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What should I buy to start imaging with a Celestron 8SE with wedge


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Hi all

I appreciate this isn't really an imaging suitable setup but I have the wedge fitted and would dearly love to get a few images of a galaxy.

I do have the Celestron solar system 10Meg camera but haven't had much success with it so far, I have had a year out and am just starting up again.

What would I need to get a colour picture of say the Andromeda galaxy?

I am partially colour blind and the colourful images I see on this forum look great to me, although obviously are not the same as you see.

Should I look at a SLR astro modified or a dedicated astronomy camera?

I would like the lowest cost to start with.

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For the lowest cost, a terrestrial (unmodified) DSLR or mirrorless will do just fine. Astro modding removes the IR-cut filter, which along with infrared also takes out the very deep red in the visible spectrum; the trouble is that the single commonest visible-light emission wavelength lives down there, hydrogen alpha or "Ha" at 656 nanometers.

Folks astro-mod cameras in order to collect Ha light, but that's primarily of interest from emission nebulae (Horsehead, North America, Seagull, Heart e.g.). For galaxies, an unmodded camera does just fine. So if you have a DSLR or interchangeable-lens compact camera, you've got what you need already. If not, an old Nikon, Canon, or Pentax body would do you well and needn't cost a mint. Dedicated astro cameras suitable for learning deep sky start at about US$1000. You can go cheaper, but there will be compromises that will irritate you, later if not right away. (Although there's always the used market there too. Astrophotographers tend to baby their kit so used gear is USUALLY safe.)

Best way to save money in deep sky is to buy and read one of the primers. I fancy Bracken's The Deep Sky Imaging Primer, Richards' Making Every Photon Count is also highly thought of. 

The 8SE would also be a pretty nice planetary rig, and astro cameras for that go for a lot less. Tiny sensor? No problem. Cooling? Feh! Get yourself one of those -- even the humble US$150 ASI 120MC-S will do -- and you can start messing around with FireCapture and AutoStakkert.

One advantage to terrestrial cameras is that you can use them without any external equipment -- their built-in intervalometer will do to start, or you can pick up a cheapo that will do even better. All the astro cameras require a computer at the telescope.

Welcome, and enjoy the journey!

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Oh, and once you have an idea of what camera you might use, truck on over to Telescopius.com -- or download Stellarium -- and play around with previsualizing various targets. The canonical beginner galaxy is Andromeda, which is a real Zen challenge. Anyone can image it, but doing it well is a never-ending journey. Anyway that one is huge, about 3 degrees IIRC, so it'll be hard to capture with an 8SE. But the universe does have a couple more :-).

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Have you got the F6.3 reducer yet? It's essential with an SCT, in its native focal length without the reducer it's only suitable for solar system objects.

Due to the long focal length you might also need to autoguide so will need likely an off axis guider, which will also require a guide camera and computer control.

Edited by Elp
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18 hours ago, Trevor Matthews said:

What would I need to get a colour picture of say the Andromeda galaxy?

8se? Our only -not too good- experience was with a ~20 year old orange tube model on an eq6. Maybe your model is more recent? Anyway...

Bearing in mind it's not going to be easy, two ideas of many...

  • If it has to be Andromeda, one of these and one of these would do it in around an hour or so.
  • Or you could choose smaller galaxies and attach one of these to the telescope via one of these

Good luck and HTH

pan_01.png.4af3e17da70815f0891862fa2985030a.png   pan_02.png.f33b86e7fe6632390fa5149c7d947104.png   pan_03.png.b6ec3ad5924b06ce49d2340be561185a.png   pan_04.png.3a76bb8d7c47200031edaa0931fba63c.png

Edited by alacant
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As some people have insinuated, imaging with an SCT isn't easy, mainly due to the long focal length and the weight. I've seen on other discussions (Celestron wedge?) also isn't ideal with the standard goto mount, you need a better EQ mount to suit.

If you've got the experience and associated supporting equipment imaging with an SCT is no more difficult than any other type of scope, if anything backspacing requirement is much easier to sort than on a refractor, but as with anything astrophotography related, it's not usually cheap.

If you want to image Andromeda it is quite easy with a DSLR and fairly decent lens around 100mm+, you can capture it within 10-30 seconds typically but you'll have to take a lot of images and stack to get the signal, having the camera on an EQ mount will help further. Some decently priced options are an Omegon LX, Skywatcher Star Adventurer or the ioptron equivalent, or an azgti in EQ mode, or you could DIY your own barn door tracker.

Smaller galaxies you really need a long focal length scope like yours but without increasing your budget to buy the extra necessary equipment it's a bit difficult.

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15 hours ago, Trevor Matthews said:

What would I need to get a colour picture of say the Andromeda galaxy?

You could make a start with an uncooled astro camera if you are not too fussed about widefield images. Several of the cameras with smaller sensors cost less than a DSLR. I started with an ASI224MC and these days you get better versions.

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For Andromeda, a 2nd hand unmodified camera would be a good place to start, doesn't need to be an SLR. You can sell it on when you're ready to upgrade and it won't cost you much at all (that's true for almost all 2nd hand astro gear if you look after it)

You don't even need to use the wedge for short exposures, Andromeda is bright, the key thing you want is to widen your field of view, so a planetary cam isn't going to work. The reducer will help. Just watch out for the camera crashing into the mount.

If you have any results from your last attempt, you can share them here and people will give you pointers on the processing as well.

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Getting colour into an astro image is also tricky - the surface brightness of most extended objects is pretty low, and everything tends to come out as shades of grey. 

Usually colour images are produced by putting filters in the way, and then balancing the colours in the image as it's processed. 

With your scope set up, you might find it more rewarding (at this time of year) to try and image the Orion Nebula. You may even get some colour out of it. If that goes well, try the Flame Nebula (also in Orion, next to Alnitak - the leftmost star in Orion's belt)   - by coincidence, that's the avatar for SamAndrew whose post is just above this one.

Edited by Gfamily
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Wow, thanks for all the replies. A lot to read through and things to check out.

I do have the focal reducer.

I am also more comfortable with a DSLR so might go with that option to start with.

I am already on thin ice with she who must be obeyed, I haven't mentioned my new Starsense Auto align yet...

 

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If you already have a dSLR, then that's a good option - particularly if it's a Canon with live-view and moreso if it has a flip out screen.

If you don't, it might be worth considering a mirrorless camera as they are significantly lighter (my Sony A5000 body is about  1/3 the weight of my Pentax K5 body). 

NB I'm not specifically recommending the A5000, as it has specific problems with its algorithms; but it was only £100 second hand, and it's now my walk-around camera because it's at least as good at photos as I am.  

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Unless you have a specific requirement for a DSLR and the price of uncooled astro cameras, you may be better off with the latter. You just need a laptop/computer for the camera to connect to which I assume you do, most astro control software on pc is free.

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Problem with a high focal length scope even with the reducer is your fov, m31 is hugel.... Even with a fairly large sensor you will need at least a 4 pane mosaic to fit it in, maybe more.. 

M81 bodes is far smaller and frames up far better but that's only half the story... The rest is up to the equipment, but depends on the level of image that you're looking to achieve..

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