Question on optics

baseballjeff

Hello!

I went to my son’s eye appointment the other day and saw the Doctor using some kind of cool lenses. It got me wondering how these would be for looking at coins?

Jeff

baseballjeff

Here is a link:

https://www.bernell.com/category/Ion_Lenses

ricko

Just get a good eye loupe.... no more than 10X..... Zeiss if you can, they make great glass. Cheers, RickO

jtlee321

This is what I use and swear by, it's a Tominon 135mm lens. It was for a Polaroid Macro kit for large format photography. The magnification is not high, it's around 2.5 - 3x. It will allow me to see a full sized Morgan Dollar in the loupe and allows me to see any and every hit. The quality of the glass is outstanding!! the price is pretty decent as well, around $30.00.

rmpsrpms

The "diopter" lenses used by optometrists are single element lenses, so they give high power but poor color and distortion correction. Most handheld loupes are similar. One step up is an achromat, which gives some color correction plus often some improvement in distortion by combining two lenses ("doublets") of different types of glass. A few "better" loupes are achromats, with some of them even using three lenses ("triplets"). But even the best loupes pale in comparison to photographic lenses such as the Tominon 135mm that @jtlee321 describes above. It's amazing that people will pay $100 or more for a handheld loupe when lenses like the Tominons are available for a small percentage of that, and offer such a substantial improvement in performance.

For folks wishing to try such lenses, there is a formula for calculating the "magnification power" given the focal length:

Magnification = 250/FL +1

So for the 135mm lens, you get 250/135 + 1 = 1.85 + 1 = 2.85x

For higher power, a 50mm lens, like a Nikon 50/2.8 EL-Nikkor, makes a fantastic 6x loupe.

jtlee321

@rmpsrpms said:
The "diopter" lenses used by optometrists are single element lenses, so they give high power but poor color and distortion correction. Most handheld loupes are similar. One step up is an achromat, which gives some color correction plus often some improvement in distortion by combining two lenses ("doublets") of different types of glass. A few "better" loupes are achromats, with some of them even using three lenses ("triplets"). But even the best loupes pale in comparison to photographic lenses such as the Tominon 135mm that @jtlee321 describes above. It's amazing that people will pay $100 or more for a handheld loupe when lenses like the Tominons are available for a small percentage of that, and offer such a substantial improvement in performance.

For folks wishing to try such lenses, there is a formula for calculating the "magnification power" given the focal length:

Magnification = 250/FL +1

So for the 135mm lens, you get 250/135 + 1 = 1.85 + 1 = 2.85x

For higher power, a 50mm lens, like a Nikon 50/2.8 EL-Nikkor, makes a fantastic 6x loupe.

I use a Tominon 35mm for looking for varieties. I get a lot of people asking me about my "loupe" at coin shows or new coins shops I visit. They all have that surprised look on their face when I let them try out the 135mm.. It's so bright and clear, I'd never use a small standard loupe again.