Focusing my new Delta Optical EX 15x70's

[Steve72]

Hi Guys, finally received my new 15x70 bins. I felt like a child at Christmas when the package arrived! On first inspection they are clearly a vastly superior quality to anything I've had previously and really are heavy duty. Now I'm just really hoping for a clear night! So far so good.

I just have a quick question regarding focusing. I've never used binoculars with individual focusing before. Am I correct in thinking that once I have focused them for astronomy I shouldn't need to adjust them again as long as they are only for star watching? And no one else is getting near them

Also, what is the best method/target to focus them? Would the moon the best target? Unfortunatly the moon is not visible at present and I'm having difficulty getting sharp focus on Venus. Mind you its not quite dark yet.

[Ruud]

They're good binos: Kunming's BA8 series are quite famous.

You're right. You hardly have to focus again once you have both eyes focussed for infinity. Put on one lens cap and focus for one eye - move the lens cap to the other barrel and focus for the next eye. Check and repeat if necessary. Make a note of the dioptre positions of the eyepieces.

Find the right pupil distance and make a note of that too. Move your head a bit to the left and the right. Both eyes should go dark at the same time.

Check the collimation of the tubes as well. This is best done with the stars. Hold the focussed binoculars in front of your eyes.  Close your eyes and open them after a while. The images should merge more or less immediately, and without strain. You can further test collimation on a very distant daylight scene by checking if the field stop cuts off the scene at exactly the same places for each eye (left, right, top and bottom).

Happy observing!

[Chris]

I have 2 pairs of BA8's and once focused that's pretty much it, they tend to stay put. I would use stars to focus and try and get them as small and tight as possible. 

[Steve72]

Thanks guys. I think I've got them reasonably well focused for now. It wasn't the best night for observing, very hazy and a lot of light pollution. Only directly above was very dark and that was a strain on my neck after a while. Jupiter was very sharp and I could easily spot three moons. M44 was also very impressive and was good target for fine tuning the focus. Need to invest in a reclining chair now or take up yoga

[michael.h.f.wilkinson]

Congrats on getting those wonderful bins. A reclining chair is an excellent investment (and not just for astronomy )