Ocular Diopter - controversial advice alert

[adamg]

I'm going to be controversial here with some advice.

From hanging around scopes rifles and their owners, I am going to say that 80% of you have the ocular diopter set wrong.

Here is a spec sheet for the diopter setting on an example scope. I tried to find this same specification for other brands but it is surprisingly absent. I'd appreciate it if anyone finds more spec sheets that list this, to reply with it here.



Note that one end of the adjustment range is a large negative value, and the opposite end is a large positive number. This suggests, if you think about it, that a setting in the middle of the adjustment is a neutral setting.

Just because your scope arrived from new with the diopter adjustment maxed out in the 'in-most' position, doesn't mean this is the baseline or normal setting. In fact you are using the extreme setting in one direction.

So what's the upshot here? What's the problem I want to help with?

When you leave the diopter set at max-in position, your reticle is optically very close to your eye. To see a sharp reticle, you have to focus your eye very close - roughly 1 foot from your eye.

You are looking at your scoped rifle target off in the distance, whether it be 50 yards or 1500 yards. You get behind your scope and you want to align the reticle on the target. Except you have to focus your eye down from that far distance to 1' to see it clearly. That's slow and bad.

Wouldn't it be better if your reticle was optically farther away - closer to your target - so you didn't have to focus your eye so close?

I set my diopter somewhere near the middle of the adjustment range. This puts the reticle at roughly 20 yards from my eye. This requires less eye focus change when I look through the scope after looking at my target. Plus, now my other eye is focused closer to the target and has better situational awareness.

 

[zupermann]

All I know for sure is that I hate doing the reticle focus thing on a new scope (if Im understanding you correctly)
Im never sure if its correct as I find it so subjective as the eye quickly adjusts to make the reticle clear.

 

[adamg]

All I know for sure is that I hate doing the reticle focus thing on a new scope (if Im understanding you correctly)
Im never sure if its correct as I find it so subjective as the eye quickly adjusts to make the reticle clear.

In my research for this post, I did read the manuals from various vendors. They all recommend a similar technique, like what you mention.

This technique is trash, IMO. It assumes the user is able to set their eye focus distance at the "right" distance, and hold it steady while they move the diopter until the reticle looks sharp.

Two MASSIVE problems:
1. The user cannot hold their focus steady during this process.
2. The user has no idea what distance they are focusing at, much less whether it is the "right" distance.

I am suggesting an alternative:
Step 1. Set your adjustment near the middle of its travel.
Step 2. If you are an advanced user, capable of seeing out of both eyes at the same time, slightly tweak the adjustment to achieve the optical focus distance you want to achieve on the reticle. For me, this is roughly 20 yards - but anything from 5 yards to 50 yards is good for me.