Difference between 1" and 30mm

[SomeOtherGuy]

Follow on question: per Burris advertising, a typical 1" scope tube will house 11mm internal lenses (I believe this is the focus lens and the image erector assembly) while a typical 30mm scope tube will house 15-15.4mm internal lenses:
http://www.burrisoptics.com/tech.html

So the internal lenses for a 30mm tube are roughly 36% larger diameter than for the 1" tube.

Lenses are, obviously, very precisely ground and finished. But there are limits to precision, and assuming that a given manufacturer and price point would use the same machinery to grind lenses whether they are 11mm or 15mm, then if a certain level of precision (WAG: 1/10,000") is possible, the 15mm lens can be expected to be about 36% closer to its intended profile than the 11mm lens, at the same level of precision. That in turn seems like it should improve many aspects of optical quality - resolution, crispness, uniformity from edge to edge, etc. It may also make it easier to prepare aspherical lens shapes rather than spherical ones, since the curve adjustments needed are 36% bigger.

I am not an expert on this so while I'm making a statement, it's intended as a question for anyone with expertise to answer. I know from experience that cameras and microscopes with larger diameter lenses are almost invariably higher quality optics than ones with smaller diameter lenses, but I don't know the extent to which that is a result of the diameter vs. the extent to which people willing to pay for quality are simply also interested in the larger diameter lenses for whatever reason.

[Bimmer]

... the 15mm lens can be expected to be about 36% closer to its intended profile than the 11mm lens, at the same level of precision...

I am not an expert on this so while I'm making a statement, it's intended as a question for anyone with expertise to answer.

AFAIK, this is pretty much a non-issue.

People talk about the quality of the "glass" or the "lenses," but for the last couple decades making top quality glass lenses has been easy and cheap.

What separates the good from the bad from the ugly scopes isn't the quality of the lenses themselves as much as the coatings (anti-reflective and anti-fog) and the assembly of the scope (the alignment of the lenses, for example).

So, given that it's not so tough or expensive to start with top quality "glass," it doesn't seem like making good lenses of 11mm diameter vs. 15mm diameter would be much of an issue at all.

[Hochsitz]

Without question a larger tube diameter allows for more adjustment range, but it can also be used to make room for things like a parallax adjustment mounted on the adjustment turret (side focus) or reticle illumination in the front focal plane. All that stuff takes room and can be a legitimate reason to use optics from a 1" scope in a 30mm tube.

On the topic of light transmission, anti-reflection coatings play a huge role, but so does the number of lenses and hence surfaces that reflect light. If the larger objective lens requires an additional lens behind it to do its job then the overall light transmission through the scope will be less. Your exit pupil will be larger but that's not what this thread is about. This is why it's SO important to get outside in LOW light when comparing optics. I see really expensive optics that look beautiful in the middle of the day because they have lots of lenses that produce a near perfect image. But take that same scope out as the sun goes down and compare it to a less expensive and lighter scope that's 10 years old and you may surprise yourself. Of course it all depends on the type of shooting you're doing. If you only go to the range and shoot in broad daylight then get the scope that looks the best under those conditions.

[Krampus]

A larger diameter tube can use larger lenses and has greater potential than a small tube. Price, length, weight and adjustability are clues to what is inside.

Krampus

[voiceofreason]

get rings that fit 30mm and get step down adapters that fit 1"

the quality of the scope and lenses/coating outweigh the difference of the tube size

quality > quantity/size