Vintage RearAdjustable Diopter for Diana/Original 75?

[Silvergriffdog]

OK.. putting this in the optimal forum section this time i hope!

A newbie question for someone who is learning...

My Original 75 has the standard rear Diopter and I am toying with changing the eye cup (?) to a modern one with an adjustable aperture and possibly optical correction such as the Gehmann 530. I have taken the measurements I can and I think its M9 or M9.5.... From the Gehmann site for new Diopters I think their new standard thread size is M9.5....

Can any one shed any light here (pardon the pun) and any recommendations . do's donts...Shooting a variety of 6 yard bell target, 10m and >35Yards Vintage comps...

[Jimlad]

Hi
We have quite a few in use in our bell target League, mostly the basic 510 model, just to cope with the different lighting conditions on different ranges, the models with magnification might not be allow in some disciplines, and the Gehmann thread is the same as the original 75, straight swop.

[MDriskill]

As Jimlad said, any Gehmann, Centra, or AHG aftermarket iris will fit the Diana Diopter 75 - as indeed will other brands of OEM eye disks. The Germans did a good job of standardizing this; any Diana, Walther, Anschutz, Feinwerkbau, or Weihrauch sight made since the 1950's has the same eyepiece thread.

An iris can be had with focusing 1.5x magnifying lens, color filters, and polarizer, in any combination desired. The magnifier is of obvious benefit where it's legal! The color filters can improve contrast under some lighting conditions (Centra's "Indoor" iris is specifically aimed at various artificial light sources). I suspect the polarizer is of use when shooting at distance outdoors, but I've never used them much with airguns. All that being said, the basic adjustable opening is of the greatest benefit by far; many competitors even at top-level 10-meter matches use only that.

Note that Gehmann now offers units in the 530 series which have a non-magnifying focusing lens; and also the 570 series that can be dialed in to a specific eyeglass prescription. I don't know bell target rules, but those are legal for ISSF competition (though the tears you shed after paying for one might well blur your view of the target). ☹️

https://gehmann.com/en/Sighting-Equi...Magnification/

https://gehmann.com/en/Sighting-Equi...Magnification/

[Silvergriffdog]

Thank you Jim!

Hi
We have quite a few in use in our bell target League, mostly the basic 510 model, just to cope with the different lighting conditions on different ranges, the models with magnification might not be allow in some disciplines, and the Gehmann thread is the same as the original 75, straight swop.

[Silvergriffdog]

Didn't get to read these until today but thank you for all the advice - I bit the bullet and ordered a 510 which just arrived....