Newbie question here!

[tagz123 (Matthew)]

Hey all, first poster here!

I have a few questions to ask in regards to Amateur Astrophotograhy. I have done a bit of research on this but just can't seem to find the right answer.

I have recently purchased my first telescope - a 10" Dobsonian Skywatcher, which came with the super wide 25mm & 10mm lenses. I also brought another lens (5mm) to get some further magnified planetary views and have had some great nights out the past month; but now would like to begin taking my first photos of the wonders out there!

I currently have a DLSR camera to use/borrow from my brother.. I understand that with my Dobsonian I need some sort of T-ring(?) that is suitable for the camera model.

Now ready for the noob question (possibly of the year):
Do you attach lenses to this? I see on some youtube videos that the DLSR camera is attached straight onto the scope without any lenses in between. Does this mean that you can't get close views of saturn (such as through my 5mm lens) with a T-ring attachment? Do I have to manually hold the camera up to the lens to get these magnified views or is there some other method for beginner astrophotography? Maybe DSLR cameras aren't the right way to start off with?

From what I have seen - the camera lens is taken off to attach the T-ring, hense why I assume you need to use to the Dobsonian lenses.. So can the T-ring be attached to the end of the camera lens to magnify the image?

Hopefully you can tell by the jumble above that my brain is currently struggling to comprehend this (probably simple) question.
Any advice would be greatly appreciated!

Thanks!

[omegacrux (David)]

Hi Matthew
Yup remove the lens and attach the t-ring
Remove the ep holders and screw the ring to your scope , this effectively turns the scope into a 1200mm lens .
Some cameras have trouble finding focus , with solid tube dobs
And you will probably need something like a 4x powermate otherwise you have to heavily crop the pic

David

[nebulosity. (Jo)]

Think of the telescope as a giant lens that you attach your camera to, so no you don't need an extra lens just telescope → camera. (they call this type of imaging 'prime focus')

Or, like you said, you can hold the camera (with lens attached) up to the eyepiece and take happy snaps of the moon ect. (known as eyepiece projection)

I have never done imaging with a dob before so can help huge amounts but I'm sure lots of people will chime in.

by the way, Welcome to IIS you have surely come to the right place.

Jo

[Screwdriverone (Chris)]

Hi Matthew,

Firstly, to Ice In Space. Great to have you on board and with such a good scope to begin with.

Assuming that you have a solid tube dobsonian with no goto or tracking motors (push-to) then you will find that keeping on target with a camera attached is pretty hard. You need to nudge-nudge-nudge to keep it on the planet and this normally requires you to look through the finder to keep it in the crosshairs.

Now, with a T Ring, you can normally undo the 1.25" eyepiece adaptor barrel and leave the adaptor in the focuser and there should be a little flange with the right thread on it so you can screw the T ring on to it.

Assuming you can do this, you will then need to activate live view, if your camera has it and then use, say the moon to try and focus. Most dobsonians with DSLR (and newtonian reflectors as well) dont have low enough profile focusers to reach focus, especially with the aforementioned adaptor in, however, you may be lucky.

For the moon, target it with the finderscope and then adjust the focus while watching on the live view until you think you have it in focus, then click a 1/4000th image at ISO100 and see if it is any good. Adjust with shutter speed and ISO until you can see the moon and fiddle with the focus and see how you go.

You WON'T need an eyepiece in the focuser, effectively the telescope becomes your new "lens".

Now with planets, as they are soooo tiny with respect to the moon, you will find that a manual dobsonian is almost impossible to line up and keep centred and therefore MUCH harder to take photos of them like this.

I used to use a powermate barlow (5x) magnifier and my Philips Toucam webcam to take video of the planet sliding past the field of view (after I had focus right) and then stack the video subframes (30 secs x 30 frames per second = 900 frames) into registax and then get some half decent planetary images from my 12" push-to dob. BUT IT WAS HARD! and frustrating......

For any decent and easy astro photos, you COULD get an iPhone holder (Orion makes them) to sit your smart phone in front of the eyepiece in place of your eye (the adaptor clamps on to the eyepiece) and take some happy snaps of the object. This is a quick and cheapish way to snap what you have already focused in the eyepiece if you think that may be a better way and easy way to get started.

It's hard without a tracking mount, so good luck with your endeavours, which ever way you choose.

Cheers

Chris

[Marios (Marios)]

Hi Matthew

To attach the DSLR you will need a T ring and a camera adapter. You will slot this into your telescopes 2 inch focuser. This configuration is called having your camera at prime focus.

No you wont need a lens for astro photography, if you do want to image planets you will need a Barlow or a power mate. These attachments magnify the object in the view by a factor of 2 x 3x 5x.

Thought for planetary photography small webcams are preferred choice as the video can be broken down to hundreds or thousands of frames which are then sorted out and stacked for a final image.

[raymo]

Skywatcher collapsible dobs come to focus just fine using the method
described by Chris; [I don't know about the solid tube models, but can't see why they should be different].
The T-ring cannot be fitted on the end of the camera lens. If you want to
increase the magnification, you can get an adaptor that fits between the
T-ring and the focuser, that you can insert an eyepiece into, enabling you to employ what is known as eyepiece projection, although, as Chris has
also mentioned, without tracking ability, it's highly impractical.
Yes, attaching the camera body directly to the scope[prime focus
photography] does mean that you get small images of the planets; the
longer the focal length of your scope, the larger the image.
raymo