1" vs 30mm light transmission?

[ejg]

When talking to optics manufacturers they seem to mention the importance of the optical calculation as being one of the most important factors. They often say that the calculations made huge improvements in the last years. Looking at the difference between R1 and the newer R2 range of Meopta scopes I believe that there is more to it than just glass and coatings. I believe that newer generation scopes have generally improved optically however some have gone backwards mechanically.
edi

 

[Southern]

Look forward to reading that.

What mechanism are you going to use for measuring 100 yard resolution?

K

I use the USAF 1951 optical resolution target, the Zeiss resolution target, the RCA grey scale target, optometrist's eye chart, and an artist's color wheel. You want something that has sharp edges, and also some patterns of various detail, which the best optics will show you, while the others will just blur into a grey patch.

All these test targets also have little images you can download and print, and keep in a ring binder, so you can look at them and see what you should be seeing through your glass.

 

[mak]

The tube has nothing to do with light transmission. The optical design, magnification parameters and required adjustment can dictate tube size. Transmission is measureable and between 3-5% variance could be noticed by the human eye. The transmission curve also relates to the light spectrum, measured in nanometers. Glass types, coatings and grinding play a huge part in light transmission as mentioned earlier and manufacturers use a variety of glass types from Hoya, Ohara and Schott to name a few and the glass type used can depend on cost, but mainly the best glass with the appropriate refractive index is used. Just a quick note on tube size, two easy equations can be used: The objective lens collects the light and the exit pupil delivers, so an 8x56 will have an exit pupil of 7mm (which is the max the human pupil will go to in low light, and that is subject to age), so it does not matter whether that scope is a 1" or 30mm tube.

What determines the tube size required to fit the rifle is aesthetics, mounts, cost and scope model preference.
Some models appear as bright as others during certain times of the day, but subject to the time of the day / evening, the resolution of those scopes can change.

There is a film on Fieldsports TV where FSTV visited the Zeiss factory and filmed the manufacture of a riflescope and the materials used, plus they measured two scopes for light transmission and show the results, without naming the alternative model or manufacturer.

 

[palmer_mike]

The tube has nothing to do with light transmission.

Think that covers it, lol!

 

[Klenchblaize]

I use the USAF 1951 optical resolution target, the Zeiss resolution target, the RCA grey scale target, optometrist's eye chart, and an artist's color wheel. You want something that has sharp edges, and also some patterns of various detail, which the best optics will show you, while the others will just blur into a grey patch.

All these test targets also have little images you can download and print, and keep in a ring binder, so you can look at them and see what you should be seeing through your glass.

‎So you have a defined image to compare but to achieve an accurate real-time comparison of each manufacturer's design and use of glass, would you not need to ensure the following?

A. Each s‎cope to be of the same magnification range and objective diameter.
B. ‎Each scope set at the same magnification and focused on the same 100 yard target.
C. Trigger ‎the recording mechanism of each scope at the exact SAME time to ensure comparable low (fading) light conditions.

Item 'C' is surely a prerequisite to credible data whatever combination of scope make, design, magnification and objective diameter compared. ‎

This subject really interests me and mainly because of that often stated assertion that suggests ‎light gathering and image ‎quality values are ultimately determined by the pair of eyes behind the ocular lens. Something I simply cannot accept would stand up to scientific ‎analysis.

All the best
‎
K‎

‎

 

[ChesterP]

‎So you have a defined image to compare but to achieve an accurate real-time comparison of each manufacturer's design and use of glass, would you not need to ensure the following?

A. Each s‎cope to be of the same magnification range and objective diameter.
B. ‎Each scope set at the same magnification and focused on the same 100 yard target.
C. Trigger ‎the recording mechanism of each scope at the exact SAME time to ensure comparable low (fading) light conditions.

Item 'C' is surely a prerequisite to credible data whatever combination of scope make, design, magnification and objective diameter compared. ‎

This subject really interests me and mainly because of that often stated assertion that suggests ‎light gathering and image ‎quality values are ultimately determined by the pair of eyes behind the ocular lens. Something I simply cannot accept would stand up to scientific ‎analysis.

All the best
‎
K‎

‎

I'll be using some photographic test cards placed at 100m, together with an incident light meter and grey card to give an indication of brightness. Mak has nailed it really and offered some sensible comments.

Funnily enough I've just finished doing some rough and ready tests (without the light meter for now) and four scopes which appeared to perform fairly closely in daylight are now gulfs apart as it grew darker. Not quite black outside but about as dark as most people would shoot without NV. The mid priced scope which excelled in daylight has lost out big time to a V3 Leup which has retained superb definition, both set to 10 times mag. What has surprised me is that the most budget offering (no names....yet!) has performed very well too and certainly good enough for a 100yd shot in darkening conditions against a dark background (and backstop). The Leup wins out though even though in daylight at higher magnifications it demonstrated some obvious Chromatic aberrations, possibly more so than the mid priced scope. The one on test uses an LR "varmint" ret and it remains good enough despite the fine ret for twighlight shooting. On balance, the Leup wins out overall which is sort of what one might expect. I haven't decided how far to go with this as I was doing it for my own reasons, but if anyone's interested I'll try and do something around a write up in due course.

 

[Southern]

ChesterP, while there are automated lense test machines for manufacturers like Zeiss, most lense testing ultimately relies up some person's visual evaluation of the targets.

Optical testing targets
Resolution Test Targets

Different lenses, or lense systems, have different requirements. Some need more resolution, while others need true colors.

Here is a technical article of a testing method, Modulation Transfer Function, which has good explanations of the various aspects of image quality, with images. You can ignore the math and still grasp the concepts of each example of resolution, contrast, etc, using some of the targets I use for telescopic sights and binoculars for MY eyes. But I have developed optical telemetry systems for robotics, QC, guidance, medical positioning and diagnostics, all of which required specific testing and calibration targets.

http://www.optikos.com/wp-content/uploads/2013/11/How-to-Measure-MTF.pdf

 

[ChesterP]

ChesterP, while there are automated lense test machines for manufacturers like Zeiss, most lense testing ultimately relies up some person's visual evaluation of the targets.

Optical testing targets
Resolution Test Targets

Different lenses, or lense systems, have different requirements. Some need more resolution, while others need true colors.

Here is a technical article of a testing method, Modulation Transfer Function, which has good explanations of the various aspects of image quality, with images. You can ignore the math and still grasp the concepts of each example of resolution, contrast, etc, using some of the targets I use for telescopic sights and binoculars for MY eyes. But I have developed optical telemetry systems for robotics, QC, guidance, medical positioning and diagnostics, all of which required specific testing and calibration targets.

http://www.optikos.com/wp-content/uploads/2013/11/How-to-Measure-MTF.pdf

Many thanks Southern, I'll read that with interest, although my testing won't be nearly as scientific as it's more a subjective comparison.

Interestingly, initial assessments continuing after dark and then testing with what little ambient light was available, something unexpected happened. Where the Leup started to shine through at twightlight, come the dark, it was comprehensively eclipsed by the medium priced scope which had a clear advantage. I think that the larger ocular lens on the medium scope helped matters a bit. One thing I'm learning is that medium priced optics should not be automatically written off. They're getting much better these days.

 

[joe soapy]

One of the US scopes is advertised as being tuned towards blue light for use in low light
Helpful or not??
My interest is use with a lamp, am finding LED light is a lot different from halogen,
and foxes and bunnies can also react badly to led