M57 first attempt.

[damp owl]

This is my first attempt at M57. Only bought the camera a month ago, and finally was able to take some images. This is just 4 subs at ISO 800.

Am quite happy with this as a start, M57 holds a special place as it was the first DSO I ever saw through a scope.

Adam.

[damp owl]

Just realised I posted this in wrong place - clearly observation skills are not my strong point .

[Quatermass]

Good shot Adam more subs darks and flats and bias shots will give you more detail for sure but thats a great pic. It was the first dso I saw as well you will find that the crab nebula is about this sort of size as well.

[damp owl]

Thanks for the comment Mark, Somehow I managed to post this twice and I swear that it was in observing rather than imaging but never mind.

There are no darks or flats in this at all, in fact I think this is only 4 subs. For the subs, is it better to get longer exposure or higher ISO. This image is stacked from 4 subs at ISO 800 for 30 seconds. ISO 1600 shots have visibly more light pollution but more stars, detail etc.

Which is best - or should you combine both?

Adam.

[Bizibilder]

I would suggest you stay with ISO 800 and concentrate on getting lots of subs. Also start to build up a library of darks - you can take these on cloudy nights, just remember to record the temperature and exposure times (take a batch of around 30 for each). Maybe make yourself a lightbox (see the DIY section) so you can take flats as well - these must be taken at the telescope as the optical path and focus must not be changed at all between "lights" and "flats" being taken - again take about 30 or so. When you have mastered that little lot - you can move on to the next step!

[damp owl]

Do the darks need to match temperature, exposure time and ISO of the lights, and should you have an equal number of darks, flats as lights?

There is certainly plenty of time with this cloud to take some darks.

One other question springs to mind, does the camera need to be attached to the scope, or can you just take the darks with the lens cap on?

Adam.

[Spikey]

Darks are used to subtract the thermal noise your camera generates so you're correct you need to match the temperature (or near enough), ISO & exposure time.

A good number of darks is 20-30 past this you get into the diminishing returns area

You don't need the camera on the scope to take darks. I've put mine in a plastic bag in the fridge before now and ran a USB lead in to control the camera

Good first go at M57 which camera are you using ?

[damp owl]

Perfect, many thanks for your advice everyone, I'm going to go and clear a space in the fridge, may have to eat/drink some stuff...... There's a bottle of wine that is clearly taking up a camera sized space.

Adam.

[Quatermass]

You can find a really good guide to your darks flats and bias shots in the deep sky stacker help files read that and you cant go wrong. I normaly stick to an ISO of 800 or 1600 lately I have been using an ISO of 1600 combined with short 80 second subs and stacking those with 30 darks flats and bias shots. I take my darks when I have finished taking my main shots or subs by leaving the camera on the scope and putting it all in my shed using a remote timer set to take 60 of them. In the morning I take my flats and bias shots. For flats keep the camera on there after the darks have done and put a clean white t shirt over the telescope front and set the camera to AF so you get the correct balance for your flats. My advice is get out there and experiment so you find what suits your set up best.