Revelation 15x70 collimation problems

[Planetesimal]

I decided to get a pair of inexpensive bins and the Revelation 15x70 looks like a good option at £60 from Telescope House. I read the reviews on Amazon and had a look through this forum as well, and it was mentioned in quite a few places that there is a risk of getting a pair that have not been collimated properly, but despite the risk of getting a duff pair I went for it... and got a duff pair!

I don't know what the problem is but, despite being able to bring both sides into focus without difficulty, I can't comfortably get the two circles to merge into one, with the result that I end up with a double image. If I move the IPD wider the double image issue is paradoxically resolved but I no longer see a single circle, and also there's a sort of grey blob / shimmer around the outside edge of the FOV.

I'm assuming there's a problem with collimation, however I don't fancy sending them back given the risk of the same problem recurring. On the other hand I wouldn't know where to begin trying to reset the adjustment - but I'm willing to give it a try if anyone can make any suggestions!   

[Steve Ward]

Just send them back as unfit for purpose. 

[jnb]

I decided to get a pair of inexpensive bins and the Revelation 15x70 looks like a good option at £60 from Telescope House. I read the reviews on Amazon and had a look through this forum as well, and it was mentioned in quite a few places that there is a risk of getting a pair that have not been collimated properly, but despite the risk of getting a duff pair I went for it... and got a duff pair!

I don't know what the problem is but, despite being able to bring both sides into focus without difficulty, I can't comfortably get the two circles to merge into one, with the result that I end up with a double image. If I move the IPD wider the double image issue is paradoxically resolved but I no longer see a single circle, and also there's a sort of grey blob / shimmer around the outside edge of the FOV.

I'm assuming there's a problem with collimation, however I don't fancy sending them back given the risk of the same problem recurring. On the other hand I wouldn't know where to begin trying to reset the adjustment - but I'm willing to give it a try if anyone can make any suggestions!   

" I wouldn't know where to begin trying to reset the adjustment"

In which case I would say send them back. The only reason to hang on to them if that is the case is, if as I did, you treat them as almost disposable and something with which to teach yourself how to assess binoculars and so learn how to collimate them.

[rory]

Yep, send back and I'd request they check a pair before posting. They have a decent reputation so I don't think there would be a problem.

[Planetesimal]

Thanks everyone. It's a shame to have to send them back but I suppose worth one attempt at a return and if the second pair don't work I'll ask for my money back.

Maybe a better plan would be to spend my cash on an AZ-4 mount for the TAL!

[themos]

Well, I got mine from the same place in June 2009 and I never sent them back, just adjusted them (and kept on adjusting them). In the last session I used them (a week ago), I found that I didn't need to use the "collimating" screwdriver on the little grub screws (just as well as I had forgotten to bring the screwdriver with me, a 40 minute drive to a dark site). So, maybe they are settling down...

PS: but yours sound like there's more things wrong with them than simple collimation.

[Planetesimal]

Well, I got mine from the same place in June 2009 and I never sent them back, just adjusted them (and kept on adjusting them). In the last session I used them (a week ago), I found that I didn't need to use the "collimating" screwdriver on the little grub screws (just as well as I had forgotten to bring the screwdriver with me, a 40 minute drive to a dark site). So, maybe they are settling down...

PS: but yours sound like there's more things wrong with them than simple collimation.

Interesting - I'd love to have the skills to be able to do that, but as you suggest, I don't even know for certain that the problem is collimation / alignment. To be honest I'm no expert in the whole binocular area - I'm comfortable collimating the mirrors in a newt but not quite sure how to deal with a twin set of lenses / prisms. I'm not really sure what the problem is, or even if there is a problem... all I know is when I tried them out today I ended up feeling seasick very quickly. I think my eyes were having to work quite hard to combine the double image I was seeing.

Maybe what I should do is look for a shop that sells bins so I can see what a working pair looks like to my eyes (incidentally I've no problems with my eyesight, so I don't think it's me! ).

[NGC 1502]

If the bins are new and faulty, I'd send them back for replacement or refund.

However, the popular 15 x 70s can be fixed with a bit of trial & error.  But if you fiddle with them, then the guarantee will be void........but worth a punt for out of guarantee binos.

Here's the link - http://www.cloudynights.com/item.php?item_id=416

Regards, Ed.

[rory]

Don't mess with them if new. I would let T.H know your sending them back for another pair and ask them to test a pair before sending to minimise the chance if another duff pair.

[Planetesimal]

Right, I can't ignore the weight of advice towards returning them, so they're going back...

I'll let you know how it turns out!

[themos]

By all means, send them back. I was trying to suggest that even if you get a good example, it's quite likely that they will go "off" at some point (due to the cost-saving in construction) and then you'd have to learn how to fix them anyway. 

[Planetesimal]

Great advice by all above, thanks! - I got back to TH and they were very helpful indeed. Even though I'd bought the bins through Amazon they sent a courier to my address to pick up the faulty pair and deliver new ones, which had clearly been extra-carefully wrapped and proved to be perfectly collimated. It worked out well because it gave time for my metal L-bracket to arrive...

Now if only I had the strength of character to get up early enough to train them on some of these comets...