Older Nikon Fieldscopes: how much does ED glass matter? (1 Viewer)

I am looking on Ebay at older Fieldscopes, because I read that some of them are very high quality, better than new spotting scopes at a lower price. But as I learned more, some have ED glass and some don't. How much difference does ED glass make to clarity and brightness?

Thanks
Jim

Hi,

extra low dispersion or ED glass is used to decrease the effect of longitudinal chromatic aberration, which means that different colors don't come to the same focus point.

If you plan to use the scope up to 30 or 40x magnification, a plain glass scope is going to be fine. Above that you will see that it gets increasingly difficult to reach good focus - there is not a distinct point of best focus but rather a fairly wide area of least blurriness.

That effect is a lot less pronounced with scopes with an ED glass or fluorite element in the objective. With the normal max magnifications of 60 or 75x you should not see it in a good example.

It has to be said though, that other aberrations also generate that lack of best focus effect at higher magnifications and not so great or even outright bad examples of ED scopes show them unfortunately. So buying scopes in person or from a business with a no questions asked return policy is recommended.

Joachim

The Nikon ED scopes have a much better image, especially at powers above 30x. I take it that you are looking at the 60 mm scopes, which come in both ED and non-ED versions. The Nikon 50 mm, 78 mm, and 82 mm Fieldscopes were only made as ED. If you are looking at 60 mm scopes, don't get the original 60 mm Fieldscope I unless you only want to use 20x or 24x eyepieces (Higher powered options for this scope exist but they are hard to find and most don't work with glasses). If you want to be able to use the zoom and the higher magnification eyepieces, you will need the 60 mm Fieldscope II or III.

--AP