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Elephant Trunk Nebula...easy or hard?


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Hi,

I have just about sorted out my guiding and with the current high pressure I am hoping that this weekend will be nice and clear!

I really want to take a stab at nebula imaging and IC1396 seems to fit the bill (Good position for me, nice and large).

If my guiding goes to plan I will attempt maybe 3-5minute subs on this subject with the following set-up:

HEQ5-PRO

Canon EOS 1000D (un-modded)

Megrez 72 Doublet

OR if my guiding fails, then back to say 1-2min subs.

I'm aware that as this is a large object and with no field flattener im going to get a lot of stretch stars around the edge of the frame but is this still a viable subject to image?

If so how much time should I aim for? Any other tips?

Ste.

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Hi Ste.

I've just had my first crack at IC1396 over the last couple of nights (same as you, good position and HUGE!). Framing was tricky for me on the 1st night - The part I wanted to get was right to the edge of the frame (http://stargazerslounge.com/imaging-deep-sky/139479-ic-1396-mn190-dslr-but-noise-not-good-timing.html#post1788176). However, that won't really be an issue for you with the FOV from your 72mm... :)

I ended up with 45x10mins on this (using an MN190/f5.3 @ Canon 40D) as I'm getting plagued by digital noise now that the temp has risen :icon_salut:

I would say that it's not a difficult subject but I would suggest you get as many subs as you can - I managed 28 x 10 mins last night, with a 10 min sub giving me a histogram about 1/3 over (I could probably have gone less...). If you can get 5mins, I'd start there and then check the histogram - If it's about right, then gets as many as you can whilst the weather's being kind :eek:

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Thanks alot that is a real help! .... Annoyingly I cant get hold of a light polution filter in 2" format for tonight's session, I do however have a 1.25" LP filter and neccessary extension tubes etc...

Will this cause any problems with the image or is it better to use this than without (Pretty light polluted here)

Ste.

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Ah - An LP filter is pretty much mandatory for DSLR imaging at most places in the UK... I use an Astronomik EOS Clip filter - It's fairly savage on LP, but it works a treat.

If you DON'T use one, you'll be capturing mostly LP, so I would go with the 1.25". I'm not sure, but you might get some vignetting, but better that than taking photo's of mostly LP...

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the 1.25" will probably cause Vignetting mate. I would try without out it if possible but if light pollution is too bad, might be worth just spending the nite getting details down for a plan so that when you have the 2" filter you can set up and let her rip.

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I will go for the 1.25" as I believe that may be the reason my M81+M82 image showed so little detail for +1 hour of data on my first attempt! (middle bit was bright but faint wispy stuff was really lacking)

Ok so I will crack out the 1.25" try and get the guiding to work properly this time and then go for some nice long exposures! :) (Hopefully)!!!

Thanks for all the help!

Will post the results over the next few days!! :eek:

Ste.

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Hope you don't mind a little constructive criticism on the m81+m82 pic?

The reason you struggled with detail there is to do with a couple of factors. Firstly it looks like there is a polar alignment issue causing the stars in the resized image of yours to lead off to one side. There also seems to a be a ring of colour around the middle of the image with could either be a reflection or dirty optics?

The FOV of the 72megrez and the 1000d combined is quite large and often small alignment issues along with trying to pick up real detail in something that small with the megrez can be a bit of fun and processing is key there.

I've take a few with my 1000d and the 250px, I need around 40x30secs to pull any real detail out and if there are any subs which are hazy or slightly trailed, it makes it a million times harder to pull the details.

I'm no imaging expert, but it would be worth trying some brighter targets and bigger targets to suit the scope and get your processing and stacking down to a T, then go back to m81+m82 and I'll be you will see a difference.

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thanks for the comments starblazer they are always welcome....

U would be spot on with the alignment... it was totally rubbish for the night and no way near accurate enough as I couldnt see the pole star due to the moon being directly behind me! So kinda roughly estimated it! The wierd ring is most probably some kind of reflection as I had various LED's around the scope not covered and am I right in thinking you have to cover the viewfinder on the camera? (I didnt)

@psychobilly

That picture is awesome :) I would be more than impressed if I got anything 1/10th as good as that! Sooooo many stars! and yes a flattener is next on my list! By the size of that image though I would have a good amount to play with!

Ste.

Edited by swlloyd3
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It might even be so old that it may have been taken with the Equinoxe-66 and FFIII...

But i am pretty sure it's with the Megrez72 FFIII...

I Really should dig out the data and reprocess it...

Turns out....

It was the first light image from the Filter removed 350D on the Equinoxe66 FFII combo from 12th Sept 2008.... ah well the mind (what little there was ) is going fast...

Peter...

Edited by Psychobilly
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Till I saw Andy and Peter's images I would have said No. But that is what forums are about! Go for it!

Dark site, CCD, HaLRGB, F3.9, no work in the morning... it gets easier by just a bit! Cheating, I know.

http://ollypenrice.smugmug.com/Photography/Widefield-images-including/IC-1396-HARGB-2-3X1-HRS/936701075_jhrMy-X2.jpg

Olly

Edited by ollypenrice
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