Trijicon 2.5-10x56

[ChrisAU]

Any initial thoughts on ease of focus (reticle and image). I find the 2-10x36 a little picky. I can get it fine, just touchy.
Look forward to hearing comparison with 2.5-15. I was comparing that to my 2-10x36 last night.

I did take it out of the box and play with it for a few minutes, it seems very very forgiving on eye placement, both side-side/up-down and fore-aft. The reticle is not as bold as I was expecting, but I really need to compare it to the 2.5-15 to make a call there. Surprisingly the turrets felt better than the 2.5-15, which already were great.

 

[ChrisAU]

Alright, final report from quick field eval.

The far edge of that food plot is right at 270 yards, and the brush in the back can make it very difficult to see a deer at last light on that side.

Again, comparing the 2.5-15x42 on my 280AI to a 2.5-10x56 I just got.

I was expecting a big difference in brightness and a smaller difference in eye placement forgiveness, but I experienced the opposite. Most definitely a difference in brightness that favors the x56, but the eye placement forgiveness was significant. Usually it is hard to judge this when comparing one mounted on a rifle and then hand holding one as it is easier to get behind a mounted scope, but all I had to do with the x56 was put it vaguely in front of my face to get a sight picture.

I compared both at 2.5x, 6x, and 10x at last light looking at a small whitetail doe around 250 yards. Optically the x56 would have easily been preferred, but the x42 was no slouch and surprised me with how well it held up. At 10x the 42 suffered the most, as to be expected.

I do wish the x56 had adjustable parallax, as fine tuning with the x42 could offer slight image improvements in those last few minutes but with the x56 you just had what you were given.

The green illum of the x56 is definitely easier on my eyes than red illumination, but that is personal preference.

The MRAD Ranging reticle of the x56 is a little bolder and better for point and shoot in low light than the MRAD Center Dot reticle of the x42. The design of it is a bit different than traditional reticles as it truly look like the image on the website linked below - it does not go all the way to the edges. The hashes are easily discernible and I think really offers a plus for the guy that wants to hold vs dial as this reticle subtended at 10x will be much easier to use than the x42's reticle at 15x IMO.

CR1056-C-2900026 | Trijicon®

Trijicon® products are known for offering legendary reliability, absolute accuracy and industry-leading technology to shooting enthusiasts, law enforcement agencies and the U.S. military and its allies.

www.trijicon.com

Lastly, as I alluded to earlier the elevation turret on the x56 is better than the x42. They look exactly the same, but the feel and sound of the x56 is just slightly better. For those with a x42, both turrets on the x56 feel like the crisper windage turret of the x42.

Now that day time big game rifle seasons are gone for 8 months or so, I'm still undecided on what to do with what. I think I'm going to pick up a NF NXS 2.5-10x42 to compare to them. I like all the optical advantages of the x56 Credo over the x42 but I do like the weight and size of the x42 over the x56. I think the NF 2.5-10x42 would have a lot of similar optical advantages as the Trij x56 over the Trij x42 due to exit pupil advantages of the x4 erector vs the x6 erector.

 

[prm]

Good write up, thanks.

The 2.5-15x42 does do well in low light, so good to read the comparison.

Funny you mention the NF 2.5-10x42 NXS. That’s one of my other options for my Kimber. Though I can’t decide what it brings to the table that my 2.5-15x42 does not. Perhaps ultra-rugged design, but is the Credo rugged enough? A little shorter, 2oz lighter. Both illum SFP. In my very limited experience NF won’t beat the Trijicon in low light size for size. Not necessarily worse either. Steep price for sure.
Actually considering a 17oz 3-9x40 Credo as well. When I asked which scope, between the 2-10x36 Credo or the 3-9, would be a more robust option, Trijicon stated that the 3-9 will be just as robust as the 30mm FFP scopes. Lower profile turrets, lighter overall weight should make for a good mountain scope. The 3-9 is more wallet friendly too.

The benefits of a x56 are a bit different, but address the low light situation which I often find myself. Definitely a weight penalty, but no other way around older eyes hunting at the edges of daylight. What is enough of any given capability? If the 2-10x36 and 2.5-15x42 Credo good enough in low light I could happily live without the weight and size of a 56. But then I remember one year looking at a mule deer right at first light and having a difficult time seeing the sage branches around him and trying to make a shot (which I never did).

 

[prm]

Also, I’m guessing what you mentioned about wanting parallax on the 2.5-10x56 is similar to what I experienced with the 2-10x36. I think that ratio and zoom to 10x is right at the edge of needing parallax. It took me a bit of fiddling with the eyepiece, but eventually found a sweet spot with the 36mm where it does not bother me at all. It’s just a narrower window of adjustment where it all works with my eyes.

 

[ChrisAU]

Good write up, thanks.

The 2.5-15x42 does do well in low light, so good to read the comparison.

