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Posts Made By: Tybee Evans

December 12, 2003 09:06 PM Forum: CCD Imaging and Processing/Solar System

IR blocking for Jupiter and Saturn?

Posted By Tybee Evans
You need the IR blocking filter when shooting through a lens. When shooting through a mirror system all the wavelengths come to focus at the same spot. A lens isn’t corrected for the IR to come to focus at the same point as the visible spectrum and since the CCD is sensitive to IR you get a fuzzy image.

You don’t need the IR blocking filter on a Newtonian. It should have little effect on a Catadioptric. It’s necessary on a Refractor.

December 20, 2003 10:29 PM Forum: CCD Imaging and Processing/Solar System

Saturn: 2nd attempt

Posted By Tybee Evans
very nice!

January 3, 2004 07:44 PM Forum: CCD Imaging and Processing/Solar System

Clavius

Posted By Tybee Evans
Here’s my humble attempt.

12” LX200 @ F10. Phillips ToUCam XS (the CMOS version)

Tybee

January 6, 2004 03:01 AM Forum: CCD Imaging and Processing/Solar System

What is Gain?

Posted By Tybee Evans
Jim,

You could think of it as the electronic equivalent of ISO. It’s the amplification factor between the CCD and the Analog to Digital converter inside the camera. The amount of signal that’s captured doesn’t change. When you turn up the gain you’re amplifying that signal more before it’s converted to a digital signal. You’re also spreading out the signal and creating a larger Quantification noise which is the individual steps between each signal level.

Let’s say that you’ve got a CCD with a full well capacity of 10mV and your digital to analog converter accepts a signal between 0 and 10V. You capture enough photons to generate a 2mV signal. You amplify it by 1000 which converts it to 2V which is then feed to the A/D converter. If you turn up the gain to 1500 then the signal that the A/D converter sees is 3V. You get a larger signal out but you haven’t really captured any more data. You’ve just spread it out more and that makes the steps between discreet levels courser.

January 10, 2004 02:18 AM Forum: CCD Imaging and Processing/Solar System

Full Moon Borg 76ED

Posted By Tybee Evans
Jose,

That's a very nice Christmas present! And a nice image of the Moon.

Tybee

April 28, 2005 12:38 PM Forum: Solar System Observing

Moon near jupiter. 04-22-05

Posted By Tybee Evans
Hi Rick,

I like it! Here's one from last month. Taken on Good Friday.

http://www.daemonet.net/gallery/albums/Astrophotos/Good_Friday_Moon_and_Jupiter.jpg

-
tybee

rick langerman said:

It is to windy to get the scope out tonight

July 4, 2006 11:53 AM Forum: Equipment Talk

Tak NJP vs. Losmandy HGM Titan

Posted By Tybee Evans
Joe, I’m in the market for a mount in that weight class also but I have no experience with Temma II or Gemini. Could you please comment on the merits and capabilities of each of those? My research indicates that both mounts have similar tracking capabilities with the nod for capacity going to the Titan. But I’ve also read that the NJP is very conservatively rated and can handle much more than 70 lbs. I wonder about the NJP’s actual capacity. I’ve read about balance issues with the Titan and rust problems with the NJP. What’s the best mount that can carry 90 lbs?

Thanks,
Tybee

July 4, 2006 03:24 PM Forum: CCD Imaging and Processing/Deep Sky

Newbie rig

Posted By Tybee Evans
Why don’t you take the C-11 off the CG-5 mount and save it for visual use only (for the time being). It’s much too long a focal length for imaging except with the very best of mounts. Get yourself a small APO refractor. Something in the 70mm to 80mm range and mount it on your CG-5. At these short focal lengths you should get pretty good results without needing to guide if you can get a good polar alignment. Later on when you get a better mount you can use the APO as a guide scope.

November 4, 2006 12:47 PM Forum: Eyepieces

More Respect for the Ortho Design

Posted By Tybee Evans
I have to agree fully William and add my observations. I have the entire set of Meade RG Ortho’s, the entire set of Meade Series II Ortho’s, The entire set of Vixen 0.965” Ortho’s and the entire set of Pentax SMC Ortho’s sans the 12mm. The Pentax SMC O-18 throws up the best image I’ve ever seen in “ANY” eyepiece. It’s simply the best of the best! The first time I put it in a scope and looked through it I used an expletive!

November 5, 2006 11:56 PM Forum: CCD Imaging and Processing/Solar System

99.73% Full Moon - from Utah

Posted By Tybee Evans
Great Image Tyler,

I was out at about the same time doing about the same thing. This one is through my 4" refractor and my Nikon D2H.

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