NikonUser, if I understand you correctly, you put protective filters on the objective lenses of your riflescope sights—is that right? There is a company that makes a polarizing filter attachment that fits on the eyepiece. The description claims that putting a filter on the objective can affect the image and therefore the point of impact. Is that something you agree with or have ever experienced? (I’m assuming now that a polarizing filter would have no more effect than something like a UV filter.)

Do you stay up a night coming up with good questions?

1- No. I do not put protective filters on my riflescope objectives. I use a sunshade, lens hood, whatever you call it. I paid really top dollar for my March-X and my NXS and so on, and I do not want to put another piece of glass in front of it. Since I use maximum magnification almost exclusively I want to make sure I get the best, brightest picture I can get from my riflescopes. Another piece of glass is only going to create more artifacts and reduce light transmission. I've use a yellow filter to see that the effect was on mirage. I don't plan on doing that again, not on the riflescope.

Earlier I said that all my camera lenses have a UV filter. Over the last month or so, I've come to the conclusion that is the wrong thing to do and I have been removing them as I use my various lenses. I always have a lens hood on for protection and that's sufficient for me. I want the best picture I can get from my camera.

The only thing I use a UV or Skylight filter on are my spotting scopes. I've already had not go into rocks objective lens first when the tripod tipped over. I'm older, sometimes it's tough to get up after a long spell behind the spotting scope. My two spotting scopes have retractable lens hood; they pull out and push it. It pushed in when the scope fell and didn't protect squat. On the other hand if I had a filter on there, it might have broken sending shards of glass on the lens and that might have done more damage to the lens than the what the rocks did, which was essentially nothing detectable through the eyepiece.

2- I definitely would not put anything between the eyepiece and my eye. I do not know if the POA would be distorted with a polarizer in front of the objective; if it did it would not be significant. I've never tried it and in photographic circles, I have never read or heard something about that. I suppose it's possible, but I have no intention of measuring it. I pretty much discontinued filter tests on the riflescopes but I will continue to play with filters with my spotting scopes. My Kowa has an 86mm filter size and the bigger the filter the pricier, but on the other hand, I'm not worried about losing f-stops or having the filter explode on recoil.

These are really great questions.

quote:

Originally posted by NikonUser:
Do you stay up a night coming up with good questions?

It’s your fault for posting stuff in the first place that piques my interest and gets me to do that dangerous thinking thing.

I wondered if the light ray path would be shifted as it enters a sight if the glass of a filter mounted in front of the objective wasn’t exactly perpendicular to the lens system and if that could cause a POA change. I experimented with some filters and a laser pointer, and that doesn’t seem to happen, but unfortunately I don’t know enough about optics to be positive about possible effects. As I say, the claim by the eyepiece polarizer manufacturer is that it could cause a problem, but they’re trying to convince us that we need to buy their product. I would consider their device but I can’t really determine how it attaches to the scope, and I don’t want something that would be difficult to mount and remove easily.

I’m not interested in mounting any other type of filter on a sight, just a polarizer for removing reflections if necessary. The method therefore needs to be something that permits quick changes. I will be pursuing getting UV filters mounted on my spotting scopes, though.

Thanks again for a very informative and helpful response.

Update:

Okay, I’ve answered my questions by checking the POA shift claim for myself. I set up a 25× scope, pointed it at a distant object, and manipulated a polarizing filter in front of the objective lens. Up, down, tilted at extreme angles, and the reticle did not move at all with respect to what it was originally positioned against.

In doing all that, I also realized that a filter could be turned around and then its objective side would slip over the end of a sunshade. I did that with a 49mm filter and the shade on my 3-18 Mark 6, and it worked fine. In use I’d just use a couple of pieces of electrical tape to hold the filter in place. The filter angle can be adjusted by turning the sunshade on the scope screw mount. Simple, easy, and best of all: Free! because I already have everything I need.

quote:

Originally posted by sigfreund:

quote:

Originally posted by NikonUser:
Do you stay up a night coming up with good questions?

It’s your fault for posting stuff in the first place that piques my interest and gets me to do that dangerous thinking thing.

