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.

 

[One Day...]

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.

Of course !

The explanation for this is very simple: there are substantially less lenses in a fixed power scope as opposed to a variable power scope. Typically a fixed power scope has 5 lenses, and a variable power has 9 or 10 lenses. Each lense blocks (reflects actually) a certain amount of light, despite its coating, however best-in-class the coating may be, hence the more lenses, the more light reflected away from going through the scope.

The following numbers are not exact, but let us say, for the sake of illustration, that for best-in-class German or Austrian 2020's scopes, each coated lens reflect 0.75% of the light and lets 99.25% of the light go through. A fixed power scope would have a light transmission of 96.3% and a variable power scope would have a light transmission of 92.7%. A very discerning eye could/would see the 3.6% light transmission difference, when comparing scopes side by side.

View attachment 669815

Now, if we compare the same best-in-class German or Austrian 2020's fixed power scope with coating allowing 99.25% of the light go through, to an American or Japanese 2020's variable power scope, or to a best-in-class German or Austrian 2000's variable power scope, both with coating allowing 98.5% of the light through, which are by no mean bad scopes!!!, the difference increases to over 10%. About anyone will see the 10.3% light transmission difference, when comparing scopes side by side.

View attachment 669817

And if for the sake of reality we compare the best-in-class German or Austrian 2020's fixed power scope, to the best-in-class German or Austrian 1980's variable power scope, many of which still sit on top of some of my (and likely yours) favorite rifles (e.g. my Steyr Mannlicher Luxus Stutzen .270 Win), the difference increases to over 16%. Any one will see the 16.7% light transmission difference, even if not comparing scopes side by side.

View attachment 669818

Two points...

First, notwithstanding any of the above, the 1980's variable scope Zeiss Diavari 1.5-6x42 and the 1980's Zeiss BGA 10x40 binoculars, with their ~80% light transmission remain perfectly adequate hunting optics, and still beat the heck out of many modern scopes and binoculars, and I will still pick them over many modern or non-continental brands (let us not be too specific here, as the purpose of this post is not to talk down or antagonize others' choices), so the 'salesman' premise that any scope or binocular that does not transmit 92% or 93% of the light is useless, is a complete novice fallacy.

Second, observe how small the "giant leaps" in coating technologies really are. A 1.5% difference from the 1980's to the 2020's for each lense in the above examples yields a 13% difference after going through 9 lenses...

I hope this was interesting...

1980's Zeiss Diavari 1.5-6x42 (and 1980's Zeiss BGA 10x40 binoculars) with their ~80% light transmission did the job then, and remain perfectly adequate hunting optics today. Actually, they are still far better than many, many modern offerings............... I only wish my own eyes would have aged with as much grace over the last 40 years.....................

 

[One Day...]

PS to above: discerning readers may have noticed that there are a total of 10 lenses in the above tables, even though variable scopes typically have 9 optical lenses. This is to account for the additional lens (the 10th one) that nowadays typically supports the etched reticle.

 

[WAB]

Of course !

The explanation for this is very simple: there are substantially less lenses in a fixed power scope as opposed to a variable power scope. Typically a fixed power scope has 5 lenses, and a variable power has 9 or 10 lenses. Each lense blocks (reflects actually) a certain amount of light, despite its coating, however best-in-class the coating may be, hence the more lenses, the more light reflected away from going through the scope.

The following numbers are not exact, but let us say, for the sake of illustration, that for best-in-class German or Austrian 2020's scopes, each coated lens reflect 0.75% of the light and lets 99.25% of the light go through. A fixed power scope would have a light transmission of 96.3% and a variable power scope would have a light transmission of 92.7%. A very discerning eye could/would see the 3.6% light transmission difference, when comparing scopes side by side.

View attachment 669815

Now, if we compare the same best-in-class German or Austrian 2020's fixed power scope with coating allowing 99.25% of the light go through, to an American or Japanese 2020's variable power scope, or to a best-in-class German or Austrian 2000's variable power scope, both with coating allowing 98.5% of the light through, which are by no mean bad scopes!!!, the difference increases to over 10%. About anyone will see the 10.3% light transmission difference, when comparing scopes side by side.

