Dioptre correction oddity (1 Viewer)

[lebiffo]

I've just had a cataract operation on my right eye and have had to recalibrate the dioptre corrections on my bins. As a result of doing this 'en mass' I have picked up an oddity which I had not noticed before. The correction of +2 dioptres on my Zeiss 8x42 HT Victory is exactly opposite to the -2 dioptres correction on my Leica 10x42 BA Trinovid, Swarovski 8x32 EL and Zeiss 7x42 B Dialyt, (sorry if this set of bins sounds dude-ish, just trying to be precise here). So my questions are, have my Zeiss 8x42 been set up wrongly or does it reflect a change in protocol by this manufacturer and anyway, does it really matter as long as the correction enables me to focus properly? The Zeiss 8x42s work perfectly well with the +2 dioptre adjustment and I am more than satisfied with the performance of these bins.

 

[lebiffo]

Addendum

I should add that in order to satisfy myself that the calibration scale is just reversed, i.e. positive instead of negative and not 4 dioptre out! I have done the following: with the dioptre setting at zero I have looked through each eyepiece in turn with my right eye only and was reassured to find that the focus setting was the same for each eyepiece.

 

[Dale Forbes]

I've just had a cataract operation on my right eye and have had to recalibrate the dioptre corrections on my bins. As a result of doing this 'en mass' I have picked up an oddity which I had not noticed before. The correction of +2 dioptres on my Zeiss 8x42 HT Victory is exactly opposite to the -2 dioptres correction on my Leica 10x42 BA Trinovid, Swarovski 8x32 EL and Zeiss 7x42 B Dialyt, (sorry if this set of bins sounds dude-ish, just trying to be precise here). So my questions are, have my Zeiss 8x42 been set up wrongly or does it reflect a change in protocol by this manufacturer and anyway, does it really matter as long as the correction enables me to focus properly? The Zeiss 8x42s work perfectly well with the +2 dioptre adjustment and I am more than satisfied with the performance of these bins.

Roger, the 4 dioptre difference does seem rather far off but generally the scale is not meant to correspond to any real measurements but just an aid for you to find your sweet spot on that particular pair of binoculars. There is variation not only between models, but also units. This means that another pair of Dialyts or Trinovids for that matter might almost arbitrarily land you at +1 or -2/3. Important is that the image works for you so if your new Victories work well at +2 then my guess is there is nothing to worry about and you can continue to just enjoy them.

 

[ceasar]

Most of my binoculars show that I need a correction in the neighborhood of minus 1, but a Nikon 10x32 LX L which I used for years required a correction of plus 1 to work properly for me.

Bob

 

[lebiffo]

Thanks Dale and Bob that's very helpful. I guessed it was nothing to be concerned about but I had read somewhere, I think on a binocular web page, that once you had set your dioptre correction on one pair of binoculars that setting remained good for all of your others, something which is patently wrong.

Thanks again

 

[lebiffo]

Just to close this one off. I sent a query to Zeiss Customer Support asking if the dioptre scale on the Zeiss 8x42 HT Victory is reversed when compared to the other models I have referred to above. I had a reply which as you might expect was a bit guarded, it thanked me 'for pointing out the variation' and the import would seem to be that, yes it is reversed but this does not matter, 'as the setting is fine and will work for you', which of course is quite correct.

 

[ronh]

Roger,

It is easy to check whether the scale is actually reversed. The setting indicates the difference from the left barrel to the right barrel. If the scale reads the correct direction, if you pull out the knob and get into the diopter setting mode, and look through the right barrel, then moving the knob to make the reading more negative (or, if the value indicated is positive, making it smaller) should bring the point of focus to nearer distances.

The concern is not with the number your knob indicates. As long as you can reach the correct adjustment for your eyes, who cares? The concern is that such a good binocular was likely set correctly at the factory, but has slipped, and may still be slipping. Slipping diopter is a common problem, and easily fixed. Watch it close for a while for frequently needing tweaks, always in the same direction. That would be a case for repair, because if that continues the required setting will eventually reach and go beyond the end of the knob's range and it will become unusable.

Ron

 

[lebiffo]

Ron,
Apologies for the delay in replying to your very helpful post. I've checked the binoculars and moving the knob in a negative direction does bring the point of focus nearer. I've recently had my eyes checked and the difference between the right eye and the left is 1.75 dioptres the same as the scale reading on the binoculars which has remained constant. So it's just the eye that is used as the stating point that determines whether the reading is positive or negative. Taking my right eye as a base, the correction on my left eye is a net +1.75 dioptres more and of course vice versa.

 

[ronh]

Roger,

Thanks for the check back. I believe I follow you. If I may restate your final sentence the other way, taking your left eyes as the base, your right eye differs by -1.75 D. In order for the binocular to compensate for this, its right barrel must differ from the left by +1.75 D. The left to right barrel difference is what the knob on the FL reads, so its setting makes sense.

What's up with your other three embarassingly dudeish binoculars beats me. Lots of dudes here, if you've got it, flaunt it!

Ron

 

[lebiffo]

What's up with your other three embarassingly dudeish binoculars beats me.

Ron

Ron,

I suppose it depends whether the point on the scale refers to the difference that requires correction or the actual correction itself. Anyway many thanks for indulging me in this rather OCD ish but nevertheless enjoyable thread