How would i take pictures through this scope (Celestron C6-N)

[Vladimer]

Hey everyone,

So with all the pictures of all these amazing shots it got me and my girlfriend rather intrigued. We dont have a tracking mount nor the cash to get one at the moment so were not striving much further then the moon at this time.

I got her a Celestron C6-N for her over a year ago
http://www.celestron.com/c3/product.php?ProdID=41

Now i've been reading lots of threads in this section and seem to find lots of info but some of its just confusing and some i cant seem to connect the dots with as to how it would work here.

What i figured (hypothetically in my head) was that i could line up the telescope with the moon and then remove the viewfinder or something and attach the camera?

Now what i imagine and what I've read too is that how would i even focus the camera to the mirrors inside, or even how would i line up the lens to the viewfinder hole to actually take the picture of it. I saw some adapter looking plates that attach the lens to the viewfinder but not sure if thats what i should be looking for in this case.

Im using a EOS 500D with a Tamron 17-50mm and got a Canon 55-250mm f/4-5.6 as well. Is there any guidance you guys can provide for us in this manner? I know the telescope itself is not amazing by any degree and as i mentioned at the beginning were not aiming to far to start, just ideas to get try this aspect out.

As a final note im recovering from a bad cold and my minds rather all over the place so i hope i got the question across alright and everything made some sense

Thanks!

[Adrena1in]

Hi Vladimer, welcome to the Astronomy forums.

There are essentially two items you need in order to attach a camera directly to a telescope to take prime focus images. A T-Ring, which is specific to your camera, and a T-Adapter that's the same size as the focuser on the telescope, which will be either 1.25" or 2" generally. These are cheap items and will have your camera connected up in seconds.

However, the Celestron C6-N is a Newtonian Reflector, and they're known for having a short back-focus. The focal point of the primary mirror, (at the back of the telescope tube), is generally only about 1 or 2 cms out of the focus tube. You need more like 5 cms+ of back focus in order to achieve focus with a DSLR. It's possible to move the primary mirror up the telescope tube, or purchase a very low-profile focuser, or maybe even use a Barlow Lens to extend the focal length, but for Prime Photography you might be looking at an additional expense over and above the T-Ring and T-Adapter. So be warned. (I started with a SkyWatcher Newtonian, and it was lovely for viewing, but I wasn't able to take photos through it.

Other options you could try are A-Focal imaging or Eyepiece-Projection Imaging. The former involves putting an eyepiece in the telescope, and then pointing your camera, with lens, through the eyepiece. This is quite tricky, but many people have got good results. The latter involves using a T-Adapter that allows you to put a lens inside it, often called Variable T-Adapters, or something like that. But I've no expierience of using this method with a Newtonian, and when I have used it with other telescopes the results were usually a bit naff as far as I'm concerned.

Does that help at all?

[A.S.I.G.N. Observatory]

Here's what I wrote on optical trains to explain it with pictures.

http://www.asignobservatory.com/index.php?option=com_content&view=article&id=76&Itemid=115

My celestron is a Schmidt Cassegrain and yours is a newtonian. i,e. mine has the eyepiece at the back and yours has it in the side.

Take your lens off your camera and fit a t-ring adaptor in it's place.

Pull the eyepiece out of the telescope and slide your camera with it's new adaptor in. Done.

Baz.

[DonR]

Hi Vladimer,

As Adrena1in said, some newtonians have a lack of in-focus that prevents prime focus photography. However, Celestron's product page (http://www.celestron.com/c3/product.php?ProdID=41) for that telescope includes a collection of astrophotos allegedly made with C6-N's, indicating there isn't a problem with in-focus.

Fortunately, it won't cost much to find out. A t-ring for a Canon DSLR is about $20, available through any astronomy dealer, most online photography deakers, and many local camera shops. The t-adapter is also inexpensive, but not quite as easy to find. For the C6-N you need a 1.25" t-adapter, and most t-adapters for newtonians are 2" (because most newtonians have 2" focusers). Celestron sells a 1.25" t-adapter, which you can see here (http://www.amazon.com/Celestron-93625-Universal-1-25-inch-T-Adapter/dp/B0000665V6).

