Where should Parallax be set for Do-All rifle?


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itgoesboom
July 10, 2005, 09:06 PM
So, yes, another optics question.

I am purchasing a Mueller 2-7x32 scope to mount on my CETME, which is my range/SHTF/fun rifle.

I want it to be set up for 25m-600m, since it's my go-to, do-all rifle.

The scope doesn't have an Adjustable Objective, which is probably ok, since that would slow down use of it, and it is Parallax Free at 100 yards.

But the company has offered to set it to whatever distance I want, as long as I let them know before the morning, when they are going to ship it out.

So, should I keep it set at 100yards? Or should I have them set it for a different distance? 200 meters? 250 Meters?

What do you think?


I.G.B.

BTW, this is the scope I am getting.

http://www.muelleroptics.com/multi-shot.htm

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mattw
July 10, 2005, 09:25 PM
what exactly is parallax? i seem to think that it only has to do with objective lenses larger than 40mm.. i admit i am probably wrong. sorry i don't have an answer for you but maybe somone has an answer for me? parallax, huh?

set the scope for 250-300 meters maybe? less than that you can use iron sights, more than that is uncommon right?

Joejojoba111
July 10, 2005, 09:57 PM
Wikipedia:
"
Parallax and measurement instruments
If an optical instrument telescope, microscope, theodolite is imprecisely focused, the cross-hairs will appear to move with respect to the object focused on if one moves one's head horizontally in front of the eyepiece. This is why it is important, especially when performing measurements, to carefully focus in order to 'eliminate the parallax', and to check by moving one's head.

http://upload.wikimedia.org/wikipedia/en/2/2e/Parallax_Example.png
"
I got a cheap red-dot sight, and it does have parallax, but it's for paintball. I also bought a more expensive (but on clearance without packaging) Bushnell 3-9x, and it doesn't. When I look at the costs, I paid maybe a little too much for the $20 red-dot, and not enough for the Bushnell (about $80-90, at cost).

edit:
To clarify, without moving the paintball marker, I just move my head around and the dot moves around, it doesn't stay centered. Those magicians at Bushnell figured out a way around this.

Oh, also had one of those tiny air-rifle scopes, 4x or so, and it had very little parallax, not bad for free.

Vern Humphrey
July 10, 2005, 10:04 PM
Parallax is the apparent displacement of objects relative to each other caused by a change in the observer's position. Imagine looking down a fence -- all the posts are lined up. Now take a step or two to one side, and the posts are no longer lined up, but seem to have moved.

In a rifle scope, parallax means if the scope is held fixed on a target, and you move you head, you will see the crosshairs move on the target.

It isn't possible to be parallax-free at all ranges. Scopes are adjusted to be parallax free at one range -- in a scope meant for .22 LR, typically at 50 yards. For scopes meant for centerfires, it's usually 200 yards (which will explain why 200 yard groups are much better than you would expect from looking at 100 yard groups shot with the same scope.)

Depending on how much you intend to shoot at long ranges, I'd have the parallax set at 200 to 300 yards.

rbernie
July 10, 2005, 11:26 PM
For scopes meant for centerfires, it's usually 200 yards I'm pretty sure that all of my non-AO scopes (Nikon, Burris, Sightron, Leupold) were advertised as being set parallax-free at 100 yards.

itgoesboom
July 10, 2005, 11:30 PM
Rbernie,

Has that ever effected you at longer ranges?

I.G.B.

itgoesboom
July 10, 2005, 11:33 PM
Double tap

rbernie
July 10, 2005, 11:43 PM
Has that ever effected you at longer ranges? Well, no - but that's probably because I really don't shoot longer ranges. Every deer I've shot has been less than 250 yards away. It's awful hard to tell how much, if any parallax was a factor in the POI when you factor in the wind, buck fever, and all of the other variables of shooting in the field. On top of that, all of my local paper-punching ranges are all 100 yards so I can't really evaluate the 'text book' side of this in a controlled environment....

Frankly, it just never really seemed to matter - I pretty much hit what I aim at and that's what I'm after.

Peter M. Eick
July 11, 2005, 07:50 AM
My experience with AO adjustables is that the distance on the adjustment does not match well to reality.

