Scope vs spotting scope??

[billslatteryjr]

Have a couple Vortex Golden Eagles and was wondering how much better would I be able to see bullet holes or hits with a spotting scope. Say with either a Vortex 20-60x85 Viper or Razor spotting scope? So if on a low mirage day I could see 6mm holes at 600yds. How much farther would the extra 30+mm of glass in a spotting scope get me? Out to 800, 1000yds?

 

[std7mag]

A whole lot better with a quality spotting scope.
With my financial disability, i've learned that there is an acceptable level of quality for lower price though.

After a LOT of research, both of optics and my bank account, while i could afford an optic in the $400-500 range, i went a different route.
I got a Celestron C70 Mini Mak.
Celestron has a good reputation of high end telescopes, and microscopes.
The Maksutov design lets lots of light in!
Light weight, short, but large diameter.
Standard telescope eye piece allows different lenses, magnifiers, filters.

I hope to compare it this spring with higher end optics at some of the matches.
Thus far, against a white background target i can make out the holes from my wifes 223 at 430 yards.

 

[Turbulent Turtle]

An interesting question. Allow me to introduce Dawe's limit.

This is the measure of the resolving power of a telescope. For centimeters, you divide the constant 11.6 by the diameter of the objective lens in centimeters. The result is the measurement of the smallest object you can possibly resolve or distinguish in that scope, expressed in arc-seconds.

So for a diameter of 85mm, that value is 11.6/8.5= 1.4. For a 56mm objective that value is 2.1.

This means that with a perfect 85mm objective, you should be able to see an object that measures at least 1.4 arc-second. At 1000 yards, a minute of arc (MOA) is 10.47 inches. A second of arc or arc-second (SOA) is 10.47/60 or 0.17 inch. A 30 caliber hole is .30 inch or about 2 arc-seconds. Of course, bullet holes on paper are usually a lot smaller than the caliber itself.

So that is the incremental resolving power going from 56mm to 85mm, about 33% more, from 2.1 to 1.4.

Then you have to deal with the quality of the glass and the visual acuity of the observer.

 

[SDDasher]

Dang.

 

[billslatteryjr]

Wow! That's good info Turbulent Turtle. Thanks.
My guess is the optical quality of the glass in the Golden Eagle is about the same as in their better spotting scopes.
So it may be that if one could see 30cal holes on a good day at 1000 with the rifle scope, the same guy should be able to see 6mm holes with his spotting scope?
Wonder if anyone with either or both could verify that?

 

[Turbulent Turtle]

Well, the issue is one field conditions and equipment. In a perfect world, you could use the formulae I showed above and say, "Hmm, looks like I will see my 30cal hole at 1000 yards with this here big-ash spotter. "

Reality can be quite different. The glass in a Vortex is nowhere near the best there is. Then you have to deal with CA, mirage, other conditions and even what the target looks like and how it's facing you.

I would use the ratio exactly as that, a ratio. Given the same (crappy) Vortex glass, the bigger objective will give me 33% increased resolution capability, but you have to deal with all the stuff I explained and your visual acuity.

What the formulae show is that someone who says they can see 30cal holes at 1000 yards with anything less than a 200cm spotter on a great day is full of something or has a LOT of imagination and should not be driving, and especially not be trusted with a firearm.

 

[Dub]

I do not try to see bullet holes. My spotter is for seeing mirage and scoring. I can see the scoring markers through my scope when I am on the line.

 

[CjC73]

A whole lot better with a quality spotting scope.
With my financial disability, i've learned that there is an acceptable level of quality for lower price though.

After a LOT of research, both of optics and my bank account, while i could afford an optic in the $400-500 range, i went a different route.
I got a Celestron C70 Mini Mak.
Celestron has a good reputation of high end telescopes, and microscopes.
The Maksutov design lets lots of light in!
Light weight, short, but large diameter.
Standard telescope eye piece allows different lenses, magnifiers, filters.

I hope to compare it this spring with higher end optics at some of the matches.
Thus far, against a white background target i can make out the holes from my wifes 223 at 430 yards.

I'm in same boat. My bank account doesn't allow me the things I'd like . But that looks like a real good possibility for a spotting scope for the range.

 

[JEFFPPC]

Wow! That's good info Turbulent Turtle. Thanks.
My guess is the optical quality of the glass in the Golden Eagle is about the same as in their better spotting scopes.
So it may be that if one could see 30cal holes on a good day at 1000 with the rifle scope, the same guy should be able to see 6mm holes with his spotting scope?
Wonder if anyone with either or both could verify that?

