TreednNC

Ive tried searching here and google as well, but after wading through several threads, I just can't find what I am looking for. Looking at what point is the objective size vs tube size and all a mute point in terms of low light transmission.


I know good quality glass is key here, but glass being equal, when is objective size not matter in terms of tube size and how much light the eye can take in?

bigcountry

The objective diameter is directly coorelated with the resolution of an object. Hense the reason a guy with a 25X20mm binocs might not be able to count the tines of a deer at 500yards, but a person with a 8X50mm might.

Also, Twilight performance factor is directly coorelated with objective and magnification. Its the square root of the two multiplied.

Brightness however is mostly exit pupil, The most a human can handle (most, depends on someone's eye) is 7mm exit pupil. Exit pupil

Exit pupil = Objective Diameter / Magnification = Eyepiece Focal Length / Objective f/number

All has to be taken into account.

Now, this is for an (ideal) lens. There is no such thing. So we have coating that is bacially thin film filters to attenuate some wavelengths, and let some thru, that the human eye is more responsive too. Human eye cannot see IR, or UV, but at the edge of night, different wavelengths are emited and more responsive to the human eye.

There are lots too it. I don't design thin films for the human eye but for an electronic eye or photonic reciever. There is a complete science for it. We used to make in house the filters. We had a 20million setup for it. It was cool. But now just like everything else, our company in its wisdom sold the equipment for pennys on the dollar and has outsourced it to China. I crap you not. Sad state of affairs.

To answer your question, the general tube size does nothing for light transmission. The coatings and objective size does. And it does this in a beautiful harmony of exit pupil along and focal lengths.

TreednNC

Ok beating around the bush to ask without looking like a complete idiot. I used to have a Simmons Atec. Believe it or not, that Simmons would let me hunt until it was too dark to see the ground. Relative to the law of 30min after sunset, that was generally within 5min according to my watch...never seen an exact official time to set your watch by in the regulation book anyway and 5min leeway seems reasonable as long as you're not shooting something with feathers and quacks lol.

ANYWAY........ I'm looking at some of the 40mm Nikon scopes. Could I expect the same light transmission as with the 44mm Atec I had?

bigcountry

You know the atec wasn't a horrible scope by any means.

I have some monarch's and like them. They are on varmit guns. Haven't did any late evening hunts with em. But top quality optics.

I myself find the conquest series or VXIII's to have the best twilight performance.

If you want top quality twilight performance, get a 50mm objective.

TreednNC

I dont like being able to not shoot something I can see with my naked eye lol.

Afraid the Zeiss and VXIIIs are a little out of my price range, as are the Monarchs right now. Probably looking at a Nikon Prostaff or Redfield....possibly the buckmasters series.

Sheridan

Hope this helps;

Exit pupil diameter: The exit pupil diameter is the shaft of light exiting the scope toward the scope users eye, this is expressed in millimeter measurement. It is also the true measure used to rate the brightness of a riflescope's sight picture. The larger the diameter the better it is for low light conditions.

TreednNC

That helps in the terminology Sheridan