recording of video - so i hope you have a lot of free hard drive space.

2) For more dynamic range it seems I have to move to the Point Grey

class of cameras such as the Flea, which puts out 12 bits. This might

be worth the extra money to me, but what exactly happens to those

extra bits? Milton's web site says the movie formats saved by Astro IIDC

supports 16 bits. Can anyone explain the specifics

of how it gets from the camera all the way through stacking to photoshop?

For the Flea camera, the Analog to Digital Converter (ADC) delivers 12 bit video, the camera converts each 12 bit frame to 16 bit and then Astro IIDC receives the 16 bit frame. So you only see 16 bit frames coming out of the camera. I've worked with cameras that deliver 9,10, 12 and 14 bits from the ADC and they are all delivered as 16 bit images - which is standard for 16 bit IIDC compliant cameras.

You can also run the cameras in 8 bit modes too.

Will it stay 12 bits if I use, say, Keith's Image Stacker (I know KIS

is 16 bit

capable, but I'm confused about how the images get in with all 12 bits).

Nope. KIS does not handle 16 bit movies or 16 bit tif images and relies on Quicktime to convert them to 8 bit. The only format that I believe KIS handles in 16 bit is FITS files.

The only available Mac product that stacks and aligns 16 bit movies with 16+ bit processing end to end is Astro IIDC.

How does the group feel about the desirability of more dynamic range

in a monochrome camera, particularly for Lunar work? Is it worth

several hundred dollars?

I feel it does, and especially for lunar. The moon has extreme contrast ranges and the wider the dynamic range of the Camera the more detail your going to capture. With the 8 bit cameras, I could not capture large images of the moon without either losing details in the darker shadowed areas or completely blowing out the bright areas.

3) I was disappointed to discover that the Fire-i is not sensitive enough

to pick up Saturn through the color filters I have, despite my 12.5" dob

telescope. So I'm limited to white-light monochrome images of Saturn.

I know the more expensive cameras are more sensitive, but can I

reasonably expect them to be sensitive enough for RGB color filter

work with Saturn? I would want the images to be at least two stops

brighter.

Then you might be disappointed with the 31BF03 or 31AF03. The main limiting factor with any similar CCD is the area size of each CCD pixel element . It's the same thing as scope aperture, larger aperture means more light collected.

The Unibrain and The Imaging Source 21AF04/21BF04 cameras have CCD pixel element that are 5.6 microns, where as the 31BF03/31AF03 pixels sizes are 4.65 microns. The size difference means that the 31AF03 CCD only captures 83% of the light per pixel that the Unibrain CCD does.

However, the Imaging Source cameras have much better Signal to Noise circuitry, no fixed pattern noise and better dynamic range - so you can increase the gains higher than the Unibrain cameras can. This may be enough to compensate for the 17% drop in pixel area.

The main limitation with the Unibrain cameras are that they are noisy (both pixel and fixed pattern), have limited gain boosting (which is a good thing considering noise levels) and have a narrower dynamic range (the range problem is because of the TSLB15V01 processing chip). All cameras built that use the TSLB15V01 processing chip suffer form these problems.

Hope That Helps..

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