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Old 30-01-2011, 09:28 AM
adman (Adam)
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Am I expecting too much of my DSLR?

I am finally at the point where I have a mount I can rely on to capture good (well - good for me) data, but I am limited by being in inner Brisbane with its light pollution.

I use a vanilla Canon 550D - no mods, no cooling, and I am wondering whether it is the camera, or my limited processing skills that are my current problem.

Here is a link to one of my raw (.CR2) subs, and I have attached a jpeg of my best effort with it - following Louie's (atalas) excellent tutorials.

Can somebody who is better at this than me have a go at it - I know it is only a single sub without calibration - but I just need to know I am on the right track.

Exposure details are:

300s, 400ISO, ED80 with 0.8 reducer-flattener
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  #2  
Old 30-01-2011, 09:45 AM
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[1ponders] (Paul)
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for a single shot Adam that looks great. I wouldn't expect it to be stretched too much more without noise starting to overwhelm signal. There does seem to be some considerable background colour noise (blotching). I've seen this in other 550 results as well.
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Old 30-01-2011, 09:49 AM
Mighty_oz (Marcus)
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Looks fine to me, all u need to do is add a few more long ones to the stack some 5 or 10 sec ones to use for the trapezium and your flying
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Old 30-01-2011, 10:01 AM
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peter_4059 (Peter)
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Looks good to me Adam. Get some darks, flats, bias' and more exposures. Also the temperature has been pretty warm up here so you are going to get more noise than you would with a cooled camera. The sensor heats up a number of degrees above ambient.

Peter
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Old 30-01-2011, 10:14 AM
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wasyoungonce (Brendan)
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Adam that is a great pic..the best way to improve this ...take 20~30 and stack them.
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Old 30-01-2011, 10:35 AM
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dugnsuz (Doug)
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Looks good Adam - I tried playing around with your RAW file but couldn't pull out the detail you've got in the posted image above.

Take some short exposure subs to use as masks for the core burnout.

Up the iso setting a bit if ambient temperature allows and heap up those subs.

All the best
Doug
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Old 30-01-2011, 11:27 AM
TrevorW
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I'll recommend you Google Jim Solomon's Cookbook

ideal starter guide for DSLR photography

If you look at my website a lot of these images where captured with an ED80 and a modified Canon 350d (no cooling)
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Old 30-01-2011, 04:04 PM
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irwjager (Ivo)
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Hi Adam,

That's a great frame and (AFAIK) pretty much in line with what you can expect from the D550. All you need now, as many have already commented, is multiple frames to stack to mitigate the noise and you're laughing - nothing wrong with your processing skills I don't think! http://www.iceinspace.com.au/forum/....s/thumbsup.gif

I attached my interpretation of the CR2, but honestly, it's probably not really that much of an improvement...

Best of luck!
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Old 30-01-2011, 07:14 PM
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jjjnettie (Jeanette)
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I spent some time today with my 550d testing the 2 different types of noise reduction built into the camera.
And may I suggest that you enable the High ISO Speed Noise Reduction, and set it to "Standard".
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Old 30-01-2011, 07:39 PM
adman (Adam)
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thanks for the feedback everyone - I feel a bit better about it now. I have been stacking several images in DSS, but have been having problems opening the TIFFs in photoshop (I have just started a new thread about this...)

jjjnettie - would setting the in-camera high iso noise reduction have any impact at 400 ISO? To be honest, I can't see that much difference noise-wise between 400 and 800 - but skyglow would get a bit much with 5 minute subs from where I am. So I think shoot at 800 for 1/2 the time....

Next clear night, I will get as many subs as I can, as well as darks and flats, and try again.

Thanks
Adam
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Old 30-01-2011, 07:43 PM
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I think you've done a great job.

Remember the DSLR (or a CCD) doesn't have the dynamic range to give detail in the bright and dark portions of the nebula. You need to blend images exposed for bright and dark portions together to give the "whole" picture. Just stacking them together isn't enough - you need to merge them together in photoshop! Just remember that every hour you spend in the field must be matched by another hour (or more) in front of photoshop.

