What contributes to Parallax Sensitivity?

[Austinma62]

Like the title states... what are all of the factors that go in to determining how sensitive a parallax adjustment/ sensitivity of the scope?

Objective lens diameter?
Max zoom?
Min through max zoom range? The erector ratio?
The scope design itself with the internals?

I've done a lot of reading and this is what I've read somewhat so far. However I'd like a better, more scientific explanation. Which scopes/ scope manufactures are know for quality parallax adjustments?

I have an athlon cronus btr 4.5-29x56
Swfa ss fixed 10x42
Bushnell 4x12x40

The cronus is by far much more difficult to setup and eliminate parallax and it is also much more expensive than my other scopes. So I'm curious what factors go into parallax? I'd like to have a scope with a decent magnification range for hunting and some long range shooting, but have it easy to adjust to where in not spending 1 minute each time I shift distances reseting the parallax while my target runs away.

 

[rhsc]

By no means am I an expert on optics, but my reading leads me to suspect that high erector ratios, shorter scope designs and other currently popular features can often result in compromises in parallax sensitivity, chromatic aberration and other issues. Maybekoshkin will see this thread and provide a more informed perspective about your question. Tagging in.

 

[Austinma62]

By no means am I an expert on optics, but my reading leads me to suspect that high erector ratios, shorter scope designs and other currently popular features can often result in compromises in parallax sensitivity, chromatic aberration and other issues. Maybekoshkin will see this thread and provide a more informed perspective about your question. Tagging in.

Which brands, or scopes would be good ones to go with that are easy and quick to adjust for parallax? I'm looking for a scope with a decent low end mag, 4x to 5x with a good amount up top, probably 15x-25x range overall?

 

[Glassaholic]

Which brands, or scopes would be good ones to go with that are easy and quick to adjust for parallax? I'm looking for a scope with a decent low end mag, 4x to 5x with a good amount up top, probably 15x-25x range overall?

Do you have a budget? Any weight or size requirements for the scope beyond the magnification?

If money is no object then I would steer you toward Tangent Theta and ZCO these are some of the most forgiving scopes out when it comes to DOF and parallax. For slightly less money look at Tangent's younger sister - the Minox ZP5 (both Tangent and ZP5 were designed by the same company - Optronika which is now GSO), I would also throw Nightforce, Vortex AMG and the Schmidt 5-25 into this price range as well. The next tier down is going to be the Vortex Gen II 4.5-27 which used to be around $2400 but can be had new for well under $2k now making it an excellent bargain. I just obtained a Burris XTR III 5.5-30x56 and have been quite surprised at the performance for a scope that sells used quite often for under $1500, but I need a lot more time behind it to make a fair assessment.

As for what designs make for a more forgiving DOF and parallax, ILya is really one of the best to address this, but you are correct that objective size, magnification/erector ratio and the length all play a part with how finicky the parallax can be in a particular scope.

I think what you are looking for are the scopes that have the history of being "set it and forget it" where you can set your side focus to 300-500, for example, and find that everything from 200-1000 is essentially in focus and parallax free - this is what I call forgiving DOF and parallax. In general the "shorter" scopes tend to struggle with this more and in this arena you really get what you pay for as the more forgiving ultra short designs have been ZCO 4-20, Schmidt US 3-20/5-20 and Kahles K318i. In my signature is a link to an alpha class ultra short review I did last year and I specifically dealt with DOF and forgiving parallax.

 

[Austinma62]

Do you have a budget? Any weight or size requirements for the scope beyond the magnification?

If money is no object then I would steer you toward Tangent Theta and ZCO these are some of the most forgiving scopes out when it comes to DOF and parallax. For slightly less money look at Tangent's younger sister - the Minox ZP5 (both Tangent and ZP5 were designed by the same company - Optronika which is now GSO), I would also throw Nightforce, Vortex AMG and the Schmidt 5-25 into this price range as well. The next tier down is going to be the Vortex Gen II 4.5-27 which used to be around $2400 but can be had new for well under $2k now making it an excellent bargain. I just obtained a Burris XTR III 5.5-30x56 and have been quite surprised at the performance for a scope that sells used quite often for under $1500, but I need a lot more time behind it to make a fair assessment.

