From: Mark Gaffney <markgaffney@me.com>
Date: March 3, 2010 5:44:45 AM MST
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] ExoPlanet Database
Terry,
I checked that seller again just now & it seems he has no more 2nd hand Point Grey Research cameras for sale. I quickly entered this companies` name in the Search box & couldn`t find any listings either. PGR cameras are 16 bit (I have a Flea 2 & the Scorpion bought on eBay) but are quite expensive new. My Flea 2 which is 640 x 480 pixels was about $1400 last May. The Scorpion which is now discontinued is 1600 x 1200 pixels..The firewire types here are supported by Milton..
They`re excellent cameras!
Mark.
On 03/03/2010, at 8:37 PM, Terrence R. Redding, Ph.D. wrote:
So the Grasshopper is a contender.
What about the cameras that have been purchased off of e-Bay recently? It seems to me they were a larger format and 16 bit?
Terry - W6LMJ - 14.287
Terrence R. Redding, Ph.D.
Redding Observatory South, West Palm Beach, Florida
http://olt.net/learningstyle/Site_2/Learning_Style_Research.html
How do amateur astronomers learn?
American Association of Variable Star
Observers (AAVSO): RTN http://www.aavso.org/
On Mar 3, 2010, at 1:45 AM, Milton Aupperle wrote:
Hi Terry;
On 2-Mar-10, at 9:39 PM, Terrence R. Redding, Ph.D. wrote:
> Milton, thank you for this.
>
> I am one of those who will be trying. BTW, what camera would you
> recommend I use?
Likely something with at least 12 bits of depth per pixel, cooled and
low noise.
A 0.01 drop in magnitude is about a 0.93 % change in brightness.
A 8 bit camera has 256 shades of gray, that means the the pixel will
change in value by about 2 out of 255 for a 0.01 mag change. With any
CCD noise, your going to lose this change in the background noise, so
it's pretty unlikely you could detect a change of less than 0.03 mags.
A 16 bit camera has 65536 shades of gray, so a 0.94% change would be
reflected as change of 655 out of 65536.
I've measured my Grasshopper 14 bit camera's noise level (at minimal
gain of 64) and it comes out to be a random change of +/- 25 out of
16384. So theoretically I can detect a change of about +/- 0.15%
change in brightness, which would be about 0.0017 magnitudes.
However I have never gotten lower than about +/- 0.01 magnitudes
because of atmospheric issues (haze, turbulence etc.) in the attempts
I've made under dark skies for 90 second exposures, which would be the
correct exposure for about Mag 12 stars.
HTH..
Milton Aupperle
>
> Terry - W6LMJ - 14.287
>
> Terrence R. Redding, Ph.D.
> Redding Observatory South, West Palm Beach, Florida
> http://olt.net/learningstyle/Site_2/Learning_Style_Research.html
> How do amateur astronomers learn?
>
> American Association of Variable Star
> Observers (AAVSO): RTN http://www.aavso.org/