Just curious - about scopes

[jonnyone]

For those that have experience is there much difference between a 25mm bodied scope as opposed to a 30mm bodied scope (assuming that the glass is of comparable quality)?
Dave

[MrGrumpy]

wider field of view

[Blackrider]

More light but more weight !

What are you shooting, targets, hunting, plinking ?

[tinbum]

Heavier

[Charlts]

Generally more room to dial and that's it.

[Bladerunner too]

Very little really, the length of scope has a baring as well . don`t get tied up in having the latest all singing dancing bull s--t.

[RobF]

Generally more room to dial and that's it.

Thats it. Nothing else. There's no more light or wider view, that's defined by the objective lens... and whilst many think the image occupies the entire tube, it doesn't... it's a much thinner 'tube' which moves up and down and left and right inside the tube as it's dialled.

Lenses of a certain size are easier to make better than other sizes, so there's improvements that can be found in that respect.

When scopes needed loads of travel they sometimes gave up moving the lenses inside and moved the whole thing externally like the Unertl's.

[jonnyone]

Thanks for the input chaps. As I mainly hunt or practice these days this iis all the scope would be used for. As such the more simple the better. In particular i have a chance in picking up an old model Hawks 30mm scope.
I'm was wondering if there are any edge on the larger tube as regards dusk shooting etc?
Dave

[RobF]

Thanks for the input chaps. As I mainly hunt or practice these days this iis all the scope would be used for. As such the more simple the better. In particular i have a chance in picking up an old model Hawks 30mm scope.
I'm was wondering if there are any edge on the larger tube as regards dusk shooting etc?
Dave

No.

For a scope using the same spec lenses, the same amount, the gain is in the objective lens size. A 56mm scope has twice the lens area of a 40mm scope to gather light.

[tinbum]

If you buy decent glass you will get more use in twilight conditions from a low mag 32-33mm scope. 40mm can be very good too, but be aware if you strap a 6-24x56, PX, AO, IR,BDC scope on your air rifle everyone will know you have a small willy

[RobF]

Just to chuck this in.

This link shows the internals of a scope.

http://www.opticstalk.com/photoserve...hotos/2743.jpg

You can see the much smaller lenses in the centre and a gap either side. That gap is the amount of adjustment the scope has. Bigger tube, bigger range of adjustment. But the light is restricted to start with by the big objective the light has to enter through to start with.

[Arthur John Smithsplease]

If you buy decent glass you will get more use in twilight conditions from a low mag 32-33mm scope. 40mm can be very good too, but be aware if you strap a 6-24x56, PX, AO, IR,BDC scope on your air rifle everyone will know you have a small willy

And too much money.

[harvey_s]

From Leupold's blurb....

"Many of today’s riflescopes use 30mm maintubes. The 30mm tube provides more strength and often more windage and elevation adjustment. This makes it easier to get zeroed at the range, and for those shooters who love to shoot long distance, it allows you to “dial up” to be on target at longer ranges."

It also allows us feel superior to those without a similar girth...

[lensman57]

For those that have experience is there much difference between a 25mm bodied scope as opposed to a 30mm bodied scope (assuming that the glass is of comparable quality)?
Dave

I think that the 30mm tubes were primarily designed for heavy recoiling rifles. The scope internals were much beefier than the old 25mm variety. The design of the scope and the size of the objective determines the amount of light gathering and the quality of the coatings and the number of the lens elements determine the transmition ratio of the light coming through the objective. A true Extra Low Disperssion glass with top quality coatings will easily out perform a much larger objective with less exotic glass and bug standard green coating. The 30 mm tube for the cheap scopes is like the old Turbo badge of 90s that was put on anything and everything to give the impression of a higher performance.

A.G

[Beretta303]

For those that have experience is there much difference between a 25mm bodied scope as opposed to a 30mm bodied scope (assuming that the glass is of comparable quality)?
Dave

Here is some text taken from an article on www.swarovskioptic.com : written by Ron Spomer.

Scopes built on 30mm tubes are inherently brighter, sharper and just plain better than those constructed on 1-inch tubes.

Not really.

Brightness is a product of exit pupil (EP) diameter and anti-reflection coatings. The EP is the little circle of light seen in an eyepiece held about 18 inches from your eye and aimed at a bright wall or sky. It's diameter is determined by the objective lens diameter divided by the scope's magnification. Thus, a 50mm objective at 10X would yield a 5mm EP. At 6X the EP would enlarge to 8.3mm and at 4X it would be 12.4mm. At 50mm objective at 25 power would produce a tiny 2mm EP. These numbers are the same whether the main tube is 30mm or 26mm (1-inch.)

A scope's EP corresponds to your own pupil, which dilates from about 2mm in bright sunlight to perhaps 7mm in the dark. If your scope's exit pupil is smaller than your pupil, it can't transmit all the light you can use. If it's larger, the extra rim of light bounces off your iris and never enters your pupil to stimulate your retina. Wasted light. But an excess diameter of exit pupil does give your eye more room to wander around in without showing edge blackout, so that's something.

The reason a 30mm main tube scope isn't inherently brighter than a 1-inch scope is because both carry internal lenses much larger than 7mm, so there is no loss of light through either. The reason some 30mm scopes appear to project brighter views is probably because they were built with the absolute finest materials and effective light transmission (how much light the scope passes through) determines brightness, is a product of the number of air-to-glass surfaces in the scope (the fewer the better) and the anti-reflection coatings on those lenses. (The more the better.)

So what, then, are the advantages of a 30mm scope tube?

The walls can be made thicker for added strength and durability or the internal lenses can be made slightly larger, which increases optical performance simply because larger lenses always perform better than smaller ones, all else being equal. Alternatively, manufacturers can keep internal lenses the same size as those in their 1-inch scopes and use the extra internal room for long range reticle adjustments.