I wondered if the light ray path would be shifted as it enters a sight if the glass of a filter mounted in front of the objective wasn’t exactly perpendicular to the lens system and if that could cause a POA change. I experimented with some filters and a laser pointer, and that doesn’t seem to happen, but unfortunately I don’t know enough about optics to be positive about possible effects. As I say, the claim by the eyepiece polarizer manufacturer is that it could cause a problem, but they’re trying to convince us that we need to buy their product. I would consider their device but I can’t really determine how it attaches to the scope, and I don’t want something that would be difficult to mount and remove easily.

I’m not interested in mounting any other type of filter on a sight, just a polarizer for removing reflections if necessary. The method therefore needs to be something that permits quick changes. I will be pursuing getting UV filters mounted on my spotting scopes, though.

Thanks again for a very informative and helpful response.

Update:

Okay, I’ve answered my questions by checking the POA shift claim for myself. I set up a 25× scope, pointed it at a distant object, and manipulated a polarizing filter in front of the objective lens. Up, down, tilted at extreme angles, and the reticle did not move at all with respect to what it was originally positioned against.

In doing all that, I also realized that a filter could be turned around and then its objective side would slip over the end of a sunshade. I did that with a 49mm filter and the shade on my 3-18 Mark 6, and it worked fine. In use I’d just use a couple of pieces of electrical tape to hold the filter in place. The filter angle can be adjusted by turning the sunshade on the scope screw mount. Simple, easy, and best of all: Free! because I already have everything I need.

Yeah, I want to use electrical tape on my multi kilobuck scope, maybe even duct tape. That will give it that redneck look.

There, there: They’ll still know it’s a multi-kilobuck scope. Putting tape on such a sight is like wearing a gold and diamond Rolex with torn jeans, $750 sneakers, and no socks. It says, “I have money and want you to know it, but I also want you to know that I’m self-assured enough that I don’t care what you think about me.” And yes, duct tape is better for that purpose than electrical tape because it’s more in-your-face obvious.

What can I tell you, I'm a purist; I find beauty in simplicity.

This too good of a topic to let die out so I'm bumping it back into the discussion. After all the talk on the new glass I took the plunge this week and ordered the new Nightforce ATACR 7-35x56mm. It is made with the ED glass so am eager to check out its handling of the mirage effect as compared to the standard glass. The only distance I have here on my farm is a 200 yard range and a commercial range nearby goes to 500. I really won't know how good it is until I get it out west this fall and try some 1000+ prairie dog shots. Currently I have a Nightforce Benchrest 8-32x56mm that I can compare it to and note the difference.

Always looking for data points. The ATACR is an awesome scope even without the ED glass. The BR model you have is an extremely good scope as well. So it will be interesting to see if there is a perceptible difference within the same brand.

I went from a Nightforce NXS 12-42X56 to a March-X 5-50X56 and noticed the difference in how the mirage was showing up in the glass.

BTT

Important to keep this going.

I'm currently working on some graphics that will help me understand more about riflescopes, always relating to my other passion, photography.

Right now, I'm trying to some up with a way to figure out the focal length of the first stage of the riflescope, the one from the objective lens to the first focal plane. From that I can then figure out the f-number for that part. I'm assuming that the ID of the main tube is the target sensor size. From that we can then guess the amount of magnification provided by that first stage.

First, thanks for a great read on scopes and mounts.

Now my question. Vertical or horizontal splits on the rings? I've read where some don't like vertical splits believing they can cause problems. I'm in the process of looking for a mount for a Vortex Razor HD (5-20x MRAD). I would like to find a mount that I could move around since this will be the highest quality scope I own. I like LaRue's QD mounts like the LT-104 which comes in the 35mm size I need. That mount will work on my Savage .308 10T bolt rifle since I've installed a MDT stock with the skeleton butt stock which has an adjustable cheek rest. But after some reading, maybe the horizontal mount is the way to go. The maximum distance for this rifle will be out to 800 yards from a prone position (and if I have the ability). I desire the QD feature since I would like to be able to use the scope on my ARs occasionally. Whats your thoughts?

quote:

Originally posted by ed308:
Vertical or horizontal splits on the rings?

