Cheap finder scope and ball head mount for barn door mount

[maxwolfie (Greg)]

I am starting a double arm barn door mount project this weekend. No doubt I'll have a lot of other questions, but I was wondering about finder scopes and ball head mounts... What are some cheap ones that will do the job?

[adman (Adam)]

check out the Giottos MH 7001 on this page.

I bought one last year - very solid. This special price is about 1/2 what I paid...

Adam

[rcheshire (Rowland)]

Not sure about cheap finder scopes - there are instructions here and there on the net, but I find bracketing and correcting star drift effective, if not time consuming. Immediate feedback with digital cameras is great for this.

You can get away without a finder scope for a while. Most of the frames taken on my DAD, were following alignment using an abbreviated drift method. Take a frame and see which way the stars are trailing - adjust polar and altitude alignment until you get nice round stars. It takes some practice but can be very accurate.

If your interested I can provide a bit more detail. Certainly, the best thing I did with my DAD was to make altitude adjustment easy to operate without disturbance to the mount. This makes polar alignment with or without a scope much easier.

[maxwolfie (Greg)]

Originally Posted by adman

check out the Giottos MH 7001 on this page.

I bought one last year - very solid. This special price is about 1/2 what I paid...

Adam

Thanks Adam, that looks perfect.

Originally Posted by rcheshire

Not sure about cheap finder scopes - there are instructions here and there on the net, but I find bracketing and correcting star drift effective, if not time consuming. Immediate feedback with digital cameras is great for this.

You can get away without a finder scope for a while. Most of the frames taken on my DAD, were following alignment using an abbreviated drift method. Take a frame and see which way the stars are trailing - adjust polar and altitude alignment until you get nice round stars. It takes some practice but can be very accurate.

If your interested I can provide a bit more detail. Certainly, the best thing I did with my DAD was to make altitude adjustment easy to operate without disturbance to the mount. This makes polar alignment with or without a scope much easier.

Thanks, I think I'll see how I go without a finder scope to begin with then, and then add one once I reach my limitations

Btw, what's a DAD?

[adman (Adam)]

Originally Posted by maxwolfie

Btw, what's a DAD?

double arm drive?

[maxwolfie (Greg)]

[rcheshire (Rowland)]

Thanks, I think I'll see how I go without a finder scope to begin with then, and then add one once I reach my limitations

A bit more detail - first point your device roughly south and level your tripod, making sure the camera arm is also level. Set your latitude (altitude) accurately.

Take a 30 second shot and check which way the stars are drifting. It helps if the camera is also reasonably level/square with the camera arm.

I use the following rules;

If trailing is left adjust azimuth right - if trailing right adjust azimuth left - if error increases either way you've adjusted the wrong way - take a frame between adjustments of course,

If trailing up/down adjust altitude up/down - if error increases adjustment was wrong way.

You get a feel for which way to adjust.

Keep bracketing (adjusting in diminishing increments) azimuth and altitude until a 60 second frame produces no trailing. I usually follow up with a 3 minute frame to see if I can refine the tracking - minute adjustments by this stage.

Takes about 10 minutes, but well worth the trouble. Hope this is of assistance?