Spotting Scope Exit Pupil

[Reed104R]

My experience with evaluating spotting scopes is somewhat limited, and I have virtually no experience with modern alpha spotters. It seems to me the exit pupil needs to be at least 2-3mm to provide a bright and clear daylight view. Does this hold true for alphas as well? Will there be significant degradation in the daylight image quality of an alpha grade 80mm scope above 40X? Most of my experience has been with vintage spotters.

 

[4th_point]

I regularly use as little as 1mm during the day, and where I live it is cloudy and rainy much of the year. I have a strong preference for high resolution and perhaps that skews my perspective in terms of putting less emphasis on brightness.

I also think that people blame lack of brightness for poor image quality, when really the root cause is poor correction in the device. It becomes more apparent at higher magnification where there's no more detail to be had. And it's dimmer of course, but the problem is really not the exit pupil. The dimmer view is just what is most apparent.

All that stated, at dawn and dusk the amount of light available to your eyeball will matter but poorly corrected scopes can be found at all prices!

 

[Reed104R]

We work with smaller exit pupils and higher powers with spotters, and this exacerbates the issue, especially for old eyes like mine. With binoculars and rifle scopes, many people likely never give it a second thought until just before dark. Using vintage spotters adds to the mix for me.

 

[4th_point]

Which vintage makes and models, and magnification?

 

[LaHunter]

My experience has been first with a Vortex Razor HD 65mm spotter (gen 1) and a Swaro HD 65mm spotter.
Better glass will provide a better image, for a given set of conditions.
Exit pupil is only one, of many factors involved.
In general, in my experience, as you increase the power setting, the perceived image can degrade. For the given atmospheric conditions, you just have to adjust the power to get the best image, to your eye.
For spotting scopes, atmospheric conditions play a huge role in the image quality. Near sea level on a humid, warm day, the image quality is going to be limited. At 10,000 ft, on a clear, cool, low humidity day, the image quality is excellent. The old saying of buy the best glass you can possibly afford holds true, in my opinion. There are no free lunches when it comes to spotting scopes.

 

[Reed104R]

Thanks for the advice. I primarily use a spotter for the range; a Bushnell (Kowa) 20x50 and a USA Redfield Regal 15-60x60. Both scopes are from the 70's.

 

[4th_point]

I don't have any experience with either of those vintage scopes, but have heard that the old Kowa-made Bushnells can be quite good.

Are you looking to upgrade to a newer scope for range use?

 

[Reed104R]

I will likely upgrade at some point and really appreciate the information. I rarely have the opportunity to test spotters, so I learn all I can from Rokslide!

 

[4th_point]

Target cameras work well for range shooting.