I need help with astrophotography.

[johnleveritt]

Sorry for the double post, but I was sent over here, so here goes.

I am just learning astrophotography, and I'm starting out with the moon. I have taken pictures with an EF 100-400mm lens, both with a tripod, and piggybacked on my telescope. I now am taking pictures through the telescope (Meade LX 200 8" 2000mm F/10 or with reducer to F/6.3), and now comes my question.

I am looking at getting the Canon EF 1.4X, and EF 2.0X extenders. Will these extenders work with my telescope, as they do with Canon lenses? They are quite expensive to just take a chance on them, and I would be foolish to try without asking here first. Canon U.S.A wasn't able to help, as they only test with their own lenses, and I couldn't get through to Meade.

I do have 1 Canon Lens that would work with these extenders, the above mentioned EF 100-400mm, would it be worth it to buy these extenders just for this lens, if they don't work with my telescope.

An update to the post on the other board. I have a friend who has the Tamron 1.4X extender, I borrowed it, and it doesn't work for my application. I got an error when I tried it with the telescope, and it worked fine with the Canon EF lenses. So Canon extender it is, if they will work.

Thank you in advance.

[mattchase]

I would not expect the Canon TeleConverter to work with a telescope. The Canon TCs have a glass element that sticks out from the center, which is why they will only work with certain lenses. If you were to use the TC on a non-compatible lens, then it could cause damage to the lens, the TC, or both. So I would probably recommend against using a TC like this on your scope. Only plan on using it on compatible lenses if you decide to buy it, or you might make an expensive mistake.

I have the Canon 400mm 5.6L and use it alone or with my 1.4x extender on it to do some astro work, and it is a nice setup. Not too long, not too slow (wish it was a bit faster), and not too big or heavy so it is easier to travel with compared to my 1000mm f8 telescope. Your 100-400 lens could be used in the same way.

[johnleveritt]

I would not expect the Canon TeleConverter to work with a telescope. The Canon TCs have a glass element that sticks out from the center, which is why they will only work with certain lenses. If you were to use the TC on a non-compatible lens, then it could cause damage to the lens, the TC, or both. So I would probably recommend against using a TC like this on your scope. Only plan on using it on compatible lenses if you decide to buy it, or you might make an expensive mistake.

I have the Canon 400mm 5.6L and use it alone or with my 1.4x extender on it to do some astro work, and it is a nice setup. Not too long, not too slow (wish it was a bit faster), and not too big or heavy so it is easier to travel with compared to my 1000mm f8 telescope. Your 100-400 lens could be used in the same way.

Thank you, that's what I was afraid of, when the Tamron didn't work. I will probably get the EF 1.4 anyway, and use it with the 100-400mm, both in the sky, and on land.

I'll wait for some others to answer, and see what they say, maybe, I'll get lucky.

[Jesper]

Did you see this thread....... :)
http://photography-on-the.net/forum/showthread.php?t=55975

[pcasciola]

I wouldn't worry about the extender damaging the scope. There's nothing there on an SCT telescope for it to hit. between the t-mount and t-adapter, there's plenty of hollow space there.

I am also interested in trying this, but have nothing else to add at this time unfortunately. If you get your extender before me and try it out, let us know the results.

[kfong]

The reason why Tamron and Canon TC don't work is that with the TC on, the camera is able to talk to the TC, but the TC can't talk to the scope. and it reports it encountered error. This can be easily get around by taping the contacts in the TC.

Ken