Another nooby imaging question.

[Woolleson]

Hi,

I'm about to venture into my first DSO imaging night, think I've got all bases covered!

I'll be using a tracked but unguided mount, now I gather 1min subs should be fine on an EQ3-2 once aligned and framed. The question is once I've taken my first sub and closed the shutter do I basically do the same all over again?

I'm aware the mount and just motor drive won't allow long exposures, but will I need to re compose between subs or just leave the motor tracking and start again?

Thanks in advance

J

[Viv]

I'm still testing this one out.

Good advice given to me, was that you have to let the camera sensor cool back down a little.

I put 45 seconds in at the mo.

[Woolleson]

I'm still testing this one out.

Good advice given to me, was that you have to let the camera sensor cool back down a little.

I put 45 seconds in at the mo.

Sounds logical advice!

I assume this is dependant on the surrounding temperature? And camera type?

My drives come tomorrow, do you know if the SW motors continue tracking ? Or do they have to be reset? Just setting up good polar alignment, focus and composure then firing the shutter seems to easy!

[Viv]

I assume this is dependant on the surrounding temperature? And camera type?

My drives come tomorrow, do you know if the SW motors continue tracking ? Or do they have to be reset? Just setting up good polar alignment, focus and composure then firing the shutter seems to easy!

That's with a DSLR, with one of the cooled cams - it could be completely different.

Are they the battery motors ?? If so, they will move the mount, at the correct speed, one powered on.

Sounds really easy doesn't it !! Interesting, complicated, head banging against wall, & rewarding - all yes. Easy no

[Woolleson]

Lol, if I can get even half the quality of images seen on here I'd be a very happy bunny!

Yes they are the battery ones, thought they might time out hence the suggestions of lower exposure recommendations.

I'll be using a canon 40D, might mod my 20D later....... If the misses lets me get a 5d mark 3

[Viv]

Good luck & keep us posted.

[JimStan]

I don't know what kind of battery your mount uses, but if it is capable of running off an external D.C. source, I would highly recommend that you get a rechargeable battery pack with some fairly high current capacity. I built a 12 volt battery pack made of rechargeable "D" cells for my Meade, and rather than running down a set of batteries in less than one night, I can now use the scope several times in a row before I have to put the batteries on a charger!

A remote camera controller is also a highly recommended device. The one I use allows you to select the amount of exposure time from less than a second, up to hours at a time. You can also select the time interval between exposures ( as mentioned above, good for allowing the sensor to cool back down ) and the number of exposures desired.

As far as re-aiming the camera between each exposure, the answer is NO, don't do that. If you have done a good job of polar aligning your setup, there should be negligible "drift" between each shot.

I have taken series of shots where I did not get good drift alignment, and I could watch the desired target moving across the screen from shot to shot. But fortunately, the exposure time of each frame was short enough that the drift did not show up in the finished stack. Oh, and BTW, I should mention that a program such as Deep Sky Stacker will calibrate out the mis-alignment from image to image, unless the jump is severe. That is one of the advantages of using an automatic stacking program, such as DSS.

I have heard of people lining up their images frame by frame in a program such as PhotoShop. That, to me, is just self-torture !

Good luck!

Jim S.

[malc-c]

The key to good imaging starts with the mount. Ideally the sturdier the better, and one with good accuracy. The EQ3 isn't the best suited mount as its neither, especially if run off a battery pack. However by the sounds of things you're not expecting to get mega long exposures and aware of the limitations you have. I would suggest you look at some form of manual guiding using an off axis guider, which will allow you to get longer exposures and bring more detail out in your subs.

Yes, you are right, you basically take lots of shots one after the other of the target. If using a digital slr camera there are software packages that can control the camera from a laptop / netbook, otherwise use a cable release and stop watch. Again the software will be more precise. You also then take a load of shots at the same settings but with the cover on the scope - called darks, and then finally take some flats, which are an even light source and then combine the lot in an imaging package such as deep sky stacker....

It's a steep learning curve but some of the rewards are worth all the effort. Can't find them now, but one member has a 150P on an EQ3 mount and has produced some stunning images...proving that it can be done without spending a fortune on a dedicated guiding ring

[Woolleson]

The key to good imaging starts with the mount. Ideally the sturdier the better, and one with good accuracy. The EQ3 isn't the best suited mount as its neither, especially if run off a battery pack. However by the sounds of things you're not expecting to get mega long exposures and aware of the limitations you have. I would suggest you look at some form of manual guiding using an off axis guider, which will allow you to get longer exposures and bring more detail out in your subs.

