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  #101  
Old 10-11-2009, 04:19 PM
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Quote:
Originally Posted by CometGuy View Post
Stan Moore has a point, dynamic range is really no different to older style Kodak chips.

..... Here is an image made of a mag 0 star, with an 8" scope and a 1 minute exposure (QHY9).

8" is OK, and i think up to about 12" may be OK in 1x1 mode.
Having looked back at my exposures, the bright stars that have minor issues were in 2x2. I have not kept any 1x1 of the same fields, so Peter may well be correct about having enough Antiblooming.
I'll get an image of a brightish star, maybe 2nd mag, and give it a 5 minute sub at 1x1. Update soon .

Theo
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  #102  
Old 11-11-2009, 09:42 PM
Bolts_Tweed (Mark)
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Alex - Alex - Alex

My wife hates you and she only met you through the car window that 1 time

I've followed this thread with interest and as you know i luv the ST10 (with the meade on the mount hunting S/N its perfect and other brighter DSOs in the refractors) but for this really deep stuff im chasing now it obviously just wont play the game (blooming wise) and that is why I am using the 350D. The ST8300 looks like the perfect compromise (keeping dollars in mind) for use on the Televue np. I am happy with the depth i am getting with the 350D on faint dust but this would definately be a leap forward. I have read Jase & Peters comments (and others) and respect both their comments but for dumb old guy like me for 2k or so this will provide a good - more sensitive alternative than the 350D for what i am doing now at higher resolution with the monochrome and a filter wheel. Cheaper than an ST1100 anyway

I head to vegas in 3 weeks and am staying at the Rio to play some poker and Scope City are just over the road (damn them) and while I usually buy in Aus I might just have to walk over the road and have a look seeing that I am there anyway.

So to end where I started - my wife hates you - well not really but it is good to have the heat off me for while - I was only going to buy a Televue wide field corrector. Now it looks like its a studio instead of a suite at the Rio

Mark
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  #103  
Old 11-11-2009, 09:57 PM
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Mwa ha ha haa!

Ps. Not only cheaper than an STL11000, but also a fair bit more sensitive too, and lower noise levels.. the only thing you're sacrificing is the expansive field of view the 35mm sensor in the STL11000 provides.

Yep, to do super deep work, the ST10 can be a real pain unless you're shooting narrowband with very very tight (3nm) filters.. moderate star blooms can be processed out, obviously you'll never recover the data that was underneath the star bloom.. The ST8300 would make a good replacement for the 350D, even just for the convenience of having regulated cooling, so you can have a dark library and not have to waste time doing darks during imaging nights..

Chewing my nails off waiting for the new SBIG...
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  #104  
Old 11-11-2009, 10:13 PM
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Bassnut (Fred)
Narrowfield rules!

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Lets not compare the ST10 with the 8300 in real life use, they are for different purposes. Just now Im imaging an object at 2250mm FL (0.6 arcsec/pix) with a 3nm Ha filter at 30min exposure subs with max of just 350 ADUs in the neb, I get no blooming, even on stars, it would need 1 hr exposures at least on a 8300 for the same flux.

The 8300 is a killer for hi res, wide field, wide FOV, bright objects in RGB/wider NB, the ST10 couldnt touch it. Long FL very NB and narrow FOV, is where the ST10 lives.

Last edited by Bassnut; 11-11-2009 at 10:24 PM.
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  #105  
Old 11-11-2009, 10:42 PM
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As I said Fred, if you're going super deep with the ST10, very NB (3nm) filters would make it perfect...

I agree too.. If I were imaging with a 2000+ mm focal length, and doing narrowband work, I would be going for an ST10XME.. And for sensitivity, the KAF-8300 has nothing on the KAF-3200ME. As you say though, Horses for courses!

Glad to hear you're running some images Fred!!
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  #106  
Old 12-11-2009, 12:04 AM
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Bassnut (Fred)
Narrowfield rules!

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Alex, yes, its been a while, expectations on my part are high, its getting very difficult cranking up the wow factor.
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  #107  
Old 12-11-2009, 12:32 AM
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Octane (Humayun)
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You need to start doing widefields.

Regards,
Humayun

Quote:
Originally Posted by Bassnut View Post
its getting very difficult cranking up the wow factor.
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  #108  
Old 12-11-2009, 01:35 AM
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Bassnut (Fred)
Narrowfield rules!

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Quote:
Originally Posted by Octane View Post
You need to start doing widefields.

Regards,
Humayun

Wha?, , que?. Thats a very confusing statement, totally counterintuative, quivering fright to the core is the effect it causes, damaging the very essence of reasonable thought. Sorry, I dont understand, at all .

