Nightforce 50mm or 56mm?? Which One..

[Blkz06]

Others might disagree about the "huge difference" part:

Tactical Scopes: Optical Performance Part 1 | PrecisionRifleBlog.com

Well I tend to trust my eyes on a regular basis. So when I'm in a double size tower stand with my hunting partner- him with a 50mm NXS on his rifle and me with a 56mm ATACR and we can directly compare the scopes performance side by side in lowlight conditions in a real hunting environment- I'll trust my eyes over what I read in a blog.

You don't have to. Some chose equipment based off an opinion of others in a forum or blog, some chose equipment off what they see for themselves in actual use. That's what makes this sport so fun.

 

[bruce_ventura]

Well I tend to trust my eyes on a regular basis. So when I'm in a double size tower stand with my hunting partner- him with a 50mm NXS on his rifle and me with a 56mm ATACR and we can directly compare the scopes performance side by side in lowlight conditions in a real hunting environment- I'll trust my eyes over what I read in a blog...

Unfortunately two different people doing that comparison can reach fundamentally different conclusions. You can prove this by comparing performance at two magnifications.

At 7X or below both scopes should appear to have very similar brightness. That's because even the 50 mm scope provides a 7 mm exit pupil at that magnification, which is larger than your eye pupils. That is, there is no exit pupil effect, so glass transmission is the dominant effect. The difference in glass transmission between the two scopes is probably less than 3%, which is very difficult for the human eye to see.

At 14X or above, there should be an obvious difference between the two scopes. The 56 mm scope has a 4 mm exit pupil at that magnification, and the 50 mm scope has a 3.6 mm exit pupil. If your eyes are dark adapted at the start or end of legal hunting, your pupils should be at least 4 mm, which is larger than the exit pupil of either scope. In this case, the 56 mm scope should appear about 25% brighter.

 

[Ingwe]

Well I tend to trust my eyes on a regular basis. So when I'm in a double size tower stand with my hunting partner- him with a 50mm NXS on his rifle and me with a 56mm ATACR and we can directly compare the scopes performance side by side in lowlight conditions in a real hunting environment- I'll trust my eyes over what I read in a blog.

You don't have to. Some chose equipment based off an opinion of others in a forum or blog, some chose equipment off what they see for themselves in actual use. That's what makes this sport so fun.

Interesting...

So do you think that the improvement is due to the extra 6mm objective of the ATACR or because the tube is 34mm??

 

[918v]

Well I tend to trust my eyes on a regular basis. So when I'm in a double size tower stand with my hunting partner- him with a 50mm NXS on his rifle and me with a 56mm ATACR and we can directly compare the scopes performance side by side in lowlight conditions in a real hunting environment- I'll trust my eyes over what I read in a blog.

You don't have to. Some chose equipment based off an opinion of others in a forum or blog, some chose equipment off what they see for themselves in actual use. That's what makes this sport so fun.

Trusting your eyes is fine, except your eyes are not his eyes and your ocular is not adjusted the same as his.

I recently had a S&B 5-25x56 next to my NF 3.5-15x50. The S&B was adjusted to the owner's eyes and was out of focus when I looked through it. I could have concluded that my NF has "better clarity" than a S&B.

The other issue is the age of your friend's NF. Current NF scopes are noticeably more contrasty than NF from 10 years ago due to improvements in lens coatings. I wouldn't buy a NF 10 years ago. I have a whole different opinion today.

 

[Blkz06]

Trusting your eyes is fine, except your eyes are not his eyes and your ocular is not adjusted the same as his.

I recently had a S&B 5-25x56 next to my NF 3.5-15x50. The S&B was adjusted to the owner's eyes and was out of focus when I looked through it. I could have concluded that my NF has "better clarity" than a S&B.

The other issue is the age of your friend's NF. Current NF scopes are noticeably more contrasty than NF from 10 years ago due to improvements in lens coatings. I wouldn't buy a NF 10 years ago. I have a whole different opinion today.

You can say the same for anyone's eyes. We all see things differently, and no one scenario is the same.

I can say however that his reticle is in focus when I look thru his scope so I would guess there's not a huge difference in our ocular focus adjustments.

We both bought our NFs at the same time approx 6 months ago. He even he saw the difference in low light performance and clarity between my ATACR and his NSX.

