TAL 100R astroimaging with 450D

[TonyD]

Hello,

I've been messing around with astroimaging for the first time.

Well, just trying to fathom how it all goes together with the TAL-100R, anyway.

Here are the accessories I have been playing with:

The adapter that goes into the telescope (or whatever it is called):

Some kind of screw thread adapter:

And here I have put it into the thing that goes into the telescope:

And here is the t-ring for my Canon 450D:

And here it is all mounted on the TAL 100R without the camera:

And finally the camera is in position too (don't worry attached the T-ring off the camera!)

It got so cold again tonight I played around with focussing on a distant light rather than try imaging the night sky.

What I found was that, using LiveView on the 450D, the focus occurred when the focusser was as far in as possible. In fact, I couldn't bring it in further to get it out of focus again. Hmmm. is it a coincidence that the focal plane is at the sensor position when the focusser is tight in?

I removed that thread adapter and attempted to screw the thing that goes into the telescope straight into the t-adapter. It threaded ok so far, but for only a few turns. Is the pitch of the threads different? Hmmmm.

In any case, I was able to then use the shortened length to pull the sensor in beyond the focal plane and out of focus again. But I am not sure if this is the right way to go about it.

How would I use the TAL 2x Barlow in this set up?

Many, many (basic) questions - so I've put this in the beginner's imaging section.

Any help most appreciated, thank you!

All the best

Tony

[sloz1664]

Tony,

You are about to enter the DARK SIDE........

You need to focus on a bright star or preferably Jupiter, as it's so bright. I fear though you may not

have enough "in travel" to get it to focus. Adding a barlow should give you enough spacing for you to focus.

The thread on the Tal is M42 x 1 (1.0mm thread pitch).

The thread on the T adaptor is M42 x 0.75 (0.75mm thread pitch).

Hope this helps

Steve

[Zakalwe]

A Barlow is the last thing that you should be adding as it will "slow" the focal speed of the scope right down. Unless you are doing Lunar work, in which case, a webcam will get better results than a DSLR.

A Tal 100R is f10 AFAIK, so it is sloooow for astro imaging. Adding a x2 Barlow would bring that to f20- good luck with that!

[TonyD]

Thank you for the replies.

Steve: the thread information is very useful - I didn't force anything (thank goodness) so no threads stripped. But it's a bit annoying that I can't screw the TAL t-mount straight into the t-ring because it would mean I shorten the distance of the camera. I'm back on the vertical learning curve! So, let me get this right: The T-ring has a female "T-thread" (M42x0.75mm ) and so I need the T-thread-to-M42x1mm adapter so I can screw in the TAL t-mount. How does that sound? Would a low-profile Canon EOS t-ring help (scroll to bottom of page).

Zakalwe: Thanks for the info - yes it is an f/10, so it is going to be slow. With a bit of luck, though, with my HEQ5 syntrek, I can get OK results with perseverence once the mount is aligned and tracking properly? Or is that wishful thinking?

Cheers

Tony

[Zakalwe]

Zakalwe: Thanks for the info - yes it is an f/10, so it is going to be slow. With a bit of luck, though, with my HEQ5 syntrek, I can get OK results with perseverence once the mount is aligned and tracking properly? Or is that wishful thinking?

You'll get something. It's got a focal length of 1 metre so you are asking a LOT of the tracking and polar alignment.

The slow focal speed is really going to hinder.....going up a f-stop doubles the exposure time. So a f8 needs double the exposure time of a f5.6.

Finally, its an achromatic scope so you'll get some colour aberrations.

In effect, you are making it as hard for yourself as possible.

Astrophotography is hard enough without making it harder. By all means, give it a go and see how you get on. But you will get better results, much easier, if you picked up a 2nd hand ED80 and focal reducer.

The TAL would be good for Lunar work with a webcam though.

[earth titan]

I have to say, when I read the thread title, I thought 'wow thats ambitious' but you work with what you've got right?

Focal ratio is very long for AP. You ideally want about f6.

Typed by me on my fone, using fumms... Excuse eny speling errurs.

[keithatrochdale]

TAL100RS, 7D

[TonyD]

Keith: Motivational and inspirational. Thank you very much.

I look forward to posting my own.

Tom: I suppose if I got a focal reducer I could pull f/10 down to f/6? Would that work?

All the best

Tony

[adrianh]

Hi Tony,

Here is one of the pics taken on my Tal-100 some time ago. It was taken on my Samsung V700 digicam directly through the eyepiece. Some half-decent pictures can be obtained, just need patience and perseverance as much as anything else.

Adrian

[earth titan]

Tom: I suppose if I got a focal reducer I could pull f/10 down to f/6? Would that work?

Tony

It would help but I still think it might be a stretch, except for lunar.

I think lunar could work well, as it's nice and bright and doesn't need much magnification.

Typed by me on my fone, using fumms... Excuse eny speling errurs.