From: Milton Aupperle <milton@outcastsoft.com>

Date: January 22, 2010 12:43:33 PM MST

To: Astro_IIDC@yahoogroups.com

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


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?