Don

[chris.bailey]

Celestrons FAQ's for imaging does contain the following "With Newtonians, the only two possible fixes are to move the mirror and its cell up in the tube and/or get a low-profile eyepiece focuser" which suggests that off the shelf their Newts dont have the required back focus. As Don says though it is inexpensive to find out though the fix if it wont focus is a little more tricky.

[DonR]

I knew I had run into this question, and an affirmative answer, before. Here's a post on CloudyNights from a C6-N owner that indicates it will reach focus with a Canon DSLR, without any surgery:

http://www.cloudynights.com/ubbthreads/showflat.php?Cat=&Board=telescopes&Number=2413932

The secret is removing the 1.25" eyepiece holder and replacing it with a t-ring. In this configuration no t-adapter is needed, because the focuser drawtube is threaded (once you remove the eyepiece holder) for a t-ring. My 8" Orion newtonian is configured the same way.

Celestron's article fails to mention another, easier solution to the in-focus problem. A low profile focuser often solves that problem for newtonians. Also, a newtonian that won't accomodate DSLR's at prime focus will sometimes work with a CCD imager, since they usually require much less in-focus. I have a Meade DSI that is close to being too short to reach focus on my newtonian.

Using a barlow lens in the t-adapter will often solve the problem as well, although it somewhat defeats the purpose of using a fast newtonian.

[Vladimer]

Thank-you for all the information guys, thats alot of help and questions answered

Hi Vladimer, welcome to the Astronomy forums.

There are essentially two items you need in order to attach a camera directly to a telescope to take prime focus images. A T-Ring, which is specific to your camera, and a T-Adapter that's the same size as the focuser on the telescope, which will be either 1.25" or 2" generally. These are cheap items and will have your camera connected up in seconds .....


Thanks that really cemented at least the items i am suppose to get. Got my mind thinking of how to get around the focusing issue but after reading all the other posts i realized my ideas were totally off



Here's what I wrote on optical trains to explain it with pictures.

http://www.asignobservatory.com/index.php?option=com_content&view=article&id=76&Itemid=115

My celestron is a Schmidt Cassegrain and yours is a newtonian. i,e. mine has the eyepiece at the back and yours has it in the side.

Take your lens off your camera and fit a t-ring adaptor in it's place.

Pull the eyepiece out of the telescope and slide your camera with it's new adaptor in. Done.

Baz.

Thanks for the link, its great to find actual pictures that have descriptions of whats going on.

I knew I had run into this question, and an affirmative answer, before. Here's a post on CloudyNights from a C6-N owner that indicates it will reach focus with a Canon DSLR, without any surgery:

http://www.cloudynights.com/ubbthreads/showflat.php?Cat=&Board=telescopes&Number=2413932

The secret is removing the 1.25" eyepiece holder and replacing it with a t-ring. In this configuration no t-adapter is needed, because the focuser drawtube is threaded (once you remove the eyepiece holder) for a t-ring. My 8" Orion newtonian is configured the same way.

Celestron's article fails to mention another, easier solution to the in-focus problem. A low profile focuser often solves that problem for newtonians. Also, a newtonian that won't accomodate DSLR's at prime focus will sometimes work with a CCD imager, since they usually require much less in-focus. I have a Meade DSI that is close to being too short to reach focus on my newtonian.

Using a barlow lens in the t-adapter will often solve the problem as well, although it somewhat defeats the purpose of using a fast newtonian.

Thats a great link! thanks, it definitively gives me another option to try before trying to figure out how i could possible go around to change the 'in focus' on the scope if it all doesn't work out but he really seems to be on something solid.

[Vladimer]

Alright so i managed to pick up a T-ring and went with the suggestion that was in the link DonR posted which also saved me a couple bucks buying a t-adapter :)

Now in order for me to be sure that it focuses correctly is there any specific distance that it has to be able to reach clearly that i know it will be ok? Because currently its snowing and theres no clearing of cloud cover for awhile so i aimed my scope a few blocks down at a roof top and with the DSLR attached i could get perfect focus through the view finder. So does that mean if i take it all out and point it at the moon i should be able to see it in focus? or can this short back focus problem still come up

[SteveInNZ]

If you still had focus adjustment left, you should be OK. There's not much left to do but try it.

Steve.

[Adrena1in]

I'd say if you can go from focusing on something close, to focusing on houses down the street, and then still have some travel, you should be fine.