In looking for the relationship between reticle movement/first-focal-plane reticles and image movement/second-focal-plane reticles, I have come across the long erector tube between the ocular housing and the adjustment turrets.

I do not recall seeing one of these things during my youth of pulling things to bits when they didn't work any more. Sure, the only scopes I dismantled were cheap image-movement fixed-powers but I am pretty sure the old Pecars did not have the reticles inside such a tube - because they were user-replaceable.

The modern nomenclature seems to come with some acceptance that the reticle is mounted either in the front of or at the back of this tube, suggesting that the tube doubles as a field stop that will, in either system, give a constantly centred image at expense of the field of view.

If nothing else is known here on this, is it possible to wind the crosswires out of centre in modern Swarovskis and Zeisses that have the FFP magnifying reticles?

OK, if no one here knows the answer to the first question, what about the second one?

Is it still possible to get the reticle out of centre with modern Swarovski and Zeiss scopes that have them in the first focal plane?

quote:

Is it still possible to get the reticle out of centre with modern Swarovski and Zeiss scopes that have them in the first focal plane?

Yes, laboratory tests of a German hunting magazine have showed very big influence on cheaper brands. With Swarovski and Zeiss it was OK, but still not zero: If I remember right it was around up to 8-10 mm offset due to second plane shift. With cheaper brands it was a couple of times more: up to 8 cm !!!

These links aren't any good for me as I don't speak German. Anybody that could provide info in English would be appreciated.

That's interesting scubapro - I'm still wondering about what it means and have stored a long reply until I trawl another optics forum for info.

Do you think these erector tubes are anything to do with the move to 30mm scope tubes?

Well, after a getting nowhere much searching ordinary word references, I finally got to accessing prior art cited in recent US patents. I notice Rudolf Noske's 1936 "Sighting Device" appears to have had a fixed erector set and that Weaver had thought of the long, moving erector tube by the 1960s.

I was interested in Noske's patent assertion that heavy, adjustable parts in a scope were most likely to move under recoil, so he made his reticle as light as possible.

Elsewhere I have found that Swarovski are concerned with this problem to the point where they use a number of coil springs at the rear of the erector tube rather than flat springs along the side. Another maker (S&B?) prefers flat springs, however, believing they are less likely to retain a memory.

All this now makes me wonder about my missing a certain chamois last year and then discovering the 4-16 Nikon Monarch was out three inches (76mm) at 25 paces. I had bumped the scope on the walk into the hunting ground but forgot to bore sight it afterwards. It was not a hard bump, certainly nothing my old Pecar and Kahles reticle-movement variables had ever been bothered by and I had blamed scope size and alloy mounts at the time - but now question if it could have been anything to do with the erector tube mass. Could the large range multiples be anything to worry about? That is to say: could a scope set on a higher (or lower) power have more erector-set inertia at play in the case of a bump?

- Paul