Adjusting Gehmann 579 sight for astigmatism

[Mtl_Biker]

I'm hoping someone here can help me with this...

I've got a new Gehmann 579 sight with 570 iris and want to set it up properly. (I need correction for astigmatism as well as vision.)

My dealer is absolutely outstanding (Cibles Canada Targets) and I've bought a ton of stuff from them including a match pistol and match rifle. They're terrific. But on this one thing they've kinda let me down. I asked them about how to adjust the 579 properly and they answered that they didn't know and pointed me to the online Gehmann PDF manual on the product. The manual gives steps for a "rough" setting of the adjustments based on your prescription but that fine tuning is to be done with a "ray diagram". But there's no info about HOW to use the ray diagram to do this. (The manual also says that the ray diagram can be downloaded from their site, but searching there high and low doesn't turn it up.)

I want to know how far away the diagram should be. Should the sight be mounted on the rifle (my assumption is that it should be), meaning that you'd then be looking at the ray diagram through the front sight also. It seems to be that some information is lacking on this in the manual.

So I emailed Gehmann directly to ask them. They replied that I should talk to their "Canadian agent", Cibles Canada Targets. So now I'm in an endless loop, without any answers to my questions.

Does anyone here have experience with this?

[tjballing]

Hi,

Gehmann has some videos at their homepage explaining how to set the sight up properly:
http://gehmann.com/english/videos.php

I think the video you're looking for is:

https://youtu.be/0XekJ6ZfKQ0

Yes, the sight should be mounted on the rifle (otherwise your achse is for sure not at the right spot)

The german description says, that the "star" should be at least 10m away.

"The ray diagram finally shows if all values have been adjusted correctly. You should attach the
ray diagram against the wall. All testing bars have preferably to be black and uniformly shaped.
Adjusted cylindrical values are not correct if the radially-shaped bars are partially black and grey.
The different values can be varied for correction accordingly."

The ray digaram is at page 6. http://gehmann.com/manuals/579-deutsch-english(1).pdf


Hope this helps to get out of the endless loop;).