Pentax correction lenses - I really need help here!

[rayfoxlee]

Please can the learned membership help me with how to arrive at the right viewfinder correction lens for Pentax M cameras which have a -1 dioptre eyepiece, as standard. I can find no definitive guide on the web. First, I am unsure whether I need the reading for distance or near vision from my optician’s prescription, although it seems logical (perhaps!) that it should be the distance reading – is this right or wrong? Assuming it is for distance, my prescription is for +1.25 dioptre of correction, so is this the power of the correction needed or does the -1 dioptre fitted as standard have to be taken into account?

Even with these two points clear in my mind, find the right correction lens might be challenging.

Thanks in anticipation.

Ray

 

[sojournerphoto]

I think, but hope others will confirm, that if you have good distance vision (I.e. 0 correction) then you need a -1 diopter eyepiece lens. So if you add 1.25 to -1, then you would want a 0.25 diopter eyepiece lens - that might need to be approximated by a 0 depending on what they make and your sensitivity.

Fwiw, I bought a Nikon FM2T that had a 0 eyepiece and could t get on with it until I replaced it with the standard -1. My shooting eye requires no correction for distance since I had cataract surgery a few years ago, but can’t adjust to focus more closely.

Mike

 

[Retro-Grouch]

I can offer my experience. My prescription is for -2.25 diopters, for nearsightedness. A -2 diopter eyepiece give me ideal correction on my Pentax MX; perhaps that can help you extrapolate from your prescription. I loathe shooting with glasses, so I've gone to great lengths to find corrective diopters for every camera that will accept one. In doing so, I've found that the manufacturers' specs for the standard eyepiece don't always mesh with my experience. Sometimes a bit of trial and error is necessary, but fortunately, Pentax diopters are plentiful and relatively inexpensive on eBay.