As for what designs make for a more forgiving DOF and parallax, ILya is really one of the best to address this, but you are correct that objective size, magnification/erector ratio and the length all play a part with how finicky the parallax can be in a particular scope.

I think what you are looking for are the scopes that have the history of being "set it and forget it" where you can set your side focus to 300-500, for example, and find that everything from 200-1000 is essentially in focus and parallax free - this is what I call forgiving DOF and parallax. In general the "shorter" scopes tend to struggle with this more and in this arena you really get what you pay for as the more forgiving ultra short designs have been ZCO 4-20, Schmidt US 3-20/5-20 and Kahles K318i. In my signature is a link to an alpha class ultra short review I did last year and I specifically dealt with DOF and forgiving parallax.

Lots of good info here! Well I don't have a budget per say, but I don't want to spend a ton of money either. I'd really like to keep it in the $2k to $3k range. Also weight is not a huge issue, but a lighter scope would be a plus. I am mostly concerned about my ability to take it hunting and engaging in shorter ranges, moving targets, but also having the ability to reach out to 1000+yards.This is going on a 6.5 creedmoor.

I have heard about Tangent scopes on a write up someone did looking for the best mountain hunting scope. Sounds like an amazing optic! However I believe it is in the neighborhood of $4k+.

So what are your thoughts on the NF Atacrs? Specifically the 4x16-50 34mm tube and 5x25x56 34mm main tube? the 4x16 is lighter, and probably more forgiving of parallax wouldn't you say? And a bit cheaper.

All in all, I don't mind adjusting parallax somewhat. I just don't want to be on the range constantly dicking with the scope trying to get it perfect at various ranges, taking a lot of valuable time, and potentially missing a shot because its not dead on.

 

[Glassaholic]

^^^ That helps. Yes, TT's are typically upwards of $4k, every once in a while you see a used 3-15 go for just under $3k but that is the exception and not the rule. Given your parameters I think you would probably like the ATACR 4-16, they are good scopes. So are the 5-25's but here's my issue with the 5-25, the FOV at low magnification is pretty poor and I gravitate towards scopes that have better FOV for my style of shooting. Something like the Minox ZP5 5-25 which has glass close to TT (they share the same design parameters) but offers quite a bit more FOV than the NF ATACR 5-25, the Minox is also 4oz lighter than the NF since you said you would prefer a "lighter" scope. I currently have the Minox ZP5 and can attest it has the most forgiving DOF and parallax I've ever used in a scope, my buddy's have Tangent's but you'd be hard pressed to tell the difference optically. If you're looking at the ATACR 4-16 I would also recommend you take a look at the Kahles K318i, it is a 3.5-18x50 scope and for an ultra short design has forgiving DOF and parallax. I also have a ZCO ZC420 that was sitting atop my 6.5 Creedmoor but I think I'm moving it over to my 7mm SAUM to play a similar role as you're talking about, the DOF and parallax in this scope is remarkable for an ultra short; however, it is above $3k and it's a little brick at almost 35 oz.

Figure out which reticle you like the most for the intended purpose of your rifle, if you'll be hunting with it as you say, my preference is for either no Christmas tree or if it has a tree reticle then it needs to be dots so it does not obscure the image. For example: Minox MR4, Vortex EBR-7c, Nightforce Mil-XT and the like. Reticles like the Kahles SKMR3 and ZCO MPCT2 with their solid Christmas tree lines is too predominant for my tastes (again, for a crossover hunting/long range scope), but that's just it, it is personal preference so you've got to decide for yourself what is going to work best for you. If you stay away from high magnification and short scope designs like the NF NX8 2.5-20 and the March 3-24 then you should do pretty well on getting decent DOF and parallax with your price range for many scopes you will find there.

 

[Stoweit]

Wjm308 is very knowledgeable and spot on with his advice. I had the K18 and it was very easy to adjust. Once was shooting between 400,600,and 800 meters. Shot the 600 first and forgot to move the parallax. I shot the 800 target, then 400 , parallax and DOF remained clear on all shots. I was very impressed, wish I still had it.