Focusing problem with DSLR

[Tums]

STUPID QUESTION ALERT!!!

Hi All, I decided last night to have a quick go and see if I could get some Moon pics with my Canon 1200d through my SW 130 P , I bought a revelation t-ring and adapter 1.25.

So I popped the camera with the t-ring + adapter fitted, it into the EP holder,and tried to focus , but I ran out of inward travel, what do I need to do to be able to focus ???.

Sorry for asking, what's probably a silly question

[steppenwolf]

Not a silly question at all - this crops up all the time. Unfortunately, your 130 P has a very short 'backfocus' making it unsuitable for attaching a camera. You *may* find that using a Barlow lens attached to the DSLR camera via the 'T' piece adaptor may make it possible to achieve focus.

[Tums]

Thanks for that Steve, it was just I wanted to try out the camera really, thought my Scope may cause issues, but I intend to upgrade in the future.

[tingting44]

its certainly not unusable, you will be able to gain focus if you use a x2 barlow, just to experiment for now, yes its not ideal but you "will" be imaging

http://www.firstlightoptics.com/skywatcher-eyepieces/skywatcher-deluxe-2x-barlow.html

here is a great place to pick up bargains! they have a few x2 barlow's for under a tenner

http://www.astroboot.co.uk/AstroBoot

EDIT, in fact the have they SW x2 barlow for £5, id pick it up for sure

[bruno]

This a question  I asked when i first started, the problem is not the focus of the scope it is the sensor on  the canon camera being sat about 40mm inside the camera & i too bought a 2x barlow with a threaded top to attach to a t ring ( you will still use the barlowso buy one anyway) I had to buy an extention piece that fits the t-ring and that will give you enough play to achieve focus.

That said my scope is a refractor, but reading your question it is the same problem i had the extension tube will give you about 50mm of play hope this helps

[tingting44]

This a question  I asked when i first started, the problem is not the focus of the scope it is the sensor on  the canon camera being sat about 40mm inside the camera & i too bought a 2x barlow with a threaded top to attach to a t ring ( you will still use the barlowso buy one anyway) I had to buy an extention piece that fits the t-ring and that will give you enough play to achieve focus.

That said my scope is a refractor, but reading your question it is the same problem i had the extension tube will give you about 50mm of play hope this helps

you wont need any extension tube for imaging with the 130-p and x2 barlow

[Cornelius Varley]

This a question  I asked when i first started, the problem is not the focus of the scope it is the sensor on  the canon camera being sat about 40mm inside the camera & i too bought a 2x barlow with a threaded top to attach to a t ring ( you will still use the barlowso buy one anyway) I had to buy an extention piece that fits the t-ring and that will give you enough play to achieve focus.

That said my scope is a refractor, but reading your question it is the same problem i had the extension tube will give you about 50mm of play hope this helps

The focusing problems associated with reflectors and refractors are completely different. The main problem with reflectors is that you usually can't get the camera close enough to the point of focus without the aid of a barlow lens (the barlow lensmoves the point of focus outwards and within the range of the focuser). With reflectors the problem is that the focuser tube is usually not long enough (I can just reach prime focus with my Meade Apo 80 but need a short extension tube if I add a barlow). 

[Leveye]

To image at prime focus wiith some Newtonians the mirror must be moved to achieve focus if your focuser does not have enough travel. You can test this by removing the focuser and with the empty hole on the scope and a bright moon one night and just hold the camera's body level with it and while using live view slowly move it in and out until focus is achieved. Note how far the camera's body is from the focuser's hole. That is where your focus point is and if your focus tube does not have enough travel most likely the prime mirror needs to come forward some towards the sedondary.

To find the position the prime mirror needs to be at using the focuser you have you can simply put the camera on with the t-ring and adjust the focuser to it's middle travel point and then carefully move the prime forward until it focuses on the moon. Mark this spot for the prime mirrors position and install it there. Keep in mind that to view with an eyepiece now you will have to put the mirror back in it's original position. Another thing you can do is get a better focuser with more travel to it. Some have built in extension tubes just forproblems like this  For that scope though that might cost a bit more than your willing to spend. Best of luck in your starquest.

Look up! -Chris-