From: "doodlebun" <gbleser@bellsouth.net>

Date: January 22, 2010 2:08:34 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: 12 bits vs 60 fps, which is better?

Thanks for your thoughts Milton. I thought the only available frame rates are 30 and 60 fps because thats all that shows in the drop down menu under standard 8 bit. I do see the Format 7 modes in the drop down menu but I am clueless as to how to use it properly. The modes as I understand it will capture at a user defined ROI at intermediate rates that will be selectable in the fps field of Astro IIDC. The use of ROI is tempting but I need the image to stay in the restricted area which can be tough depending on conditions.

Under conditions of average seeing and a bright planet wouldn't you give more importance to getting up to 60 fps without having to resort to the Format 7 modes?

Now some thoughts on your Flea2. When you 2x2 bin, you essentially have pixels that are 9 microns square vs my 7.4 microns square with no binning on my Dragonfly2. Wouldn't the Flea2 configured that way make a far more sensitive planetary camera than the Dragonfly2 or the Skynx for that matter?

Dave

--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@...> wrote:

Hi doodlebun;

Actually, have you tried any of the FMT7 modes for it? I have a Flea2

(FL2-08S2C) 1024x768 here and if I run it at 516x388 in 16 bit with a

FireWire 400 cable I can capture at 53 fps delivered to disk.

According to the tech specs for the 640x480 DragonFly2, at 640x240

size you should be able to run as high as 50 fps in 16 bit. Cropping

it using ROI (see pages 27 and 28 of the Astro IIDC Manual) may help

too.

Over all I would agree with what your saying, especially when your

being forced to under expose to achieve better frame rates and then

stretching the image.

If you have really good seeing, you likely can tease a bit more subtle

information from Mars for 12 bit rather than 8 bit.

HTH..

Milton Aupperle

On 22-Jan-10, at 12:13 PM, doodlebun wrote:

I have recently graduated from a DMK21AF04 to a DragonFly2 camera.

I've been photographing Mars in two different monochromatic modes...

30 fps @ 12 bits and 60 fps at 8 bits. You cannot capture at 60fps

at 12 bits as we all know. I captured 1500 frames and took the best

400. Astro IIDC processed the movie and I compared the two RGB

images. Not a hell of lot of difference. With Mars we have a bright

planet that can be captured (with a C14 @ f/25)) at 60 fps @ 8 bits

with a minimum of noise yet a wide histogram that contains at least

200 of the 256 available levels of grey. Naturally the 30 fps

capture was even somewhat brighter at the same noise level.

So my question is this: Should one even bother using 12 bits on

bright objects that don't require much histogram stretching? It

would seem to me that if you captured a dim image (say Saturn, right

now) 12 bits would be more appropriate. If a Saturn image was

captured at only 10% as bright as maximum (i.e. the image had only

26 levels of grey in it, then when you stretched the 8 bit image the

banding could ruin the image. But if you captured the dim image at

12 bits, then you have effectively captured 400 out of 4096 grey

levels. This should yield a much better looking image when stretched

should it not?