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Go Back   IceInSpace > Beginners Start Here > Beginners Astrophotography

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  #41  
Old 20-02-2018, 11:05 AM
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That is a fantastic result given everything you have had to contend with.
Reading your diy thread entry you say colmination goes off if you move it...do you mean to a new sky region? I mean will it stay ok for a certain object...it looks like it was ok for your capture above.

I would keep at it and work within its limits...I think I said you may have to colminate for specific regions...and balance.
Could you add a guutar string type brace system.
When I was using the 12 inch on eq6 I would balance for a specific region generally directly above or as close as possible.
Anyways great effort.
Alex
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  #42  
Old 20-02-2018, 12:44 PM
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PKay (Peter)
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Quote:
Originally Posted by xelasnave View Post
That is a fantastic result given everything you have had to contend with.....
Alex
Thanks Alex

Quote:
Originally Posted by doppler View Post
Great to see you got a result, and it's not too shabby at that....
Thanks Rick

I am in a complete quandary as in what to do.
It will work if set up for each individual target, maybe I should just allow for the extra 30mins. set up.
I will need to spend ~$500 for lens re-coating.

And Alex may have been joking about getting a hernia, but I do have a sore back.

Last edited by PKay; 20-02-2018 at 12:44 PM. Reason: yes
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  #43  
Old 20-02-2018, 01:35 PM
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Mirror re silvering is always painful especially with an older scope, you can start pondering the economics. There is a cheap DIY method that works but the coating doesn't last as long as an over coated al mirror. http://angelgilding.com/kits-chemicals/pouring-silver.html and then my dodgy home recipe.
http://www.iceinspace.com.au/forum/s...ight=silvering

If it's a good mirror it's worth getting a professional job. Your mirror looks pretty good though from your images, not a lot of coma showing.
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  #44  
Old 21-02-2018, 09:20 AM
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Now this is interesting.
Since this is a comparison thread, attached are 3 images.
(Hover over each image to get the right one)

The first (Seagull_4inch) is using the 4" EON refractor.
FOV = 110' X 83'
56 of 240sec subs = 4 hrs integration time. Cropped

The second (Seagull_12inch) is using the 12" reflector.
FOV = 40' X 30'
14 of 240sec. subs = ~1 hour integration time.
(this scope has a badly corroded mirror)

The third is all of the above images integrated together.
This meant the FOV became the smaller of the two.

The most obvious outcome is the bigger scope gets more detail in a fraction of the time, however both scopes can arrive at pretty much the same result.
Attached Thumbnails
Click for full-size image (Seagull_12inch.jpg)
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Click for full-size image (seagull_2nights_12inch_4inch.jpg)
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Click for full-size image (Seagull_4inch.jpg)
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Last edited by PKay; 21-02-2018 at 11:38 AM. Reason: yes
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  #45  
Old 21-02-2018, 03:51 PM
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I think that's the whole point of the bigger scope, the same result but "in a fraction of the time". I have a 150mm RC that does a good job but at f9 takes 4 times as long to get the same result as my 10" f4'8. Resolution is also a factor to consider, a larger aperture will resolve finer detail (assuming that the scope is well collimated and the camera sensor is a good match for the ota). And I guess the longer focal length of the larger aperture scopes is also better for smaller DSO's.
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  #46  
Old 21-02-2018, 04:13 PM
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With objects that display a wealth of fine detail, no matter how long you expose with a 4" scope, you will never produce the same result as an
identical but 10" scope, simply because of your already mentioned superior resolution.
raymo
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  #47  
Old 21-02-2018, 04:39 PM
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All we need is a 12 inch f3 five element refractor on a, yet to be invented, eq 15 on a bed rock anchored pier English equatorial mount with a 100 meg cam...
alex
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  #48  
Old 21-02-2018, 05:36 PM
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Nice comparison!

Ah come one, the difference is just the larger f-ratio on the refractor. Unless aperture is king?
That 12" F3 sounds good though.
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  #49  
Old 21-02-2018, 07:44 PM
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Quote:
Originally Posted by ChrisV View Post
Nice comparison!

Ah come one, the difference is just the larger f-ratio on the refractor. Unless aperture is king?
That 12" F3 sounds good though.
Aperture is king.

"Another important function of the telescope is resolving power. This measures how well you can separate two objects, and of course this is related to how sharp the image looks. Both of these functions, light gathering power and resolving power, depend only on the size of the telescope (called the aperture)."

Of course bad seeing stuffs all that up.

Last edited by doppler; 21-02-2018 at 08:06 PM.
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  #50  
Old 22-02-2018, 11:27 AM
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How about with a Sony RX100?

I think I got the faintest bit of nebular, its not much but I think I see something.

Sony RX100m4
70mm
9x120sec
ISO1600
Stocked in DSC and poorly edited in PS.

Regards
Chris
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  #51  
Old 22-02-2018, 12:24 PM
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Good one Chris

Definitely there, diving down into the ocean.
The Seagull actually measures about 2 degrees by 40 minutes.

So it is very big!

You may have captured Sirius going supanova
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  #52  
Old 26-02-2018, 10:59 PM
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Finally got enough to put up something. ASI071 with 80mm F5.9 refractor. Captured with APT (90sec subs at unity gain), processed with PI.

I got 1hr on 15 Feb (no moon). And just under 3 hrs on 24 Feb (half a moon there). Except I buggered up, must have rotated the camera a bit between these nights so had to chop off a fair bit of the top and bottom after stacking.

I haven't found this an easy object. Needs twice as much and darker nights.
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  #53  
Old 27-02-2018, 12:23 AM
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Very nice Chris,
raymo
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  #54  
Old 27-02-2018, 08:15 AM
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Well done Chris

You may have chopped off a few feathers, but is still a great image.

Plenty of detail and some good star colours.

We could work on this one for another 24 hours and still not reveal everything. Maybe make this a permanent February target, so the comparison goes on for a full year.

---------------------------------------------------
Time to think of another animal to shoot?

Or maybe Markarians Chain in Virgo?
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  #55  
Old 27-02-2018, 04:51 PM
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Thanks Raymo & Peter

Chopped a few feathers. You can see it falling out of the sky !!
And one one its wings has disappeared. It didn't stand much of chance once I got to it.

___________________________________ _______

Markarian Chain sounds a good idea. Individually small, but brighter than that pesky seagull. So will allow different scopes to get bigger, or smaller clumps of galaxies.
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  #56  
Old 03-03-2018, 08:26 AM
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The seagull is flying west so time to March on.
Once again some great images and all very unique.
In this comparison it is easy to see how the different equipment produces a variety of results.
Well done to Rocky, Cam, Tony, Rick, Chris and ChrisV.
And special mention to Alex who forgot to take the chips.

So a proposal for March is the constellation Crux.
The Crux would offer both wide & narrow field opportunities.
And it easy to findů

Any thoughts?
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  #57  
Old 03-03-2018, 09:29 AM
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Chips?

All I did not bring and the most needed was my dry as a bone and gum boots.

Anyways moving on what do you have for March Grand Master.

Something that requires only 8 minutes exposure please, given how much time I managed in February:mad2

I at least after over a decade of having goto mounts (three) actually did a two star alignment and got to use the feature for a whole 5 minutes.. the second try worked when I put in 24 hour time

alex
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