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IC 1396, MN190, DSLR... but noise and not good timing

AndyUK

By AndyUK
in Imaging - Deep Sky

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AndyUK

AndyUK

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As the full(ish) moon was rising later tonight, I managed to get out in the garden early(ish) for what I hoped would be at least a few hours... The problem is that I'm fairly limited to objects as my outlook is limited. However, after topping up on another couple of hours of M51 subs (I think I have 9 hours now), the sky still seemed dark for another run... I've had a couple of sessions at NGC 7023 (Iris Nebula) and I know I could do with a few more subs, but being fairly faint I thought I'd see if IC 1396 was up yet... which it was (barely!)

This was 17x600s (20 flats, 30 bias), stacked in DSS, processed in CS5 and with a fairly strong use of Topaz denoise. I know the framing could have been a lot better, but to be honest I had no idea how to frame this - I just trusted the goto and prayed I was taking frames of something! Still, I shall now know for next time...

The noise is pretty bad so I'm going to try a reprocess with darks, but to be honest, I'm not hopeful. Still, with any luck, Mr posty will be bringing me a shiny red Atik 314L+ today, so hopefully I'll be able to play with that soon!

post-18819-133877567084_thumb.jpg

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MikeWilson

MikeWilson

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There's not a lot wrong with that. The sky here last night was so noisy that I gave up.

As regards framing, check the bright star patterns in your field of view with a star atlas or planetarium program.

Dennis

Or if you're really stuck, upload them to Astrometry :)

Nice image, Andy :-)

Mike

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AndyUK

AndyUK

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Thanks Dennis - It was interesting noting the background % rise on DSS as the night went on, although it did seem quite dark at about 11pm, but then by midnight it was showing 10%+ (which it stayed at for all the subs for this!)

I did try using Stellarium last night to see where I was, but it doesn't actually show the nebulosity when viewing IC 1396, so it didn't help much - I know some people use Carte du Ciel (I'll have a look at it and see if it's any better), and I did also try looking up some images of IC 1396 to see if I recognised any star patterns, but no luck. However, now that I know where that bright star is in relation to the main area, I should be able to do much better next time...

Similarly, to date I've steered clear of being "attached" to a laptop when DSLR imaging, but I'm expecting that to change now with the imminent arrival of the CCD camera - In future I'll also be able to take a sample frame and stretch it to pieces to find out where I am...!

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AndyUK

AndyUK

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Cheers Mike - Now that I've sussed out how to stop the laptop/netbook from automatically rebooting after a Windows update, I no longer fear having it connected... Astronomy.net would probably be a better option as the netbook only has 1Gb RAM and trying to run Elements on it is painful!

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MikeWilson

MikeWilson

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Thanks Dennis - It was interesting noting the background % rise on DSS as the night went on, although it did seem quite dark at about 11pm, but then by midnight it was showing 10%+ (which it stayed at for all the subs for this!)

I did try using Stellarium last night to see where I was, but it doesn't actually show the nebulosity when viewing IC 1396, so it didn't help much - I know some people use Carte du Ciel (I'll have a look at it and see if it's any better), and I did also try looking up some images of IC 1396 to see if I recognised any star patterns, but no luck. However, now that I know where that bright star is in relation to the main area, I should be able to do much better next time...

Similarly, to date I've steered clear of being "attached" to a laptop when DSLR imaging, but I'm expecting that to change now with the imminent arrival of the CCD camera - In future I'll also be able to take a sample frame and stretch it to pieces to find out where I am...!

Hi Andy,

Depending on what laptop you use it's not really a burden to be attached at all. I've got an Acer One (bought a couple of years ago from Asda for £150) and a huge battery that sticks out the back like a handle (thanks to eBay). It handles all the software (CdC/Stellarium, PHD, APT, EQMOD) just fine and on battery will last around 7 hours outdoors.

I've attached a USB hub to my mount with velcro and a single long Belkin USB extension cable runs from the mount USB hub to the netbook so it's not really any different to having a bigger, fatter hand controller on a longer cord.

