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28286 Posts in 3356 Topics by 280 Members - Latest Member: jsteinberg48 June 20, 2013, 02:36:04 AM
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East Coast Astro  |  The Imagers Lounge  |  DSO's DSLR Color  |  M100
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Author Topic: M100  (Read 1189 times)

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Offline jambroseus

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Re: M100
« Reply #30 on: May 08, 2011, 01:14:05 PM »
Jason, the f/3.3 FR is really not designed to be used with the SCTs so the vignetting and focus roll-off are severe and strange things are happening. I agree that this is not sky glow and appreciate you guys bringing me to see that. I should have known since my images with my 200mm f/2.8 lens at one-min subs do not show a sky glow like that or anything close.

I looked back in my files and I did have flats with the f/3.3. I will plug these in to the calibration and see if I get any improvement. My feeling is that it will flatten the field but also kill all the detail in the faint areas of the galaxy. I may not be able to do any better than I am doing now. I expect I am going to leave go of the f/3.3 shooting. That CGEM is coming back into view again. <g>

One more thing I would like to try is shooting at ISO 6400 with the f/6.3 FR.  (Then we'll see Les)

John
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Offline Les (t_total123)

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Re: M100
« Reply #31 on: May 08, 2011, 01:36:07 PM »
Ok John Have Fun  with it.
 I used a OIII with the 40D  1600 ISO with 10min SUBS and a F5 Scope 

Les
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Offline Jason C

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Re: M100
« Reply #32 on: May 09, 2011, 07:21:37 AM »
Another thing I found while looking into the 3.3 is that it was designed for use with the Meade DSI with a chip size of only 1/2" so that explains the severe vignetting. Also, to agree with Les any nb filter use is going to require much longer exposure times due to their very narrow pass. I have an OIII  that you can try to see the results before going and spending any money.
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Offline David (djrLX90)

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Re: M100
« Reply #33 on: May 09, 2011, 08:45:02 AM »
I have found [OIII] difficult to capture clean data with from my LP skies.  I used a SXV-H9 mono CCD and 1200 second exposures @ f/6 and was not happy with what I was able to get.
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Offline El Paso Eric

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Re: M100
« Reply #34 on: May 09, 2011, 11:16:16 AM »
Quote from: djrLX90 on May 09, 2011, 08:45:02 AM
I have found [OIII] difficult to capture clean data with from my LP skies. 

I'll second that one!
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Offline jambroseus

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Re: M100
« Reply #35 on: May 09, 2011, 07:48:53 PM »
Hey guys, you misunderstood, I was not planning to use the OIII at f/6.3 w/30-sec subs I fully expect it would be futile, but just shoot full frame color at ISO 6400 to check noise and image density. I would like to shoot M100 again for comparison.

Jason, thanks for the offer, perhaps later with a different rig.

John
« Last Edit: May 09, 2011, 07:51:13 PM by jambroseus »
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"If you see a bomb technician running, follow him and try to keep up."

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