From: albe albo <richter1956@yahoo.com>
Date: May 8, 2009 7:56:56 PM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Re: New file uploaded to Astro_IIDC
Dear Milton, Alan & Mark,
thank you for your comments.
LOL I'm been sooo silly since i forgot completely that i took 6 shots for that mosaic but i processed only 4 of them.
Now i'm finishing the processing in order to complete the image in the lower part under Eudoxus until half Cassini.
I must reduce the image approx 56% because of the micro-seeing (i call it this way) that makes me crazy for a double ghost image that makes all so blurry and doubled.
Luckily with a self -dimmed-shifted subtraction procedure i can reduce that defect otherwise the mosaic would have been not presentable.
Milton i didn't update my site since some time (i'll do it soon) and i didn't publish the original size because the quality is not enough to keep the full res.
Anyway I have no problem to upload the full res too if you may be interested.
Please let me know if i understood correctly.
Regarding the measure Kilometres X PIxel.
My way is very pragmatic: no calculation at all about the optics.
When the image is finished at its final size i check the moon atlas and i perform several measures of the distance between various point both horizontal measures than vertical measures.
After that i repeat the same exact measures on my image.
After i do a simple calculation Example a crater is 30 Km and my crater image is 90 pixels so 30/90 = 0.3 Km x pixel.
repeating several measures even using the measuring tool that returns the real distance on the Moon i can measure even larger distances but i noticed that the result of the calculation was enough constant.
The difference between vertical and horizontal is due not to the camera pixel but to the proiected moon surface.
When we go closer to the border (in this case closer to the north pole) there is a big difference between horizontal and vertical.
You can see that aristoteles appear as oval while it is round. Measuring the same pixel distance means different moondistance.
This difference is not important in the center of the moon of course while at the border on of the two values tend to be infinite.
To be more precise in my image i should declare the vertical resolution both in the lower part of the image than in the upper part of the image because there is some difference.
In my image of sinus iridum i declared the lower vertical and upper vertical.
Hope that my explanation is not a mess.
Now finishing the complete 6 tiles mosaic.
cheers
PS: Milton i was really surprised (and pleased) to read my name (latest AIIDC manual) between your cooperator for testing.
Thank you so much. I guess that you understood my feelings and my possible criticism (sometimes we had some really FRANK exchange of opinions!) is due to the affection to the product and not the opposite reason!
If i don't like a product and i don't consider it very important then i won't criticise it but.. i will ignore it.
Sometimes one would desire that a very valid product could become even better and better!
On italian forums i'm pretty proud when they ask me the way i control the DMK and which parameters of IC Capture i set.
I answer "Sorry I don't know what is IC Capture because i use Astro IIDC on Macintosh and i have a full control of my camera"
ROFLMAO
Ok now working on the image, it's 04:00 am.....
TTYL
Da: Milton Aupperle <milton@outcastsoft.com>
A: Astro_IIDC@yahoogroups.com
Inviato: Venerdì 8 maggio 2009, 18:32:02
Oggetto: [Astro_IIDC] Re: New file uploaded to Astro_IIDC
Hi Alberto;
Very Nice Shot, thanks for sharing.
Do you have a full sized version of it on your web site?
Like Allan, I'm not sure about your measurement of pixel resolution. Why is vertical and horizontal different values, as the pixels on the CCD are square?
With my C8 and at a focal length (measured) of 5,000 mm using the Televue 2.5x, I come up with 480 meters per pixel resolution by measuring multiple known features on the moon. Assuming turbulence doesn't get in the way, you should be able to 200 to 220 meters per pixel.
Also, I suggest anyone using a barlow or televue that they should actually measure a known object's dimensions to calculate out what their true focal length is.
Something like Saturn's disk (19" arc seconds) or Mizar - Zeta (14.4" ) or Albireo - Beta (34.4") make for good targets so you can calculate out how many zzz pixels cover yyy arc seconds.
And the only accurate way to figure out what your real focal length is to shoot at prime focus, then shoot with your barlow / televue in place and then calculate the arc seconds per pixel value for both. Then divide the barlow view arc seconds per pixel by the prime focus view arc secs per pixel and you known you true magnification factor. Then it's multiply the prime focus F ratio or focal length by the multiplaction factor and you know the real F ratio and real focal length.
The reason I'm bringing this up is that the further back your CCD is from the barlow, the more magnification you get. So it's pretty easy to use an extender tube between the barlow and the camera, such that your 2x becomes 3x or even 5x. With Televue it's different and in most cases it makes either no difference or very little difference in back spacing, except for the 5x.
http://www.televue. com/engine/ page.asp? ID=42
HTH..
Milton Aupperle
--- In Astro_IIDC@yahoogro ups.com, Astro_IIDC@yahoogro ups.com wrote:
>
>
> Hello,
>
> This email message is a notification to let you know that
> a file has been uploaded to the Files area of the Astro_IIDC
> group.
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> File : /Lunar/090501- Aristo-Eudox- V1-1100.jpg
> Uploaded by : richter1956 <richter1956@ ...>
> Description : Aristoteles- Eudoxus & Co.
>
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