Hardware Question (Mounting a camera to a telescope)

[Lance]

I have a Meade LX-50 10" telescope and an Olympus C-3040 digital camera that I'd like to get coupled. I also already have the Meade Variable Projection Adapter and the Olympus Lens Adapter Tube (which gives me 43mm accessable threads).

All the solutions I've found on-line so far begin at the camera body and end at the telescope and provide all the necessary hardware in between. They also range in price from ~$80 to close to ~$200. My problem is that I don't need all that. I really only need to get from a 43mm internal thread (on the camera) to a 42mm external thread (t-mount, on the adapter). You'd think that wouldn't be too tough, wouldn't you? Not so much...

So, does anyone have any ideas on how I can couple these two beasts without it costing me an arm and a leg in the process? I'm out of work at the moment so I'd like to spend some of my sleepless, worry-filled nights doing something fun without having to incur a hugh (a hundred bux is hugh right now) additional expense.

Thanks in advance.

[frogesque]

Do you have a small one man engineering work shop locally, a tech college or even better a model engineer that might be interested enough to make one for free in exchance for a squint up the tube. Most modelers would be only too willing to help out.

[Lance]

Thanks, that's a good idea. I'll check it out.

I'm not completely sure that:

...need to get from a 43mm internal thread to a 42mm external thread...

is exactly the solution I'm looking for though. An adapter ring with a .5mm wall probably isn't doable.

Perhaps a better wording for my question would be:

"Given the pieces I already have, what would be my best and cheapest solution?"

It isn't necessary that the solution use all the pieces, just take into account the pieces I do have so I don't have to buy things I don't need.

[frogesque]

I'm not completely sure that:


Lance wrote:
...need to get from a 43mm internal thread to a 42mm external thread...


is exactly the solution I'm looking for though. An adapter ring with a .5mm wall probably isn't doable.

If I read the problem right and if the thread pitches are the same then something like a Helicoil (TM) might be the answer. No idea whether they are made to 43/42mm dia though. Normally the tapped hole is a mirror image of the thread you want to size down to, ie the internal thread takes a diamond shaped wire coil with 60deg flanks and this then forms the flanks and crest for the part you wish to assemble to it. My experience is only with small thread sizes ~ 6mm to 15mm so I don't know if this would be applicable but I don't see any reason why it shouldn't work. It's also the standard solution for a stripped thread in an aluminium cylinder head where a plug has been overtightened.

Note: for a low load application you might just get away with winding hard copper wire round a former and inserting that into the larger internal thread. The thread pitches MUST be the same though or you will damage the threads

Could you give an indication of what the relevent pitch(s) is (are)? I have a fair bit of thread data here and may be able to be more specific and determine if an internal/external adaptor is possible (it would need to be a fairly fine thread)

Edit: I am assuming that the focal plane of the telescope will be correct for the camera set up you envisage.

[Lance]

After much more reading and hunting solutions, I've discovered that the Variable Projection Adapter I have won't allow the eyepiece and lens to get close enough to be a viable option. I would just end up with terrible vignetting. Sadly, I found that Scopetronics has the appropriate step ring for ~$31 that would do the job, but now I no longer think I need it. I'll probably just have to go with something like their Digi-T System at some point down the road.

Thanks for your help.

[frogesque]

Seems a shame you have all that kit and can't take a few happy snappys

If you come up with any solutions or other ideas please post again.

Also good luck in the New Year for the job hunting