March Scope Update

[BHarvey]

The drums are painted blue. They are painted pretty often for the sake of seeing new holes, or splatter. The holes are of various sizes, from 22-30 caliber, but yes, the holes are larger than they would seem to be because the egdes do fold back.

Conditions at 6 am were as you would expect in Alabama. It was light enough to see the targets, and holes in drums. The sun comes up at the shooters 4 oclock and sets at the shooters 10 oclock. Once the sun started getting up and bringing mirage with it, at about 9 am, the clarity was still excellent. You could count the holes easily. At 10 am, you could still see and count them very easily. At 11 am, mirage starts to get the better of ANY optic and small details get lost. Even Leica's APO spotter struggles on this range. Much over 10x past 11 am and things look more like they do when looking through a digital camcorder, with digital zoom. You know what I mean, clear, optical zoom is good but once digital zoom takes over, it looks more like shaky blocks of color. Mirage on this range will challenge you. Your target will wander around by at least an moa, every direction. Palma can back me up on this.
This range is very flat and is surrounded by tree's and temps get up to 105 with ease. No such thing as a constant wind of any sort. Goes from 1-5 moa value one direction, to the same in another direction, all in the time it takes to load the next round.
I shot an NXS 5.5-22 at this match for 2.5 years, and I can see certain things better with the March, than with the NXS, even in the mirage.

 

[rstreich]

I don't know what caliber Mr. Harvey was shooting, but to resolve a .243in hole at 900 yards,0.026 MOA) that equates to the Dawes resolution limit for a 75mm objective lens. The March has a 52mm objective which would have a Dawes resolution limit of 0.037 MOA which equates to a 0.350in hole at 900 yards.

Fred, maybe this is a case where you need to apply the Optimistic Sparrow Limit: 0.022 MOA,0.211" at 900 yards) for the 52mm objective at 42x.

Jeez it's fun to pretend like you know what you're talking about

Personally, I don't see any use for side focus in a fixed-yardage competition. That's the one feature of the March that always puzzled me.

 

[Fred Bohl]

To Mr. Harvey in particular and all

First - Let me say my post on resolution of bullet holes was not meant as a critique of or challenge to Mr. Harvey's observations. If anyone inferred that from my post I am very sorry.

Second - The intent was to point out that there are real physical limits on optical performance even for the best quality devices. As we get near these limits it is very important that we are careful in our choice of terminology, selection of standards of performance and description of observing conditions. This post was one that I obviously erred on the side of brevity,rare for me) and should have made my intent more clear.

Third - Robert has an excellent point that I may have not chosen the most applicable standard for resolution limit,fell into my own trap on selection of standards of performance). It may be that the March optics can beat the Dawes Limit of Resolution,very doubtful but I'm open to proof) and/or that Mr. Harvey has better than normal visual acuity,common for the better competitive shooters).

LAST - Mr. Harvey, thank you for your clarification of your observation conditions. For me at least that adds so much to my understanding of your March scope performance report. I also found your description of "seeing" conditions and changes over time thereof very helpful. Please join in my thread Spotting @ Long Range - Beating Bad Seeing at http://www.websitetoolbox.com/tool/post/6mmbr/vpost?id=2067783. You could probably contribute much observational insight to that project.