APT is the best reason for having a laptop in the field with a DSLR. There are a lot of awesome features, including EXIF temperature reading, FWHM focusing and job/timer scheduling. It works great with live view.

EQMOD and PHD are pretty neat too, being able to align/sync on whatever stars you like rather than the pre-determined list.

You'll love it, Andy. Just be sure to bring cable ties. Lots of cable ties.

Best,

Mike

EDIT, RE: "trying to run Elements on it is painful"

Oh yes - don't do that :) I have the netbook saving images to a folder in DropBox and inside in the warm my PC picks up the images hot off the press. But whilst I can't use Elements or CS5 or anything like that out in the field (CdC runs doggedly slow too), it's easy to open an image in Windows explorer, do a 100% zoom on a star to check for elongation or artefacts and so a simple "auto" exposure adjustment to check framing. My workflow for framing usually involves using APT to take some large JPG images @ 30 seconds @ ISO 1600.

Clear skies,

Mike

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swag72

swag72

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Nice image there Andy - I am looking forward to your Atik pics!! Lucky you!!

Why do you think noise was such a problem? Warmer ambient temperature? Interested to hear thoughts on this as obviously in Spain I am used to quite a warm ambient temperature, and do wonder how it will effect noise.

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AndyUK

AndyUK

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Hi Mike - I have a netbook (allegedly 7-8 hrs battery life) which I'm intending to use... It's nothing special, but the intention is to connect everything to that, but then use my laptop indoors to monitor.

EQMOD is something I expect to look at in the future - Although the 314 will mostly be imaging, I do have the option of using it as a guidecam when I'm imaging with the DSLR, and that might be a way in for me to compare ease of use of the Synguider with PHD... (and also an excuse to start using APT :icon_salut:).

Cable ties / Velcro strips... yes... I could do with a few of those already - I think someone's sig says... "and cables, lots of cables" and now I know what he means!

PS - Shiny Red Atik will be taking some setpoint darks soon (PLEASE can tonight be clear :)?!)

Hi Peter - Thank you too! I had no idea where the centre of IC 1396 was :eek: - All I did was perform a PAE on Alderamin and then slewed to IC 1396 (and kept my fingers crossed. Not very scientific, but I guess I was lucky!

Cheers Sara! - I fear that I'm on another steep learning curve with the camera and the new processing skills I'm now going to have to learn, but thankfully my family have left me baby-sitting the dog this week so I can do whatever I like when I like!

The noise seems to have become more noticeable over the last 3-4 weeks or so... about the time that the temperature started rising over here. My 40D seems to have a threshold - Although ambient temp a few weeks ago was 4C, after 3 or 4 600s frames, the chip heated to c. 12C, but at that temp the noise seemed to be okay. However, now that ambient has crept to 8C, the chip temp is now rising to 22C and it doesn't like it at all...

I must admit I do find it a bit odd as, like yourself, there are plenty of other people based in warmer climes and I haven't heard anyone else report this as being a particular problem with DSLR's, although Mike has also started suffering a little (but, unlike me, has managed to control his :BangHead:)

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AndyUK

AndyUK

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Sadly I didn't get the chance to give the Atik it's first light - I discovered there's not enough back focus on my moonlite focuser and the only extension tube I have (well, de-lensed 2" ED barlow) was too long :eek:... (However, the good news was that when I noticed the defocused star on the screen I realised I'd never actually done a star test... and my collimation is spot on :)!)

So I took some more subs of IC1396 with the DSLR - The now waning moon was much kinder last night so I was able to add another 28x600s to the 17 from the previous night...

I'd like to think that the noise is going down a bit and the detail coming out a bit more, although I wish I'd centred the framing of the first session a little more to the left...!

post-18819-133877567641_thumb.jpg

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Uranium235

Uranium235

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When you do get your 314L+ set up, make sure you get a B mask for focusing otherwise its going to be a long-hard slog with FWHM. And as a good start in this warm weather, run it at -10.

Tape up the power cable too, its really flimsy and it doesnt take much thrashing to wear it out. Oh, another thing (really important): route the power cable seperately from the USB cables (dont bunch em all together) otherwise you may get nasty black lines across your subs.

