Idiots Guide to Imaging?

[Ancient Star]

I was wondering if there was anywhere or anyone who provided a sort of Idiot's Guide to Astrophotography.

I'm talking basic level here, obviously you need your telescope, mount and camera (In my case an EOS 350D), but where does one go from there. Assuming you're using a reflector telescope, how do you attach the camera to the telescope? Do you leave the lens on? What are the best adaptors and where does one find them?

There is plenty of info on guiding, image processing and the like, but nowhere definitively states how exactly you attach a DSLR to a reflector telescope for example. Just thought it might be a useful guide to have, if anyone has the time to write a few words.

[Ant]

Hello,

For the moment I'll assume that you have 2" focuser (which scope have you got?)

You image at "Prime Focus" usually with a dSLR. This means you remove the eyepeice from the focuser and you remove the camera lense from the camera.

Use one of these Adaptors - Max DSLR Camera Adaptor adapters to join the camera to the telescope.

Then it is a case of focusing, the focus point for a dSLR is closer to the fully in position - but some reflector telescopes do have issues with dSLR's.

But you'll not know untill you try.

Let us know what scope you have...

Cheers

Ant

[AlanB]

Hi,

if you have a skywatcher reflector then you might find that if you unscrew the supplied eyepiece holder (as opposed to loosening the lock nuts) and then you can screw in a T-ring adapter which you lock the camera on with.

With mine I find I can leave the T-ring in place and then just remove the eyepiece holder when i want to do some imaging.

HTH

Alan

[Ancient Star]

Until now I've been using a refractor someone gave me years ago, that was easy, but it was small and somewhat pathetic, so I'm in the process of (hopefully) acquiring an SW 150P reflector, and given the entirely different nature of the two, I realised I don't actually have much idea about the differences between the two in terms of affixing a camera.

I take it the adaptor allows for focussing since on the 350D the normal focus is on the lens (which in this case has to be removed)? I'm planning on starting off with some images of the moon to get used to it before I try tracking anything more distant.

[kev 102 42]

what about camera settings for the 350d?............kev

[brendant]

Ancient Star :- one of the common problems encountered in fitting a DSLR to a Newtonian telescope is that you find you cannot reach focus, you usually do not have enough "in" travel on the focuser to reach focus, it is always advisable to try and connect your camera with the minimum of connectors possible. I do not have a Skywatcher Newt but understand that you can connect a T-Mount directly to the focuser. With Prime Focus you basically use your telescope as the lens.

Attached is a pic of how I connect my 400D to my Tal Newtonian telescope, I found I could not reach focus with a standard T-Mount so got an M42 to Canon EF bayonet from eBay and it worked for me, luckily the Tal has an M42 thread.

HTH

Brendan

[Ancient Star]

Hmm, the problem seems to be that the T-mount has a 55m focal length wheras the EOS standard EF lens mount has a 44mm focal length, presumably getting an EOS compatable T2 ring for the T-Mount would also solve the focussing issue?

[adamsp123]

how about getting Steves' book "making every photon count" it is great for beginners

[brendant]

A T-Mount and T2-Mount are basically the same thing, the T2 version was an improvement on the original in that it is a 2 piece unit allowing you to reorientate the camera by means of rotating the unit, it is secured by three small grubscrews, if incorrectly adjusted can allow the camera to fall of the scope. Some see it as an advantage, others see it as a potential problem, both have the same overall width dimension.

There are no electrical connections on the T-Mount, although there are units available for Canon and other makes which contain a chip to enable the center AF focus point to become active and assist in focus confirmation, they work reasonably well in practice.

I am assuming the 55mm referred to is the distance to the focal plane with the T-Mount attached to the camera (44mm being from lens mount flange to CCD focal plane), what matters is where the point of focus is in relation to the focuser / how far it is outside the optical tube, because it is optimised for an eyepiece it is generally not enough to allow the camera focal plane to be positioned correctly as there is insufficient "in" travel, if it is insufficient the common fixes are to fit a low profile focuser or to move the primary mirror up inside the tube by a couple of millimeters, hopefully neither will be required. Best bet is to get a T-Mount and give it a try.

Brendan

[Psychobilly]

IIRC The original use of the t mount was to allow the same "independent" lens to be used on a range of different cameras which had varying "flange" to focal plane distances...using a t adpator which would then give a "standard" flange to focal plane distance of 55mm

Peter...

[Ancient Star]

Ok, I guess I'll have to see what happens, then when it all goes horribly wrong I can come back to this thread and ask for mor confused questions.

[Coco]

I was wondering if there was anywhere or anyone who provided a sort of Idiot's Guide to Astrophotography.

I bet I could write one at the moment

No seriously tho' there seems to be no hard and fast rules, there are so many personal formulas that its best to learn by self experimentation., better still meet an astro buddy whos already imaging.

Ive only been imaging 6 months and the Astrotrac / DSLR has given me the most confidence.

Guy...

[Psychobilly]

Ok, I guess I'll have to see what happens, then when it all goes horribly wrong I can come back to this thread and ask for mor confused questions.

Yep or start a new one - Just ask away... dont worry how daft it may seem or spend ages searching the forum... if its been discussed in detail before someone will point you in the right direction...