Advice on astrophotography with new telescope and accessories

[pblackwell]

Hi all,

I've just upgraded to a Celestron SCT 9.25 (f/10) on an AVX mount.

I have an old Cannon Rebel XL camera, a T-Adapter, Corrector/Reducer (f-6.3) and an adapter to use my 2x Barlow.

Can I have some advice as to what I should use for Planetary (Jupiter, Mars and Saturn), Nebulas, Galaxies and also Star Clusters. Also rough exposure times.

I was thinking -

1. For Planetary just try with the camera connected, and also try with the 2x Barlow. Very quick exposure times?

2. Nebulas, try with just the camera, or should I also use the reducer? Exposure lengths of 40 seconds upwards?

3. Galaxies, no idea. Same as with Nebulas?

4. Star Clusters no idea, but I think use the reducer, and no idea of exposure lengths.

Any advice on the above would be really helpful folks.

Many thanks

Paul

 

 

 

[carastro]

Not had any experience with SCTs but the principles are pretty much the same. 

1. The scope should be great for planetary with a Barlow.  Take an AVI video 2mins approx with a planetary dedicated camera and keep the DSLR for DS images.

2. For Nebulae, the Canon will come into its own with the reducer (this will bring the focal ratio down from F10 which is a bit slow).  Depending on your mounts capabilities, anything up to 5min exposures 800 iso will be best.  You might also consider modifying your Canon camera to reveal more Ha.

3. Ditto galaxies.

4. Star clusters, you can do shorter exposures than 2 & 3 as you are not trying to reveal any nebulosity.

I don't know your mount but if it is capable if guiding, you will need that for the long exposures needed for DSOs.

HTH

Carole 

[pblackwell]

Thanks for your reply and valued info Carole. I'm not sure if I can do an avi vid on this camera. It wasn't bought specifically for astrophotography, but rather a big sister hand me down old DSLR with RTFM when I asked her how to use it

The AVX mount should be able to hold the weight of the 9.25 and camera (it can handle an 11" but that pushes it to its limits).

That being said, for planetary 2 mins is too much surely? It would let too much light in and just end up being white? That's kinda what I found with my old newbie telescope when taking pictures last year of Jupiter.

A quick exposure I was able to just about make out the orange bands. A longer exposure it was a white ball but captured the 4 moons.

Cant remeber the timings, that's why I ask. But they were super quick, like less that a few seconds, or less than a second exposure time.....I think.

Make sense?

Paul

[Mick J]

Paul, that make's sense - you are starting and the learning curve is steap.  Canon Rebel XL, that's a 350D in real money.  I don't believe this camera can take video. Planetary imaging is mostly taken using video (later dslr's can but not ideal), used as if it is series of short exposures best of which is stacked on top of each to produce a better image. Software is mostly free/cheap.  You may be able to take lots of short exposures to emulate video.  Or perhaps a webcam or dedicated planetary camera would be better/easier.  We started with a 350D, get your software sorted - windows/mac? or I think you can get a remote timer thingme for the canon.

I have seen results from short exposure deep space imaging, lots of subs but if you can track (not guide) longer is possible and less subs. Don't discount the use of a camera lens in AP, what's big sister got to share?

[carastro]

That's correct, you really need a dedicated planetary webcam for taking videos of the planets, the frames get stacked together to make a cleaner result using dedicated software.  Your 350D won;t be able to do this, but you could take very fast individual exposures of the Moon with the DSLR. 

The DSLR will be able to take up to 5min exposures of Deep sky objects and the only things that will get burnt out with that would be things like the trapezium core on M42, but if you make a start on that target you really need 30sec exposures for the core and 5 minute exposures for the rest of the target, but this is really too complicated for a beginner.

Something like the Rosette Nebula would be a good starter.

Carole 

[pblackwell]

2 hours ago, Mick J said:

Paul, that make's sense - you are starting and the learning curve is steap.  Canon Rebel XL, that's a 350D in real money.  I don't believe this camera can take video. Planetary imaging is mostly taken using video (later dslr's can but not ideal), used as if it is series of short exposures best of which is stacked on top of each to produce a better image. Software is mostly free/cheap.  You may be able to take lots of short exposures to emulate video.  Or perhaps a webcam or dedicated planetary camera would be better/easier.  We started with a 350D, get your software sorted - windows/mac? or I think you can get a remote timer thingme for the canon.

I have seen results from short exposure deep space imaging, lots of subs but if you can track (not guide) longer is possible and less subs. Don't discount the use of a camera lens in AP, what's big sister got to share?

