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PostPosted: Sun Apr 05, 2009 12:06 am 
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I had a quick look on a star map and saw that Saturn should be high up. But could I find it? I wasn't familiar with the constellations currently up there, plus the light pollution seemed fairly bad tonight and what I saw with my naked eye was something like this:

Image

There were some more stars outside that, but in that region that's all I could see. Chertan was barely visible with naked eye. Having located what I thought was Saturn, I pointed my scope at it. It was cloudy earlier on in the evening so I didn't check until very late. It was getting on to midnight so I didn't want to make a noise outside. I used a desperate method. I shot through the double glazed patio doors. I know that wouldn't help quality.

Anyway, pointing at what I thought was Saturn with eyepieces giving a magnification from 54x to 270x, I saw, at best focus, a long blob. Sticking the camera on, I got this:

Image
100% crop, 1/2s, ISO1600

To verify if my focus was on or not, I moved the scope to the brightest point object, which I think is Arcturus. I got this at best focus:

Image
100% crop, 1/10s, ISO1600

The pattern was largely static and didn't change. Must be some serious diffraction going on somewhere, probably the windows as they're not in the best condition or cleanness.

Weather allowing, of course I'll have another go another day but realistically I don't expect to get any more resolving ability. The annoying thing was there was very little wobbling due to air movement, but the moon was too high up for me to shoot.

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PostPosted: Sun Apr 05, 2009 9:18 pm 
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Hi popo, interetsing patterns you got there! I think before making any conclusions from them though you need to take your scope outside!

Saturn can be hard to spot, but remember it won't flicker like most stars, and it's a kind of yellowy, orange colour. I pointed my scope at it about a month ago in an attempt to spot the rare moon transit that was occurring that evening, but my resolving power just wasn't there. The planet looked great (albeit tiny as always), but no sign of a black dot crossing its surface. I do only have a 4in refractor though...


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PostPosted: Sun Apr 05, 2009 9:30 pm 
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Coincidently I just had another go. Now outside it was so much clearer. I think most of what I had yesterday was probably more the door glass than the target.

Image
100% crop. 2650mm, f/26, 1/20s, ISO3200

Definitely need a bigger scope to get the aperture value down.

The moon has moved relative to the star field. Even if it is clear tomorrow I think it will be too close to have another go. I forgot to do an overexpose on this occasion, which I did with Jupiter to bring out its moons before.

Also got the moon but strangely that was visibly more wobbly so I wont be setting any personal records in sharpness tonight.

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PostPosted: Mon Apr 06, 2009 8:40 am 
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Hi popo,

Pointing your telescope through the patio doors is what I call real armchair astronomy. :lol:

But even if the doors were open the results would still have been poor as heat loss from houses causes a shimmering effect rather like that you can see from the ground on a really hot day. The effect is a lot smaller, of course, but then you are magnifying it hugely with the 'scope.

Bob.

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OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
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PostPosted: Mon Apr 06, 2009 11:31 am 
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I know it was bad, but as said I left it rather late and didn't want to annoy the neighbours by moving stuff around the garden at night. The motor on the scope mount is pretty noisy too.

One of my longer term hopes was to have the scope set up in the garden, and remote control it from a PC. From a practical point there isn't an easy way to get decent alignment within my garden FoV. Never mind the bigger scope, moving house would help too.

Right now I do want a bigger scope just to see what I can do, but realistically I can't see it being economic in the long term for the use I'd get out of it. I wonder if there's anywhere that'll hire out large (12 inch+?) scopes at affordable rates?

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PostPosted: Mon Apr 06, 2009 1:05 pm 
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popo wrote:
...I wonder if there's anywhere that'll hire out large (12 inch+?) scopes at affordable rates?

May not be quite what you are after but check out Slooh. I've not used this service, nor do I know anyone who has, but I bookmarked it a while back "just in case". Another option might be Galaxy Zoo, though this is dedicated to working with images that already exist.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Mon Apr 06, 2009 4:48 pm 
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Thanks for the links. I've heard of remote controlled scopes before, but it isn't "hands on". And I've poked about Google Sky too.