DT
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Old 30-01-2011, 07:52 PM
adman (Adam)
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thanks David - I haven't tried mixing different length exposures yet - but I know that particular learning curve is sitting there waiting for me - I did notice that Louie had a tutorial on it, so I will have to have a look.

Adam
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Old 30-01-2011, 07:53 PM
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Adam, I'll post a thread in a couple of days re. the ICNR. I'll include some 100% crops so you can make up your own mind.
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Old 30-01-2011, 08:04 PM
adman (Adam)
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Quote:
Originally Posted by jjjnettie View Post
Adam, I'll post a thread in a couple of days re. the ICNR. I'll include some 100% crops so you can make up your own mind.
thanks - that'd be great!
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Old 30-01-2011, 08:28 PM
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I can't get it to look as good as you've already done Adam. You're really up against in so many ways here:

- Single sub, so no chance to stack out noise
- Tremendous amount of noise (darks, flats, etc would take out a LOT of this)
- sky pollution (poor signal to noise ratio)
- dynamic range (the Trap is totally blown)
- data collected at warmest time of year (although darks would help immensely)

M42 is actually a deceptively tricky beast to image well because it has such a huge brightness variation. A cooled CCD helps with colour noise and dynamic range, but you still need all the grunt work with calibration, stacking etc. Definitely worth learning it all well with the DSLR. Its quite a revelation how much easier it is to work with lots of well calibrated data from a dark sky site.

CCDs are getting better and cheaper in the background while you're learning the longer you hold off. ICNR as JJJ says well worth a go while you're experimenting. The only time I used to avoid it was if I was at a real dark sky site and wanted to make every minute count - better to use library darks then.

Don't ever underestimate the humble DSLR - just look at what Humayan and so many others here have done in the past with them.
BTW, your tracking in that is wonderful. Beautiful round stars even when blown up all the way
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Old 30-01-2011, 08:54 PM
adman (Adam)
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thanks Rob - I'm not really worried about the appearance of this sub - but whether or not it is representative of what I should be aiming for. I really wanted to know whether subs like this, if I have 20 or 30 of them, are going to give me a decent image, or if I am better off barking up another tree...

I am very happy with the way the G11 performs - and I haven't even tried to fiddle with it yet. A quick run through PEMpro the other night gave me about +/- 11 arcsecs for tracking. I am eyeing off one-piece worm blocks at the moment - but guided images with the ED80 are pretty forgiving....it will generally guide at +/- 2 arc secs or so - at least as far as I can work out. My image scale is just over 2 arcsecs/pixel and the PHD graph wavers between the first gradation either side of zero for the most part....

Cheers
Adam

Quote:
Originally Posted by RobF View Post
I can't get it to look as good as you've already done Adam. You're really up against in so many ways here:

- Single sub, so no chance to stack out noise
- Tremendous amount of noise (darks, flats, etc would take out a LOT of this)
- sky pollution (poor signal to noise ratio)
- dynamic range (the Trap is totally blown)
- data collected at warmest time of year (although darks would help immensely)

M42 is actually a deceptively tricky beast to image well because it has such a huge brightness variation. A cooled CCD helps with colour noise and dynamic range, but you still need all the grunt work with calibration, stacking etc. Definitely worth learning it all well with the DSLR. Its quite a revelation how much easier it is to work with lots of well calibrated data from a dark sky site.

CCDs are getting better and cheaper in the background while you're learning the longer you hold off. ICNR as JJJ says well worth a go while you're experimenting. The only time I used to avoid it was if I was at a real dark sky site and wanted to make every minute count - better to use library darks then.

Don't ever underestimate the humble DSLR - just look at what Humayan and so many others here have done in the past with them.
BTW, your tracking in that is wonderful. Beautiful round stars even when blown up all the way
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Old 30-01-2011, 10:28 PM
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RobF (Rob)
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The G11 is such a good investment - great to hear its behaving (although not surprised).

I'm sure you could get a fantastic M42 with 20-30 calibrated subs and a number of shorter exposurers to round out the trap. Was fun playing with the sub too...
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