Advice on where I'm going wrong.

[Slim]

I'll start by saying I'm very new to this and have an awful lot to learn. I set about imaging only my second DSO last night. M51 was the target of choice and the equipment I used is in my sig. I captured in Sharpcap and got what I thought was a pretty decent image well focused using a Bhatinov mask on Alkaid. Exposure time was 30 seconds, I took 30 exposures and 10 darks.

However, when I came to process in DSS I could only get it to stack 2 frames due to a lack of stars. Below is a typical exposure, could you have a look and suggest what I might be doing wrong. Is my exposure not long enough or gain too low? I followed a tutorial on the use of DSS I found on Astronomy shed so understand changing the threshold to use 12 stars in this case. Any advice would be greatly appreciated.

[Quatermass]

My advice would be ditch the webcam for targets like this and keep it for planets. Get yourself a second hand Canon 350d and start using that with your set up you have a great telescope and fantastic mount so with an slr camera you can get some fantastic images. Deep sky object like this one would come out much better with a camera I feel although I have seen good images done with webcams a canon 350d would be better and a second hand body only on ebay is pretty cheap. I have a set of standard setting for deep sky stacker on my blog. Hope that helps a bit QM

[Slim]

Thanks QM. I had a feeling that would be the advice

Another question. Is it essential to get the DSLR modded? Money is fairly tight at the moment and modding the camera seems to add another £200 to the cost.

[rfdesigner]

You can try IRIS. Iris software

There are a whole suite of alignment tools. I've been able to align images like yours (like my M51 next to my name) for which the individual subs were much like yours

Best to download the software, and the commands list. Whilst you can drive it through menu items it's the command line where IRIS really wins. (accessible through the

>=

>=

button)

My gut feel is that preregister would best be used first, then maybe coregister2. preregister will not try and move an image by a fraction of a pixel nor will it rotate it, so it's quick and get's everything close. Then you can run coregister2 to get things bang on.

Then you can stack with composit2 which is a nice sigma clipping routine. (many commands come in x, x2, x3 versions for dealing with either just the file you're looking at or various lists of files)

I've tried Registax but I don't like it as I don't feel I get the control I can get with IRIS, others like Registax as they can get a long way in a short time.. I think it's just horses for courses.

The only issue I've had with IRIS is the file names, which must be in the name1, name2 ... name10, name11 etc. format. I did find a nice little utility called filerenamer which worked very well to get things aligned.

Derek

[Dave]

Although you can see a hint of a spiral arm there, the field of view of the webcam is extremely small. You are therefore looking at a tiny pary of the sky, so the chip is collecting only a small amount of light, making the image very dark. Did you use the 2x Barlow as well? That would make the field of view even smaller and knock the brightness down again. Go for a wider field of view and you should hopefully see an improvement. I second that comment that webcams are better for bright planets and a DSLR would be much better for deep sky objects.

Dave

[Slim]

Although you can see a hint of a spiral arm there, the field of view of the webcam is extremely small. You are therefore looking at a tiny pary of the sky, so the chip is collecting only a small amount of light, making the image very dark. Did you use the 2x Barlow as well? That would make the field of view even smaller and knock the brightness down again. Go for a wider field of view and you should hopefully see an improvement. I second that comment that webcams are better for bright planets and a DSLR would be much better for deep sky objects.

Dave

Yeah the field of view is very small and that's without a Barlow! I know that a DSLR is going to be better but I was trying to do it on a budget. Oh well, we live and learn.

@rfdesigner Thanks will have a look at that tonight.

[terrym2002uk]

Besides what others have also said re the DSLR path, 15 minutes of exposure for M51 is not really enough. You need to be looking at 2-3 hours to see a good level of detail.

[Slim]

Besides what others have also said re the DSLR path, 15 minutes of exposure for M51 is not really enough. You need to be looking at 2-3 hours to see a good level of detail.

Thanks for that. How do you find the unmodded DSLR? Does it limit you at all?

[garethmob]

i actually took a nice photo (well im pleased with it ) of m51

it was with a 135mm camera lens with a unmodded dslr (this is the image after stacking with no other processing

i vagely remember it was about 10 images stacked each one 1 minuit long maybe 1.30 for really really fantastic images hour and hrs of data, but you can get that detail fairly quickly, the main thing is the mount thats key to everything

[terrym2002uk]

Thanks for that. How do you find the unmodded DSLR? Does it limit you at all?

To be honest I brought the DSLR for my wife So modding is not really an option at the moment. But If you look around there are plenty of great images out there that have been done with unmodded cameras. A modded DSLR will be more sensitive across the spectrum though, and show more detail.

I've been doing a bit of imaging for the last year and although in essence its straight forward, there are a lot of hurdles to get over, like good polar alignment, guiding, general kit issues (you know why are my stars like eggs in space and all that), processing techniques, etc. And with the few decent nights we get, it tends to take a while to work through them.

More importantly you need to learn to be consistent. So at the moment, until i get to the point where I am resaonable happy with my method and results , I cant see the point in shelling out modding a DSLR, or going on to CCD with a filterwheel. The later is just a complication I don't need at the moment if you know what I mean.

And besides, its meant to be fun, so take your time and enjoy it. The universe isn't going anywhere soon

My last effort from last night (M51) is on my flickr page. and that is the longest I've taken. Just wish I stayed up to do the flats.

[tony]

modding is not essential slim but will give better results.

i recently bought a canon 1100d and i'm really happy with the results i'm getting from it, but its not modded although by this time next year it maybe:D

have a look around at what results others are getting, you'll be surprised. i too had spc webcam but that now is going to be used to make finderguider so dont ditch it completely.

oh and qm's blog is a must read too.

couple of pics from my 1100d unmodded

both are 40 x 90sec subs at iso 800.

