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WokMaster1
07-10-2007, 6:03 PM
Hi guys,

Total noob here when optics are concerned. I have been searching for a scope for my AR. Purpose is just fun target shooting 75-200 yards. I have been looking at Nikon Monarchs, ProStaff, Leupolds, IORs & the usual suspects. And the more I looked, the more overwhelmed i get with all the numbers.

1. what do all these numbers mean?
2. 33mm vs 1 inch tube? difference?
3. 3-9 X 40mm vs 3 X 9 X 33- flew right over my head.
4. what's the difference between a 50mm vs 20mm?

Is there a place to do some reading to understand what all these terminology, etc. A "Scopes for Dummies" book, website.

Please help! Thanks.:o

New Shooter II
07-10-2007, 6:08 PM
Sorry, I can not help you. I am in the same boat.

I will be observing along with you.

FatKatMatt
07-10-2007, 6:15 PM
Hi guys,

Total noob here when optics are concerned. I have been searching for a scope for my AR. Purpose is just fun target shooting 75-200 yards. I have been looking at Nikon Monarchs, ProStaff, Leupolds, IORs & the usual suspects. And the more I looked, the more overwhelmed i get with all the numbers.

1. what do all these numbers mean?
2. 33mm vs 1 inch tube? difference?
3. 3-9 X 40mm vs 3 X 9 X 33- flew right over my head.
4. what's the difference between a 50mm vs 20mm?

Is there a place to do some reading to understand what all these terminology, etc. A "Scopes for Dummies" book, website.

Please help! Thanks.:o

1. Which numbers?
2. If a tube is 30mm or 1 inch just means that the tube is 33mm or 1 inch thick. I do not know the individual merits of each, but there are more rings made for the 1" tube than the 30mm
3. If a tube is 3-9x40 it means that the magnification range is 3x to 9x, and the objective size has a diameter of 40mm. The objective is the largest part of the scope at the end. The smaller the objective, the less FOV (field of view) you have. However, the bigger you go with the same quality glass the less quality you will have
4. I assume you're referring to objective size; a 50mm is much larger than a 20mm. The smaller the objective, the smaller the scope, and the lower you can mount it in relation to the barrel.

Mute
07-10-2007, 6:20 PM
Here's a basic breakdown using the following example:

3-9x40mm

In this example, the 3-9 is the magnification on a variable scope (3x through 9x). If you only see one number here (e.g. 10x40) it's a fixed magnification scope. The second number (40mm) is the diameter of the objective. That will be front-most end of the scope (towards muzzle).

The tube (1" vs. 30mm) is the main body of the scope. 1" and 30mm are the two most common, though there are other sizes. The larger this number is, the more adjustments you have available in the scope because the size of the body determines how much room the elements inside the scope have for movement.

That's the basics regarding the nomenclature on scopes. For additional detailed information regarding scope technology take a look at the link below. Although it's deals mostly with long range, tactical style shooting, the information is still applicable.

Link - PRACTICAL LONG-RANGE RIFLE SHOOTING - PART II: OPTICS (http://demigodllc.com/articles/practical-long-range-rifle-shooting-optics/)

WokMaster1
07-10-2007, 8:11 PM
Matt & Mute, thanks for the clarification & link.

Technical Ted
07-10-2007, 8:14 PM
30mm tubes allow more light to be gathered by the tube.

3-9X40mm: variable 3 to 9X magnification; 40mm objective (front bell) diameter (Also determines the height of the rings you'll use to maintain clearance above the rifle reciever).

Pthfndr
07-10-2007, 8:42 PM
The smaller the objective, the less FOV (field of view) you have.

This part is incorrect. This is from Leupold's FAQ:

Objective Lens vs. Field of View
Does a larger objective lens give a wider field of view? No. The larger objective lens will increase the diameter of the exit pupil, but will not change the field of view. The magnification level of the scope and its optical design actually determine the field of view.

PistolPete75
07-10-2007, 9:39 PM
if your going 200 yards or less, i say get the Nikon Monarch 3-9x40mm . very clear glass, with a simple duplex or bdc. most important thing i think for this range is just really clear glass, and good eye relief. it also has 1/4 moa adjustments which is a plus for fine tuning, and i think it goes for $229 at midway. downside is that it does not have a mildot recticle, but you don't need it for 200yards or less anyways.

aplinker
07-10-2007, 9:56 PM
if your going 200 yards or less, i say get the Nikon Monarch 3-9x40mm . very clear glass, with a simple duplex or bdc. most important thing i think for this range is just really clear glass, and good eye relief. it also has 1/4 moa adjustments which is a plus for fine tuning, and i think it goes for $229 at midway. downside is that it does not have a mildot recticle, but you don't need it for 200yards or less anyways.

For just a little more $ he can get the Buckmaster with the mildots. It's worth it, imho.

Also, the last number (in 3-9x40) tells you how much light collection there is. The difference between 40 and 50mm might seem small, but it's area that matters. That's 150% increase in light, which adds to perceived brightness. Size becomes more important as you increase magnification. I would say anything beyond 10X really needs a bigger than 40mm objective.

I'd heard people make mention of tube diameter making a difference in brightness, but from an optics standpoint it doesn't make sense. Anyone know why people say this?

maxicon
07-11-2007, 7:35 AM
The tube diameter gives more adjustment range. A 30mm tube gives more MOA of horizontal and vertical adjustment than a 1" tube, especially when one is off center.

That is, when your horizontal adjustment needs to be off from center, that limits the amount of vertical adjustment, because the adjustments will run into the wall of the tube sooner as you get closer to the sides. The extra 0.2" diameter gives a bit more adjustment room.

