My first M31.

[Adamar98]

I started out doing fixed tripod AP about 2 months ago. After my first few images i was hooked. Posted my first images and got a lot of feed back and advice from some advanced members of SGL. Then christmas came and santa bought me a better tripod, Astrotrac and a cheap Canon 100-300mm lens. Here is my first attemp at M31 using this setup and the advice i was given. I'm chuffed to bits with it! Didn't think i would get close to anything like this.

20 subs

5 darks

stacked in DSS

processed in CS3

Any more advice would be welcome.

[Adamar98]

Forgot to mention:

60 second subs, iso800 @ 300mm

[springbok]

Good start, well done. More data will bring even better detail.

[StuartJPP]

I agree, a good start.

The Astrotrac is quite a capable mount and you should be able to get some great images with it. I would try and get more subs and push each exposure as long as possible without trailing, probably 2 minutes at 300mm, just make sure you aren't clipping the core. You can get 2 hours worth of subs overall, weather permitting, before resetting so try and aim for that. I use ISO 1600 and it seems to work quite well for me using a 7D. Also make sure your polar scope is properly collimated (there are guides on line to explain how to do this), no point trying to do a precise polar alignment without it being collimated.

One other thing to note is that on my set-up my lens changes focus very slightly over time as it gets colder. Every x subs, I make small adjustments to ensure that focus stays sharp. Additional to that, make sure you use a lens hood to remove any stray light and help prevent the front element dewing up.

[Adamar98]

Cheers Stuart! That's exactly the type of advice I'm after!

[Adamar98]

Just checked the polar scope and it was way off! No wonder I was getting trailing after 1 1/2 mins! Cheers for that little tip.

[DrRobin]

I would agree, more subs. Aim to take around 90 @ 60 secs and then expect to throw away around 30-50% depending on tracking. I would have thought around 90 secs at ISO 800 would be good and take around 20 darks, depending on the speed of your lens. Longer exposures can be a problem if you have light pollution and I have found that 800 ISO is the sweet spot, but it does vary from set up to set up.

Have you any way of taking flats? Also take some bias shots, these are really quick and you just do them with the lens cap on.

M31 is actually not that easy as I found out. The core is very bright in comparison to the arms, so your first effort is very good. Last time I tried, I spent about 4 times time post processing as I did capturing so try fiddling more with brightness, contrast and levels to bring out the detail.

Of course you could have a go at an easier object, try M42 the Orion nebular that is very rewarding.

[DrRobin]

Hi,

Just looked at your image again and you do need longer exposures and/or higher ISO.

Until I got used to it I found DSS would only select a small number of stars and then it would discard a reasonable number of frames, yet when I looked at the subs they looked quite good. The problem was the threshold setting. DSS assumes 16 bit picture depth and your DSLR is probably lower, mine is 14 bit, but some are only 12. They all produce a 16 bit raw file but to the best of my knowledge just use the lower x bits of the files colour range.

To compensate try setting a value for the multiplier in DSS or try setting the threshold to a lower value. Aim to try and get upwards of 150 stars to do the alignment, but don't go over board otherwise it will try and align on noise. I often have to try 2 or 3 times until I get it right, but I am still no where near from an expert in DSS.

[Pete Presland]

very nice start, like everyone has said there is no substitute for more data!

[Adamar98]

Cheers guys! I've tried longer exposure but I've got a lot of light pollution so I don't seem to gain anything. Same with upping the iso. I think its a matter of more data like you all say. I've tinkered with it a bit more in cs3 and managed to get a bit more detail from it. Going to give it another go tonight. Also going to try and take some flats to add.

[DrRobin]

You could take flats during the day, just defocus slightly on clear sky or blank cloud and shoot a few at the same ISO on auto exposure. sometimes they don't work so well, so it is worth processing in DSS with and without flats.

Another post mentioned the lens misting up. This happens quite a lot and it creeps up on you. You can see it on the lens with a torch, inbetween images and just warm it slightly to get rid of it. If you have a dew shield even better, it cuts down on stray light as well. I once took my flats with so much dew on the secondary mirror it made them completely useless.

If you haven't got a dew shield, roll a piece of card in to a tube and slot this over the end. Foam is even better or anything that traps the air above the objective lens. I use a tube length about 1.5 to 2x the size of the objective lens, so if your telephoto is 60mm diameter, make your dew shield extend out the front by about 80-100mm.

Dew is difficult to get rid of, so if my scope des up I use an old hair drier on an extension cable and gently warm the dew off the lens. I am lucky as I have a mains supply in my shed, close to where I do my observing.

Finally I don't know if you use any software to help with the process of taking and reviewing the pictures? I use APT, it is not expensive and well worth the money if your Canon is supported.

[StarRaver]

Backyeard eos is another good little capture programe,

http://www.backyardeos.com/

[love6060]

Backyeard eos is another good little capture programe,

http://www.backyardeos.com/

Hi, just a thought, if you know how to take photos of the night sky, can you teach me what you know! PLEASE

[StarRaver]

lol i could try, Im only starting out in astrophotography myself. But i'll gladly help if i can,

Where in plymstock do you live as im also from plymstock

[Adamar98]

Sounds like a good idea. Easier to learn by watching rather than reading! You both don't fancy moving to York do you?

[StarRaver]

lol, im sure my other half would love that. I found youtube a great help in learning the basics for astrophotography and for the processing side of it.

i would highly recommend the book Making every photon count, if you don't already own it as this will help you on choosing future equipment and maybe help save a bit of money on the way.

I was recommended to buy it when i fist started out and it has helped me no end and i still go back to it now.

Your pic is very good and with the astro trac you will get some stunning results. I would also go for a prime lens at a fixed focal ratio if you plan on using lenses, don't get me wrong you can still get fantastic results with the telephoto lenses but the primes are faster and have a lower f stop allowing more light to the sensor,

With the dark, bias, and flats i would go for around 20 to 30 for best results helping with the noise and being able to pull more data out in the final pic the more lights the better

[DrRobin]

Another thing you might tryis a wide field shot of the milky way. I have seen some fantastic images, even unguided and with your mount you could probably get some stunning photos. You might also like to try driving out somewhere, your gear is very portable so you could be set up in minutes at a dark site. This will allow you to take pics for longer and get much more detail.

Anyway it is nicely dark now and according to the forecast for your area clear, so you should be out taking photos. Unfortunately, I am on holiday and it is only the middle of the afternoon here, so no chance of seeing anything.

[StarRaver]

i second that, wide field of the milky way is breathtaking under a dark sky I had a little try at this before i got my scope and mount

heres a few i took, the shot with the meteor is a single sub, and the other two are stacked images from my first attempt at dss

These were my very first attempts so please be kind lol

[Adamar98]

Wow! Those are fantastic! I've only got the standard 18-55 kit lens. But I'd love to give that a try.

[StarRaver]

these were taken with a 18-55mm kit lens and a 50mm prime lens

[Adamar98]

Very good to know! I've just bought the nifty 50 to try a few milkyway shot but I've been told I'll be better off with the kit lens at 18mm. Still the 50mm will be good for wide fields of Orion and such. Just had a look at your gallery. Your M31 is amazing! All the pictures are. And those are your starting out images! Ha! I wish I was at your starting out level!