Scope obj size

[BunnyDoom]

I had a 3-12x50 Zeiss (30mm tube), and downgraded because I needed some dosh... to a 6x42 S&B (1" tube) - I haven't noticed any loss in brightness... in fact the 6x42 S&B seems brighter!

As Slimjim says there's no science behind larger objectives, though they are heavier and do mean your scope is mounted much higher on the barrel (= bad).

I've recently become interested in diamonds (looming engagement) and have seen a lot of stuff about glass and crystal also - so would guess it's more about things like cut, clarity, cleanliness (Slimjim! ), allignment, etc

Put enough sheets of glass in front of something and it will become dull or obscured due to imperfections and misallignments - so there's an argument for fixed power being brighter than variable (variables use another lense as I understand it?). Snipers used to be issued with a 10x42 fixed power scope and a .308 eh?!

It's not surprising that a famous crystal maker (svarovski) are renound for making good quality optics... zeiss manufacture laboratory equipment and machinery glass... and as far as I'm aware S&B are specialist scope manufacturers - though I think many scope manufacturers share glass-makers?

High mag scopes are useful for longe range "varminting" (hitting squirrels at 500m or whatever) as you wouldn't see them with a low power, but take one on a woodland stalk and you'd never acquire your target... even if you could lift your gun having lugged the bloody thing around all day.

I'm debating ditching my moderator to save weight (following a couple of stalks trying to keep up with a mate with a lighter set up, who is admittedly also fitter than me) - so I definitely wouldn't add the useless weight of a variable or large-objective scope.

 

[David T]

Variable x 50 for me.

 

[Simjim33]

I had a 3-12x50 Zeiss (30mm tube), and downgraded because I needed some dosh... to a 6x42 S&B (1" tube) - I haven't noticed any loss in brightness... in fact the 6x42 S&B seems brighter!

As Slimjim says there's no science behind larger objectives, though they are heavier and do mean your scope is mounted much higher on the barrel (= bad).

I've recently become interested in diamonds (looming engagement) and have seen a lot of stuff about glass and crystal also - so would guess it's more about things like cut, clarity, cleanliness (Slimjim! ), allignment, etc

Put enough sheets of glass in front of something and it will become dull or obscured due to imperfections and misallignments - so there's an argument for fixed power being brighter than variable (variables use another lense as I understand it?). Snipers used to be issued with a 10x42 fixed power scope and a .308 eh?!

It's not surprising that a famous crystal maker (svarovski) are renound for making good quality optics... zeiss manufacture laboratory equipment and machinery glass... and as far as I'm aware S&B are specialist scope manufacturers - though I think many scope manufacturers share glass-makers?

High mag scopes are useful for longe range "varminting" (hitting squirrels at 500m or whatever) as you wouldn't see them with a low power, but take one on a woodland stalk and you'd never acquire your target... even if you could lift your gun having lugged the bloody thing around all day.

I'm debating ditching my moderator to save weight (following a couple of stalks trying to keep up with a mate with a lighter set up, who is admittedly also fitter than me) - so I definitely wouldn't add the useless weight of a variable or large-objective scope.

That is a very good explanation of why my second hand fixed power 6x42 £30 Niko is as good at low light, as my 3-9x40 ziess conquest which cost almost 10x more!

The other comment about coatings is good too. But there can only be so much in the verience between the different makers.

Bunny Doom, I have cleaned that big scope now. And yes I can see through it now. See you Sunday.

 

[Monkey Spanker]

I had a 3-12x50 Zeiss (30mm tube), and downgraded because I needed some dosh... to a 6x42 S&B (1" tube) - I haven't noticed any loss in brightness... in fact the 6x42 S&B seems brighter!

As Slimjim says there's no science behind larger objectives, though they are heavier and do mean your scope is mounted much higher on the barrel (= bad).

Higher mounted scope doesn't make any real difference on a centrefire, and if anything, it helps at longer ranges as the line of sight looks down the trajectory as it falls away.

