What are front focal plane/1st focal plane reticles?

[sarki]

Hi guys,

Hoping someone can tell me what the difference is with a front focal plane reticle exactly?

Or 1st focal plane, whatever the correct term is.

Cheers.

[dustin]

The difference is with a first focal plane reticle as you zoom in the reticle gets bigger.

I just know that from looking through one though, couldn't tell you the reason.

[Streamline]

I'll do my best to explain, I'm sure one of the experts will step in if I butcher this explanation too much

Second focal plane reticles are the standard ones you have on your scopes. When you zoom in or out the reticle doesn't change.

Like dustin said, when you zoom in or out with a first focal plane reticle, the reticle gets bigger/smaller. They do this on tactical reticles for measuring distance.

For example, if you have a mildot reticle on the second place which didn't move, to be measuring distance using your target accurately you have to be at a specific magnification for it to match up. If you zoom in or out your target is still the same size but your reticle spacing is different in relation to it.

With a mildot reticle on the first focal place so the reticle gets larger/smaller as you zoom in and out, you can zoom in and out at different targets at different ranges and match the reticle to them for accurately measuring distance.

Make sense? Hopefully I haven't butchered that too much

[Jessie]

I notice they often do it with hollow circle reticles instead of cross hairs.

Increasing the size of this would also let you see your target at further ranges instead of the crosshairs covering it.

Probably more useful for military situation where losing your target just for a moment could still be disaster.

[portph]

Good demo of it here by Vortex optics.

http://www.youtube.com/watch?v=4XgugJSqpoE

About 1 minute in to see the first focal plane reticle stuff.

[sarki]

Ah, got it.

The video is good, thanks portph.

So that would be no good to me. I'll be sticking to second plane reticles.