focus..???

aaronkmk (Aaron) · #1 27-05-2014, 04:39 PM

Hey all just got my t ring. in the mail along with a 2xbarlow t adapter...
I took the star diagonal out of my celestron c8. And put the adapter into the back of my scope..expecting to see some trees as I tested it in daylight I was shocked to see nothing at all but a blur.. not a blurry tree just blur like I had my scope pointed at a wall or something...
Am I missing something here how can I focus..was hoping to do my first bit of photography tonight...:shrug

traveller (Bo) · #2 27-05-2014, 04:46 PM

Hi Aaron, you need an extension tube. When you took out the diagonal, you have reduced the overall focal distance between the mirror and the imaging chip on your camera.
An extension tube will make up that difference.
Bo

aaronkmk (Aaron) · #3 27-05-2014, 04:58 PM

Okay bugger thanks bo if I use the diagonal will this help

Amaranthus (Barry) · #4 27-05-2014, 05:05 PM

Depending on how far away the trees are, their focus could be a long way from infinity. I assume you tried refocusing your C8?

I use a T-adaptor on my C8, and have no problem focussing by DSLR at prime focus, with no need for an extension tube.

traveller (Bo) · #5 27-05-2014, 05:06 PM

Yes, attaching the camera onto the diagonal will/should allow you to focus. Two major disadvantages: added weight to the scope (you can overcome this by balancing the scope with everything attached before hand). Also, hard to see/control the camera with the position, again, you can overcome this by running a USB to the laptop and control the camera via the laptop.
Bo

aaronkmk (Aaron) · #6 27-05-2014, 05:11 PM

Ok cool just tried with the diagonal can focus no worries..
Barry the trees are probably 1 or 2 ks away

mithrandir (Andrew) · #7 27-05-2014, 06:55 PM

Aaron, there is a lot of focus travel available on an SCT. Have you run the focuser all the way in and out without the diagonal to see if it will come good? It works for me with my C8 and CCD or DSLR, however I do have a Moonlite Crayford that acts as an extension tube.

Amaranthus (Barry) · #8 27-05-2014, 07:07 PM

Yep, I agree Andrew, and that is what I was trying to say. Just by racking in or out my stock focusser on my C8, I can achieve focus with my DSLR or imager with just about every combination you can think of, including with various barlows, tele-extenders (for eyepiece projection), direct t-adapator connection, afocal - the works. You should have no issues. Just be patient as you search, and start with something bright like the Moon or Jupiter.

aaronkmk (Aaron) · #9 27-05-2014, 07:18 PM

Hey Andrew no I Havnt tried that the the clouds have just rolled in.and I'm off to work for the week tomorrow so it's gonna have to wait till Monday.. I tried to get a few shots of some stars with 30 sec exposure and high iso but nothing showed up..

Can u point me to somewhere that has a step by step method..

I have a cg5 eq mount with goto for guiding. but can't quit get the polar alignment correct ..
Is it possible to take some photos of something without tracking just to see how it goes