Swaro ATX/STX 65mm vs 85mm Objective Lens

[marktole]

Did some looking around in the optics forum and didn't find a ton of information, a few accounts, but not a lot. There seemed to be a lot of info on the 65 and 95, lots of guys saying to go with the 95! I don't know that the trade off in weight and size would be worth the optical improvement for a 95 over a 65 for me because I like to backpack hunt and quite frankly, I don't want to carry a 95mm tank. I already have a 65, and its great, but just curious to know if an upgrade to an 85 would be worth the cost, weight, and size for any optical improvements.

Specs from Swaro has the 65 and 85 at the same FOV, which I thought was interesting. Anyone out there have some experience comparing a 65 and an 85?

Feel free to throw out your opinions/arguments for a 65/95 combo or the 85 by itself!

 

[Steve O]

An 85 objective is 11.5 oz. heavier than a 65. A 95 objective is 8.8 oz heavier than an 85. When it’s all loaded in your pack, do you think you can tell? I only have the 95 in the Swaro so I cannot compare to the smaller versions...but I’d bet optically it is ahead of the others and I decided to take the minor weight penalty.

 

[marktole]

An 85 objective is 11.5 oz. heavier than a 65. A 95 objective is 8.8 oz heavier than an 85. When it’s all loaded in your pack, do you think you can tell? I only have the 95 in the Swaro so I cannot compare to the smaller versions...but I’d bet optically it is ahead of the others and I decided to take the minor weight penalty.

That was a common argument I found while looking around the optics forum, and a valid one at that. I may not be able to tell the difference of one pound in my pack when its all loaded up, but I bet I can tell the difference of the size the thing will take up. But I might be convinced come the time to get one to go for the 95, we'll see.

 

[FlyGuy]

This wont help you any, but that fairly large gap between the 65 and 85 is one of the things that helped push me to the Kowa 77. It pretty much splits that difference fits good in a backpack and still powerful enough (for me) from the truck.

Not trying to convince you to go with Kowa. I understand that if you are already invested in the ATX system you would want to stick with it. Just relaying that I was scratching my head with that same problem you mentioned and went a whole different way. I'm sure you'll be happy though with whatever one you pick.

I've never looked through the 95, but it seems to me that it makes the biggest impact when used with the BTX. Is that something you are planning to add one day?

Sent from my SM-G610F using Tapatalk

 

[Steve O]

That was a common argument I found while looking around the optics forum, and a valid one at that. I may not be able to tell the difference of one pound in my pack when its all loaded up, but I bet I can tell the difference of the size the thing will take up. But I might be convinced come the time to get one to go for the 95, we'll see.

I’ve got a note into Pods8 about making a stay on padded case to keep the 95 BTX in that will attach to the outside of my Stone Glaciers.

 

[marktole]

I’ve got a note into Pods8 about making a stay on padded case to keep the 95 BTX in that will attach to the outside of my Stone Glaciers.

For every problem, Pods8 has a solution! Ha, he’s made me a few things and have always been pleased with his work.

 

[marktole]

This wont help you any, but that fairly large gap between the 65 and 85 is one of the things that helped push me to the Kowa 77. It pretty much splits that difference fits good in a backpack and still powerful enough (for me) from the truck.

Not trying to convince you to go with Kowa. I understand that if you are already invested in the ATX system you would want to stick with it. Just relaying that I was scratching my head with that same problem you mentioned and went a whole different way. I'm sure you'll be happy though with whatever one you pick.

I've never looked through the 95, but it seems to me that it makes the biggest impact when used with the BTX. Is that something you are planning to add one day?

Sent from my SM-G610F using Tapatalk

Not planning to get a BTX eyepiece in the future. I hadn’t thought about bugging out on the Swaro and trying Kowa actually. I would be more convinced to get on board with that if I could look through a Kowa a little, but I live 3.5 hours from Denver and 5 from KC and don’t make it there all that often to try one at a dealer.

 

[Fedster]

An 85 objective is 11.5 oz. heavier than a 65. A 95 objective is 8.8 oz heavier than an 85. When it’s all loaded in your pack, do you think you can tell? I only have the 95 in the Swaro so I cannot compare to the smaller versions...but I’d bet optically it is ahead of the others and I decided to take the minor weight penalty.

For what is worth, when Swaro came up with the three sizes, they expected the 85 to outsell the other two (some sweet spot in terms of cost/performance). Yet, and unexpectedly, the 85 is the model that sells least. People either go for 65 or 95 apparently.

