Dioptre Question

[Fantomas]

Hi

I am looking to buy a new pair of Bins. after my Busnell 8x40 Natureview "went missing". They will be mainly used for local birdwatching in woodland, moorland and on some reservoirs rather than sea watching and long distance stuff.

I am can only spend around £150 max. and I am considering the Hawke range. I will be going to test some in the shop soon.

I am just interested if somebody can give me some info. on what the dioptre lens is. I never really took much notice of it before on my Bushnells.

Also, is the difference between Roof prism and Porro Prism more about the shape, style and feel of the binoculars are is there likely to be a sifnificant difference in quality at admittdly Budget end of the market.

As I said I will be having a look through a few before buying but would like a bit of info. before I go to the shop.

Many thanks

[Lancashire Lad]

Hi Fantomas, and welcome to WAB.

The dioptre lens is there so that you can ensure perfect focus with both eyes.

To set the bins up, you focus on a subject using your eye and the lens that doesn't have the dioptre adjustment, (usually left lens/left eye).

You will now probably have the situation where your left eye (view) has good focus, but your right eye (view) might be blurry.

Without changing focus, adjust the dioptre ring until your right eye also has perfect focus. Having done that, both eyes should be seeing the best possible focus.

Regards
Mike.