Crayford 10:1 focus question

[batema (Mark)]

Could someone please explain how to set the allum key nut and the function of the thread screw on the underside of the focuser. it seems to have a mind of its own. I do adjust it when I'm photographing straight up and either the weight of the camera causes the whole focuser to slide down or when I'm trying to focus the focuse knob will not actually wind up the camera??????? Is the function of the nut to lock the focus in place?????
Thanks Mark.

[gbeal]

Depends, and maybe a piccie would assist those trying to answer.
On some focusers, the knob underneath "disconnects" the focus knob from any involvement in moving the draw-tube in or out. This could be what is happening with yours, and when it is pointed straight up, the weight is pulling the focuser out. There is sometimes a knob on the top to adjust the tension of the draw=tube, do you have one of these?
Gary

[davewaldo]

Hi Mark, Some more info would be nice, like what sort of scope you are using.

However, I believe that this setup usually functions like this:

The alan key screw usually adjusts your tension on the focuser tube. The other is to lock the focuser so it can't move.

Usually you would adjust the tension with the alan key so that the tube doesn't slip when focusing near zenith, but isn't too tight that it makes the focus motion tight. Then you only use the thumb screw when you have achieved focus and don't want it to move. Generally you only need to adjust the tension every so often, once its set it will stay good for some time.

Hope this helps,

Dave.

[batema (Mark)]

Dear dave and Gary,
Thanks for your responses. I will include a photo and other info. It is a Williams Optics and photo shows nut behind allum key tensioner. What you have said makes sense. I will adjust allum key tonight with camera on back. Dave how do you find the C8 on the heq5 because we have just ordered the the equipment to remove our other school scope (celestron c8) scope from the wedge mount and attach a dovetail bar and guide scope rings. We hope we will be able to get closer to things we are photographing (only beginners) that our wonderfull Skywatcher ED80 allows us to.
Mark

[davewaldo]

Hi Mark, yes I think the methods I discussed are correct for your focuser.

I really like my C8! Its a nice all round scope. And its the perfect size for a HEQ5. Once you add a guidescope, and all the other bits, its very near its imaging limit though. I think its a great combo, but I'm yet to image through it, still getting all the bits I need.

Dave.

[[1ponders] (Paul)]

Maybe you two should get together at Ron's next weekend and compare notes.

[batema (Mark)]

Hi Paul Sounds great. Thanks for the help Dave. Will most likely be there. Mark

[davewaldo]

Hope to see everyone there!