I would venture the 95 would need an even beefier tripod (unless you like to waste your money on an expensive scope mounted on a flimsy base -- life choices) than either the 65 or the 85. I have an ATS 80HD. I plan to get an ATX 85, because the 65 objective lens is not enough for low light in my use, and I do walk with suff on my back, quite a lot. Any weight I can avoid carrying the happier I am. Also, I prefer less bulk, it is easier to pack.

 

[Fedster]

Let me add, assuming you have a stable base and normal to very good specimen the 95 will always outresolve the equivalent 85, BUT, in low light the exit pupil of the 85 (at 25x) is larger than the exit pupil of the 95 (at 30x), with 15% more *surface* for gathering light. That makes, to me, the 85 the best all around.

 

[marktole]

Let me add, assuming you have a stable base and normal to very good specimen the 95 will always outresolve the equivalent 85, BUT, in low light the exit pupil of the 85 (at 25x) is larger than the exit pupil of the 95 (at 30x), with 15% more *surface* for gathering light. That makes, to me, the 85 the best all around.

That is some very technical info, more than I had bargained for, thank you for your input!

 

[Steve O]

Interesting. When you take the *surface* area of the two divided by the respective magnification rather than just the diameter, the 95 has a 9.6% advantage.

 

[Fedster]

Interesting. When you take the *surface* area of the two divided by the respective magnification rather than just the diameter, the 95 has a 9.6% advantage.

Cannot quite follow. The area is pi*r^2, and the exit pupil of the 85 at 25x is 3.4mm and the 95 at 30x is 3.16666667. If you have

((3.4/2)^2)/((3.166667/2)^2) the ratio is 1.15 meaning the 85 has 15% more surface (one can ignore the pi constant).

I just do not see where the 9.6% figure comes from. I do see that if you use both at 30, the 95 would actually beat the 85, having 20% more light delivering surface than the 85, but the again I would not see the point using any mag that gives me anything but the highest exit pupil. I do see that 25x is not 30x, but the again 25x has a greater FOV than 30x.

 

[Steve O]

85/2= 42.5

42.5*42.5= 1806.23

1806*3.146= 5674.515

5674.515/25= 226.98


95/2= 47.5

47.5*47.5= 2256.25

2256.25*3.1416= 7088.235

7088.235/30= 236.275


226.98/236.275=.9606

1-.96=0.04 or 4% not 9.6%—that was my error—but the 95 surface area divided by 30 is definitely larger than the 85 surface area divided by 4%.

Also, the 95 will have a better “twilight factor” than the 85 as well, correct?

 

[Fedster]

Isn't the exit pupil the objective lens diameter divided by whatever magnification one is using? I.e. one would first have to divide the objective lens diameter by the mag to find the diameter of the exit pupil, then use that to calculate the area of the area of the circle of light one can actually see at a given mag?

Alternately, one can cheat and look up the exit pupil sizes ate the two ends of the zoom range from Swaro -- those match my diameters (SWAROVSKI OPTIK - ATX / STX / BTX Spotting Scope).

 

[Shrek]

Having owned both the 85 objective and the 95 objective I can tell you I still own the 95 objective. It’s a long and heavy beast but the view in low light , or any light , is in a league of its own. You can argue the specs all you want but sitting behind the 95 will make you a believer.

 

[Fedster]

Having owned both the 85 objective and the 95 objective I can tell you I still own the 95 objective. It’s a long and heavy beast but the view in low light , or any light , is in a league of its own. You can argue the specs all you want but sitting behind the 95 will make you a believer.

As much as I know *facts* are not high in people's list these times, I will provide a few. Before, terminology: cherry == an optically perfect scope; lemon == a scope that should have not passed quality control.

1) With the exception of one model [1], all scopes use a fixed objective lens and a zoom eyepiece (or a fixed eyepiece in some cases). The objective lens (the big lens at the front) determines how much light the scope can get, the zoom determines magnification, field of view and exit pupil

2) exit pupil determines in its entirety how much light the image we see has. End of. This is not an opinion, it is physics. Exit pupil is calculated as objective_lens_diameter/magnification. This means that at the same magnification a scope with a larger objective lens will have a more luminous image. At the same time, if we use two different scopes at their largest exit pupils, the images are different in FOV and magnification, but the image coming from the larger exit pupil is brighter.

3) everything being the same (the Swaro ATX is perfect for this statement, since the only variable is actually the objective lens), a larger objective lens gives greater detail and resolution. Once more, this is physics, not an opinion. If your see more detail out of a 65mm scope than a 95mm scope, you are comparing a moderns HD glass cherry with an old, not HD glass lemon.