I want to see it by eye first to really experience it. Only after that do I try to photograph it for record.

I did find this place which is about an hours drive from me. £25 a week for 8 inches. If I can time that with some clear skies it should be fun.

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PostPosted: Mon Apr 06, 2009 9:22 pm 
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Hi popo, I think it's a good image you've got there - maybe try grabbing a few next time and stacking for a cleaner result...

As for accessing a bigger scope, how about joining a local astronomy society? There's lots in the Uk and many have some really decent equipment...


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PostPosted: Mon Apr 06, 2009 9:41 pm 
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I only had 8 shots in that sequence (others were worse). Finally figured out registax enough to put it thought it, but the output was blurrier. Looking closely at the original frames again, one was sharper than the rest so there was no net gain overall.

I could spam the 6.3 fps of the 50D next time, but I think I overwork the shutter enough already. Just looked at dedicated cameras again, on the cheap end. They seem to have gone up a load like most kit though.

As for an astronomy club... I had looked into that previously. The "local" one for me meets an hour drive away. I'm not sure I'm that motivated yet. I'm more impulsive and shoot what I see at the time.

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Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
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PostPosted: Mon Apr 06, 2009 11:17 pm 
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popo wrote:
...I could spam the 6.3 fps of the 50D next time...

Hi popo,

I'm virtually inactive on the astrophotography front these days but fading memory suggests that at high magnifications using the camera's burst mode is likely to make things worse as the shutter and mirror motion are likely to set the whole assembly vibrating away.

Try mirror lockup and a cable or remote release. Statistically I don't see why six shots in one second is any more likely to grab a spot of clear seeing than six shots in one minute and the latter approach allows vibrations to damp down between shots and may actually achieve better results as you can allow several seconds to elapse between each shutter press that locks the mirror up and the subsequent press that releases the shutter. Worth a try, I think.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Tue Apr 07, 2009 6:37 am 
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Very true. I found that with early moon shots where the 1st shot in a continuous sequence was usually sharpest. Since then I manually take single shots with a corded shutter. But for planetary stuff I understood you typically do need a lot of averaging to get the noise down, and a DSLR doesn't seem best suited to that. Putting aside vibration, high speed continuous would help build up the number faster, at the cost of eating the shutter life quickly.

I'm wondering about getting one of those "universal" compact adapters so I can use video mode on my compact, although I'm not sure how happy the focus system will be...

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PostPosted: Tue Apr 07, 2009 8:01 am 
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popo wrote:
Image
100% crop, 1/10s, ISO1600

The pattern was largely static and didn't change. Must be some serious diffraction going on somewhere, probably the windows as they're not in the best condition or cleanness.


Oh my ...
I think you just found another proof for dark matter. :shock: It appears to be causing fluctuations in a gas cloud. :lol:


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PostPosted: Wed Apr 08, 2009 9:48 pm 
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Bit better...

Image
2650mm, f/26, 1/13s, ISO1600, Up to 25 frames stacked.

I say "up to" as I really have no idea what I'm doing in registax but seem to be getting close enough to a usable output most of the time. It decided it didn't have enough memory when I asked it to drizzle (think I should crop these down!) and I got bored of waiting when I tried feeding it raws instead of jpeg.

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PostPosted: Thu Apr 09, 2009 9:52 pm 
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Nice result popo... did you manually reject frames that didn't look good before feeding them into the program?

If you get into this technique, a webcam can be a great ally


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PostPosted: Thu Apr 09, 2009 10:09 pm 
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I fed all I had since I didn't take that many shots plus they all looked quite similar. I'm not sure what the defaults are in registax as it does seem to have some quality threshold that can be set.

I have ordered a compact camera to scope holder. The ebay seller was a bit slow and didn't make it in time for the long weekend. With hindsight, that might not have been the best idea since the video mode on a compact will likely be downsampled and I'm not going to get any subject size from that. Not that I have a clue how to get around the focus...

The webcam method does seem the most practical, but as I never got my scope tracking working correctly I think it might be a bit tough to manually keep the subject in the ultra-small FoV. I really should work out the tracking some day...

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Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
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