Newbie with inherited gear

[refurbmike]

Hey all,

My grandfather passed away and I've inherited his homemade telescope. He built it about twenty years ago, so I've been working on bringing it a tad up to date, learning as I go along. For the most part, I'd like to take pictures through it with my Canon 5D.

I already bought a 2" t-ring for which fit nicely. However, no matter how far  I screw back the focuser (forgive me if that's the wrong terminology), it's still out of focus. I'm not using a lens between the camera and the telescope, am I supposed to?

I have a few eyepiece lenses that work nicely, but they don't fit the camera.

Any suggestions?

[Geoff Barnes]

Hi Mike and welcome to the forum.

Firstly commiserations on the loss of your grandfather, but how nice that you can remember him with his telescope!

I don't do astrophotography but have been around the forum long enough to know that you will need an extender between your camera and the scope to reach focus.

I'm sure others will give you better guidance than me but I believe something like this is what you need...

https://www.firstlightoptics.com/zwo-accessories/zwo-m42-m42-extender-21mm.html

[PeterCPC]

A Barlow lens should let you get focus. Assuming that we are talking about a Newtonian reflector.

Peter

[Physopto]

Hi Mike and welcome.

Sounds like a great project. I would agree with others that an extended will be needed to get focus. Problem is the extension distance. A good way is to take a photograph during daylight through the scope of a distant object. You can hold the camera (without lens) up to the scope with the camera in a "dark bag" if you have one, so that one of the arm holes covers the scope focuser. Keep altering the distance from the focuser between shots to find a very approximate focus point. Keeping  light out is key. I have done this and it can work if done with care. Keeping still and in line is the real difficulty.

Anyway best of luck.

Derek

 

[Gfamily]

6 hours ago, refurbmike said:

Hey all,

My grandfather passed away and I've inherited his homemade telescope. He built it about twenty years ago, so I've been working on bringing it a tad up to date, learning as I go along. For the most part, I'd like to take pictures through it with my Canon 5D.

I already bought a 2" t-ring for which fit nicely. However, no matter how far  I screw back the focuser (forgive me if that's the wrong terminology), it's still out of focus. I'm not using a lens between the camera and the telescope, am I supposed to?

I have a few eyepiece lenses that work nicely, but they don't fit the camera.

Any suggestions?

You're more likely to have to rack the focuser in than out if you are using a dSLR. 

If you can't get focus with it fully racked in, as @PeterCPC has suggested, a Barlow may allow you to get focus.

As Derek has also suggested, experimenting during the day will be a lot easier.

[Cosmic Geoff]

With a Canon 300D you can check the focus while looking through the viewfinder.

Typically with a standard Newtonian the camera will not go far enough in, and the standard fix, drastic as it may sound, is to shorten the tube/ move the main mirror up, pushing the focal point further out. This is done in the imaging-ready 'PDS' models from Skywatcher.

A Barlow may help, but don't ask me how or where you are supposed to fit the Barlow with the camera mounted to the focuser by a T-ring.

[refurbmike]

Hey all,

Thank you for the feedback. A couple of follow-ups:  

1. Yes, it is Newtonian.

2. It's just under 5' long with a ~15" mirror (that he ground himself). 

3. I was able to keep checking the focus through the viewfinder. I had Jupiter as an easy target to play with. I'm familiar enough with cameras to know that it does need to come out more. 

For the barlow idea, I found this diagram. I would think the barlow would fit inside the focuser, while the t-ring would grp to the edge of the focus (where the screws would tighten the fit)? Am I anywhere close?