Rifle Scopes Parallax setting mechanics, how does it works?

[Peter83]

Hi guys. I have a Vortex Viper PST gen2 5-25x50. I was wondering how the parallax setting mechanical works inside the scope. I am interested if its possible to "wear" any parts in the scope when dialing on the parallax setting? Is there any parts inside that is prone to wear if the parallax is dialed ALOT back and forth?

Peter

 

[koshkin]

The last lens in the objective lens group moves front to back a little. Like with anything mechanical, it can be worn out to a certain degree, but that will take a LOT of work.

ILya

 

[Lowlight]

it does have a separate lense and can be out of tune, but wearing is a bit extreme, though not impossible. Also if your front rings are tight or out of spec they can bind that lens causing issues.

There is a cheater lens in front of the erector that is moved to bring the target image into focus and helps with parallax.

Some times they are out of spec and will not work correctly. if you have a screw on the parallax knob like your elevation or windage you can maybe try to adjust it, but I don't know with that model scope if you can move it or if it's locked in place?

Also if your diopter is not properly focused that can throw the image out of whack too, you have to set up the scope with the diopter first then the parallax focus should be better throughout the adjustment range.

Lens in front of the turret, the tiny one inside

 

[Peter83]

Thanks alot guys! But how does the lens inside the scope moves? I figure there must be some threads, small gears or something like that?

 

[Lowlight]

It pushes against the spring here,

the mechanics are a bit flat but the lens does not move far,

 

[Peter83]

the mechanics are a bit flat but the lens does not move far,

Thanks alot Is it generel how the side parallax setting works on all scopes? Im not sure i know what you mean when you say the mechanics are a bit "flat"?

 

[Peter83]

When i first got the scope, it felt like the parallax was a little inconsistent in the resistance it took to turn it, so i thourgt it might be grease that needed to be spread out internally. Therefore i worked that parallax back and forth alot, and it worked. However, it did take a long time with a lot of dialing the parallax turret back and forth, and i cant help but wonder if i have introduced wear on the internal mechanics.

 

[Peter83]

The last lens in the objective lens group moves front to back a little. Like with anything mechanical, it can be worn out to a certain degree, but that will take a LOT of work.

ILya

it does have a separate lense and can be out of tune, but wearing is a bit extreme, though not impossible. Also if your front rings are tight or out of spec they can bind that lens causing issues.

Thanks both When i first got the scope, it felt like the parallax was a little inconsistent in the resistance it took to turn it, so i thourgt it might be grease that needed to be spread out internally. Therefore i worked that parallax back and forth alot, and it worked. However, it did take a long time with a lot of dialing the parallax turret back and forth, and i cant help but wonder if i have introduced wear on the internal mechanics.

 

[Lowlight]

By flat, the layers in the tube wall are what move,

See those extra silver layers that lay flat, there

 

[koshkin]

Thanks both When i first got the scope, it felt like the parallax was a little inconsistent in the resistance it took to turn it, so i thourgt it might be grease that needed to be spread out internally. Therefore i worked that parallax back and forth alot, and it worked. However, it did take a long time with a lot of dialing the parallax turret back and forth, and i cant help but wonder if i have introduced wear on the internal mechanics.

If you managed to introduce significant wear, parallax will start shifting with recoil. If after you fire a string of shots there is no significant parallax shift you are likely fine.

Another potential symptom is to see if the mechanics wore out to the point when there POA shift as you adjust parallax, but to be able to check for that you would have to stop down the aperture significantly.

ILya

 

[Peter83]

Another potential symptom is to see if the mechanics wore out to the point when there POA shift as you adjust parallax, but to be able to check for that you would have to stop down the aperture significantly.

Actually, i checked if the POA moved when adjusted the parallax when the scope was brand new, and POA have always shifted slightly down when setting the parallax at lowest and dialed to infinity. I have seen this in many scopes, so i think its normal? How much dialing back and forth, back and forth do you think it would take to hurt anything? Im not quite sure what you mean by " you would have to stop down the aperture significantly", sry, english is not my main langue ;-)

 

[koshkin]

Actually, i checked if the POA moved when adjusted the parallax when the scope was brand new, and POA have always shifted slightly down when setting the parallax at lowest and dialed to infinity. I have seen this in many scopes, so i think its normal? How much dialing back and forth, back and forth do you think it would take to hurt anything? Im not quite sure what you mean by " you would have to stop down the aperture significantly", sry, english is not my main langue ;-)

As you rack through the parallax know while looking at a stationary target you are inducing focus shift and associated parallax issues. Because of that, it is very difficult to figure out if you are seeing parallax or POA shift. Your eye would have to be perfectly on the optical axis and not moving which is not practical. If you put a small limiting aperture onto the objective, you get much greater depth of field and much smaller exit pupil, so you can clearly see the target in good light at any parallax setting.