Thanks Mick, yes the old camera definitely doesn’t take video. So for planetary I'll take lots of short exposures and then stack them (never tried stacking before). I will try using 'GIMP' software on my windows machine. That’s meant to be a pretty good freebie I hear?

For now I want to see how I get on with my existing camera along with the accessory bits'n bobs I have. At a later date I'll probably buy a proper astro camera with a guider etc.

Yes you are right this will be a steap learning curve! But I think its going to be one of those ‘try and try again’ scenarios, and getting better with more practice.

I'll send you my first attempts when I eventually get the chance to try take some pictures....the weather has be awful for so long now. I’ve only had the chance to use my new SCT twice in the past few months since getting it! :\

Many thanks

Paul

 

[pblackwell]

5 minutes ago, carastro said:

That's correct, you really need a dedicated planetary webcam for taking videos of the planets, the frames get stacked together to make a cleaner result using dedicated software.  Your 350D won;t be able to do this, but you could take very fast individual exposures of the Moon with the DSLR. 

The DSLR will be able to take up to 5min exposures of Deep sky objects and the only things that will get burnt out with that would be things like the trapezium core on M42, but if you make a start on that target you really need 30sec exposures for the core and 5 minute exposures for the rest of the target, but this is really too complciated for a beginner.

Something like the Rosette Nebula would be a good starter.

Carole 

Thanks Carole

[carastro]

Quote

or planetary I'll take lots of short exposures and then stack them (never tried stacking before)

That will work with the Moon, but it won't work with the planets, they will be too bright on the screen, and too small on a DSLR.

For AVI (video) stacking you can use Registax or Autostakkert. 

Registax will also stack 2 or 3 BMP or tiff files from the DSLR but it won;t take too many at a time.

Carole

[pblackwell]

1 minute ago, carastro said:

That will work with the Moon, but it won't work with the planets, they will be too bright on the screen, and too small on a DSLR.

For AVI (video) stacking you can use Registax or Autostakkert. 

Registax will also stack 2 or 3 BMP or tiff files from the DSLR but it won;t take too many at a time.

Carole

Hmmm ok Carol. I'll start with some Nebula. However I won’t be able to try taking pictures of Rosette or Orion Nebula because of a whooping big tree being in the way by the time it gets dark those targets are right behind it now at that time.

Do you have any other easy target suggestions? The Ring Nebula perhaps?

Paul

 

 

[carastro]

You haven't really chosen a good time of the year for DS imaging as we are coming into galaxy season, and if the stuff in Orion is out of view for you, its a job to know what to suggest.  M57 is not rising until after midnight and it will be quite small anyway. 

Galaxies will be small with a DSLR.

The only decent sized nebula I can think of this time of the year is the Heart and Soul Nebula (In Cassiopiae).  Jellyfish Nebula just at the foot of Gemini if you can get it. 

Otherwise it is galaxies:

M81/M82

Markarian chain is quite nice in a DSLR behind Leo

I would use this time for practice, and by the time the nebulae start coming round again you'll have hopefully got the hang of things.

Carole 

 

[pblackwell]

9 minutes ago, carastro said:

You haven't really chosen a good time of the year for DS imaging as we are coming into galaxy season, and if the stuff in Orion is out of view for you, its a job to know what to suggest.  M57 is not rising until after midnight and it will be quite small anyway. 

Galaxies will be small with a DSLR.

The only decent sized nebula I can think of this time of the year is the Heart and Soul Nebula (In Cassiopiae).  Jellyfish Nebula just at the foot of Gemini if you can get it. 

Otherwise it is galaxies:

M81/M82

Markarian chain is quite nice in a DSLR behind Leo

I would use this time for practice, and by the time the nebulae start coming round again you'll have hopefully got the hang of things.

Carole 

 

Thanks Carole, yes I was thinking about trying a Galaxy. Would I need to use my reducer do you think, or not?

long exposure time I’m guessing?

[carastro]

Well your scope is slow without a reducer, this means it will take ages to capture enough data especially if you're only doing short exposures to start with, so although the reducer will reduce the size of the target, it would be best to use it, and apart from all else you need it to correct the coma.

Yes I would do the Markarian chain it's nicely placed at the moment. Think the main galaxies are M84 & M86.  If you are guiding do 5min exposures at 800iso.  If you're not guiding do as long as you can get away with.

