Help - Finderscope - using both eyes

[erick (Eric)]

I've only been using a scope for a few months. When I started, I found that I would use the finderscope with both eyes open and could easily overlap the crosshairs with the view of the sky in my free eye - this made it easy to get the object of interest into the FOV of the finderscope. I also recall that the alignment was good - when the object was under the crosshairs in the finderscope, I also saw it under the crosshairs in my free eye.

However, more recently, the two views aren't well aligned. the object may be a third of the way from the center to the edge of the field of view, yet my free eye sees it under the crosshairs. This has been throwing me off somewhat when it is fainter stars/objects I'm trying to center. Anyone have any ideas about why this misalignment occurs?

I figure it has to be alignment of the two lens in the finderscope. However both seem to be properly in position - nothing loose. If I loosen the small lens - simply unscrew the tube it is in - to where I can wiggle it around, I can see the image can move a fair distance across the FOV. At some stage, I adjusted the front lens for better focus and perhaps the alignment went off at that stage.

Any suggestions are welcome, before I fiddle around some more. It's a standard GSO 8x50 ex Bintel.


Many thanks
Eric

[ballaratdragons (Ken)]

I have a security camera shoved inside my Finderscope, so I don't get that problem.

But when I use the one at the club on SVAA nights I only use one eye (bad habit), or as you saw, when I use my 12" I don't use a finder.

But whenever I attempt to focus my GS Finder (the one with the camera in it), I notice that the smallest turn on the Focus (front element) that the centre of the crosshairs gets slightly mis-aligned from where it used to be. Not that it's easy to notice, but it does move. I think it has to do with the sloppyness in the threads.

[erick (Eric)]

Yes Ken, I reckon it changed when I tweaked up the focus some time ago. That gives me an idea of what to look at, thanks.

[ballaratdragons (Ken)]

The crosshairs are in the rear lens housing (EP end), so check for sloppiness in the threads there too Eric. The thread in my rear lens housing is very sloppy.

[erick (Eric)]

Well, I haven't been able to solve this by fiddling machanically with the Finderscope - but as long as I don't rotate the finderscope, I am getting used to the "offset" between what my left eye sees in the sky superimposed on my brain's view of the crosshairs and what my right eye sees through the viewfinder. Kinda like chewin' gum and walkin' at th same time, while hanging upside down off the OTA, lookin' at the zenith trying to push the beanie out of my eyes, keep my glasses on and not fogged up - simple really

[astro_nutt]

Hi Ken..try some teflon tape on the thread of the rear lens housing for a better fit...