No

 

[billslatteryjr]

Yo Jeff, how are you?
I'm thinking on shooting steel up at Mifflin this year and maybe 800 at Ship too. Wondering if there's any sense in spending the money to buy a decent spotting scope. What's your no to? Never really shot past 500m.

 

[rsmithsr50]

basically what he said is, with the known variable of the quality of the glass, to see x dia bullet hole at y distance, you need z dia front lens.
the scope lens seldom matches the spotting scope lens dia.
decide what distance you need to seem what dia hole...and then save up a whole lot of money
I have seen 6/30 holes at 1000 yards with a 100 mm lens on a 450 celecstron...when the conditions were right.
much easier with an m2 ed glass celestron for 750
and while I have gone down to an 82, I went way up in glass with a meopta 82s

 

[mchees1]

An interesting question. Allow me to introduce Dawe's limit.

This is the measure of the resolving power of a telescope. For centimeters, you divide the constant 11.6 by the diameter of the objective lens in centimeters. The result is the measurement of the smallest object you can possibly resolve or distinguish in that scope, expressed in arc-seconds.

So for a diameter of 85mm, that value is 11.6/8.5= 1.4. For a 56mm objective that value is 2.1.

This means that with a perfect 85mm objective, you should be able to see an object that measures at least 1.4 arc-second. At 1000 yards, a minute of arc (MOA) is 10.47 inches. A second of arc or arc-second (SOA) is 10.47/60 or 0.17 inch. A 30 caliber hole is .30 inch or about 2 arc-seconds. Of course, bullet holes on paper are usually a lot smaller than the caliber itself.

So that is the incremental resolving power going from 56mm to 85mm, about 33% more, from 2.1 to 1.4.

Then you have to deal with the quality of the glass and the visual acuity of the observer.

From what I have read, Dawe's limit is specific to telescopes and resolving two points of light (stars) that appear very close to each other (they look like one star if there is not enough resolution). Will it apply correctly to rifle scopes and spotting scopes looking at a dark hole instead of a point of light? It also seems that Dawes's limit is more of a rule-of-thumb than an absolute law. Just thinking out-loud. Still probably good food-for-thought about what can be seen in a shooting setting versus astronomical setting, and what kind of optic may work best.

 

[500yards]

The reason you want a spotting scope is for the high magnification they have. Even basic scopes have higher magnification than 24x, usually 15 - 45x. They also have better light-gathering ability because they have a larger objective diameter. If all you can afford is to take a 24x rifle scope, it is better than any 8 - 10x binoculars but I'd look into getting a mid-range spotter that goes up to 45x or 60x. Heck, you could sell that Swarovski rifle scope and by a pretty nice spotter for the money you would get.

 

[Turbulent Turtle]

From what I have read, Dawe's limit is specific to telescopes and resolving two points of light (stars) that appear very close to each other (they look like one star if there is not enough resolution). Will it apply correctly to rifle scopes and spotting scopes looking at a dark hole instead of a point of light? It also seems that Dawes's limit is more of a rule-of-thumb than an absolute law. Just thinking out-loud. Still probably good food-for-thought about what can be seen in a shooting setting versus astronomical setting, and what kind of optic may work best.

I totally agree, which is why I had a whole bunch of caveats in my post, where I mentioned the target appearance, the holes, etc. But Dawe's limit applies to telescopes and microscopes and allows you to calculate or approximate the smallest size that can be resolved.

For most of the glass found on rifles and tripods, that limit is a pipe dream.

 

[rsmithsr50]

just not so.
I shoot 2 15-55x's.
while it is a help, as was pointed out it, is dia and quality of the glass in a spotting scope.

The reason you want a spotting scope is for the high magnification they have. Even basic scopes have higher magnification than 24x, usually 15 - 45x. They also have better light-gathering ability because they have a larger objective diameter. If all you can afford is to take a 24x rifle scope, it is better than any 8 - 10x binoculars but I'd look into getting a mid-range spotter that goes up to 45x or 60x. Heck, you could sell that Swarovski rifle scope and by a pretty nice spotter for the money you would get.

 

[Fred Bohl]

Please see the attachment on Scope & Spotting Scope Resolution and Magnification.

On a more practical level, our ability to resolve two bullet holes spaced one calibre apart will be limited by the atmospheric conditions and contrast on the target.

 

[spudgun]

I solved the problem with a down range camera...

 

[Bisson1990]

I solved the problem with a down range camera...

Or (in my opinion), even better, shotmarker or SMT solo e-targets.