bigpapa

I feel stupid asking this question but...Why is the 40mm scope the scope of choice? Why wouldn't you want a 50mm scope instead? I mean wouldn't a 50mm scope let more light in and increase your field of view?

HeadHunterII

Not neccesarily. The human eye can only use so much light. The light transmission differences between a 40mm and a 50mm will be very small if the quality of the glass is high and the size of the exit pupil is the same. As long as you have an exit pupil of atleast 5mm you should be good to go.

Edit- I should also add the advantages of using a 40mm scope. You can mount the scope closer to the gun, therefore sighting the scope in is easier, the gun is less top-heavy due to the lower mount and lighter scope and the firearm is generally just lighter. There is nothing wrong with using a 50mm scope, but the weighing the pro's and con's makes me want to stick with 40mm.

bigpapa

Ummm o.k. sooo An exit pupil of 5mm. Do I need to go to a eye doctor to get glasses for that? Just kidding. Thats deviding the 50mm or 40mm by the power right?

While were at it here is another stupid question. Right now I have a Simmons Whitetail 4x20x50AO. It's mounted on my Ruger using Ruger rings etc. However, it's as farback (towards thestock)as I can get it and I'm still streaching my head forward to get a complete view. Is that because the eye releif is not enough? I havent had a problem with the scope other than that.

trailer

No stupid question here. A few years back I always thought the 50 mm was the way to go. Wider field of view and thought the 50 mm would be the best choice for low light situations. After getting a couple of 50 mm scopes I have found no real benefits over the 40 or 42 mm scopes. Clarity is nearly equal and being that we hunt 1/2 hour before and after daylight the 40 mm will do just fine for legal hunting hours. The 40 mm is not as bulky and mounts lower to the rifle as previously mentioned. Overall I’ll stick with 40 mm or 42 mm scopes for a hunting rifle...

trailer

Eye relief could definitely be part of the problem but also the design of the scope might come into play. Scope have a certain amount of play when mounting onto a rifle and the front obj. lens body may be longer, not allowing for much adjustment. I had this problem with my Ruger #1. Depending on the make of rings you have, you could get extended rings to help with your problem...

HeadHunterII

Yes, the exit pupil can be found by dividing the diameter of the objective lens by the magnification number. Basically it is telling you that a 3-9x40 scope will have an exit pupil of 4.4mm at 9 power and a 13.3mm exit pupil at the 3 power.

I would guess that either the eye relief is too short but I doubt that in a modern scope. It would help if youcould post a picture.

mouthcaller

Papa

I posted this in another thread about Simmons scopes so you may have already seen it. MyDad bought a Simmons Whitetail Classic scope for the the gun our kids shoot, a Remington model seven in 7mm-08. The scope had such poor eye relief that the kids couldn't see the whole sight picture through the scope, and even I had to careen my head forward in an uncomfortable position to be able to see through it - and this was with the scope mounted as far rearward as it would go. I also thought the image was fuzzy, dim, and lacking in contrast. I took the scope off myself and replaced it with a Nikon Buckmaster to everyone's satisfaction.

bigcountry

50mmhas better resolution. I mean alot better. In other words at long distances, you would be able to resolve if a moose had 40 points much better than a 40mm. Also, things will appear brighter with a 50mm. There is no such thing as light gathering. Just how transparentlens are. I have a jig setup at work that will measure this. Basic collimator with a broadband LED light source and a broadband detector. Just about all scopes over 200 dollars will pass 90% of the light. They are all pretty good. And you can take 10 high dollar scopes and they will vary cause every lense is individually ground and coated. Its when you get past 95% where things get expensive as yeild drops like a hammer.

Saying all that, 99% of hunters do not need that much resolution. 40mm gets the job done. For me, anything over 44mm is just too big. sticks up too much and too far from teh barrel. Also, 50mm is just more expensive.

For a varmit rig shooting groundhogs 500 yards away, sure the 50mm can be a real benefit. For deer, one should take the extra money and buy a good set of binocs.

timbercruiser

Much more important than the size of the glass in a scope is the quality of the glass and the coatings of it. I had rather have a Conquest or other quality 40 mm scope anyday over a Simmons or other similar quality scope with 50 or 56 mm glass....