View attachment 669817

And if for the sake of reality we compare the best-in-class German or Austrian 2020's fixed power scope, to the best-in-class German or Austrian 1980's variable power scope, many of which still sit on top of some of my (and likely yours) favorite rifles (e.g. my Steyr Mannlicher Luxus Stutzen .270 Win), the difference increases to over 16%. Any one will see the 16.7% light transmission difference, even if not comparing scopes side by side.

View attachment 669818

Two points...

First, notwithstanding any of the above, the 1980's variable scope Zeiss Diavari 1.5-6x42 and the 1980's Zeiss BGA 10x40 binoculars, with their ~80% light transmission remain perfectly adequate hunting optics, and still beat the heck out of many modern scopes and binoculars, and I will still pick them over many modern or non-continental brands (let us not be too specific here, as the purpose of this post is not to talk down or antagonize others' choices), so the 'salesman' premise that any scope or binocular that does not transmit 92% or 93% of the light is useless, is a complete novice fallacy.

Second, observe how small the "giant leaps" in coating technologies really are. A 1.5% difference from the 1980's to the 2020's for each lense in the above examples yields a 13% difference after going through 9 lenses...

I hope this was interesting...

View attachment 669830
1980's Zeiss Diavari 1.5-6x42 (and 1980's Zeiss BGA 10x40 binoculars) with their ~80% light transmission did the job then, and remain perfectly adequate hunting optics today. Actually, they are still far better than many, many modern offerings............... I only wish my own eyes would have aged with as much grace over the last 40 years.....................

Agreed, I believe I said that in a previous post, although not so thoroughly. My point was that I was surprised at the magnitude of the effect. Swarovski has arguably the best lenses in the world, but each additional lens still has a negative impact on light transmission.

 

[One Day...]

Agreed, I believe I said that in a previous post, although not so thoroughly ... each additional lens still has a negative impact on light transmission.

Yes you did, here it is (my underlining)

... 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.

I just figured that I would explain why and how the number of lenses impact overall light transmission - as it is an iterative process - and provide supporting illustrative data, which I am re-attaching here under as it seems to have disappeared from the above post

As previously noted, the following numbers are not exact, but for the sake of illustration.

As I also mentioned in other posts, this is why coating technologies (both coating chemical composition and deposition processes) are more jealously guarded by Zeiss, Leica, Schmidt & Bender and Swarovski than nuclear weapon secrets, to the point that they do not even share them with their own foreign subsidiaries, which explain why top-of-the-line optics (e.g. Zeiss V8, Swarovski Z8, etc.) are still made in Germany or Austria while less advanced models (e.g. Zeiss V4, Swarovski Z3, etc.) are generally produced overseas. When you think about it, it is logical, but it still feels quite incredible that just a 1.5% light transmission difference for each lense in the above examples yields a 13% difference after going through 9 ocular lenses and one etched reticle lens.

Whether the almost double price for, as an example, Zeiss V8 with 8x zoom ratio and 92% transmission and Zeiss V4 with 4x zoom ratio and 90% transmission, is worth the price, each will decide for themselves.

For what it is worth (?) I have personally reached the conclusion that there is a diminishing return on investment in the V8, Z8, etc. as I see no need for spatial-telescope magnification and as my older eyes (and most human eyes) do not capture the difference between 90% and 92% light transmission.

After owning Zeiss, Leica, Swarovski and Schmidt & Bender scopes of various vintages from the 1980's to the 2020's, my own personal price/performance sweet spot over the last few years has been Zeiss V4, although I do consider the Leica Magnus 1-6.3×24i that sits on my .458 Lott barrel as the best scope I own, from a light transmission point of view, especially when set around 3.5x magnification.

 

[0002S]

Z8i 1.7-13.3x42 is the best hunting scope I’ve ever used. With the addition of the target turrets its covers all bases on all my rifles out to 600m.