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Thread: 1" vs 30mm scope tube

  1. #1

    1" vs 30mm scope tube

    Hi all, this may seem like a very basic question but what are the benefits or properties of 30mm over 1" or visa versa? I can see from a very basic point of view is that a 30mm will allow more light but from various threads on the size of objective lenses its not as simple as that. Do any of the manufacturers actually state the differences between the two sizes or benefits of either? I've settled on the objective and magnification for the scope I want but can't really see why a 30mm tube usually costs quite a few quid more?

  2. #2
    My understanding is that it enables you to have more adjustment for height or windage, (wider angles) rather than improve light transmission. So probably of greater benefit for long range target work. The 30mm must be a bit stiffer all other things being equal, so that may make them more resilient to the odd bump when stalking.

  3. #3
    Ah that makes more sense as understood the whole mag divided by objective gave you the exit pupil and there seems to be nothing by any manufacturers about different specs due to tube width. As I'm looking at a fixed power for shooting under 200 yards I guess it won't make much of a difference.

  4. #4
    If you check the actual numbers there is no benefit to having a 30mm tube in light transmission. Remember to compare similar lens sizes or the results will be out . Originally it was for extra elevation adjustment but then as they became a must have fad some unscrupulous manufactures used a 30mm body tube but the same internal adjustments as the 1" tubes but of course elevated the price of the 30mm version.

    On thing that is often not mentioned is that if the wall thickness of the same as the 1" version the 30mm tube should be a bit stronger.

    Of course a 1" tube can be mounted that bit lower and in more easily obtained mounts in most cases. For normal stalking I fail to see any advantage in having a 30mm tube.

    However it's your money to get what you fancy .

  5. #5
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    A 1" tube is, of course, lighter in weight an so will its mounts be.

  6. #6
    Quote Originally Posted by enfieldspares View Post
    A 1" tube is, of course, lighter in weight an so will its mounts be.
    Material makes more of a difference. Steel 1" will outweigh a 30mm alloy, weight difference on mounts is negligible.

    An example of a 30mm tube with no advantage is the Zeiss Duralyt, elevation and windage is a bit pants.

  7. #7
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    if the glass is cr@p, then the tube could be 2" and its not going to help.

    glass quality and the correct scope for your needs is more important than anything else (apart from accuracy)

    bob.
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  8. #8
    Quote Originally Posted by nun_hunter View Post
    Ah that makes more sense as understood the whole mag divided by objective gave you the exit pupil and there seems to be nothing by any manufacturers about different specs due to tube width. As I'm looking at a fixed power for shooting under 200 yards I guess it won't make much of a difference.
    Wrong Sir !
    To get `exit pupil diameter` you divide the set magnification into the objective diameter.
    For example, if you have an objective lense diameter of 50mm and your 3-12X50 scope is set at 10 power then the expected `exit pupil diameter` will be 5mm.
    Under difficult light conditions it is generally recognised that the average human eye can accept a 7mm beam of light.
    If the beam is wider than this the position of the eye in relation to beam centre is less critical.
    Large magnifications and small objectives are bad news at dawn and dusk.

    HWH.

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