I’m surprised to learn that vertically split scope rings are even available today.

Okay, that’s an exaggeration, but it took a search to learn how many are offered. I mount all my scopes on Picatinny rails and use a device that keeps the scope from turning in the rings when tightened thereby eliminating one nuisance with horizontally split rings. There’s more than one way to accomplish that.

Vertically split rings do obviously offer a smaller side to side profile, but I’ve never found the wider horizontal rings to be a problem in any practical way, even when using things like scope levels and angle indicators. I certainly wouldn’t want something that sticks up above the scope and interfered with seeing and adjusting my elevation knob, but that might not be an issue anyway.

I do believe that horizontally-split rings are available in a wider variety of selections these days because they’re more popular.

As for the mount, this is purely my preference and others may disagree, but for precision shooting I wouldn’t rely on a QD mount when moving the sight between rifles. I am very skeptical that lever mounts will always return to absolute zero when taken off and put back on, and therefore the zero would have to be confirmed.

And once we do that, I’d rather just have something like a Leupold Mark 4 mount system: To remove it from one base I loosen the nuts with an appropriate wrench, put it on the other base, tighten the nuts with a 65 inch-pound torque wrench, and I’m done. To switch back, do the same thing again. It may take a couple/three minutes longer to do that than using a QD mount, but I would know I had a solid setup.

The only vertical split ring I have is my Larue QD mount on my AT-10. I loathe vertical splits, but that's what this mount came with.

All my other mounts and rings are horizontal splits.

I very much like my LaRue QD mount. No flies on it.

Ultra Dot red dot scopes come with vertical split rings, but I rarely see them at a match. I've never actually seen a set of vertically split scope rings on any rifle, but that doesn't mean anything. Anyway, here's a little information on the ergonomic and engineering issues involved. It comes from Warne, and they make vertically split rings.

http://warnescopemounts.com/why-vertically-split/

Thanks for the quick responses. Will try it and see how it works. With QD mounts, LaRue's are hard to beat. I've used them on most of my of my ARs and really like them. But I've never used one to shoot past 200-300 yards. I could always upgrade to a horizontal and convert the LaRue mount to where it would work on one of my ARs.

There is nothing wrong with vertical splits, per se. If it works for you, there is no "upgrade" to horizontal splits. The reason I like the horizontal split rings is simply for mounting purposes. I find it much easier to have the rifle in a cradle and then install the bottom rings on the it, using the spacing that I want.

Once the bottom rings are on, I place the scope in them and then play around until I have the scope set to my eye, the way I like it. Then I carefully put the tops of the rings on and loosely turn the screws. I recheck position and then it's easy to tighten the screws in an X pattern, making sure I have the same distance between the rings on both sides. I use a torque screwdriver set to the recommended setting.

When I was installing a scope with vertical splits, sometimes the scope would twist as I tightened the screws. And tightening the screws from the side was not quite as easy as from the top. (pushing down versus pushing sideways.)

Once properly installed there is no difference between the two types.

The vertical splits are taller and the horizontal splits are wider. It's aesthetics here.

The only reason I asked which is better is due to a post on another forum claiming vertical split rings can cause problems with the scope not returning to zero. I'm not sure how that would be possible since the force used to clamp the scope would seem to the same whether vertical or horizontal rings.

quote:

Originally posted by ed308:
The only reason I asked which is better is due to a post on another forum claiming vertical split rings can cause problems with the scope not returning to zero. I'm not sure how that would be possible since the force used to clamp the scope would seem to the same whether vertical or horizontal rings.

Wow, thanks. That's a new one on me. I have never heard that one; someone can make claims about virtually anything I guess.

Early next month, March is introducing a new riflescope, currently slated to have the name Genesis.

This promises to be a "game-changer" and will probably cause me to go update some aspects of the explanations given at the beginning of this thread.

I confess to being, if not excited, at least anticipating the arrival.

I believe the introduction is on March 9th.