Why scope length varies so much?

Rifle scopes, iron sights and optics. Spotting scopes and target acquisition devices.

Why scope length varies so much?

Post by balter » 24 Dec 2013, 8:40 am

Hi guys,

Can someone explain the following to me. Two scopes as an example...

This Bushnell 4.5-30 scope is 34cm long.
bushnell-4pt5-30x50.jpg
bushnell 4.5-30
bushnell-4pt5-30x50.jpg (23.01 KiB) Viewed 3465 times


This Bushnell 8-32 scope is 46cm long.
bushnell-8-32x40.jpg
bushnell 8-32
bushnell-8-32x40.jpg (18.71 KiB) Viewed 3465 times


Almost the same max zoom. Only 2x more than the first one, but 12cm longer.

Plus 46cm is a pretty damn long scope?

Does the length give you something? What's the story?

Thanks.
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Re: Why scope length varies so much?

Post by Boatman » 24 Dec 2013, 10:10 am

There's basically two elements to a scope. What's best for the purposes of magnifying an image, and what's convenient/practical for use.

How they balance these two depends on the scopes purpose.

The 4.5-30 is a little outside of the norm because that's a pretty far range, 4.5x for stalking/close range and 30x for long range. Pretty sure that's like a $1,200 scope though, right?

As for the second one, that's definitely a bench scope.

46cm is a seriously long scope, too long for lugging around in the scrub, that particular one has a high magnification range as well which would make it no good for closer range hunting and would have a real small field of view.

When you're shooting bench though, and going for long range and ultra accuracy, the length or weight doesn't matter. It's not going to get in your way at all. They can more easily make the scope for optimal performance without having to do anything clever to get it into a compact size.

The same, if not better magnification performance are available for less $$$ because it's easier to make when weight/size isn't an issue. e.g. That second scope is about $700 according to a quick Google.
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Re: Why scope length varies so much?

Post by Ariat » 24 Dec 2013, 10:18 am

50mm objective on that 4.5-30 too.

40mm objective lens on the 8-32 so mounted closer to the barrel. Another typical 'target scope' feature.
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Re: Why scope length varies so much?

Post by beepar » 24 Dec 2013, 12:02 pm

46cm is hoooge. That like half my rifle lengths...
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Re: Why scope length varies so much?

Post by Grated » 24 Dec 2013, 12:39 pm

Boatman wrote:46cm is a seriously long scope, too long for lugging around in the scrub.


You wouldn't be able to reach the objective lens adjustment on that thing while using is as a sporter :lol:
Thin out their numbers, Ned!

Mmm, thin out their numbers!
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Re: Why scope length varies so much?

Post by Weepy » 24 Dec 2013, 2:27 pm

Never mind sawn-off shotguns.

Need to saw off that scope to do anything off a bench with it :lol:
Weatherby Mark V Accumark 7mm Rem. Mag.
Leupold VX-3 4.5-14x40mm

Browning BL-22 .22LR
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Re: Why scope length varies so much?

Post by Chronos » 24 Dec 2013, 7:05 pm

there is a factor working here that is affected by the tube diameter, the 6500 at the top has a 30mm tube, the AO scope below only has a 1" main tube and so all the angles of refraction are reduces requiring a longer distance between lenses, all of this is affected by lens sizes and the amount of light available. this is also why better glass often has better field of view from a similar size lenses

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Re: Why scope length varies so much?

Post by balter » 21 Feb 2014, 12:34 pm

beepar wrote:46cm is hoooge. That like half my rifle lengths...


That was basically what prompted me to ask :lol:

I wondered what you were getting for putting up with such a huge tube on your rifle :D
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Re: Why scope length varies so much?

Post by balter » 21 Feb 2014, 12:35 pm

Thanks for the replies Boatman, Ariat, Chronos.

Appreciate it.
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