No stars...

[sletts02]

I went out to Kingaroy this weekend to give my telescope a whirl and had some problems. Excuse my lack of technical knowledge, it was my first time out with a telescope ever.

I have a 12" newtonian reflector and wanted to do some astrophotography. When using an eyepiece (25mm) I could see stars and focus - great. However, when I tried using my DSLR 550D all I got was black (I tried varying ISO's, exp times etc with no avail).

I went T-Ring > Projection Tube > Telescope

What am I missing here? :/ Thanks for your help! I'm still very, very much learning.

[Stu Ward]

My advice would be to concentrate on visual first.
If you've never used a scope before, jumping headfirst into AP is a surefire way of fastracking your scope appearing in the classifieds.
Sorry to sound negative, but AP is a struggle for experienced astronomers with a few years under their belts.
Learn and enjoy the skies first, if you really hunger for imaging, Saturn is up at the moment and is a much easier target.
You have a dslr, why not drop it on a tripod and try some widefield shots of the milky way


Stu

[bartman (Bart)]

What exposure times and iso are you using Sletts?
Using a dslr on a newt can have some focus issues ( ie not being able to focus).
Try targeting a bright star first and use live view(if your camera supports it) try and focus and zoom in a bit. If you can see the star in the LCD panel, then you should you be able to take shots.

Bartman

[sletts02]

Originally Posted by bartman

What exposure times and iso are you using Sletts?
Using a dslr on a newt can have some focus issues ( ie not being able to focus).
Try targeting a bright star first and use live view(if your camera supports it) try and focus and zoom in a bit. If you can see the star in the LCD panel, then you should you be able to take shots.

Bartman

This Newt apparently can focus a DSLR.

The thing is, even with liveview on, I was not getting anything, just a pure black screen. Tried ISO6400 with 1 sec through to 30sec. Also tried ISO as low as 400. I tried all spectrums of the focus ring and nothing. So really not sure what I am doing wrong. It'll be atleast another week before I can head out and test it again.

So the setup was correct and should yield at least some kind of stars?
T-Ring > Projection Tube > Telescope

I'm thinking it would be a focus issue... I have PM'ed the guy I bought it off for some ideas.

Originally Posted by Stu Ward

My advice would be to concentrate on visual first.
If you've never used a scope before, jumping headfirst into AP is a surefire way of fastracking your scope appearing in the classifieds.
Sorry to sound negative, but AP is a struggle for experienced astronomers with a few years under their belts.
Learn and enjoy the skies first, if you really hunger for imaging, Saturn is up at the moment and is a much easier target.
You have a dslr, why not drop it on a tripod and try some widefield shots of the milky way


Stu

Thanks Stu. Really wanting to get into AP. I've done quite a bit of WA fixed tripod shooting hence the upgrade to a telescope.

[bartman (Bart)]

Originally Posted by sletts02

This Newt apparently can focus a DSLR.


So the setup was correct and should yield at least some kind of stars?
T-Ring > Projection Tube > Telescope

Not sure what you mean by projection tube?
At 6400iso and 30sec you should see something....even if it is just the skyglow I would have thought. You didn't inadvertently put the dust cap back on the scope did you ( I have).
Bartman

[sletts02]

Originally Posted by bartman

Not sure what you mean by projection tube?
At 6400iso and 30sec you should see something....even if it is just the skyglow I would have thought. You didn't inadvertently put the dust cap back on the scope did you ( I have).
Bartman

Haha, nope, definitely off. I immediately tried the eyepiece to ensure that some light could make it's way through.

It says something like "Camera Projection Tube" on the box....
http://www.clearvueoptics.com/EP_400.jpg

[adman (Adam)]

I'm going to go out on a limb and say that it almost certainly is a focus issue. If you can focus it with the eyepiece, you will almost always need to move the focuser inwards to find the position it will focus with a camera. This is the problem with most newts - they don't allow enough inwards travel to get focus with a camera. I had to move the mirror in mine up the tube by fitting longer collimation bolts and stiffer collimation springs - but there are other solutions such as a low profile focuser, or more drastically cutting the tube to get the mirror closer to the camera.

The best thing to do is try to focus it during the day on something suitably distant - the further the better (just not the sun! ) so you can get a feel for where the focal point is. Then make a mark on the focuser drawtube so that you can get it somewhere close when you go out in the dark

Good luck
Adam

[bartman (Bart)]

I concur with Adam.
I have used a barlow to get focus on my newt. This does mean a narrower FOV. The Projection tube might be the clincher. It pushes the distance away from the focal point. You need to get the camera as close to the tube as possible and then draw out from the focuser, all the while checking the lcd screen. ( this is how I found out the hard way).
Do you have a 1.25" focuser? or is it 2".
What I'm trying to say is that if you are putting this projection tube in between the cam and newt, your adding distance.
Can you remove the end piece( 1.25" part) ?
Bartman

[Visionoz (Bill)]

From what little I know. the projection tube is supposed to be used as in "eyepiece projection focus" mode - whereas what you're attempting to do is "prime focus" mode ie you connect your camera directly to the end of the telescope where the diagonal/eyepiece usually sits in the drawtube - so perhaps the use of that projection tube will definitely cause you to have no image as its focal point is way too far out

In the eyepiece projection focus mode you would attach one end of that tube to the eyepiece and the other is where your camera gets fitted

Perhaps what I just stated above is all wrong!! and others with better experience will be able to put you on the correct path

HTH
Cheers
Bill