[RogerTheDodger]

Until you get a DSLR persevere, get your polar alignment as good as you can - I took this with an LX modded SPC webcam, 30 x 100sec images. The arrow is pointing at last year's supernova (SN2011dh)

[Slim]

To be honest I brought the DSLR for my wife So modding is not really an option at the moment. But If you look around there are plenty of great images out there that have been done with unmodded cameras. A modded DSLR will be more sensitive across the spectrum though, and show more detail.

I've been doing a bit of imaging for the last year and although in essence its straight forward, there are a lot of hurdles to get over, like good polar alignment, guiding, general kit issues (you know why are my stars like eggs in space and all that), processing techniques, etc. And with the few decent nights we get, it tends to take a while to work through them.

More importantly you need to learn to be consistent. So at the moment, until i get to the point where I am resaonable happy with my method and results , I cant see the point in shelling out modding a DSLR, or going on to CCD with a filterwheel. The later is just a complication I don't need at the moment if you know what I mean.

And besides, its meant to be fun, so take your time and enjoy it. The universe isn't going anywhere soon

My last effort from last night (M51) is on my flickr page. and that is the longest I've taken. Just wish I stayed up to do the flats.

Your M51 looks great. And thanks for the tips, I've got my eye on a few DSLR's on eBay, and maybe I'll get one modded in the future. One other question, I see you've got a 200PDS. Is that the scope you image with? If so did you run into any focuser inward travel problems? I've got a 250PDS and have read elsewhere that it might be a problem. I know the PDS is more suited to prime focus photography but can you put my mind at rest?

modding is not essential slim but will give better results.

i recently bought a canon 1100d and i'm really happy with the results i'm getting from it, but its not modded although by this time next year it maybe:D

have a look around at what results others are getting, you'll be surprised. i too had spc webcam but that now is going to be used to make finderguider so dont ditch it completely.

oh and qm's blog is a must read too.

couple of pics from my 1100d unmodded

both are 40 x 90sec subs at iso

Nice images tony and thanks for the info. Had a look at QM's blog earlier and it looks like essential reading.

Until you get a DSLR persevere, get your polar alignment as good as you can - I took this with an LX modded SPC webcam, 30 x 100sec images. The arrow is pointing at last year's supernova (SN2011dh)

Thats a great shot and very nice to get the supernova, well done Roger. Looks like I just need to up the exposure time to get enough data. I'll have a good look at the link in your sig thanks.

[terrym2002uk]

One other question, I see you've got a 200PDS. Is that the scope you image with? If so did you run into any focuser inward travel problems? I've got a 250PDS and have read elsewhere that it might be a problem. I know the PDS is more suited to prime focus photography but can you put my mind at rest?

Yes I image with my 200PDS.

I use a bader MPCC (coma corrector) which screws in to the EOS T-Ring. This gives me a bit of extra back focus, so focusing is not an issue in this case.

I once tried my x5 TV powermate screwed in to the T adapter, but could not reach focus. Don't know if I would have a similar problem with just a plain old 2" adapter.

btw, if you take the top ring of the focuser tube there is a T-thread which you can screw directly into the camera. From memory this is fine for reaching focus. The down side is there is no where to screw a LP filter in.

(as i said lts a learning experience and these things do come to try us)

[lukebl]

Re: modding a DSLR. Don't get too hung up about getting a modded cam. You can get fabulous results with an unmodded camera, and DSOs like galaxies aren't really improved with a modded cam anyway. Modding improves captures of emission nebulae, but even those can still be captured with an unmodified camera. Like this Rosette nebula:

Stargazers Lounge - lukebl's Album: Luke's DSOs - Picture

[RikM]

All of my deep sky images have been taken with an unmodded DSLR.

[Spikey]

All of my deep sky images have been taken with an unmodded DSLR.

Ditto that, although I have modded my 1000D its yet to have it's first light and my few images were mainly taken with an un-modded Canon 1000D.

I only modded mine to make it more sensitive to Ha and that was for targets such as the Rosette and the veil nebula.

You have the kit capable of some class images in your sig, pick up a cheap DSLR for £100-200 and see how you get on.

[Slim]

Yes I image with my 200PDS.

I use a bader MPCC (coma corrector) which screws in to the EOS T-Ring. This gives me a bit of extra back focus, so focusing is not an issue in this case.

I once tried my x5 TV powermate screwed in to the T adapter, but could not reach focus. Don't know if I would have a similar problem with just a plain old 2" adapter.

btw, if you take the top ring of the focuser tube there is a T-thread which you can screw directly into the camera. From memory this is fine for reaching focus. The down side is there is no where to screw a LP filter in.

(as i said lts a learning experience and these things do come to try us)

Thanks Terry. I realised I had a lot to learn when I first bought a scope a year ago. And when I'd learned that I realised I had a whole lot more to learn!

Re: modding a DSLR. Don't get too hung up about getting a modded cam. You can get fabulous results with an unmodded camera, and DSOs like galaxies aren't really improved with a modded cam anyway. Modding improves captures of emission nebulae, but even those can still be captured with an unmodified camera. Like this Rosette nebula:

Stargazers Lounge - lukebl's Album: Luke's DSOs - Picture

That's a great shot Luke, thanks for the encouragment.

All of my deep sky images have been taken with an unmodded DSLR.

Seems my fears of using an unmodded camera are pretty much unfounded, thanks a lot Rik.

Ditto that, although I have modded my 1000D its yet to have it's first light and my few images were mainly taken with an un-modded Canon 1000D.

I only modded mine to make it more sensitive to Ha and that was for targets such as the Rosette and the veil nebula.

You have the kit capable of some class images in your sig, pick up a cheap DSLR for £100-200 and see how you get on.

Thanks Spikey, I'm watching a few cameras on ebay as we speak.