Carole 

[pblackwell]

1 hour ago, carastro said:

Well your scope is slow without a reducer, this means it will take ages to capture enough data especially if you're only doing short exposures to start with, so although the reducer will reduce the size of the target, it would be best to use it, and apart from all else you need it to correct the coma.

Yes I would do the Markarian chain it's nicely placed at the moment. Think the main galaxies are M84 & M86.  If you are guiding do 5min exposures at 800iso.  If you're not guiding do as long as you can get away with.

Carole 

Thanks Carole. Will let you know how I get on.....if there’s a clear sky eventually!

Paul

[Handy_Andy]

Fellow AVX'er here. I've spent the stupid amount of time under cloud writing up a target list for the year and with your sct you could go with M101, it's just off to the west of the plough and fills about 25% of your field of view, with a couple of smaller fuzzies nearby. Also you could do 2 out of the 3 galaxies in the Leo triplet (M65 & M66)

[Cosmic Geoff]

3 hours ago, carastro said:

That's correct, you really need a dedicated planetary webcam for taking videos of the planets, the frames get stacked together to make a cleaner result using dedicated software.  Your 350D won;t be able to do this, but you could take very fast individual exposures of the Moon with the DSLR.

Indeed, it seems that planetary video webcams + stacking software is what people use.  Look in the Astrophotography section of the Forum to see.  Unlike the prices of telescopes, the prices of planetary USB cameras seem to be falling, and you can get a serious one for under £130.   If you don't want to spend that much, I have seen unbranded entry level cameras for as little as £29.99 or even £7.  

[pblackwell]

2 hours ago, Handy_Andy said:

Fellow AVX'er here. I've spent the stupid amount of time under cloud writing up a target list for the year and with your sct you could go with M101, it's just off to the west of the plough and fills about 25% of your field of view, with a couple of smaller fuzzies nearby. Also you could do 2 out of the 3 galaxies in the Leo triplet (M65 & M66)

Hi Handy man, what exposure times do I need for Galaxies, and should I use a reducer, x2 Barlow or nothing?

....that’s if I’m still alive when there are finally clear skies!

many thanks

Paul

[carastro]

Never use a Barlow with long exposure, it will vastly increase your focal ratio making it extremely slow  with your SCT to get much data.

Carole 

[pblackwell]

Thanks Carole. I’ll show you my first efforts

Paul

[Handy_Andy]

I leave my reducer on mine though not yet done much imaging with my sct, just been getting to grips guiding with my ed80. 5 mins is a good figure to go for in my experience for galaxies and nebulae. Any longer and stars tend to be oversaturated.

[alacant]

5 hours ago, pblackwell said:

Would I need to use my reducer do you think, or not?

Hi. Lovely telescope for galaxies:) The reducer will make no difference to the length of time you need to capture the image, just make the field of view wider which is probably not a good idea for galaxies on view at this time of year as they are all very small. Perhaps the main challenge you'll face is guiding at such a long focal length.

HTH, good luck and clear skies.

[pblackwell]

5 hours ago, Handy_Andy said:

I leave my reducer on mine though not yet done much imaging with my sct, just been getting to grips guiding with my ed80. 5 mins is a good figure to go for in my experience for galaxies and nebulae. Any longer and stars tend to be oversaturated.

Thanks buddy

[pblackwell]

5 hours ago, alacant said:

Hi. Lovely telescope for galaxies:) The reducer will make no difference to the length of time you need to capture the image, just make the field of view wider which is probably not a good idea for galaxies on view at this time of year as they are all very small. Perhaps the main challenge you'll face is guiding at such a long focal length.

HTH, good luck and clear skies.

Many thanks. Need those clear skies! Only been able to view through my new telescope 2 times in the past 3/4 months since I got it!...

[carastro]

Quote

The reducer will make no difference to the length of time you need to capture the image

It won't probably make any difference to the length of exposures, but it will make a difference to the amount of data captured as the reducer will make a lower focal ratio and speed up the optics.  With the SCT having a focal ratio on F10 it really needs to have the FR on to reduce the focal ratio, but I agree it will make the target smaller.

M101 is indeed another galaxy that could be done but I have been imaging for some 8 years now and have found it one of the most difficult targets to get decent data on, in fact I haven't manage a decent image of it yet, I think it is rather faint, and maybe not a great choice for a first image. 

Carole 

[alacant]

12 minutes ago, carastro said:

a lower focal ratio and speed up the optics

No, I'm afraid not. The only way the OP could speed up the optics would be to move to a bigger aperture;)

HTH

[pblackwell]

Thanks all. Will let you know how I get on!