Rifle Scopes Why such small objectives on CQT optics?

[dbooksta]

Why are so many low-magnification scopes coming out with tiny objective lenses -- i.e., <= 20mm? I particularly don't understand those that have a larger ocular than objective.

Is this just to save money and weight, or is there a functional reason to forgo the brighter image and greater eye relief of a larger objective?

 

[BOLTRIPPER]

Re: Why such small objectives on CQT optics?

stop using the airsoft crap............

 

[Powder_Burns]

Re: Why such small objectives on CQT optics?

I'll wager a guess that it has something to do with a balance of overall weight and maximum effective range/focus constraints..ie if you are only running 4x you wouldn't need a 56mm obj. because its not really going to take you out to 600yd in the first place so the larger FOV and light gathering qualities the larger objective has is not needed and contributes additional weight.

 

[prplhaz72]

Re: Why such small objectives on CQT optics?

It has a lot to do with exit pupil. For day time shooting 3 to 4 mm of exit pupil is all that is needed even less works in a lot of cases. So a 1-5x scope only needs a 20mm objective. Even the Nightforce 2.5-10x32 still has 3.2mm of exit pupil on 10x which is plenty for any type of light shooting. If it gets darker and you need more light you can turn the power down a bit and give yourself more exit pupil so you can see the image better.

There is just no need to have a large objective on a low power scope. It really offers no advantage in how bright the image is or how well it "gathers light" (which is really an improper term as scopes do not gather light, they transmit light to your eye)

 

[chrismadrid]

Re: Why such small objectives on CQT optics?

If the Exit Pupil is TOO large there is more of a risk of Parallax error due to you being able to see despite your eye NOT being centred 100% behind the eyepiece. Low power scopes tend NOT to have PX adjustment.

 

[prplhaz72]

Re: Why such small objectives on CQT optics?

Good call on that.

But also remember that low powered scopes have much less of an issue with parallax in the first place. High magnification and distance are what cause most parallax issues.

 

[LFOD1776]

Re: Why such small objectives on CQT optics?

Guys, parallax is unrelated to magnification or exit pupil size. The latter merely make the effects of the former more visible.

 

[prplhaz72]

Re: Why such small objectives on CQT optics?

Exactly, the more magnification the more the error is compounded.