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M16 unguided - first attempt.


davy999
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Taken with nexstar 6se and focal reducer with Atik Titan

Poor seeing with bright moon and fine cloud. 20 subs of 20 seconds if I recall, captured using Nebulosity, used Maxim, DSS and PS to process.

First real attempt at image manipulation. I know I got it totally wrong but the subs showed no signs of anything so I was surprised when some structure became visible.

Comments / criticisms / suggestions most welcome, or maybe I am beyond help?

I was very impressed, especially at 3am!

post-19779-133877459123_thumb.jpg

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Well its cetainly M16 the Eagle Nebula ... and for such a short exposure it a good result...

How did you have the FR setup was it a 1.25" filter thread fitted one or was it a SCT one?

What reduction ratio was it and what spacing did you use between the reducer and the camera?

Im a bit supprised by the level of vignetting...

Peter...

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The fr is 0.6 and is a filter thread screw in type so the distance I have no idea, I just screwed it to the end of the camera and that is it.

I think the vignetting was made worse by my post processing.

I know its not great but I thought for my setup and my total lack of skill it wasn't bad.

I intend to revisit this with and without the FR and see the difference I get.

I will also experiment with the filters i have once i have read up more on the subject and have a plan during sessions so that i am not so haphazard as I currently am.

My only concern is that with no focal reducer my f ratio is back to 10 and this reduces exposure length as my first attempts without were even worse.

Edited by davy999
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Hi Peter

Thanks for the suggestion of flats, I did read about them, I just have to find out a way to get a nice even light source.

Am I right in assuming that flats would be less necessary if I didnt use the focal reducer?

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It's always worth doing flats never mind how the scopes and camera are setup...

A white t-shirt over the scope and it pointed at a clear patch of sky away from the sun will be a resaonable place to start , or aim it at a piece of evenly illuminated white paper..

An effective light box can be built from foam board and LED lights. Laminating pouches make quite good diffusers...

Have a look at this thread...

http://stargazerslounge.com/diy-astronomer/74918-lightbox-my-zs80.html

Peter...

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Hi Peter

Thanks for the link, looks like another little project for me :D)

I was contemplating getting a wedge but so many comments I have read in the last few days say that the mount and spur gears just are not up to proper RA tracking with a wedge that I am now dubious.

I would love to get a goto decent GEM but they aint cheap! and as I have only just started and bought my kit in the last month my pockets are running short of funds! As I cant see polaris from my observing location I would have to drift align, I do understand this concept but I am not sure how you do this with a motorised mount but would be fun trying.

I am confused that the mount is criticised for long exposure AP yet me with almost no knowledge and skill managed to get the POC with some definition. I think without the focal reducer it would improve even though the FOV would be severely reduced. Just wish the nights were darker and longer so that I could actually do some longer trials and make my own mind up!

Anyhow, thanks again for the link if I do try it out I will stick a pic of the lightbox here on the forum!

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Very well done Dave... that's come out great for a first go.

The problem with the mount, isn't that it can't be used for deep sky, but you are limited by how long a sub you can get before field rotation becomes a problem. That limit is determined by where in the sky you are targeting. It's longer in the east and west (up to 2 minutes I think) and gets shorted overhead and north and south. Down to something in the order of 20 to 30 seconds. Long exposure deep sky, you're talking 5 minutes plus.

this will help with what I mean

What is the Maximum Exposure in Alt/Az? | AstroPhoto Insight

and

What is the Maximum Exposure in Alt/Az? - SkyInsight

This is, apparently, not affected by the focal length you're using, but the longer focal lengths are more demanding on drive train accuracy.

As for a goto gem.. it's worth looking at the SynTrek mounts... they don't have the goto hand controller, but otherwise are identical... then you hook up a laptop running eqmod, and use the laptop as the goto controller and guider.

onwards and upwards

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Hi John

Thanks for the reading material, more to learn :D

I don't notice image rotation much, because my subs are short but it seems to find and align ok and follow for a while then it will start to drift things out of view, I then get it back but it drifts offline more and more.

Maybe my alignment needs improving, will have to try to ensure 3 star align from now on and see how it copes.

With regards flats, at work we make the diffusers for a lighting company and we make a part that is a round flattened dome made in opal polycarbonate. Maybe putting this over the scope and aimed at the sky should give a nice even diffused light for flats?

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Not sure on the drift... make sure the mount is as perfectly level as you can, powered from an external power source, ideally regulated.. I used to use 1 star aligns with my NexStar SLT and didn't have any noticeable issues with drift. Equally, a small amount isn't a bad thing, as long as it doesn't ruin the subs, as you can use that to remove noise in stacking.

I'm no expert on flats... I use a laptop screen... but that dome sounds like a good plan to me.

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Opalescent polycarb is good stuff i use it as a diffuser on my light box...

I wouldnt rule out a basic wooden wedge for the 6SE ... It would be easy to get fairly decent PA...

I made the "WWW" or Wobbly Wooden Wedge as the first prototype for the "SAW" or Scrap Ally Wedge....

If you want some pointer let me know.. i might still have the drawings for a 6SE one on one of the computers in the house I will just need to know your "observing" latitude...

Peter...

Edited by Psychobilly
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Hi Peter

That sounds like a plan! I have access to various machinery at work to make stuff, and a 3 axis router that is great for cutting out templates and stuff from various materials. so if you can dig out your plans I can get it drawn up and made at work, if I ever have time!

FYI viewing lat/long are as follows

50N

Thanks for the offer!

Edited by jgs001
adjust location
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Hi Peter

That sounds like a plan! I have access to various machinery at work to make stuff, and a 3 axis router that is great for cutting out templates and stuff from various materials. so if you can dig out your plans I can get it drawn up and made at work, if I ever have time!

FYI viewing lat/long are as follows

50.5x.xxN

2.4x.xxW

Thanks for the offer!

I would delete that info if i was you.. i have it written down...

Peter...

Edited by Psychobilly
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