My suggestion is to bench the gun very solidly. Now without touching the gun, look through the scope and focus on a target at the distance you think it should be set with no parallax (probably for general work, say 150 yards or thereabouts). Now move your head a bit. Does the crosshairs move on the target also? If yes, adjust the AO/Parallax adjuster and do it again. Once you get it set right, moving your head will have no impact on the point of aim.

This has worked for me.

JohnBT
July 11, 2005, 09:30 AM
FWIW, from the Leupold.com Answer Guide:

Our scopes are set to be parallax free at the following yardages:

Handgun scopes - 100 yards
Shotgun scopes - 75 yards
Rimfire scopes - 60 yards
Hunting scopes - 150 yards
M8 2.5x20mm Compact - 100 yards
Turkey Ranger - 40 yards

Father Knows Best
July 11, 2005, 10:12 AM
Burris sets all of its non-adjustable scopes to be parallax free at 100 yards. I have a non-adjustable Burris Signature 3x-9x on a .22LR rifle that I frequently shoot at 50 and 75 yards, and have never found parallax to be a problem.

taliv
July 11, 2005, 11:11 AM
+1 what peter said


but to answer the question, it depends on where you're going to be shooting most of the time. if you live in the desert and shoot 300 yrds a lot, the answer will be a lot different than east tennessee, where the foliage is so dense this time of year, you're better off with an ACOG on your SHTF machette.

just keep in mind that at shorter ranges, parallax will be less important, practically. i.e. if parallax causes you to be off 1 inch at 50 or 100 yrds, do you care? depends on whether you're shooting paper or zombies

Rockstar
July 11, 2005, 11:21 AM
Just a wild thought: Borrow a $1000 scope from somebody and mount it on that CETME. Shoot a few groups @ 600-800 yds. and get back to us with the results. ;)

itgoesboom
July 11, 2005, 12:48 PM
Rockstar...

That is a great idea!! Anyone have a $1,000 scope they want to lend me? But really, 600 yards is as far as I would ever want to shoot.

Although I am sure you were being sarcastic, here is a photo that shows my rifle and what it can do. 75 yards, group is 1 1/4" center to center. And I have gotten several groups <1" at 75 yards.

I think it would do just fine at 600 yards.

http://www.thehighroad.org/attachment.php?attachmentid=25091&stc=1



Mueller got back to me this morning, and told me that they can change the parallax setting closer, but not farther away on the non-AO scopes, but that 100 yards should be fine.

So that is what I am going to go with.

I.G.B.

GunGoBoom
July 12, 2005, 12:43 AM
That should work, IGB. Nice gun and nice shootin. I too have a 2-7x32 on my so-called "MBR", the saiga .308. It's a Bushnell elite 3200. IINM, most makers put theirs at 100, whereas Leupold's of 150 for riflescopes, while making more sense arguably, are in the minority on that. Their ranges for Para-free make sense, except the shotgun, which should be about 50 yards, like the "turkey" scope (40 yds), which is, after all, for a shotgun. The handgun scope arguably ought to be 75 instead of 100, but either is fine since they're both compromises.

My *understanding* from my limited knowledge, is that, for shooting at ranges *shorter than* that for which your scope is set to be parallax-free, the amount of parallax error greatly increases, to be logarithmic-like increases at very short ranges, whereas when shooting at ranges *longer than* the para-free point, the actual magnitude of the parallax error only slightly increases - anyone know for sure?

Rockstar
July 12, 2005, 02:05 PM
Meant to be humorous, more than sarcastic. I don't think it'll much matter what quality scope you use @ 600 yds. I'm betting you won't shoot a 1' group at that range.

itgoesboom
July 12, 2005, 02:34 PM
Rockstar,

Nope. But not trying to.

I will be happy with a group smaller than 10-14" at that range.

I.G.B.

Gun Go Boom,

Thats kinda what I was thinking. I figure I will have plenty of time to use the cheekpad to get a good, consistant cheekweld for longer shots, but that shorter range shots I would need to be quicker (atleast if I shoot any competitions).

BTW, nice name.

I.G.B.

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