A thorough conversation with Swarovski - Conclusion: Rookhawk knows nothing and is wrong about everything

[Paul K]

Well, about the only thing that my optics gather is dust. But most of them do an outstanding job of transmitting light.

Paul

 

[One Day...]

All absolutely correct. However these formulas present the maximum possible outcome. Actual transmission is reduced by quality of glass (none are perfect so all reduce transmission), lens coatings, and number of lenses. A variable, by definition, cannot transmit as much light as a fixed power scope of like magnification, lens quality and coating.

Add to that, 30 year olds best case have 5.5mm pupil aperture, maximum. Every decade on average you lose .4mm more.

While I agree with everything you are saying, WAB, these are technically 2 different issues.

The diameter of the light beam, as determined by the diameter of the objective and the magnification, is entirely independent from the amount of light carried within the light beam.

Admittedly it all comes together in as much as better light transmission in a smaller diameter light beam will make up for the smaller diameter, but all parameters being constant (same glass, same coatings, same number of lenses, etc.) a wider beam will carry more light than a narrower beam.

As to whether the shooter's eye can fully benefit from it, it is indeed a wide ranging variable rookhawk. Age is an obvious factor, but far from being the only one.


All of that to say one more time what we all agree on: get the best you can afford, and I would add that paying for a few months a credit card's interests is probably worth it when it comes to getting top quality glass that will last you a lifetime if you are reasonably careful.

 

[One Day...]

Most people don’t understand the light gathering math which leads to a fallacy you need big glass.

Men over 35 year’s old can typically get about 5.5mm of pupil dilation. Meaning, that’s as much light as you can let into your eye. So hypothetically, a 60mm exit objective lens on an optic may present no more light gathering than a 24mm objective.

Here’s how that math works:

Swarovski 3-9x36mm scope. 36mm / 5.5mm your eye can absorb = 6.54x. So that scope at twilight is giving you all the light you can use at 6.54 magnification.

Swarovski 1-6x24mm scope. 24mm / 5.5mm your eye can absorb = 4.36x.

2-10x42mm scope. 42mm / 5.5mm your eye can absorb = 7.63x.

Perhaps some of you will have an “a-ha” moment here. If you’re shooting leopard or black bear at twilight, what power are you setting a scope for that 75 yard shot? Yeah, probably 2.5x to 3x zoom. In that situation, ALL the above scopes are going to work just fine. Inside of 200 yards, 4x is sufficient for many people, in which case the light gathering and zoom are far greater than most peoples tolerance to take a long shot in low light.

I’ve never found a straight tube optic of high quality at 4x, 5x, 6x to be lacking for the distances I shoot. YMMV.

I am afraid, I need to amicably disagree rookhawk

For what it is worth (?) I believe that the science is a little less drastic than what you state. Pupil size indeed decreases approximately 0.043 mm per year ("senile miosis") , but only after the second decade of life, so assuming a 7 mm pupil (at full dilatation at dusk or dawn), a 20-year-old will have a 7 mm pupil, and a 35-year-old will have a 6.35 mm pupil. The math is 7 mm - (0.043 mm x 15) = 7 - 0.645 = 6.35.

(It seems that your calculation resulting in a 5.5 mm pupil for a 35-year-old accounted for 35 years of aging: 7 - (.043 x 35) = 7 - ~1.5 = ~5.5. In reality, since senile miosis starts at 20, a 35-year-old accounts for only 15 years of aging, hence 7 mm - (0.043 mm x 15) = 7 - 0.645 = 6.35)

In fact a 60-year-old has lost approximately 1.72 mm in dilatation (.043 * 40) and still has a 5.28 pupil.

The other variable is that the human pupil is not strictly 7 mm at full dilatation. It is in fact in a range of 7 to 8 mm. So, folks blessed with a larger pupil in the 8 mm range can still enjoy 6.28 mm at 60 years old.

While I can only speculate, I believe that this is the reason why conserving a 7 mm light beam in full dilatation conditions (dusk and dawn) was the objective of the German optics manufacturers in the days when science still mattered in product design: most likely a fair amount of their clientele in their 40's and 50's could still benefit from a 7 mm light beam... Hence the classic 1.5-6x42 or 2-8x56 scopes from Zeiss, Schmidt & Bender, Swarovski, etc.

All models of course long discontinued, as were discontinued most of what made technical /practical sense (e.g. extended eye relief) as you otherwise lament, since science as nothing to do in the marketing decisions made nowadays when evermore magnification inflation seems to drive the optics market. There was a time when professional salesmanship consisted of educating the client, but this too is obviously long obsolete. Deep sigh...............

All of this still supports your practical guidance, which I have myself often explained on AH when it comes to optics characteristics. I agree with the logic of the examples you take. For example, a best quality 1-6x24 is fine for leopard (or lion) at dusk and dawn, assuming - as you suggest and as I agree with - that it is not cranked up to more than 3.5x magnification for a less than 100 yards shot over bait.

I just figured that you would not mind me clarifying the senile miosis starting age

 

[WAB]

While I agree with everything you are saying, WAB, these are technically 2 different issues.

The diameter of the light beam, as determined by the diameter of the objective and the magnification, is entirely independent from the amount of light carried within the light beam.

Admittedly it all comes together in as much as better light transmission in a smaller diameter light beam will make up for the smaller diameter, but all parameters being constant (same glass, same coatings, same number of lenses, etc.) a wider beam will carry more light than a narrower beam.

As to whether the shooter's eye can fully benefit from it, it is indeed a wide ranging variable rookhawk. Age is an obvious factor, but far from being the only one.


All of that to say one more time what we all agree on: get the best you can afford, and I would add that paying for a few months a credit card's interests is probably worth it when it comes to getting top quality glass that will last you a lifetime if you are reasonably careful.

I was amazed at the difference between fixed and variable power scopes. My buddy’s S&B 8x56 is the brightest scope I’ve looked through. I’ve got bee hives 200 yards from my office door. I’ve tested that scope against my full range of Swarovski variables. It is brighter.