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Comet ISON Sept 15

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#1 kbastro

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Posted 15 September 2013 - 01:05 PM

Took my 1st image of ISON this morning at 5am lets hope it's not the last and the comet fizzles out,,,

1 image, 60da, r/c 200 seconds iso 1600

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#2 ben2112

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Posted 15 September 2013 - 02:01 PM

Very cool. I am hoping I can maybe get an image of it when I get to the mountains this Nov. Should have some dark skies where the cabin is.

#3 mmalik

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Posted 15 September 2013 - 03:03 PM

Good looking result for a single exposure.

#4 Doneb

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Posted 15 September 2013 - 05:59 PM

Nice! What did you mount the camera on?

#5 kbastro

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Posted 15 September 2013 - 05:59 PM

I was only able to get one,,, comet was moving behind a massive tree,,, bad enough I was battling zodiacal light too..

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#6 kbastro

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Posted 15 September 2013 - 08:41 PM

Nice! What did you mount the camera on?


a Ritchey-Chretien scope

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#7 Darren Bly

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Posted 18 September 2013 - 01:34 PM

Nice, what was the focal length?

#8 srosenfraz

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Posted 18 September 2013 - 06:49 PM

Congrats on a very nice early capture, Kev!

#9 kbastro

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Posted 18 September 2013 - 09:14 PM

Nice, what was the focal length?


3200mm,, scope has a native f.l. of 2000mm and the camera is using an aps-c sensor giving it a 1.6x factor,,

yeah, comet isn't very big

#10 Tonk

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Posted 19 September 2013 - 03:33 AM

3200mm,, scope has a native f.l. of 2000mm and the camera is using an aps-c sensor giving it a 1.6x factor


Does the size of the sensor really change the focal length of your optical system?? - I believe thats just a myth

#11 JoseBorrero

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Posted 19 September 2013 - 10:27 AM

wow! it really start showing that tail! nice job! :waytogo:

#12 jwheel

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Posted 19 September 2013 - 11:24 AM

Nice shot!

#13 srosenfraz

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Posted 19 September 2013 - 03:06 PM

,,, bad enough I was battling zodiacal light too..



Well, that sure sounds like a great problem to have!

#14 kbastro

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Posted 19 September 2013 - 08:47 PM

3200mm,, scope has a native f.l. of 2000mm and the camera is using an aps-c sensor giving it a 1.6x factor


Does the size of the sensor really change the focal length of your optical system?? - I believe thats just a myth


I really not too sure if it does,,, But I do know using small chips on large sct really helps with those small glx's

#15 Case

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Posted 19 September 2013 - 11:05 PM

3200mm,, scope has a native f.l. of 2000mm and the camera is using an aps-c sensor giving it a 1.6x factor


Does the size of the sensor really change the focal length of your optical system?? - I believe thats just a myth


It does not really change the focal length - it's still the same, of course. But since you're using a smaller sensor, you're effectively "zoomed in" more into the picture (you're effectively "cropping" the outer parts of the available image, which is bigger than your sensor - that's why it's called "crop factor"), which makes the final picture (or what you see in viewfinder) seem more or less like it would if it would be taken with a lens of focal length equal to "current focal length x crop factor" on a fullframe camera.

What it means is that if you put a 1000mm scope on a 1.6 crop camera and take a picture with your subject dead in the center of the frame, the image you get should be framed more or less the same as if you took the same shot using 1600mm scope on a full frame camera. The two images wouldn't be 100% identical, but they would be framed very similarly.

#16 kbastro

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Posted 19 September 2013 - 11:38 PM

one other example is that when I use my full frame dslr on my 5"f/6 apo I can fit M31 nice onto the sensor,,, when I use my 60da there is not a hope in hell that it fits,,

I have not done any side by side comparison of the over all sizes of the two images,,, whether M31 is indeed bigger on the aps-c size or is just more cropped as compared to my full frame dslr,,,,

#17 kbastro

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Posted 19 September 2013 - 11:48 PM

interesting,,, about sensor sizes and effective views & focal lengths!!
Next time I'm out I'll switch the 2 cameras around on the same target,,, like the moon which will easily show magnification change vs cropped view

Anyway the scope is at a f.l. of 2000mm and the image of the comet was cropped (by me) but it does show that the comet is not a large one (yet).

#18 Tonk

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Posted 20 September 2013 - 05:55 AM

but it does show that the comet is not a large one


yes - but its brighter than C2011 W3 Lovejoy was at the same distance from sun - and Lovejoy performed very well for southern observers - even though it completely lost its nucleus shortly after perihelion. What was observed was a bright headless comet with a huge tail! There is a very good chance that same will happen with ISON

#19 Tonk

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Posted 20 September 2013 - 05:59 AM

BTW Terry Lovejoy found his 4th comet a couple of weeks ago - though this time not with a DSLR (he was the first person to find a comet using a DSLR - actually first to find 2 comets with DSLR as his second was bagged only a short time after the first)

#20 kbastro

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Posted 20 September 2013 - 08:04 AM

BTW Terry Lovejoy found his 4th comet a couple of weeks ago - though this time not with a DSLR (he was the first person to find a comet using a DSLR - actually first to find 2 comets with DSLR as his second was bagged only a short time after the first)


yeah I saw that about the new comet,,, regardless of how the ISON show unfolds, there are at least 3 comets brighter than 7 mag come nov/dec... going to be a lot of comets flying this way and that way. Time to cool down your imagers and invest in a alarm clock.

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