Rifle Scopes First AND Second focal planes?

[Ledzep]

Please don't take the simple manner of me asking this question as me thinking that doing it would be simple, but why not have a fine or medium-fine SFP cross, and thicker (so that they may be seen across the variable range of zoom) stadia lines at Mil/MOA intervals in the first focal plane.

My best guess is parallax issues, but I am pretty ignorant to fine details of the inner workings of modern optics.

 

[JFComfort]

Re: First AND Second focal planes?

US Optics does DFP (dual focal plane) scopes on some of their lower magnification models.

Maybe DFP on higher magnification scopes is a pain and its easier to go with something like a RDP MOA reticle on the FFP.

Good question

 

[ken226]

Re: First AND Second focal planes?

My guess would be that most scope makers wouldn't want to add a feature that increases the cost unless its a feature that will sell, even at the higher price. Just a guess, but perhaps they don't see the advantages as being worth the price increase.

 

[calling4life]

Re: First AND Second focal planes?

Reticle on two lenses that are spaced apart. Wouldn't this create a problem if you weren't perfectly straight behind the optic, any slight imperfection in alignment translating to incorrect measurements down range.

Or I may be misinterpreting what you are asking.

 

[remau308]

Re: First AND Second focal planes?

I read it as having two different reticle components on two different planes. A duplex reticle in the SFP would keep the line the same thickness throughout the mag range. Also, on the FFP would be the mil measurement lines, so they increase proportionally and are accurate throughout the range.

The only thing I see wrong with this (and I also don't know everything about scopes), but if you add an extra lens to accommodate the other reticle, you would flip the image upside down. This means you would either have to design it with one less lens, or add another to compensate for the image flip, which would end up making the image less clear.

Either way though, I think something like this would sell like crack in Detroit for all types of shooters.

 

[buffybuster]

Re: First AND Second focal planes?

The concept has actually been done and produced, just not very well. Shepherd scopes had a dual plane reticle with two sets of adjustment knobs. The main duplex reticle was SFP and it had a holdover reticle that was FFP. They each had their own adjustments so could be zeroed independently if desired.

The quality of the optic and the company left something to be desired.

Conceptually a dual-plane reticle certainly is possible. A Gen-2XR in SFP with the Christmas tree in FFP would be nice.

 

[warbird2006]

Re: First AND Second focal planes?

SFP for benchrest, FFP for everything else

 

[Coloradocop]

Re: First AND Second focal planes?

Interesting concept being suggested in this thread, though I suppose I can understand the limitations that some others have described (extra lenses, etc).

 

[Mactrev]

Re: First AND Second focal planes?

I didn't know much about scopes until I started reading on here. I went with the SWFA 1-6x FFP - for my Rainier Arms RUC. Made my decision based on reading so many posts on the hide !!

 

[turbo54]

Re: First AND Second focal planes?

I'm no optics engineer, but I don't believe this concept would require an extra lens - just an extra reticle etched on an existing lens.

An immediately apparent challenge would be the perfect alignment of the two reticles. Obviously, the dual reticle would SUCK if they weren't *perfectly* overlapping.

 

[Rafael]

Re: First AND Second focal planes?

Did you miss this discussion I started in 2006?

http://www.snipershide.com/shooting...icle-static-size-cross-hair-any-interest.html

Here are the reticle images that resulted from that thread:
https://plus.google.com/photos/113029124...amp;gpsrc=pwrd1

 

[JoeZ]

I have to agree with the dual focal plane idea for a couple of reasons.

With scopes getting 5x and more magnification, the FFP reticles either are too thin to use at low power or unnecessarily thick at high power so the solution could be a duplex(minus the lower vertical leg like Shephard) or even a circle (Burris XTR II is doing this) in the SFP for a point blank range zero, and all the hold overs on a tree in the FFP. The tree could apparently disappear (not obstruct) at low power and then be visible at high power when you need it for longer ranges.

A shooter could zero the SFP duplex(independently of the FFP) to a point blank zero(battle sight zero) or a 100 yard zero, both of which are tricky when using hold overs, especially if one has a high sight over bore dimension. Night Force implicitly admits the dilemma as their program calculates your zero range for the Velocity series reticles to make the FFP hold overs true and its alway something off like 180 yards or so.

The Shephard also has an moa ruler in the FFP that crosses the SFP duplex at it's extreme top and the extreme right. This allows a shooter to see, while viewing the target, any dope(wind or elevation) dialed into the scope.

JoeZ