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02-04-2013, 10:40 PM   #271
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Simply stunning, Josh. This wider field of view than most M42 shots shows it at its best.

Jack

02-05-2013, 01:06 AM   #272
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QuoteOriginally posted by jbinpg Quote
Simply stunning, Josh. This wider field of view than most M42 shots shows it at its best.

Jack
Thank you Jack! That's actually as close as I can get to it right now. I'm using my ED80mm which has a focal length of 480mm. I think that would be multiplied by 1.54 if I'm correct since I'm shooting with an APS-C sized sensor. (?) It sounds right to me? I'd like to hook up my camera to my Celestron 8" but I don't think the Astrotrac would like me very much if I put it on there. Although that would be funny looking. Maybe I'll do it just for laughs. I'm waiting until I get back to the States to get a CGEM. Thanks again!
02-05-2013, 01:12 AM - 1 Like   #273
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QuoteOriginally posted by GWARmachine Quote
Great shots everybody! Here is on of my latest.
K-5, Orion ED80mmCF, Atrotrac, 139 second single exposure, pp w/CS5
That's super-cool! There is so much in that shot.
02-05-2013, 10:00 AM   #274
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QuoteOriginally posted by GWARmachine Quote
Great shots everybody! Here is on of my latest.
K-5, Orion ED80mmCF, Atrotrac, 139 second single exposure, pp w/CS5
Very nice for a single exposure. I really am running out of time to capture M42 outside of the city before it starts leaving the local sky. *crosses fingers for more clear nights*


Last edited by Dr_who; 02-05-2013 at 10:13 AM.
02-08-2013, 12:06 AM - 2 Likes   #275
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Here is my attempt of M42

K-5, 4 X 700 sec (average) @ ISO 80, 3 X 1000 sec (avg) @ ISO 100, Sirius EQ mount, Orion ED 80 telescope. SSAG.
02-08-2013, 09:55 AM   #276
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Oh, wow. Spectacular! Did you use DSS to stack the frames? All these stellar shots are going to drive me into big telescopes and mounts.

Jack
02-08-2013, 10:08 AM   #277
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Thanks and yea I stacked with DSS
02-09-2013, 02:20 PM   #278
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Took this image last night. Quick stack of two sets, one for the outer area and one for the central core. I'll probably be tinkering with the data for some time.

Camera: Pentax K5 IIs
Telescope: Orion 8" Newtonian
Mount: Skywatcher HEQ5
Guiding: PHD Guiding
Stacking software: PixInsight
Location: Just East of Elk Island National

Exposures:
26 x 3 minute exposures
34 x 45 second exposures



02-15-2013, 09:00 PM   #279
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I'm curious.. I'm seeing that indeed some of you are using Newtonian Scopes but I keep reading that you can't overcome the back plain issue with them or at least not with a Dob..

What exactly is a back plan issue?

I realize that Dobs aren't the best mount for long exposures in fact wouldn't work at all but with stacking is that even an issue ?

Ack.. nevermind. I found my answer on another forum. Planets and such I should be fine. Deep space is another story but can be overcome with stacking.

Last edited by downhill; 02-16-2013 at 01:06 PM.
02-16-2013, 03:07 PM   #280
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QuoteOriginally posted by downhill Quote
I'm curious.. I'm seeing that indeed some of you are using Newtonian Scopes but I keep reading that you can't overcome the back plain issue with them or at least not with a Dob..

What exactly is a back plan issue?

I realize that Dobs aren't the best mount for long exposures in fact wouldn't work at all but with stacking is that even an issue ?

Ack.. nevermind. I found my answer on another forum. Planets and such I should be fine. Deep space is another story but can be overcome with stacking.

Just out of curiosity, what do you mean by back plain issue? Do you mean back focus?
02-16-2013, 06:21 PM   #281
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Dr. Who I have no idea. It was something I read on a forum about astrophtography. Another had asked about using a Dobson with GoTo features and one of the answers was that the back plane issues needed to be solved. It's why I was asking here because I'm not a member there.

After more reading though, it seems I've found my answer.
02-17-2013, 12:42 AM   #282
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QuoteOriginally posted by downhill Quote
Dr. Who I have no idea. It was something I read on a forum about astrophtography. Another had asked about using a Dobson with GoTo features and one of the answers was that the back plane issues needed to be solved. It's why I was asking here because I'm not a member there.

After more reading though, it seems I've found my answer.
From what I understand is the mount is important to guide, but it's not only important to follow a star as its moving left to right but also that round star is also rotating and causes field rotation if your setup isn't proper.
02-17-2013, 05:56 AM   #283
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QuoteOriginally posted by downhill Quote
Dr. Who I have no idea. It was something I read on a forum about astrophtography. Another had asked about using a Dobson with GoTo features and one of the answers was that the back plane issues needed to be solved. It's why I was asking here because I'm not a member there.

After more reading though, it seems I've found my answer.
What you should realize is that a Dobsonian mount moves in small steps in the horizontal (Azimuth) and vertical (Altitude) directions. Thus, with a Dobsonian Go-To telescope you may keep the cenral object centered in you field of view but, as Dr-who says, stars away from the centre will NOT keep their position during longer exposures. They will rotate in small arcs that become longer the further away they are from the centre. That is what is called Field Rotation and you will need special software (not just ordinary stacking software) to do a digital de-rotation of your field in post-processing. Or, you will need some means to rotate your camera/sensor to counter the Field Rotation.

What you see in this thread, when we talk about images taken with telescopes, is mostly from telescopes (Refractors, Newtonians, Catadioptrics) mounted on an Equatorial Mount. Here, you have one axis of rotation parallell with the rotational axis of Earth, i.e.: pointing towards true georaphical North or South, and with such a set-up you avoid the problems with Field Rotation. If the axix is properly aligned all stars will keep their places during exposure.

Last edited by Stone G.; 02-17-2013 at 06:03 AM.
02-17-2013, 06:35 AM   #284
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QuoteOriginally posted by SointulArt Quote
I can't compete with your technical skills Dr-who, but here's my humble attempt with a 50mm f1.7 lens and the O_GPS1
Hi SointulArt, what;s your settings like? Thanks....
02-17-2013, 12:36 PM   #285
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Stone and Dr. Who. yeah I understood that for long exposures you would need an equatorial mount.

I made my own 10 inch Dobson about 20 years ago after gaining interest in them from watching a program on PBS. I even ground my own mirror. I sold it when I had to relocate for my job and just got busy with life. This next go round I'm not interested in building but looking at some of those Orion Dobs with Goto the goto features are really started to get my attention.

I've seen some pretty impressive pictures taken with DSLR's. and those scopes but of course tons of stacking. I think I might be interested but even the moon and planets seem pretty doable with a Dob.
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