I've recently become interested in diamonds (looming engagement) and have seen a lot of stuff about glass and crystal also - so would guess it's more about things like cut, clarity, cleanliness (Slimjim! ), allignment, etc

Put enough sheets of glass in front of something and it will become dull or obscured due to imperfections and misallignments - so there's an argument for fixed power being brighter than variable (variables use another lense as I understand it?). Snipers used to be issued with a 10x42 fixed power scope and a .308 eh?!

Glass is naturally reflective to light. It is the non-reflective coatings that expensive optics have which set them above cheaper models without.

It's not surprising that a famous crystal maker (svarovski) are renound for making good quality optics... zeiss manufacture laboratory equipment and machinery glass... and as far as I'm aware S&B are specialist scope manufacturers - though I think many scope manufacturers share glass-makers?


High mag scopes are useful for longe range "varminting" (hitting squirrels at 500m or whatever) as you wouldn't see them with a low power, but take one on a woodland stalk and you'd never acquire your target... even if you could lift your gun having lugged the bloody thing around all day.

That's why a vari-power is the scope of choice as it gives the best of both!

I'm debating ditching my moderator to save weight (following a couple of stalks trying to keep up with a mate with a lighter set up, who is admittedly also fitter than me) - so I definitely wouldn't add the useless weight of a variable or large-objective scope.

My 2-12 x 50 is probably a few grams heavier than a fixed power if that! Don't make the scope your excuse! Eat less pies and do some exercise!
MS

 

[Simjim33]

My 2-12 x 50 is probably a few grams heavier than a fixed power if that! Don't make the scope your excuse! Eat less pies and do some exercise!
MS

Well you don't know bunny doom personally then do you. The man is positively Athletic.

That aside would you like to explane how much light is reflected from non coated high purity glass as used in scope lenses? I am sure you will correct me if you think I am wrong,but, are the anti reflective coatings not applied on the inside (sealed) side of the lens not the outside where it would where off? And why would that be needed?

Could it not be that as the big old obj lets more photons into the scope body not all of photons can be absorbed by the scope body as it bottle knecks down into the main body. So they heat up the body which then causes other photons to be deflected back into the path of the constant influx of new photons heading down the center of the tube. These now random photons create haze on the inside surface of the front obj. The only way you can stop that is to coat the inside surface with a anti glare coating.

So what has your big old obj done for you? Given you more glare than you needed and the had to be resolved by adding a new process to combat it. No wonder they cost so much more. All that extra work needed to get a decent picture.

I bet a 34mm tube with a 34mm obj would be about as bright as any human would need.

Also a high mounted scope would only " see down the trajectory" for a very sort time in the bullet flight.

 

[BunnyDoom]

My 2-12 x 50 is probably a few grams heavier than a fixed power if that! Don't make the scope your excuse! Eat less pies and do some exercise!
MS

I think the scope height debate is worthy of another thread - however if your scope is 3" higher than your barrel then that's 3" you are potentially off target if shooting close range. When you raise the scope height you increase or decrease your LOS Drop depending upon the calibre and ranges you are working with. Most of us have a specific combo of average ranges and specific calibres so each person has their own preference.

Increased scope height also increases the effect of scope cant - so even if its perfectly mounted if you're slightly off a higher scope will have a greater effect!

On the subject of scope height I'm amazed how many people can't measure scope height - I was taught it is the centre of the bore to the centre of the scope (not the height of your mounts as some people seem to think!)

i personally think non reflective coatings are bollox.

...and methinks you are picking a fight

 

[Monkey Spanker]

Well you don't know bunny doom personally then do you. The man is positively Athletic.
No I don't, but it was he that suggested that he might be a fat knacker!? To blame the objective of your scope on your ability to stalk is laughable!

That aside would you like to explane how much light is reflected from non coated high purity glass as used in scope lenses? I am sure you will correct me if you think I am wrong,but, are the anti reflective coatings not applied on the inside (sealed) side of the lens not the outside where it would where off? And why would that be needed?
Glass is reflective! If the coating was applied to the inside you have lost most of your light from the outside! Of course the outside is coated!

