Focusing on Saturn

[long_arms]

Hello,

I woke up at the ludicrous time of 5am to figure out if Saturn would be visible from my garden.

Thankfully it will be nicely placed between 2 trees for about a hour.

The next clear morning I will therefore be setting up and having a first go at another planet (I have only seen jupiter so far).

I was just wondering if anybody has any tips for focusing on Saturn? I understand it will be a lot smaller than Jupiter through my 200p. Plus for Jupiter, I use its moons to achieve perfect focus whereas I won't be able to do this with Saturn.

I've never tried focusing on a star through the camera before and am a little bit skeptical as to how accurate this will be for a planet.

Thanks,

Dan

[atmenterprises]

You could try a Hartman mask or a Bahtinov mask.

[Baz Pearce]

Hi Dan,

With it's rings Saturn, is about the same size as Jupiter, even though He's much farther away than his big bro. Use the rings and the gap between them and the planet to focus on. I got chance for a sweet little peek this morning too. I used my Bahtinov mask to focus, and could see it nicely with it on. So you should have no trouble with the 8".

Baz.

[Welrod50]

I would try focusing on a star or Jupiter prior to Saturn with the naked eye at the EP, or better still with a bhatinov mask. If you can leave the scope focused then ready for Saturn great, if not then just use a bright star immediately before you go for Saturn. Because they are all so far away, infinite focusing will work, in much the same way as a camera lens will focus on something a mile away or ten miles away - beyond a certain distance it doesn't really make that much difference.

I made my own bhatinov mask from a downloadable template (google) and it took me half an hour to cut it out. It works spot on and allows me to focus perfectly using the live view on my Pentax Kx.

Good luck

[Josh Wilson]

If the moon is out, I always use it to get the focus right. If not, I either try to get the focus as good as I can and test my skills or use the a planets moons and get them down to the smallest point possible.

For planetary imaging, people tend to use any where from f/10 all the way up to f/50. At an f/ratio like that, the difference of distance between a star and the planet is not a problem at all. And most, if not all, telescope are focused to infinity when looking at the moon or planets or anything further out.

Josh

[perrin6]

As mentioned above the Cassini division should be a good feature to focus on, it will be a very narrow black line. Either that or Titan which will be a tiny disc. Both these are assuming seeing conditions allow these details to be visible.