DSO imaging.. almost hands-free.

[iceman]

Well with a clear night tonight, no planets or moon up for some time, I wasn't really fussed on the object I captured (really just testing things) but NGC253 is well placed without having to worry about it going past zenith for some time so that's my target for tonight.

I spent some time yesterday with my side-by-side adapter to be able to mount my ED80 and the 400mm f/5 refractor side by side.. one for imaging and one for guiding. Put it on the mount today, and all looks and works great. Some slight adjustment of the rings on the guide scope allowed both scopes to point almost exactly at the same piece of sky (within enough error).

I was going to setup PHD guiding tonight, but honestly couldn't be bothered. I've got the GPUSB unit and cable, but after spending an hour getting everything setup as it was, I figured I'd just do some hand-guiding tonight. I didn't polar/drift align with any accuracy either.

I put the DMK in the guidescope, and use ICCapture plus Al's fantastic ICCA application to put the reticle on my screen, and just used the hand controller to roughly guide. I've been lazy though as this is just a practise run, so I only re-center the star when I can be bothered. I'm just capturing 60s exposures for now.

It's also the first light for the WO-2 0.8x reducer/flattener. Not sure what to think of it yet. In some earlier tests, the corners looked curved - much worse than without. But I might be doing something wrong, i'll play with it again next time but i'll just crop the corners for now. I was hoping it would be nice and flat so I could capture NGC253 and the little glob in the same FOV, but with the corners so warped it would ruin both objects as they only just fit.

So anyway, i'm almost there.. Next step is to get PHD guiding working with the GPUSB kit, and some auto-guiding love. Then I can be as lazy as I want with drift aligning :)

This whole DSO imaging thing is so frustrating though.. so much longer to set everything up and start capturing photons. I'm sure I might think it's worth it when I get a good image, but at the moment I almost throw it in every 5 minutes :)

Oh and it can be quite hard to find a bright enough star to guide on, to keep the exposures relatively short (< 1 second is nice, shorter would be better). Is there a trick to it when there's no guide star in your FOV? Do you point the guide scope somewhere else?

Flats - that's the other thing I need to do next. White shirt over the ED80? Right, got it.. maybe :) I think i'll just wait for h0ughy to go commercial with his light box and buy one of his :)

Oh and some other frustrating things - the finder on the ED80 is a straight thru, so I end up on my knees craning my neck to try and find the object to image (or at least, close enough that I can use 20s exposures with the 350D to get me there). I really should align the SkyScan and use that to take me to the object. I've never used it, not sure on the process.. maybe next time after i've done some reading.

And of course focusing.. using IP focus control is pretty good and gets me to where I want to be, but the crayford focuser on the ED80 is hard to use when you really want the very fine adjustments. With the tension lock loose, it drops down too quickly and you can't make fine adjustments, and doing the tension knob tight sometimes shifts focus!! :mad: A 10:1 fine focus would be nice.. oh and computer or hand-controller controlled too (Orion AccuFocus maybe?).

Anyway that's my story for the night.. 30 out of 50 exposures done..

I was planning to put the 12" on after this in preparation for Mars in the morning, but I think i'll just go to bed.. Oh and darks, no thanks - not tonight. I'll use the master dark frame from a previous session :)

Thanks for reading if you made it this far :) Results some time tomorrow, hopefully :)

[iceman]

Oh I also forgot to mention, I don't need to worry about camera batteries.. while at home at least. I'm now running the 350D off 240v AC Adapter, with the US-AU adapter to be able to put in the power socket :)

One less thing to worry about, it's great.

[Dennis]

Hmm, makes the old fashioned 35mm film manual guiding 30 minutes exposures seem like a walk in the park when you put it like that Mike.:lol::lol:

The worst thing I ever did was nod off after 45 mins, head hit the OTA and the exposure was ruined.:(

Cheers

Dennis

[beren]

Don't know if it's happened to you yet {but it will :P} getting clouded out after setting up, drift aligning,balancing, target and guide star acquisition and focusing without the images has to be the most frustrating thing I have ever experienced :doh:

[jase]

Hands free? Don't think you're close yet Mike...;)

Welcome to the world of DSO imaging. To do it right takes dedication and patients. There is no such thing as simplicity in this game. Now that you’ve tried it, you can appreciate the effort involved. Seriously though, the more money you throw into hardware/software, the easier you can make it, but in return typically technical complexity increases.

Take computerised focusing as an example. While some may disagree, computerised focusing is the only way to accurately focus a telescope for DSO imaging purposes. Computerisation will guarantee that you’ll hit the critical focus zone every time (and usually under 90 seconds). However to achieve this you need a stepper motor mounted to a focuser that can be computer controlled. Then, the software to control the stepper motor. Software like FocusMax is free. It’s not too difficult to set up, but I’ve had quite a few headaches building a good focus v-curve model – thus the complexity.