4) our eyes gather images, our brains see. Our eyes gather images that are upside down, have a hole in them, and have no perspective correction. Our brains put together two partially overlapping images, give us 3D vision, put the image right side up, hide the blind spots and correct for perspective. Again, a fact.

5) image perception is determined by how luminous, detailed and contrasty an image is, plus colour perception.

The upshot is that at 25x the 85mm gives a larger exit pupil than the 95mm at 30x (if you do not believe me just check the specks on Swaro' site). So, at the maximum possible exit pupil the 85mm gives a brighter image in low light, fact. For my use, the loss of a 5x mag (going from 25x to 30x) is less important than losing ~15% of the exit pupil surface.

I have no doubts that, comparing two good samples, the 95mm will give a more detailed and contrasty image. I have no doubts that comparing scopes at the same mag will advantage a larger objective lens in all metrics. Yet, in low light one goes to the lowest zoom point to gather as much light as possible -- in low light I care about exit pupil size above all other parameters. Hence, the 25x mag of the 85mm gives it an advantage in low light compared to the 30x of the 95mm, accepting lower mag and overall less resolution and contrast (at all mags).

Having said that, I have no doubt that detail and contrast can make up for loss of light for some people in some circumstances. If someone is colourblind the loss of brightness might be less of a problems compared to the loss of detail (as one example). All eyes are different, that's why our subjective perception through a scope is ours only, yet it matters above the specs on paper. Once one has gathered the information about the specs of different scopes the rational course of action is to go to the store, to see how our eyes and brains interact with the scope, and what actually matters most. Ideally spend hours in the store looking through the scope, to let your eyes adjust to it (eyes adjust to scopes, and change the performance over a few hours).

If you find the image coming from the 95mm better at low light, that is what you see. But that is your own experience, not a physical fact. At the same time your own personal experience of the image is really the only thing that matters

[1] the Zeiss Harpia has a zoom lens and a fixed eyepiece. The advantage is a very large FOV, the disadvantage is a small exit pupil size.

 

[Fedster]

Rereading my latest post I realise it can come across as quite aggressive, which is not my intention. Irrespective of the tone, the optical performance of a scope is a an objective, quantifiable, fact. How we experience of the image is subjective, most likely just personal, but still a fact (potentially the only fact that actually matters).

 

[1shotgear]

Did some looking around in the optics forum and didn't find a ton of information, a few accounts, but not a lot. There seemed to be a lot of info on the 65 and 95, lots of guys saying to go with the 95! I don't know that the trade off in weight and size would be worth the optical improvement for a 95 over a 65 for me because I like to backpack hunt and quite frankly, I don't want to carry a 95mm tank. I already have a 65, and its great, but just curious to know if an upgrade to an 85 would be worth the cost, weight, and size for any optical improvements.

Specs from Swaro has the 65 and 85 at the same FOV, which I thought was interesting. Anyone out there have some experience comparing a 65 and an 85?

Feel free to throw out your opinions/arguments for a 65/95 combo or the 85 by itself!

The Swarovski ATX 95mm is the best spotting scope on the market there is no question about that. The 65mm is a great spotter as well. It is very light weight and easy to move around. I personally have the 85mm and I like that probably the best. It has a better field of view than the 65 (in my opinion) and is lighter than the 95mm. The only difference between the 3 spotters is obviously weight and a little field of view comes in to play. Also the bigger the optic the better light transfer you will get. Sometimes this can make a difference if you're glassing first thing in the morning or right at dusk. The only people that carry a 95mm in the back country that we have talked to are sheep guides. This being said it all comes down to what would be a better fit for you.

 

[marktole]

Rereading my latest post I realise it can come across as quite aggressive, which is not my intention. Irrespective of the tone, the optical performance of a scope is a an objective, quantifiable, fact. How we experience of the image is subjective, most likely just personal, but still a fact (potentially the only fact that actually matters).

I thought your last post was awesome, and not aggressive at all. Just factual. And very good information at that. Thank you very much for taking the time to post it up, it is the info I am seeking.

Interesting to know the 85 has a brighter image at 25x. I am curious to see an 85 and 95 side by side to see how much of a difference there is in image clarity/resolution.

 

[Buck1]

I have a 95 & my buddy packs the 65 and after comparing them in the field I can't tell the difference. Im sure there is but not enough for me im going to the 65. If your a backpacker the 65 is impressive. The 95 is a heavy for my outdoorsman pod.