ILya

 

[Peter83]

As you rack through the parallax know while looking at a stationary target you are inducing focus shift and associated parallax issues. Because of that, it is very difficult to figure out if you are seeing parallax or POA shift. Your eye would have to be perfectly on the optical axis and not moving which is not practical. If you put a small limiting aperture onto the objective, you get much greater depth of field and much smaller exit pupil, so you can clearly see the target in good light at any parallax setting.

ILya

Yeah, that makes sense. How much would you think i would have to turn the parallax back and forth before it hurts anything? I did spend quite alot of time dialing on the parallax to try and even out any grease inside as i mentioned.

 

[koshkin]

Yeah, that makes sense. How much would you think i would have to turn the parallax back and forth before it hurts anything? I did spend quite alot of time dialing on the parallax to try and even out any grease inside as i mentioned.

Noone knows for sure how much it would take and it would vary from scope to scope. Unless there is something obviously wrong in how it functions now, I would not worry about it.

ILya

 

[Guthwine]

Usually if the parallax mechanics are damaged it is instantly noticeable and most often a catastrophic failure.
I think wear is not really an issue in this area since the mechanism is basically two gliding, well fitted "pipes". I would not expect it to be a problem in a userlife if it is well made.

 

[Ratch_V]

It varies based on how the internal mechanics are designed in a scope, but usually the amount of moving parts in a parallax adjustment is less than the amount of parts moving when you adjust magnification.

The most common failure in a side parallax adjustment I have seen, which is a very uncommon failure point, has nothing to do with over use or design, its people who mount rings wrong and pinch the tube. If the portion of the tube that the lens controlling parallax moves in is pinched or crushed, it wont be able to adjust correctly or at all.

 

[Denys]

ILya described an adjustable objective (AO) where you focus the scope by twisting the objective lens and lowlight described a side focus (SF) which uses an extra lens in the scope just as he described. These are two different methods of doing the same thing.

There are many scopes that experience some amount of backlash with the side focus knob and to counteract that, it's a good idea to go back to infinity and then focus on the distance you need, rather that change directly from one distance to the next. This is especially so in lesser scopes than the very top tiers.

Also, the progression is logarithmic, which is why close distances have more focus travel whereas longer distances have very minimal travel. The movement of that extra lens inside the scope is very short, in the order of millimeters.

 

[Peter83]

Thanks all, its great to learn about theese things!

 

[Peter83]

but usually the amount of moving parts in a parallax adjustment is less than the amount of parts moving when you adjust magnification.

Great to know Would you say, that with the moving parts with the magnification adjujstment, that its possible or prone to wear in that area ( i know it depends on scope model and so on, but generally speaking )

 

[Ratch_V]

Great to know Would you say, that with the moving parts with the magnification adjujstment, that its possible or prone to wear in that area ( i know it depends on scope model and so on, but generally speaking )

Everything wears down eventually, but for perspective I've tested scopes that are 30 years old and still adjust and hold zero just fine. In general, how you treat a scope is going to have far more of an impact on its longevity than its design.

 

[Denys]

Great to know Would you say, that with the moving parts with the magnification adjujstment, that its possible or prone to wear in that area ( i know it depends on scope model and so on, but generally speaking )

I wouldn't say that. The mechanisms are different. A magnification adjustment (zoom) is accomplished by twisting the inner tube which causes a couple lenses in the tube to move along grooves and thus go forward or back. The AO is similar where twisting the objective just moves a lens forward and back. Those motions are direct and they have been used in camera lenses for decades and they get exercised far more in those devices than anyone can even dream about in a riflescope.

The side focus on the other hand, probably has some type of rack and pinion gizmo that allows the twisting of a knob to move a lens back and forth. The attachment is not direct, like the zoom on a lens or a riflescope, so it's more prone to some type of problem.

