Rifle Scopes Scope or optic ‘IQ’ formula?

[bobke]

See frequent reference to a scope’s IQ, but no explanation as to how to calculate same. What are the factors and what is the formula to establish a rating? Seems to relate to power, light transmission, objective diameter, eye relief, field of view and other data points that make sense, but I’ve come up empty in search for further explanation and calculation. A bit of group wisdom appreciated.

 

[spife7980]

Yeah, here, knock yourself out

 

[bobke]

Seem to have misplaced my super computer access code-a simple explanation will suffice.

 

[spife7980]

There isnt one. You cant rate a subjective topic objectively.

 

[bobke]

Okay then, as you seem to be the subjective matter expert here, what are the components to consider in IQ? Or could wait for WJM or Koshkin for their take on it. Either way...

 

[Rerun7]

Interesting. I don’t think I’ve ever seen reference to a scope iq.

Did a google search and nothing came up.

Got any links where they are talking about it?

 

[bobke]

http://www.snipershide.com/shooting...rst-hand-comparison-of-eyebox-and-iq.6964481/

http://www.snipershide.com/shooting/threads/nf-2-5-10x42-any-other-options.6964012/

WJM has mentioned it in a thread I cannot locate yet as related to LRTS/LRHS. Will keep looking for it.

 

[b6graham]

everything you mentioned plus lenses and coatings and erector size and time of day and humidity and temperature and air density and weather

oh yeah and each individuals eye

 

[koshkin]

IQ stands for Image Quality.

Ilya

 

[Rerun7]

Lol. Should have caught that...I literally thought he meant someone was discussing an IQ formula for scopes.

 

[koshkin]

We used to test this back in the day.

Our tests used the B&H photo resolution chart and a DSLR behind the scope.

The dslr was a Nikon D2 with an adapter and zeiss natural prime lens.

Scope FOV was broken up into concentric rings and zoned out for resolution. We would measure how many pixels of chromatic aberration were present and where things started eating shit on the coincident lines charts and such.

Then measure exit pupil with a bright light and a measuring board and such.

Then we would do a tracking test and all.

I can’t disclose the purpose of it due to NDAs but it was well funded and really an eye opener.

Chromatic aberration was the most objectionable of IQ failures IMHO

That's about a third of what you need to do to really characterize image quality.

ILya

 

[bobke]

So...in simplest of terms, ease of use and image quality, all in? For those without either budget or access, when shopping for new optics, how would you weight the top 5 or so data points to review if looking at a manufacturer’s spec sheet, or are those key points just not accessible until in hand? New NF an example of what looks great on paper, but in apparent user experience, not all the specs would suggest? Was ready to buy one, but waited for user reviews, and still in holding pattern. Thanks for feedback to date.

 

[TheGerman]

Maybe.

Sometimes.

 

[Rerun7]

Maybe.

Sometimes.

But not always.

Just depends.

 

[b6graham]

But not always.

Just depends.

but its a possibility

ymmv

what scopes you looking at?

 

[bobke]

I’ve gone largely Bushnell through migration to better optics for handful of AR’s and a couple of 6.5CM AR’s and bolt guns. Have several each of both LRTS/LRHS, HDMR, ERS and two PRO’s. Would like the thinner center reticle of the PRO for the TS/HS and would be pretty GTG, but always on the hunt for ideal optic, without having to buy/sell my way to that alleged end point, if there truly is one. Quest continues.

 

[koshkin]

So...in simplest of terms, ease of use and image quality, all in? For those without either budget or access, when shopping for new optics, how would you weight the top 5 or so data points to review if looking at a manufacturer’s spec sheet, or are those key points just not accessible until in hand? New NF an example of what looks great on paper, but in apparent user experience, not all the specs would suggest? Was ready to buy one, but waited for user reviews, and still in holding pattern. Thanks for feedback to date.

It is difficult to have a singe number numerical score, partly because human eye is part of the equation and they are all different.

Most specs you see in a riflescope brochure tell you virtually nothing about image quality. Some are worthwhile (eye relief, FOV, weight, etc), but image quality deals with the balance between resolution, contrast, color balance, sweet spot and distortion. They can't allbe optimized at the same time, so it is a compromise.

For most of this stuff you really have to be hands on with the scope.

The company I work for builds test equipment for optical devices, so all of these things can be objectively measured, but interpreting the results is a different ballgame altogether and that is its own skillset.

That is one of the reasons I always try to explain how a particular scope performs with respect to others, hoping that the reader may have seen on of the scopes I am comparing, so there is some sort of a frame of reference.

ILya

 

[bobke]

Thx for further explanation. On my climb up the optical learning curve, and in my obvious ignorance, thought there might be some other reference to a theoretical optic IQ, other than simple image quality. Smarter now-appreciate the assistance.