Needless to say I am very new to this, so where necessary, forgive my terminology. I have a Meade LX90 telescope with an LPI attachment, which seems to work pretty good. I also have a Meade 'T' adapter for a camera.
Last night I set up the telescope, using the 'T' piece adapter to which I connected a Nikon SLR digital camera. As the adapter only allows for the camera to be attached I had to set up the focus prior to removing my telescope eyepiece viewer and attaching the camera, doing so I could only then use the camera viewfinder for final focusing.
The final result, though reasonable for the initial experimenting with getting a photo, was not very sharp.
Can anyone suggest a method whereby I can set up the camera and still keep a sharp focus for both viewing realtime and also in the camera?
Also the moon was about full and tended to be rather washed out dueto the brightness. Can I get a filter which would overcome this and if so, how do I attach such a filter (over the telescope lens, or between the telescope and eyepiece).
If you set the focus with an eyepiece, it won't be in focus for a camera (unfortunately!).
The best way is to use a focusing mask (Bahtinov) - you take several brief exposures and assess the focus on each, adjusting until it is right. I had a mask made for my LX-90 by a fellow IIS member - fantastic quality.
As for photography during a new moon - filters won't really help, unless you try narrowband imaging (but that's not for beginners).
It's quite a challenge to image at 2000+mm focal length. I had a crack at this with my LX-90 and then went back to 400-600mm with much more success.
Do you have your LX-90 on a wedge? If not, you'll get field rotation unless your exposures are quite brief. I found an article on the web that went through the maths of it all - basically if you shoot object that are due east or west below an altitude of 45 degrees, you won't get too much field rotation with an Alt-Az setup. Tracking is also an issue for the LX-90. Maybe try starting with some widefield piggybacked exposures using a 50-200mm lens.
Keep at it - it's addictive.
DT
Last edited by DavidTrap; 19-02-2011 at 11:07 AM.
Reason: added info
Colin, I'm really not sure what the setup you're using is like but my LPI came with a parfocal ring which can be used to adjust the EP/camera so that both achieve focus. The parfocal ring is used to hold either the EP or the LPI in position once the correct position is found by sliding in and out after focus. The adjustment is best done during the day. I'm sure there is something in the Meade documentation about parfocal ring use.
Can be done LX90 8" on a wedge
This is canon 450D and 8 exposures of 47 seconds at iso 800 - UNguided.
noisy as all outdoors due to last month's nearly full moon -
Focus using the bahtinov mask made from the back of a resume folder!
Thanks for the advice. I got my scope 4 years ago and became frustrated at not being able to set it up properly. I sent two letters to Meade, and even a couple of e-mails, none of which were answered, so I gave up and put the scope away. I have now decided to give it another go, but decided to try other means of seeking information, so here I am. I am not sure that a Meade scope was my best selection after all. I have decided to join an astronomy club.
Your post resonated quite strongly with me. I remember spending a week on holiday in Maine (USA) in autumn, with an ETX80, trying to work out how to set it up and align it so the goto pointed at what it was supposed to.
In the end I worked it out. But the pain and frustration was considerable. If you have the opportunity, seeking help from the local astronomy people is a much less painful way to go forward.
I think that an average person can work an LX90 - if they get some instruction at the start. It is quite civilised. But getting the idea behind the Autostar is not so obvious. The people at the astronomy club will be able to help here.
I cannot say if the Meade LX90 was the right scope for you. Mine has been for me. I am quite delighted with it. I acknowledge its limitations. But it gets me a long way forward for very little effort.