There's a good overview of scope terms and technology here:

http://www.opticstalk.com/forum_posts.asp?TID=5027&PN=1

chickenfried
07-11-2007, 7:56 AM
From what I've read 30mm vs 1" does not affect light gathering.

A few discussions on the subject
http://www.opticstalk.com/forum_posts.asp?TID=3828&PN=1
From the leupold website http://www2.leupold.com/resources/MyInfo81/Answerbook/findanswers.aspx
Advantages of a 30mm Maintube Does a 30mm maintube give you more light?

The principal advantages of the 30mm tube are added strength and increased adjustment range for windage and elevation. For example, the M8-12X (1" maintube) has a total elevation adjustment of 51 minutes. The Mark-4 M1-10X (30mm maintube) has 90 minutes. The percentage of light passing through a scope is a function of lens coating and optical design, and has nothing to do with tube diameter.
30mm tubes allow more light to be gathered by the tube.

Mute
07-11-2007, 8:43 AM
This has seen alot of pass discussion. Most conclusions is that the increase in tube size has very little, if any effect on light transmission. Nothing like increasing the size of the objective.

mike452
07-11-2007, 10:04 AM
The size of the objective determines light transmission and eye relief you get. The tube size can offer you more elevation adjustments.

xenophobe
07-11-2007, 10:26 AM
30mm tubes allow more light to be gathered by the tube.

Actually, larger tubes make the unit more durable, and also allow for a greater range of windage and elevation with the reticle. A 30mm tube will not allow more light through than a 1" tube.

A larger objective will increase the exit pupil, transmitting more light.

aplinker
07-11-2007, 2:04 PM
Actually, larger tubes make the unit more durable, and also allow for a greater range of windage and elevation with the reticle. A 30mm tube will not allow more light through than a 1" tube.

A larger objective will increase the exit pupil, transmitting more light.

Hmm.. How does the larger tube make it more durable? The adjustment part is obvious.

Light collection is increased by a larger objective, not transmission. Transmission increases have to come from improved clarity of the lenses and reduced reflection from surfaces (plain glass reflects ~4%). Just a terminology thing...

xenophobe
07-11-2007, 2:39 PM
Hmm.. How does the larger tube make it more durable? The adjustment part is obvious.

A larger diameter tube is more difficult to bend or break than a smaller one. Try taking a 1/4" copper pipe and try bending it.... then take a 3/8" or 1/2" and try bending it. Same principal.


Light collection is increased by a larger objective, not transmission. Transmission increases have to come from improved clarity of the lenses and reduced reflection from surfaces (plain glass reflects ~4%). Just a terminology thing...

Yes, I did somewhat misspeak. Better anti-reflective coatings will increase light transmission. A larger objective will increase the amount of light collected. That would be correct.

WokMaster1
07-11-2007, 5:42 PM
OK, you guys are going to laugh but out of the blue I decided to pick up a Nikon Prostaff 3-9 X 40. $160, Warne Hi-scope mounts & headed to Richmond R&G Club & played sniper for an hour. 100 yards, yes, I didn't hit anything inside the 5 ring....
It has been a very disappointing day. :(

At least it was a beautiful day, a bit windy. The glass on the Nikon is pretty clear but I need help in zeroing the scope, lots of help.:p

aplinker
07-11-2007, 8:59 PM
A larger diameter tube is more difficult to bend or break than a smaller one. Try taking a 1/4" copper pipe and try bending it.... then take a 3/8" or 1/2" and try bending it. Same principal.


Not sure it is. If I recall correctly strength of a cylinder is a function of the ratio of the diameter and wall thickness. I think it's essentially normalized by volume of material. In other words, the reason the 1/4" pipe is weaker is that it has substantially less copper than the 3/8". To do the comparison you'd have to have the same mass, maybe even less for the thinner tube. I hate pulling out these old physics recollections cause I don't always remember perfectly...

OK, you guys are going to laugh but out of the blue I decided to pick up a Nikon Prostaff 3-9 X 40. $160, Warne Hi-scope mounts & headed to Richmond R&G Club & played sniper for an hour. 100 yards, yes, I didn't hit anything inside the 5 ring....
It has been a very disappointing day. :(

At least it was a beautiful day, a bit windy. The glass on the Nikon is pretty clear but I need help in zeroing the scope, lots of help.:p

If you're on the paper, firing multiple shots with the same zero and still all over the paper, it's not the scope that needs to be zeroed. :D

PistolPete75
07-11-2007, 9:23 PM
OK, you guys are going to laugh but out of the blue I decided to pick up a Nikon Prostaff 3-9 X 40. $160, Warne Hi-scope mounts & headed to Richmond R&G Club & played sniper for an hour. 100 yards, yes, I didn't hit anything inside the 5 ring....
It has been a very disappointing day. :(

At least it was a beautiful day, a bit windy. The glass on the Nikon is pretty clear but I need help in zeroing the scope, lots of help.:p

bring the target in the 50yard range, stabilize your rifle, then shoot off 3 or 4 rounds. look through a spotting scope and you should have a descent grouping somewhere on paper. adjust your settings on your scope, and fire a few more shots, and repeat until you are dead center. then take it back a 100yards, shoot a few more rounds, then reset your scope, and keep repeating till it's dead center. note, the hotter your barrel get's, your grouping might get wider. it's not the scope, it's your barrel. you might have to cool your rifle off for a bit. good luck.

if this is too much trouble, get someone to bore sight it for you, then readjust accordingly.

Technical Ted
07-11-2007, 9:29 PM
At the 50, take the upper off the lower and remove the BCG. Prop the upper with sandbags and sight down the bore. adjust the bags until the target is centered in the bore.

Adjust the scope elevation and windage until the cross hairs are on the target.

Reassemble the rifle.

This should put you on the target paper if not in the black.

Adjust the scope accordingly to align your point of impact with your point of aim.