Another example is telescope pointing. I couldn’t tell you the last time I looked through a telescope to see where it’s pointing and if it’s framed the object correctly. I use software to handle this. The software (ACP/Pinpoint) takes a picture to match stars in the field, then plate-solves these stars against a well known accurate catalogue. If the original image indicates the pointing is out by sub arc second accuracy, the telescope is instructed to move to the exact position (and in the process builds a pointing model for future corrections). Again, more complexity in software configuration.

This is just the tip of the iceberg in automated image acquisition. When all software/hardware components work harmoniously together, the imaging sessions are very productive. However, if one component fails, precious time is wasted as they’re typically dependant on each other. I’ve shared your frustration before. I suggest making small steps as you advance. You’ve probably already realised that acquiring the data is mundane work (when things are working well), it’s the image processing where things get tricky (and even more frustration).

Remind me why I decided to enter into DSO astrophotography again...:P

[Lee]

Equatorial neck.... Sort of like tennis elbow for astronomers! :D

The problem is without a straight through, you'd have little idea how close you were to adjust.... Need a telrad and a right-angle finder together.....

[okiscopey]

That's the idea I've been working on for when I get my hands on my $3 million retirement money (I wish!), but I've no illusions it will make me an instant expert with prize-winning photos.

I am amazed at the dedication Mike S. and so many other IIS folks have, considering they have to juggle family, work and other commitments as well. Their information, encouragement and discussions are invaluable for anyone comtemplating the same sort of crazy activity. I'm sure i'm not the only one who reads and tries to remember every word of these practical reports. So, please keep at it, if only for the sake of new recruits!

Hopefully, one day soon I'll be able to join the esteemed ranks of those who can say "Remind me why I decided to enter into DSO astrophotography again ..."

[[1ponders]]

:lol: Welcome to the Jungle Mike. :lol: Ditto to what Stuart said about setting up and then the cloud moving in. But take heart, it will only be cloudy up until you get sick of waiting and move the last of you setup back inside. ;)

But seriously folks...... :P

How have you got your guidescope mounted Mike? You should be able to adjust it enough to get a guidestar and with the DMK and an exposure of half a second of so you should have guidestars popping out your whazoo.

[iceman]

haha I can imagine, Stuart.. I'm not looking forward to it at all. I keep forgetting the basics too, like re-balancing after I put the cameras on, and then wonder why I get trailing after 60s unguided exposures.

Frustrations like that can happen with planetary imaging too, but it takes far less time to setup and start capturing..


Great post Jase, definitely highlights the potential problems in automated imaging, but also the rewards if it's all done right.
I have no intention of going to those extremes though - I just don't have the money, the equipment or the location to go to those lengths. If I had a permanent setup in an observatory, i'd definitely start down that road - at least with computer controlled mount, focus, etc.
But for now, I think i've almost got everything I need to take acceptable images from my backyard. I just need my skill to advance :) And more time in the night!
I'll never produce great images, but i'm happy with the progress i've made and can now do better DSO images than I thought I could.


My guidescope is in some rings that have the 3 adjustment screws like a finderscope - so it can be pointed somewhat away from the imaging scope, but not too far.
Just while imaging NGC253 the other night, while composing the shot I noticed that the DMK sometimes had some bright stars, and sometimes didn't (as I panned around). In the end I had a FOV where I was able to use a 0.5s exposure which was bright enough, but I can imagine times where there isn't a bright star nearby?
Would a (cheap) focal reducer on the guidescope be an option? The faster focal ratio would then allow brighter images with the same exposure time.. perhaps picking up stars that were too faint before? Maybe the focal length would be too short then?

I'll take some pictures of my DSO imaging setup next time I'm out.

[[1ponders]]

A wider field of view will give you more stars to choose from and the reduction in FL won't affect your autoguiding accuracy when only imaging through the ED80.

[leon]

Mike what you, and others here have said about DSO imaging is quite correct, I know, as I'm going through it as well, but it is fun.

And a permanent set up certainly makes a hell of a difference.

I know what you mean about not finding a guide star at times, bright enough to guide on, I too have that problem from time to time.

I sort of get around it while the set up is in Guiding mode, and any corrections with the mount after centering the object is very small.

I just use the hand controller and move the mount a little, and watch as a star appears, works for me, but then i do very strange things when it comes to imaging.

Leon :thumbsup:

[Alchemy]

nice to read some are getting out under a clear sky,

as long as you are happy with the results you are getting thats all that matters, over time you will improve and get even better images. Enjoy the journey as much as the destination.

Cheers AL

[Aster]

Mike, If you are manually guiding a longer focal length guide scope will give you better results as any drift of your image is noticed more in the guide scope do to it's longer focal length.
Clear as mud:)

I used to do Off Axis guiding through the main scope, 12.5" F6, as any shift of the image either through flexure or drift was real, but finding a guide star bright enough sometime took as long as the exposure time.

Hopefully my 250mm F6 will be ready within a couple of weeks and I will go down the same path as you.


Alexander