At one point you will be crying out for the simplicity that a DSLR offers (esp. when doing LRGB), but in the end the extra bit of effort is well worth it :)

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AndyUK

AndyUK

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Cheers... and thanks for the tips!

B Mask - Check. (Got those - I tried to use one last night, but the outer spikes were way out and the centre spike wasn't even showing!)

Temp = -10. Okay. I was working on the basis that the manual said to remain within a delta-T of 27C (Still, I doubt we'll get many nights of 17C+ in the UK!)

Tape up power cable - Okay. (I also need some velcro straps for all the other cables, otherwise I may end up garrotting the dog when he comes out a-sniffing :)). I'd read about the enduced noise between USB and power cable, but will keep an eye out for it...

I still intend trying to keep my eye in with the DSLR ocassionally, not least of which is the fact that it provides a far greater FOV (I'm going to have to save up for registar as ilters come first, so mosaics will have to wait a bit :eek:).

I'm going to post a separate thread about software for analysing the frames as Artemis Capture doesn't seem to include anything that will actually help set the correct exposure (ie a histogram maybe) or is it just a case of looking at the frames on screen...(?)

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AndyUK

AndyUK

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Thanks...! My laptop seems to have a lot of folders with "subs that I can add to" at the moment...:)!

Fortunately this one's just rising so I'm sure I can get some more on it, although to be honest I'd really like to start again and move LDN1105 to the centre (pushing that central star to left if frame...)

The other option now is to use the 314 and go in even closer on LDN1105 itself :eek:... If ONLY I had a 50mm extenstion tube I could probably have tried it tonight :icon_salut:.

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Uranium235

Uranium235

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The past couple of nights when I took the Atik out, the ccd temp at the start was 12C, hence the choice of -10. You could probably drop it later on but its best just to leave it where it is and take all your subs at the same temp. Dont think Id ever dream of using it as a guide cam though ...lol.. most expensive guide cam ever.

In regard to extension tubes. Do you have any synta 1.25" barlows you can take apart? That might work, it would be shorter than the other barlow you used.

Filters: get the 7nm Ha first - youl love it! Especially when the moon is about, you can happily sit there and give the moon a big V sign :)

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AndyUK

AndyUK

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... best just to leave it where it is and take all your subs at the same temp. Dont think Id ever dream of using it as a guide cam though ...lol.. most expensive guide cam ever.
Yes... that's exactly what I wanted to do, and maybe "refresh" the darks annually (just in case of any degradation over the course of the year)... I must admit, it does seem odd there being an ST4 socket on it... although as I only have a synguider, I guess it IS an option if I wanted to strap the DSLR back on again... but the Synguider seems to be sensitive enough and it works, so I think I'll stick with it!

Sadly I no longer have any Synta barlows... Only an ultima - I did see if I could take apart, but the lens is in the barrel itself - There's nothing for it but to buy one...

Filters - Yes, I bought that 7nm Baader Ha filter with the camera... my fingers are ready!

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Uranium235

Uranium235

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Huh... are you joking?

FWHM with teh 314l takes 1 min for perfect focus??

It doesnt seem to work that way for me, the numbers seem to jump around too much for me to get accurate focus. I prefer the "visual" method that the B or Y mask offers. Why take one minute when you can do it in 30 seconds :eek:

Andy, im not sure whether its worth getting a barlow just to take it apart as its normally the "free" options available becuase SW always throw so much stuff in with their OTAs. You might be better served by getting a set of t extension rings and a couple of rubber O rings (can be found at a hardware shop) to act as variable spacers or to prevent over-tightening. I think my t extension set was 15,10 & 6mm, it was less than 20 quid anyways :)

Not sure if youre aware, when calculating corrector/flattener distances to the CCD - on the 314L+ the distance from the top of the t thread to the ccd chip is 12mm. Also, you will find that the t thread is quite shallow on the camera, so any t thread rings I use (apart from the male/male one I got with filter wheel) doesnt sit quite flush against the camera (threads still showing), so you will gain about 2 or 3mm there too.

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