Autofocus

Ok so the Starlight Instruments Crayford focuser turned up today. It’s now fitted ready and waiting, and like all new gear it’s induced a weather change. Cloudy, apparently for days on end.

The gear was very quick to install but for some reason they forgot to send me two grub screws again. Down the road to a fastners store that sells strange US threads and all is well. This is the second time this has happened. Still the gear looks great, fitted easily and worked first time.

I’m having trouble with the Maxim focuser step size. The device does not know the number by auto detect, so I got out the calipers and measured: 6.52 mm for 1000 turns or 6.52 microns per turn.

First Attempt at Solar Observing

Holidays! So I’ve had a few hours to practice with the solar scope. I tried it on my camera tripod. A major disaster. It was to heavy and the tripod was just not able to cope. Down to the store again to find a decent tripod. I just brought the Bintel Skyview Alt Az mount. It seems to work very nicely and is sufficently stable to support the scope and my 5D camera with ease.

First real views of the Sun clearly showed detail on the surface, a Sun spot and many prominences. I am constantly amazed at being able to see these things in real life. It makes me stop and wonder…

If nothing else astronomy teaches me patience. I was waiting for clouds to move today and was just thinking how nice it is to learn to be still and wait instead of the crazy, frenetic pace I normally live at.

Hopefully first photos tomorrow.

Autofocus Progress!

So I gave up and tried FocusMax, what a most excellent piece of software. So to be fair all my comments should be prefaced with the fact that I have never used it before tonight and all my results so far from an hour of use without reading the manual.

The automatic Vcurve plotting failed, however when I tried it the manual way it worked briliantly. I could see my star getting closer and closer to focus, truly an exciting moment after 2 weeks. Just a word of advice though, the V curve plot does not work so well when there is a wind blowing. My roll on/roll off roof leaves my dew shield on my LX200 exposed, not unlike a sail.

Some numbers. I used the End Option, the start and finish where seperated by 700 units and the steps were set to 10 and the circles on the curve graph overlapped nicely. The star went from doughnut to doughnut brilliantly. When the wind moved the scope Focusmax even enlarged the subframe until it reacquired the star and then kept going. This software has been well thought out.

OK so I’m still not there but my star got to 12.85 1/2FD. Can’t wait until tomorrow night.

More Autofocus trials (and errors)

Saturday night was a mixture of high cloud and long periods of clear still skies. Back to the autofocus testing. It was a cool evening around 7 degrees. The temperature was static between 8 and 11pm.

I spent a few minutes confirming that the same problems existed. I am still using the Feather Touch micro on my LX 200. Some observations: I did note that when the step size was set to less than 10 strange things happened after the first few focus measurements. The autofocus jumped about 2000 in an attempt to find a new start location. I ended up settling on about 45 and the jump was only a few hundred. It seemed to make more sense?? Additionally I noted that the stars were often not even vaguely spherical. I tried increasing/decreasing the exposure time but it had no impact. I focus with guiding turned on. If I don’t do this the star drifts out of the subframe (which is set to 200×200). I can’t say for sure but I think the lack of spherical stars was either due to my movements and their impact on the scope or the guiding movements.

After repeated autofocus attempts I developed a method for producing vaguely reproducable results. If I moved the focuser 2000 greater than the starting focus point and then brought the focuser back to the orginial starting point the stars looked the same, visually at 100%.

At this point I gave up on autofocus again, did a manual focus and took some pictures of M61. I did note that doing up the focus lock appeared to make no difference to the focus of the image and very little movement of the stars on the image as well.

I gave up about 11pm, the dew got to the scope. Time to fit the dew shield.