Author Topic: Windage dots question (Read 729 times)

eeleater · « **on:** March 23, 2005, 04:40:10 PM »

I am having a Leupold 6.5 X 20 EFR bumped up to 18X40, with a 5/8
MOA dot. In essence, a Silhouette special, being done by Premier
Reticles. My intended use is with an Air-rifle- a FWB 300 I recently traded for.

I did some shooting outside testing pellets with a different scope.
It was a gusty day, leading to significant horizontal stringing. I
recalled someone having talked about having windage dots and after
looking at the spread I was getting I called up Premier and
asked to have 1/2 min dots 4 min to either side. He mentioned that
with the dots in the second focal plane the MOA distance of the
windage dots will vary with the magnification. In Smallbore I shoot
a 36xi leupold. so I specified the 4 MOA at 36X. The MOA spacing
will go up as the magnification decreases :cry:. (I wich they still did the first focal plane)

It will be a while before they get to my scope, and I am now
questioning my choice. I have never had windage dots to use, so
have no experience to go by. My thought was that 4 MOA would be far
enough from the primary dot to not be distracting, and I would only
use them if the wind was strong enough that I could not hold at the
edge of the animal.

Any one have any comments or suggestions?
Dots too far? Closer dots at 36X and figure if the wind is up and you need them further just reduce the magnification?

dave imas · « **Reply #1 on:** March 23, 2005, 04:59:59 PM »

hold over, hold off. forget the dots.
dave

lucho · « **Reply #2 on:** March 23, 2005, 06:19:58 PM »

ditto. wind is why you have a spotter. Same some money and buy more ammo to practice with.

Lucho

nomad · « **Reply #3 on:** March 23, 2005, 06:31:49 PM »

Have you used a 40X with a 5/8 moa dot?
That's a pretty good choice at 20X. You might find it a bit large at 40...

eeleater · « **Reply #4 on:** March 24, 2005, 12:31:55 AM »

On my small-bore gun I have 36 Leupold with a 5/8 dot. I do not consider it too big. If my gun shot 1/2 MOA groups I might think different. Not a great risk of that becoming a problem for the Turkeys or Rams. With Chickens/Pigs it does shoot "within the dot"- but it is easy to sight in to hit where the center of the dot is. If there is white around the edges of the dot it is dead!

With the dots on the second focal plane the size of the dots varies with the magnification. It will be:
5/8 at 20X
1/2 at 24X
3/8 at 36X

I tried graphing those values out, and it is not a straight line.

Cost wise it is adding about $25 to have the two dots added.

nomad · « **Reply #5 on:** March 24, 2005, 06:34:08 AM »

Are you certain that the dot 'size' varies in a 2nd focal plane scope?
Or does the 'subtension' vary?

Hornetx60 · « **Reply #6 on:** March 24, 2005, 11:41:32 AM »

In a 2nd focal plane scope when you change the magnification the size or MOA of the dot will change. as you increase power the dot will get smaller. In the old style first focal plane conversions that Premier did this was not the case. In them the dot would stay the same MOA at all magnifications but it would look different because the target was being magnified. The old style was logically the better way to go but Dick Thomas could no longer put up with the whining and discontinued the first focal plane work.

Hornetx60 · « **Reply #7 on:** March 24, 2005, 11:44:00 AM »

eeleater, Don't mess with the extra dots. To confusing in the scope. Learn to hold off in the changing conditions and you will benifit from the practice.

nomad · « **Reply #8 on:** March 24, 2005, 12:34:26 PM »

The size of the dot doesn't change in a 2nd focal plane scope. The image gets larger with power increases and the dot covers less of it. (The subtension -- which is an angular reference -- changes.) That's why 2nd focal plane reticles are referred to as non-magnifying. (Point your scope into a featureless sky and change the power. You'll see no visible change in the reticle. Only when you can make a comparison between the reticle and a visible image do you see an 'apparent' change.) Size of the dot and moa coverage (subtension) of the dot aren't the same things...

In 1st focal plane scopes, the reticle magnifies directly with the image -- they're in the same plane -- and the subtension remains the same. (That's why the Europeans prefer 1st focal plane scopes -- since the image and reticle are in the same plane, there is no mechanically induced [due to manufacturing tolerances] POI shift with changes in magnification and the scope is intrinsically more accurate. The fact that ranging reticles can be used at any power setting -- since the reticle/target relationship is constant -- is an added benefit.) Point a 1st focal plane scope into that same blank sky and change the power and watch what happens to the reticle.

eeleater · « **Reply #9 on:** March 24, 2005, 03:30:40 PM »

Looks like my question is not going to change what I get. I got an E-mail notice today it has been shipped. Faster than I thought as Tuesday he thought it might be a couple of weeks, as this is a busy time of year.

I have made some graph paper with MOA lines at different distances. and will use this to make some comparisions and post what I find.

Below is a site which has various graph papers you can print- and has programs allowing you to design you own. If you go to the "easy custom" you can put in the size of the square you want. At 100M 1 moa is 1.1452 inches. so you can enter that( or what ever fraction of that you want), and then the number of squares. This will not give you a full page unless you calculate how many of your squares it will take to fill the page. The "full Custom" willfill the page- but!!!- requires you to enter the lines per inch. To get 1 MOA at 100M you need to enter 1/1.452 which = 0.873.

http://www.incompetech.com/beta/plainGraphPaper/