Let's talk - scopes and diopters

[Dusty Britches]

I have been shooting with a 4x Extreme scope (don't know the diopter) for many years now and I'm thinking I need some understanding about some things.

Wikipedia says a diopter "is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres (that is, 1/metres). It is thus a unit of reciprocal length. For example, a 3-dioptre lens brings parallel rays of light to focus at 1⁄3 metre."

I'm thinking that simply put in archery terms, it is the distance from the eye to scope lense at which parallel rays of light come to focus. I'm thinking that means, if I was to use a 32mm diopter lense, it needs to be 32 mm from my eye to obtain the best focus potential of the lense. Wait, 32 mm is not very far is it?

So how do I decide what size diopter to use?

[JBS]

Sure Loc saves you all the math. Just go here, look on the right side and plug your numbers in and it will give you the lens you want.

http://www.sureloc.com/scopes/index.html

[Dusty Britches]

Thanks, JBS, I've been looking at the sure loc web site, but it does not answer my question about diopter. In fact, that's the site I was looking at when I came up with the question.

[Arrowsmith]

Use the power that gives you the clearest, sharpest sight picture. Don't get bogged down trying to figure out Sure Locs formula. Been there...done that. Let your eyes tell you which is the correct power. For some it will be a 2x or 3x for others 4x or 5x. Try to not use a clarifier, but it may be necessary for absolute clarity.

I wear fairly strong contacts which makes things more complicated. I am already looking thru a "lens". I have tried every lens power from every lens manufacturer. For a really clear sight picture I personally have to use a #1 clarifier with a 4x lens. I own a Sure Loc .50 diopter (approx. 4x) but I have never had any Sure Loc that was perfectly clear for me. For years I have a used a Shrewd 4x lens with a #1 clarifier. I have just recently got on staff with Classic Scopes. Steve Mack (owner of Classic) and I are business partners. I thought it was only right since we are partners (ArcheryProStaff) that I represent Classic. After trying all power Classic lens I again settled on a 4x with a #1 clarifier. I also have found that the Classic lens produces the very clearest, sharpest sight picture, for me, that I have ever experienced. Talk to Steve at Florida or give him a call. He knows more about archery optics than anyone I know of.

[Goldeneagle]

I wish ya'll would speak english!!!!!


Mike, I think your set up is the same as I'm using. 4X with #1.

[Dusty Britches]

I have the saem question on AT. Someone there explained to me that diopters only come into consideration after measuring the distance from the eye to the scope lense and determining the actual desired magnification power. Those 2 put together will dictate the size diopter to use.

Next question - what are the decision factors for the size (diameter) of lens to use? 1"? 1 3/8"? 1 3/4"?

[Goldeneagle]

I like a 1 3/4 diameter lense. I gives me a larger field of view. But, at the same time, that could be some of my shooting trouble. I may narrow my field of view down to see if it helps me concentrate on the target better.

[Dusty Britches]

Here's the AT thread. It just got really interesting to me.

[JBS]

Read this info and it will explain why you get an improvement with a small peep. It has great advantages and drawbacks as well. When I shoot High Power I used a Gehmann rear peep turned down to .020 everything was sharp as a razor, but I could only do this in bright sunlight. As the amount of light went down the peep had to get bigger and the effect of sharpness went down.

http://www.newton.dep.anl.gov/askasci/phy00/phy00948.htm

[Goldeneagle]

Here's the AT thread. It just got really interesting to me.

He's right about the optical center and physical center. I shoot with glasses on. When I went to get a pair to shoot in, my optom ( eye doctor ) said he could get the optical center ground towards the nose piece of the lense. When I aim, I'm not aiming with the physical center of the lense, i aim with the inside of the lense. This put the focal point over where I need it. It helped a bunch. So, I can see if a lense is not ground exactly on center, it could casue problems.