New Wide Field Imaging Setup

[avandonk]

Managed to win a 16mm to 160mm F1.8 zoom for 1" sensor c-mount camera on Eba.. While a zoom is not very good for high quality astro imaging it is fine coupled with a GstarEX for a real time electronic finder and guidescope. The apeture on this lens is 88mm so it collects a lot of light. Spent Mon & Tues cobbling this together from bits I had. Tested it last night and even guiding at 100mm on the zoom, stars were pinpoint on the Canon images. This is a lot lighter and more compact than the system I used previously with a F5 600mm achromat as guidescope.
The pictures below tell the story better. The wood is well seasoned Red Gum.
I hope to use this setup at some dark sky sites as it is far more portable.

Bert

[Striker (Tony)]

Nice little set up Bert.

I see you still have that homemade stepper focusing system on Canon....looks to be working well.

[avandonk]

Thanks Tony. The stepper focuser is invaluable not only can I now get perfect focus I can maintain it as the temperature changes. The other thing I hope to do next is put the 5DH inside a peltier fridge. Being able to focus without accessing the camera makes this practical.
Below are a couple of pics of another lens I won on eBa.. This one has remote focus and zoom and aperture. It is also 15mm to 180mm at F1.9. This makes its aperture 95mm! I managed to get a circuit diagram for the electronics (before I bid) so this will save me tracing the circuits and guessing how they work.

Would you believe new it cost $2500 US!

Bert

[leon]

Bert your a bloody genious, that looks great, and BTW, when you have finished with that lens can i have it..... just joshing..

Cheers leon

[LeoLion (Len)]

Hi Bert , Your homemade stepper focusing system on the Canon lens looks interesting. I have an interest in 'remote' focussing of c mount video lens using steppers/ servos for my meteor camera set ups to 'pin point' my star images . Any guidance ( link direction pointing ? ) would be great . There are some lens gems on eBay (sssHHH )
Len Entwisle (LeoLion)

[acropolite (Phil)]

As usual excellent work Bert, you sure your last name's not McGuyver ....

[Gama]

Originally Posted by LeoLion

Hi Bert , Your homemade stepper focusing system on the Canon lens looks interesting. I have an interest in 'remote' focussing of c mount video lens using steppers/ servos for my meteor camera set ups to 'pin point' my star images . Any guidance ( link direction pointing ? ) would be great . There are some lens gems on eBay (sssHHH )
Len Entwisle (LeoLion)

You can achieve electronic focus by using an Rs-232 or parallel port controlled stepper controller and using a small pulley on the stepper shaft and running a belt over the focus grip on the lens. Then you can control the focus remotely by stepping the motor one way or the other. As the motor rotates it also rotates the lens as well.
You need to use microstepping to acheive the high resolution you need. Plus you need to limit the voltage/current to the stepper to allow the stepper to stop rotating in case you go to far in focus and it hits limit. This way the belt doesnt slip. Basically reduce its torque.