Again, this is during critical low light hunting. I cannot comment on full, sunny bright conditions. I would assume they have similar performance.

 

[Blkz06]

Unfortunately two different people doing that comparison can reach fundamentally different conclusions. You can prove this by comparing performance at two magnifications.

At 7X or below both scopes should appear to have very similar brightness. That's because even the 50 mm scope provides a 7 mm exit pupil at that magnification, which is larger than your eye pupils. That is, there is no exit pupil effect, so glass transmission is the dominant effect. The difference in glass transmission between the two scopes is probably less than 3%, which is very difficult for the human eye to see.

At 14X or above, there should be an obvious difference between the two scopes. The 56 mm scope has a 4 mm exit pupil at that magnification, and the 50 mm scope has a 3.6 mm exit pupil. If your eyes are dark adapted at the start or end of legal hunting, your pupils should be at least 4 mm, which is larger than the exit pupil of either scope. In this case, the 56 mm scope should appear about 25% brighter.

That's interesting stuff.

However its been batted back and forth around the forums debating the ATACRs better clarity and contrast vs the NSX in true hunting conditions. Doesn't mean everyone sees the difference but there are enough who do to make me comfortable enough to recommend the ATACR and its bigger 56mm to guys who ask about clarity and specifically low light performance.

I think its worth the small weight penalty.

 

[Blkz06]

Interesting...

So do you think that the improvement is due to the extra 6mm objective of the ATACR or because the tube is 34mm??

I don't believe the 34mm tube has anything to do with it. It certainly adds more adjustment for the long range guy.

Anyways I think the 6mm adds to it but a lot of the NF guys say the glass is better too. That may have the biggest effect overall.

 

[bruce_ventura]

I don't believe the 34mm tube has anything to do with it. It certainly adds more adjustment for the long range guy.

Anyways I think the 6mm adds to it but a lot of the NF guys say the glass is better too. That may have the biggest effect overall.

I agree the ATACR should be better in low light. The ATACR webpage talks about ED glass and >90% transmission. That statement implies to me an upgrade from the NXS series. NXS transmission isn't bad (probably 87-88%). So, we're talking about ~3% difference in glass transmission between NXS and ATACR? I don't think any of us could see that difference.

The exit pupil effect due to the 56 mm objective is much larger (up to 25%).

 

[Garycrow]

I have a NXS 8-32x56, one friend has a NXS 5.5-22x56, and another an ATACR 5-25x56. All three of these scopes are around a year old so they're new manufacture.

Having compared all three of them as it got dark while shooting at the 1000 yd gong on the pipeline behind my home, it's not even arguable-the ATACR has better glass. It's not the objective size since all three of our scopes have 56mm objectives, the glass in the ATACR is a noticable upgrade. I have two really good scopes designed for low light, a swarovski PH 2.5-10x56 and a meopta 3-12x56. I didn't have either of them out there to directly compare, but looking through the ATACR looked like looking through my swaro or meopta. The two NXS's were just kind of average.

 

[bruce_ventura]

Do you recall what magnification each of the scopes were set to?

 

[Garycrow]

22X across the board when we compared them. It really didn't matter though, one look through them and it was obvious the ATACR glass was better. You didn't have to study it much.

 

[LONGSHOOTER]

And as it got darkER, or darkEST, did you compare all three scopes on say, 10x, or 8x. to see which one was the last one in the game? Or, perhaps, did they all cancel the viewing at the same time? That's the real test.

 

[Blkz06]

22X across the board when we compared them. It really didn't matter though, one look through them and it was obvious the ATACR glass was better. You didn't have to study it much.

We were sitting at around 175 yards to the deer we were scoping, so we compared ours at the lowest settings.

The ATACR was definitely easier to see thru. The image has more contrast and clarity...its the only way I can describe it. Its definitely on par with my S&B and my Kahles.

Again, I think the 56mm is worth getting even with the added weight if the OP plans on doing any late hunting where that little bit of extra resolution could mean the difference between taking the shot or not taking the shot.

If its a daytime-only type scenario and low light performance is secondary I'd go with the smaller 50mm.

 

[LONGSHOOTER]

This thread is about comparing the NXS scopes, the 50 and 56, not the ATACR scope, which is a completely different animal. The ATACR has greater size, weight, diameter, and above all, a LARGER OCULAR LENS. So, back to the OP's questions.