Last edited by Bassnut; 12-11-2009 at 10:40 AM.
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  #109  
Old 12-11-2009, 05:16 AM
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Being that I own one of the widest field telescopes on the forums, Allow me to clear something up. Wide field imaging is for sissies.. Processing can be tricky because the field is expansive, and you can have a few objects in the field that just don't want to balance nicely etc. But narrowfield imaging is just down right difficult, finding the target can be very hard, framing it correctly is hard, finding a guide star is hard, taking long enough exposures is hard.. When it all comes together and the computer downloads a good sub from the camera, its exhilarating... I have a few shots from my ST10 @ 1756mm and a few at 1630mm that were pretty exciting to have captured. but capturing M83 at 2800mm with my ST9E was a real rush!

So, whilst im imaging with a very wide field at the moment.. I am going to side with Fred here... Narrowfield + Narrowband is where excitement lives... Wide field is fun, big expansive pretty pictures etc... Narrowfield is dramatic and is all about impact.
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  #110  
Old 12-11-2009, 08:01 AM
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My comment was a joke. I think Fred picked up on it. Thanks for referring to the rest of us as sissies.

Regards,
Sissy
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  #111  
Old 12-11-2009, 08:32 AM
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yea i got the joke h. Re. The sissy comment, i'm a sissy too at the moment. Seriously, 90% of everything i say is a joke..
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  #112  
Old 12-11-2009, 10:28 AM
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Alex, just out of interest what settings were you using for guiding with the OAG and laong focal length? Were you using the internal guide program of say CCDsoft or Maxim or were you using PHD. I had the settings right for long focal length and a guide scope but I cannot seem to get it 100% with the OAG. The focal length jump in guiding is really making it hard for me. I now have the spacer in the QSI that allows the stars to come to focus but the graph is very exaggerated.

Currently in PHD I am using 30% aggression, 5 hysteresis, 0.05 min motion, 500 steps on calibration and everything else is just standard. With the guide scope I had 80% agg, 10 hysteresis, 0.15 min motion and 750 steps on calibration. Guiding was near perfect and my 40D images showed it.

Long focal length imaging is way tougher than wide for sure in my experience but I do like a challenge.
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  #113  
Old 12-11-2009, 10:55 AM
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paul, i used ccdsoft for guiding the rc through the oag. I've got the settings saved on my pc at home, when i get home i'll contact you via pm. Don't want this thread going way off topic.
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  #114  
Old 12-11-2009, 11:38 AM
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Alex, on the way too 6000
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  #115  
Old 12-11-2009, 03:34 PM
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Quote:
Originally Posted by telecasterguru View Post
Can I just ask then if the camera would be suitable for my ED127 running at f7.5.

I don't understand the technical side of the issues involved but am reading and trying to learn.

Frank

Quote:
Originally Posted by AlexN View Post
frank, yes, the resolution would be good, i would think about 1.3 arcsec per pixel. Would have to check that when i get home, but i would say the KAF-8300 would be well suited to any optical system between 350mm and about 1700mm. Anything under 350mm will be undersampled. Although at that short a focal length you're not likely to notice. Anything over 1700mm will be heavily oversampled.. I'll be using mine at 480mm and 1000mm. If i can make a lens adapter, i might do some super wide field work at 50 to 135mm.. Would love to do a wide field view of orion at 50mm in sho pallete!
When you are talking about sampling are you talking about airy disk size in relation to pixel size? If this is the case you only need to take into account the focal ratio of the optics. For a F7.5 you have an airy disk that is 9.3 microns across (at the green wavelength). To adequately sample the airy disk you will need at least 4 pixels (2x2) so that means a pixel size on your sensor somewhere in the 5-8 micron range, which this sensor falls within.
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  #116  
Old 12-11-2009, 03:46 PM
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Im talking amount of sky in arc seconds that fall onto one pixel... You generally want between 0.8 and 2 arc seconds per pixel. Anything less (ie - 3.35 arcsec per pixel as I was getting with my Orion SS Pro + TMB 80/480) and you will not capture fine detail. Not only that, but small stars may take up less space than one individual pixel, resulting in square or blocky stars... Smaller pixels = less sky per pixel = better sampling...

Your way of looking at it is very similar, and you are correct.. I just go by arcsec : pixel ratio rather than airy disk
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  #117  
Old 14-11-2009, 04:30 PM
Bolts_Tweed (Mark)
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Quick update.

All stores between LA and Vegas pre sale sold out and there is a 3 month waiting list from SBIG.

I'll wait and hear how you go Alex and get one here early next year I think - better for warranty etc and just sits better with me.

Mark
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  #118  
Old 14-11-2009, 05:04 PM
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I am buying mine from Australia Mark... Contact Advanced Telescope Supplies... As you say, when you're spending this kind of money, having local warranty is important... Even though its essentially "Cheap" for an SBIG imager, its still a lot of money for a toy..
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