Issues with Camera + 2x Barlow

[joshman]

well, i think the picture will make my issues apparent...

apart from the balance issues, it's heaps long!

basically, what can i do? is there someway around this? i'm not exactly comfortable with the amount of tube sticking out the back of the scope. this setup would really only be used on faint fuzzies and the moon, maybe a mosaic down the track. what you can't see is that for focus on stars and whatnot, the focuser has to be all the way out pretty much, it's only halfway out at most in the photo (from memory)

[Dennis]

To make it physically shorter and keep the load nearer to the main 'scope body, the only suggestion I can think of is to insert a 2" star diagonal.

Here is a photo of my CCD on the WO 66, but using a 1 ¼ inch diagonal. A 2” will give you a longer path so you should be able to wind the focuser in further to reduce the leverage.

Warning: Don’t go out and specially buy a quality 2” diagonal until you have done a test run on a borrowed one – it may not work!

Cheers

Dennis

[joshman]

well i've already got a 2" diagonal (for observing purposes, makes life easier, that's for sure!) so when i get back to my scope, i could give it a go, but from memory, i didn't have enough in-travel...but then again, i think my imaging train went either:

scope -> extension tube -> diagonal -> barlow -> camera
or
scope -> barlow -> diagonal -> extension tube -> camera

have to give it a go without the extension tube.

[Gama]

You wont need the extension tube as the diagonal will act as one.

So procedure is Beer - Scope - Beer - barlow - peanuts- diagonal - camera - Beer - Beer.

But you could leave out the Beer and nuts !.

Theo.

[joshman]

you sure i shouldn't be doing this over at the pub? :P

beer and nuts, sound like a good idea, ease the frustration...

[[1ponders]]

You won't be wanting a barlow to shoot galaxies Josh. Using a barlow will make you exposures way to looooong. ie if the ed80 has an f ratio of 7.5 doubling it will make it f/15 which means your exposures will need to be about 4.5 times longer to achieve the same detail.

[joshman]

ah, so true!!!! oh wel, the moon shall be my main target then!

[rogerco]

My experience with a diagonal (and a Nikon) is that the camera is too heavy and the diagonal gradually rotates. You need a 80 mm extension tube but probably not the barlow for nebula. I am still experimenting but am held up by cloud. The big problem with all those tubes and joints is the weight of a DSLR camera on them, CCD and web cameras are a whole lot lighter. But there is nothing you can do about it from what I can see the ED80 is designed to allow for a diagonal (which adds 80mm to the folcal path) so you need the extension tubes if you don't use one.

Roger

[joshman]

mmm, that's basically what i've found from my experimenting, but i've still yet to try a few configurations, i'll definitely let ya'll know what i find out in my investigations

[joshman]

alrighty, i'm finally back with my scope and have tried out a few configurations with the barlow and camera. ok i tried:

scope -> barlow -> diagonal -> camera.
this is most likely the configuration i'll be using as i was able to bring some extremely distant trees to focus fairly easily, without alot of out-travel on the focuser, so this configuration should focus at infinity, but i won't know for sure until i have some stars to test on. this configuration also sits fairly close to the central axis of the scope, thus lowering the amount of torque that's being applied to the diagonal, so slippage and rotation shouldn't be too much of an issue.

scope -> diagonal -> barlow -> camera.
this one allowed me to focus in the range of about 7-15 metres and no where outside of that, by moving the barlow out as far as i could, i achieved focus as close as about 3 metres. interesting if i wanted to view small insects at my feet, but not much else.


sorry if this post looks screwy, i'm on my parent's computer and they live in the dark ages.