Funny you mention the NF 2.5-10x42 NXS. That’s one of my other options for my Kimber. Though I can’t decide what it brings to the table that my 2.5-15x42 does not. Perhaps ultra-rugged design, but is the Credo rugged enough? A little shorter, 2oz lighter. Both illum SFP. In my very limited experience NF won’t beat the Trijicon in low light size for size. Not necessarily worse either. Steep price for sure.
Actually considering a 17oz 3-9x40 Credo as well. When I asked which scope, between the 2-10x36 Credo or the 3-9, would be a more robust option, Trijicon stated that the 3-9 will be just as robust as the 30mm FFP scopes. Lower profile turrets, lighter overall weight should make for a good mountain scope. The 3-9 is more wallet friendly too.

The benefits of a x56 are a bit different, but address the low light situation which I often find myself. Definitely a weight penalty, but no other way around older eyes hunting at the edges of daylight. What is enough of any given capability? If the 2-10x36 and 2.5-15x42 Credo good enough in low light I could happily live without the weight and size of a 56. But then I remember one year looking at a mule deer right at first light and having a difficult time seeing the sage branches around him and trying to make a shot (which I never did).

So, the constraints on exit pupil size presented by the 6x erector of the 2.5-15x42 I think will put it at a disadvantage to the 2.5-10x42 NXS as far as low light performance. I don't claim to fully understand calculating exit pupil area between stated manufacturer specs - calculated linearly can create some confusing data points, but, the NXS starts with a EP diameter of 15.5mm while the Credo starts at 10.67mm. That has to flow down through the mag range to equal a larger EP diameter at each given magnification and therefore a low light advantage for the NXS, given sufficient quality glass.

 

[prm]

Exit pupil is simply calculated as Obj dia / zoom, so those two scopes are the same through 2.5-10x, then the Credo will continue to decrease to 15x. Whether the lenses transmit the same amount of light for the given (42mm) obj I do not know, but I’ll bet it’s very, very close.
Perhaps there’s more going on in there that I am not aware. Not an optics engineer!

 

[ChrisAU]

Exit pupil is simply calculated as Obj dia / zoom, so those two scopes are the same through 2.5-10x, then the Credo will continue to decrease to 15x. Whether the lenses transmit the same amount of light for the given (42mm) obj I do not know, but I’ll bet it’s very, very close.
Perhaps there’s more going on in there that I am not aware. Not an optics engineer!

That is a myth. Go look at manufacturer specs. That works for binos, and maybe 3x erector scopes. It gets more complicated for 4x erector scopes and diminishes as zoom ratio goes up.

 

[ChrisAU]

For example, Trijicon specs a 10.67mm exit pupil at 2.5x for the 2.5-15x42 while NF specs a 15.5mm exit pupil at 2.5x for the 2.5-10x42. Neither are 42/2.5.

 

[prm]

I do know small differences are due to scopes not actually having the exact zoom that they say. Those zoom numbers can be tweaked a bit to fit traditional numbers. It may actually be 2.7-9.8 vice 2.5-10. I don’t know if that explains it in this case. Some manufacturers will tell you the actual zoom in the specs.

I can’t explain the Trijicon number except to assume it’s an error.

 

[ChrisAU]

I do know small differences are due to scopes not actually having the exact zoom that they say. Those zoom numbers can be tweaked a bit to fit traditional numbers. It may actually be 2.7-9.8 vice 2.5-10. I don’t know if that explains it in this case. Some manufacturers will tell you the actual zoom in the specs.

I can’t explain the Trijicon number except to assume it’s an error.

Its not an error. Go look at specs from multiple scopes from multiple manufacturers for 5x, 6x, 8x zoom ratio scopes. Their exit pupils don't come close.

NF NX8 2.5-20x50 - by the obj/mag it should be ~20mm right? Nope...its a paltry 7.1mm. Its already on the cusp of not being 100% useful for a dilated pupil at 2.5x.

Meopta Optika6 3-18x50. Should be ~16.67mm at 3x - nope, 9.5mm.

I have discussed it briefly with Ilya Koshkin somewhere...there is a downside to high zoom erector ratios and exit pupils and consequently usability/user friendliness. This is why you always hear about "tight eye boxes" when people talk about NX8's and March scopes.

 

[prm]

I’m not an engineer so won’t argue! I can see with higher ratio zoom scopes where some light may be blocked at the extremes.
If thats the case, it should be apparent when comparing in low light.

edit: all specs are just numbers. Actual comparison in use is where I decide whether a scope offers a benefit, or not.

 

[Formidilosus]

I can’t explain the Trijicon number except to assume it’s an error.

There’s no error- Chris is correct. He corrected me a couple years ago. High zoom ratios just kind of suck all around.

 

[prm]

Sounds like a good excuse to stick to 2.5-10. Then again, if I use the scope and I either don’t notice, or it doesn’t have too negative of an impact, I won’t worry about it. All the more reason to do side by side comparisons of alternatives.

 

[ChrisAU]

Sounds like a good excuse to stick to 2.5-10. Then again, if I use the scope and I either don’t notice, or it doesn’t have too negative of an impact, I won’t worry about it. All the more reason to do side by side comparisons of alternatives.