Could it not be that as the big old obj lets more photons into the scope body not all of photons can be absorbed by the scope body as it bottle knecks down into the main body. So they heat up the body which then causes other photons to be deflected back into the path of the constant influx of new photons heading down the center of the tube. These now random photons create haze on the inside surface of the front obj. The only way you can stop that is to coat the inside surface with a anti glare coating.
Heat? Photons? Bottle necks which somehow store or reflect energy? Have we invented some kind of 'light collider' here? WTF are you talking about? It's a simple tube with some glass seperators which transfers light!

So what has your big old obj done for you? Given you more glare than you needed and the had to be resolved by adding a new process to combat it. No wonder they cost so much more. All that extra work needed to get a decent picture.
My big old obj is merely a x50mm which provides all I need.
I bet a 34mm tube with a 34mm obj would be about as bright as any human would need.
Yes, any toilet roll tube will give you that kind of performance. I'd like a little more!
Also a high mounted scope would only " see down the trajectory" for a very sort time in the bullet flight.

So what benefit does a low mount give you on a centrefire?
MS

 

[Monkey Spanker]

scopes

I think the scope height debate is worthy of another thread - however if your scope is 3" higher than your barrel then that's 3" you are potentially off target if shooting close range. When you raise the scope height you increase or decrease your LOS Drop depending upon the calibre and ranges you are working with. Most of us have a specific combo of average ranges and specific calibres so each person has their own preference.
Even a 56mm scope with high mounts is only about 2" low at the muzzle! This quickly comes up to line of sight at a sensible zeroed range of 100-150m. The shot then falls away down the line of sight. Not exactly,but not far off. If you shoot most deer at long range, this is a bonus. If you shoot most deer at short range, you are still never more than a couple of inches out worst case.
Increased scope height also increases the effect of scope cant - so even if its perfectly mounted if you're slightly off a higher scope will have a greater effect!
How can that be? The scope is fixed to the rifle no matter what the height!

On the subject of scope height I'm amazed how many people can't measure scope height - I was taught it is the centre of the bore to the centre of the scope (not the height of your mounts as some people seem to think!)

i personally think non reflective coatings are bollox.
I personally think you haven't used a good quality scope at low light!

...and methinks you are picking a fight

Not picking a fight at all mate, I just think your argument is void!
MS

 

[BunnyDoom]

For me personally it reduces the line if sight drop at closer ranges (.243 @ 50-125yds) by up to an inch - I know it's just an inch but if I make a mistake it might tip the scales in my favour.

If you play around with ballistics programmes on various calibres at different maximum ranges and zeros you'll see what I mean.

I don't disagree that higher mounts are better at certain distances by the OP was asking about woodland stalking wasn't he? (Closer ranges)

You said in your response to my post that scope height made no difference - I disagree

 

[BunnyDoom]

Not picking a fight at all mate, I just think your argument is void!
MS

Ok first thing is I'm not fat LOL - see profile pics!

Scope mounts will take scope height up to 3"+ (are you measuring it right?)

To me I'd rather not be a couple of inches off at the ranges I shoot 99% of the time.

Scope Cant -where to start on your comment mate lol! - if you hold your gun sideways so the vertical crosshairs are horizontal you realise your zero will be off yeah?! Gravity means the bullet rises and drops vertically, and as you're not looking down your barrel you need to make sure your vertical crosshair is in line with the barrel and is truly vertical. If your crosshair is tilted to the left you will see your bullet go high/right or low/left depending on range. Make sense? Assuming it does it should now be clear that the higher the scope the more the issue of scope cant creates misplaced shots.

I'm not saying your 50mm is big, just that I don't see the benefit over a 40mm

 

[BunnyDoom]

Well you don't know bunny doom personally then do you. The man is positively Athletic.