That said, I use the snot out of my side focus knob on my March scopes, they even have the large wheel to allow granular control with my arthritic hand and they have never failed me. I have many scopes with side focus and some with AO and none of them have ever had any issues.

 

[Peter83]

I wouldn't say that. The mechanisms are different. A magnification adjustment (zoom) is accomplished by twisting the inner tube which causes a couple lenses in the tube to move along grooves and thus go forward or back. The AO is similar where twisting the objective just moves a lens forward and back. Those motions are direct and they have been used in camera lenses for decades and they get exercised far more in those devices than anyone can even dream about in a riflescope.

The side focus on the other hand, probably has some type of rack and pinion gizmo that allows the twisting of a knob to move a lens back and forth. The attachment is not direct, like the zoom on a lens or a riflescope, so it's more prone to some type of problem.

That said, I use the snot out of my side focus knob on my March scopes, they even have the large wheel to allow granular control with my arthritic hand and they have never failed me. I have many scopes with side focus and some with AO and none of them have ever had any issues.

Thank you so much for the replies. The Viper PST gen2 5-25x50 feels uneven in the resistance when adjusting the zoom. In som areas it feels like there is more resistance than other areas. It is most noticeable when adjusting the zoom down/lower. It could feel like the grease is uneven applied, or that there is too much some places, but i dont know if thats the case, just a guess. Is that normal?

 

[Peter83]

Everything wears down eventually, but for perspective I've tested scopes that are 30 years old and still adjust and hold zero just fine. In general, how you treat a scope is going to have far more of an impact on its longevity than its design.

Yeah, makes sense

 

[10ring'r]

Thank you so much for the replies. The Viper PST gen2 5-25x50 feels uneven in the resistance when adjusting the zoom. In some areas it feels like there is more resistance than other areas. It is most noticeable when adjusting the zoom down/lower. It could feel like the grease is uneven applied, or that there is too much some places, but i don't know if that's the case, just a guess. Is that normal?

I just purchased this same scope (last fall), I do not have much time behind it, yet and this is not normal. Mine is flawless in operation and has been smooth from the start. I installed a Throw Lever on it but, in my opinion, it didn't really need it, but I had a spare in my War Surplus box, so I used it. I would send it in and have it checked. Vortex's warranty, is, well....... Vortex. Good luck! Mac

 

[Peter83]

I just purchased this same scope (last fall), I do not have much time behind it, yet and this is not normal. Mine is flawless in operation and has been smooth from the start. I installed a Throw Lever on it but, in my opinion, it didn't really need it, but I had a spare in my War Surplus box, so I used it. I would send it in and have it checked. Vortex's warranty, is, well....... Vortex. Good luck! Mac

It aint much noticeable, mostly if you turn it lightley. I live in euroupe, so its a long way to send it if its nothing. It could get more even over time maybe, so il wait and see if its gonna cause any problems

 

[10ring'r]

It ain't much noticeable, mostly if you turn it lightly. I live in europe, so its a long way to send it if its nothing. It could get more even over time maybe, so i'll wait and see if its gonna cause any problems

Didn't realize you were in Europe. In your case, maybe once it's worked a bit, like you said, it will rotate more freely/evenly. Mine is stiff, but it's the same stiffness throughout it's rotation. Hope you get it to work to your satisfaction. Mac

 

[Denys]

Thank you so much for the replies. The Viper PST gen2 5-25x50 feels uneven in the resistance when adjusting the zoom. In som areas it feels like there is more resistance than other areas. It is most noticeable when adjusting the zoom down/lower. It could feel like the grease is uneven applied, or that there is too much some places, but i dont know if thats the case, just a guess. Is that normal?

I don't know much of anything about scope manufacturing, but I seriously doubt there is grease involved anywhere in there. I should think the last thing you want is a loose compound running around in a sealed environment. But what do I know?

 

[DDT]

there are a few places where grease is applied for smooth mechanism function and also works as water / dust seal at some places.

 

[Guthwine]

There certainly is grease in scopes. With old scopes this is also sometimes a problem because it drys up and locks some of the mechanics. Had an old Kahles which was in perfect contidition but it had this problem. They cleaned it up and it ran like it was 1975 again.