Its fun to compare stuff. I'm not down on the 2.5-15x42, just saying that is a downside of it compared to some of the 2.5-10 flavors out there. I wish Trijicon would have just done a 2.5-10x42 that's a couple inches shorter and a few oz lighter and I think my search would be over ha.

 

[prm]

I’d be interested to peel that onion back a bit. In this case the 2.5-15 goes from 10.6 down to 2.8. The 2.8 fits what you’d anticipate. Does it linearly decrease to 2.8, or rather stay at or near 10.6 until whatever is limiting the light, or it reaches the typical obj/zoom ratio, and then decrease to the 2.8? I don’t know, but for arguments sake assume it stays around 10.6 until ~3.9x then begins to decrease. IF (big IF) that’s true, and you compared other 42mm scopes at 4x they would then be comparable. Or maybe higher ratios just suck and loses everywhere. This is all more of a question. I didn’t even stay at a Holiday Inn Express last night.

edit: I’m leaning towards the 2.5-10x56 being a scope that will do well the things I want done well on this particular rifle. Little heavier than I’d prefer, but overall rifle will still be well under 7lbs. Not a bad place to be.

 

[ChrisAU]

I’d be interested to peel that onion back a bit. In this case the 2.5-15 goes from 10.6 down to 2.8. The 2.8 fits what you’d anticipate. Does it linearly decrease to 2.8, or rather stay at or near 10.6 until whatever is limiting the light, or it reaches the typical obj/zoom ratio, and then decrease to the 2.8? I don’t know, but for arguments sake assume it stays around 10.6 until ~3.9x then begins to decrease. IF (big IF) that’s true, and you compared other 42mm scopes at 4x they would then be comparable. Or maybe higher ratios just suck and loses everywhere. This is all more of a question. I didn’t even stay at a Holiday Inn Express last night.

edit: I’m leaning towards the 2.5-10x56 being a scope that will do well the things I want done well on this particular rifle. Little heavier than I’d prefer, but overall rifle will still be well under 7lbs. Not a bad place to be.

Yep...I'm so nuts I made an excel sheet yesterday that compares the exit pupils (and min FOV, weight, and overall length) of 4 different Trijicon Models and the NF NXS 2.5-10x42, IF the relationship is linear. I wasn't going to put it on here because I don't know the answer to that, and I suspect it is not linear because there are examples in the data that are highly suspect for certain scopes at certain mags. I'm going to reach out to Ilya Koshkin on the subject. I'm curious.

 

[BjornF16]

Yep...I'm so nuts I made an excel sheet yesterday that compares the exit pupils (and min FOV, weight, and overall length) of 4 different Trijicon Models and the NF NXS 2.5-10x42, IF the relationship is linear. I wasn't going to put it on here because I don't know the answer to that, and I suspect it is not linear because there are examples in the data that are highly suspect for certain scopes at certain mags. I'm going to reach out to Ilya Koshkin on the subject. I'm curious.

Nice spreadsheet.

Would be interested to see the Trijicon Tenmile 3-18x50 added...

 

[prm]

My GUESS is it is not linear. You can only bend light around so much in a short and narrow tube, and when they have to move the lenses relatively far for the high ratio zoom, they are running into limits (my thory…). It makes sense to me that they would shift it such that the low end is impacted because even though it’s limited, it’s still adequate. If you cut off on the high zoom end it would be unusable. Do any have wacky numbers on the high end? By wacky, I mean far off obj/zoom.
I wish I could remember where I read the actual zoom for some scopes. Many scopes are not exactly what they say. Sort of rounded off you could say. Says 3-9, actually 2.8-8.6 for example.

Leupold have (had?) actual zoom numbers. Here is more info:

Tactical Scopes: Optical Performance Part 2

In the previous post, I reviewed the overall optical performance scores, and the details of the opti...

precisionrifleblog.com

 

[ChrisAU]

Nice spreadsheet.

Would be interested to see the Trijicon Tenmile 3-18x50 added...

I'll see if I can add it, but I still question the data - for example, I don't see how the 2.5-15x56 could have a bigger exit pupil at 10x than the 2.5-10x56 would.

 

[ChrisAU]

My GUESS is it is not linear. You can only bend light around so much in a short and narrow tube, and when they have to move the lenses relatively far for the high ratio zoom, they are running into limits (my thory…). It makes sense to me that they would shift it such that the low end is impacted because even though it’s limited, it’s still adequate. If you cut off on the high zoom end it would be unusable. Do any have wacky numbers on the high end? By wacky, I mean far off obj/zoom.
I wish I could remember where I read the actual zoom for some scopes. Many scopes are not exactly what they say. Sort of rounded off you could say. Says 3-9, actually 2.8-8.6 for example.

Leupold have (had?) actual zoom numbers. Here is more info:

Tactical Scopes: Optical Performance Part 2

In the previous post, I reviewed the overall optical performance scores, and the details of the opti...

precisionrifleblog.com

Just for clarity, both the max and min specs are taken from the manufacturers. None match up to remotely close to the old formula.

But, I do agree and surmise that it is not linear - tunneling between 3x and 4x magnification on the SWFA 3-9x42 for example is a clear and obvious example of exit pupil actually growing before decreasing.