That aside would you like to explane how much light is reflected from non coated high purity glass as used in scope lenses? I am sure you will correct me if you think I am wrong,but, are the anti reflective coatings not applied on the inside (sealed) side of the lens not the outside where it would where off? And why would that be needed?

Could it not be that as the big old obj lets more photons into the scope body not all of photons can be absorbed by the scope body as it bottle knecks down into the main body. So they heat up the body which then causes other photons to be deflected back into the path of the constant influx of new photons heading down the center of the tube. These now random photons create haze on the inside surface of the front obj. The only way you can stop that is to coat the inside surface with a anti glare coating.

So what has your big old obj done for you? Given you more glare than you needed and the had to be resolved by adding a new process to combat it. No wonder they cost so much more. All that extra work needed to get a decent picture.

I bet a 34mm tube with a 34mm obj would be about as bright as any human would need.

Also a high mounted scope would only " see down the trajectory" for a very sort time in the bullet flight.

Good points mate

Athletic?! 10 years ago maybe but thanks anyway not quite a porker yet but will be working on it over Xmas!

 

[HotDogsForTea]

Gravity means the bullet rises and drops vertically.


Interesting comment. Please explain how gravity makes the bullet rise?

Cheers,
Fatty.

 

[Simjim33]

Dear Proff Monkey Spanker.

Photonic behavour is discussed in quite good detail in GCSE's and probebly even better coverd in the old O level. The A level physics sylibus then covers it in much better detail. Which is where I left it at.

However. My next door neighbour has got a PHD in partical physics. His thesis was written on photonic deflection. He is also quite keen on air rifle shooting. So when he came over for a BBQ two summers ago. we had a very, very long conversation about how a scope works. He went to great lenghts to dumb it down for me. And I have further condensed it for your information.

If however your research has found something new. When do you publish? He would be the first to congratulate you when you do.

Good luck.

 

[Tamus]

My 2-12 x 50 is probably a few grams heavier than a fixed power if that! Don't make the scope your excuse! Eat less pies and do some exercise!
MS

Do you leave it cranked up to 12 most of the time?

Because, unless you do... or at least use 12 for most shots... why bother with the 50mm glass?... It is only fully in use at max mag and at min mag you'll only be using about 28mm of the diameter of that massive chunk of crystal.

I'm not actually sure of the calculation but I wouldn't be surprised if you were using less than 42mm at 6 power too... In other words a regular 6x42 fixed power Swaro is arguably better than a 2-12x50 Swaro set on 6 power.

 

[BunnyDoom]

Gravity means the bullet rises and drops vertically.


Interesting comment. Please explain how gravity makes the bullet rise?

Cheers,
Fatty.

lol you argumentative shite - but ok... if there were no gravity the bullet wouldn't ever drop meaning we wouldn't need a vertical crosshair; so to our eye gravity is the reason why bullets rise in our line of sight!!!

But yeah obviously I was talking about bullet drop being caused by gravity!

 

[Monkey Spanker]

Do you leave it cranked up to 12 most of the time?

Because, unless you do... or at least use 12 for most shots... why bother with the 50mm glass?... It is only fully in use at max mag and at min mag you'll only be using about 28mm of the diameter of that massive chunk of crystal.

I'm not actually sure of the calculation but I wouldn't be surprised if you were using less than 42mm at 6 power too... In other words a regular 6x42 fixed power Swaro is arguably better than a 2-12x50 Swaro set on 6 power.

No mate, I generally have it at about x7 when stalking around as it makes it quicker to acquire a target. I then crank it up to 12 if I have the time or the light levels allow. Sometimes, if it is quite dark you see more at a lower mag.
MS

 

[Monkey Spanker]

Dear Proff Monkey Spanker.

Photonic behavour is discussed in quite good detail in GCSE's and probebly even better coverd in the old O level. The A level physics sylibus then covers it in much better detail. Which is where I left it at.

However. My next door neighbour has got a PHD in partical physics. His thesis was written on photonic deflection. He is also quite keen on air rifle shooting. So when he came over for a BBQ two summers ago. we had a very, very long conversation about how a scope works. He went to great lenghts to dumb it down for me. And I have further condensed it for your information.