Yes, you are right, you basically take lots of shots one after the other of the target. If using a digital slr camera there are software packages that can control the camera from a laptop / netbook, otherwise use a cable release and stop watch. Again the software will be more precise. You also then take a load of shots at the same settings but with the cover on the scope - called darks, and then finally take some flats, which are an even light source and then combine the lot in an imaging package such as deep sky stacker....

It's a steep learning curve but some of the rewards are worth all the effort. Can't find them now, but one member has a 150P on an EQ3 mount and has produced some stunning images...proving that it can be done without spending a fortune on a dedicated guiding ring

Thanks Malcom,

There's a post lurking around for budget setups and some of the images on an EQ3-2 are pretty amazing !!!

I'm honest enough to realise mine is the bear min (bought this rig after reading every photon counts) for imaging, but up north where I'm at we get very few clear nights, so dumping a load of dosh into a mount that may get little use wasn't logical to me.

If I find down the line I out grow my rig I can always upgrade (Astro stuff seems to hold it's price SH), but I need to way up use against cost...............

I've filled my legs with sand and also got anti vibration pads fitted to the mount this has made a vast difference to it's stability, it wasn't to bad before just took time to settle.

Been looking at off axis, might go this way and attach my SP900 for a cheaper guide route. Good call on the batteries I'll look at rigging up a power supply.

Thanks for the info, much appreciated..............

[Woolleson]

I don't know what kind of battery your mount uses, but if it is capable of running off an external D.C. source, I would highly recommend that you get a rechargeable battery pack with some fairly high current capacity. I built a 12 volt battery pack made of rechargeable "D" cells for my Meade, and rather than running down a set of batteries in less than one night, I can now use the scope several times in a row before I have to put the batteries on a charger!

A remote camera controller is also a highly recommended device. The one I use allows you to select the amount of exposure time from less than a second, up to hours at a time. You can also select the time interval between exposures ( as mentioned above, good for allowing the sensor to cool back down ) and the number of exposures desired.

As far as re-aiming the camera between each exposure, the answer is NO, don't do that. If you have done a good job of polar aligning your setup, there should be negligible "drift" between each shot.

I have taken series of shots where I did not get good drift alignment, and I could watch the desired target moving across the screen from shot to shot. But fortunately, the exposure time of each frame was short enough that the drift did not show up in the finished stack. Oh, and BTW, I should mention that a program such as Deep Sky Stacker will calibrate out the mis-alignment from image to image, unless the jump is severe. That is one of the advantages of using an automatic stacking program, such as DSS.

I have heard of people lining up their images frame by frame in a program such as PhotoShop. That, to me, is just self-torture !

Good luck!

Jim S.

Thanks Jim,

God, couldn't imagine trying to stack them all manually !!!!!

I've got a cable release for the time being, but have the capabilities to link to the laptop to control my camera, so might do that. Just have to get some leads and stuff..........

All good info mate, thanks read and digested........ twice

J

[Woolleson]

All done

Thought I'd share my first night of DSO photography........

Picked up my drives tonight, they took no time to fit. I'm a bit dissapointed by the speed of them at 8x but can't believe I've never got them earlier. All that time tracking by hand, what was I thinking!

So off to the garden to set up, skies are ok-ish. We tend to get a low lying fog here, this seems to enhance LP, but better than it has been.

First time I've polar aligned with a scope, what a nightmare! The EQ3-2 scopes fitting instructions are rubbish, plus once out in the garden the the overlay is nigh in possible to see. Resorted to shining a torch back and forth (red light) over the opening to see the over lay. I'm not 100% I got Polaris, there seemed to be 2 stars at my compass and dialled in latitude, just went for the brightest!!!!

Found M42 in my scope (well has to be your first, didn't want to waste all night finding stuff as usual ) and after focusing through my mask set to work...........

Got about 3/4 hour of subs, then flats, biased and darks. On the back of the camera I can see the colour in Orion so I'm well chuffed! The only problem I can see is the sky has a horrible orange glow, LP I presume? Going to try to remove this in PS.

So sat feeling very happy, will process and share over the next day or so and see where I've gone wrong

Thanks for all you help, feeling on top of the world!

J

[Woolleson]

My first image!

Thought I'd share, thanks for all your help in achieving it........

Ok I know it's poor, just 20 1min subs plus darks and biased, it was plagued by low mist and Orion dipping low.

No matter, I'm happy and now have a base to build on, next time a clearer sky and longer subs!

J