focus problems

[prbaxter]

This morning I spotted Saturn whilst I was supposed to be de-icing the windscreen on the car so I grabbed my 20x80s and sat in the kitchen doorway gazing up.

This was the first time I had used the bins in non-night conditions as it was just about day break and although saturn, venus and the moon were visible, no stars could be seen. there was also a little bit of thin cloud but not enough to obscure the target.

I found I was having trouble getting a good focus on saturn. It was as if the 2 circles of the bins wouldn't line up properly and there was a bit of a shadow too (a bit like when you catch a nearby object in view slightly).

Also when I adjust the right diopter focus it seems to also move the centre focus.

user error? or should I look at sending these back and getting them looked at? are there any standard tests I can perform?

[jgs001]

the 2 circles and shadow I think is caused by the interpupiliary distance (how wide the two arms of the binos are).

I can't remember exactly, as I've loaned out my book (Stargazing with Bino's) but you should set the interpupiliary distance first, then covering the right hand objective, adjust focus for the left with the main focus knob. When that's right, uncover the right, and cover the left and adjust focus with the diopter adjustment.

I don't think the diopter adjustment should move the main centre focus, although I think if you are applying pressure along the axis of the bino's when adjusting this may well cause slippage, and the effect your describing.

[prbaxter]

thanks John, I'll have another go with them later.

As it turns out, I think it was Arcturus I spotted and not Saturn.

[prbaxter]

yeah that sorted it, thanks John.

I'm finding that I'm resting the binoculars on my face and it's pushing the central focus back in. guess I'm getting a bit over enthusiastic and pulling them closer to my eyes. Brilliant pair of bins these 20x80s. just been out in a light cloud covering and it's stars galore.

[jgs001]

Glad you're sorted, i bet they're great, my 15x70's are. as for stars, what are they, haven't seen any in a couple of weeks