If however your research has found something new. When do you publish? He would be the first to congratulate you when you do.

Good luck.

I did both O and A level physics but don't remember going into any detail about scope design.
However, if your learned friend is correct, then he needs to have a chat with the worlds leading optics designers who are clearly taking us all for mugs! If what you're saying is correct, anyone with a scope larger than 34mm has been ripped off!! That will be pretty much all of us on here, oh, and most of the worlds military!
Damn your learned friend! He's so clever!
MS

 

[Tamus]

No mate, I generally have it at about x7 when stalking around as it makes it quicker to acquire a target. I then crank it up to 12 if I have the time or the light levels allow. Sometimes, if it is quite dark you see more at a lower mag.
MS

I made a mistake.... Having just checked the Swarovski "technical data" I see that at 2 power your scope only uses a 19.3mm diameter portion of the 50mm lense.

If the relationship of diameter of objective lense in use to maginfication power in use is a linear one then at 7 power, being half way between 2 and 12, the lense area in use at that setting would be half way between 19.3 and 50 = 34.65 mm ....... Would you buy a 7x35 scope? It's a very useful configuration but most folk on here, I suspect, would not give such a scope any consideration at all... s'a funny old world.. init?

Incidentally, this is why a 6x42 gives a better view in low light than a 2-12x50 set at 6 power. I should know... I've got both and feel a right mug for being conned into thinking the big scope would be "better" ... it isn't.... unless I'm trying to take 600yd shots on bright clear days, using max power, in which case it starts to come into it's own then.

I've only shot at anything live over 300yds once. It was a fine big dog fox on a very still night at what turned out to be 315yds... I held a little high and nailed it... but was shocked at the range when we measured it out the next day (it was a very big fox and I "thought" it might be about 250yds away). That was with a 6x42 scope and clear "sighting" was never an issue.

You might have guessed, I'm not convinced that strapping massive lensed scopes onto stalking rifles gives any realworld benefit. All the above is partly why.

 

[JabaliHunter]

That would appear to be confirmed by the exit pupil specs; 9.65mm (not 25mm) at 2x and 4.17 at 12x
I suppose that means that there is an internal field/aperture stop which is used to reduce the effects of optical aberrations at the edges of the lens to stop light passing through them from reaching the eye. I think that it is correct that these effects become progressively harder to correct the more you increase the field of view.

 

[Sharpie]

That would appear to be confirmed by the exit pupil specs; 9.65mm (not 25mm) at 2x and 4.17 at 12x
I suppose that means that there is an internal field/aperture stop which is used to reduce the effects of optical aberrations at the edges of the lens to stop light passing through them from reaching the eye.

The maximum exit pupil of 9.65mm is most likely determined by limitations of the eyepiece design.

It makes no sense to use eyepiece lenses big enough to support e.g. a 25mm exit pupil at low mag. It would have to be huge, heavy and very expensive. And pointless.

I expect that this maximum exit pupil probably remains fairly constant as the 'scope is zoomed, probably until about x5. From then on, I would expect the normal relationship to apply, i.e. at x7 the full benefit of the 50mm objective would be available, exit pupil of over 7mm etc.

Tamus, I think your estimate that at x7 only 35mm of the objective lens is used is likely to be completely wrong.

This could be simply tested, e.g. by projecting the image from the eyepiece onto a sheet of paper, whilst adjusting the zoom setting. The circular image on the paper will be the diameter of the exit pupil.

Or somebody could ask Swarovski for more detailed technical data.

Also consider e.g. the Swaro 1-6 x 24. Once again maximum exit pupil is 9.6 mm, not the theoretical 24 mm at x1. This strongly suggests to me that Swarovski design their eyepieces for a maximum exit pupil of about 9.6mm, which seems eminently sensible, and can make full use of a 50mm objective at magnifications above about x5. Likewise their 2.5-15 x 56 also has a max. exit pupil of 9.5 mm.