Focussing with 350D

Hi,

I am having problems trying to focus with the Canon EOS 350D (Canon EOS Digital Rebel XT in North America). As you will know, this doesn't have live view. I have attached it to a telescope with a T-thread thingy. It has been very difficult trying to get it to focus properly. I guess some of the problems have been due to the clouds coming and going. I am in Wales, and therefore we get a lot of clouds during the evening.

This is my attempt at capturing the moon this morning.

Hey,

Even with live view it is trick. When shooting stars, even with live view I'll use a bahtinov mask, they go for around $30.

http://en.m.wikipedia.​org/wiki/Bahtinov_mask

You hold it, or blu tac, it to the end, then focus on a star and when you're close you'll see two sets of lines on the star. An "x" and a "l", when the two overlap, making a six pointed "*" you're focused.

Using it on a star to focus then swing to the moon would be my workflow.

Hope it helps, and good luck with the clouds!

- Daniel

The trick with the 350D is to take two exposures with different focus settings and then zoom right in on the resulting image. You can then use the arrow buttons to move between the two images which will stay at the same zoom. You can then judge whether the change in focus made it better or worse and adjust the focus accordingly. Repeat until it's spot on.
It works really well for stars and probably takes a few minutes with 10 sec exposures. The same approach will work for the moon but I find it much harder to tell if one shot is better or worse than the other with the moon. I would focus on a bright star or planet and then go back to the moon.

Steve.

Focusing with the camera mounted to a telescope requires patience and practice. If the focuser doesn't have a two stage focus knobs, (one for micro focusing) then you'll need to take extra care, just keep trying and post back with your results.