ray_parkhurst
09-10-2021, 03:30 PM
I have advocated using "real" photographic lenses as loupes to view coins for many years. The best loupes tend to be triplets, ie they have 3 elements, and are designed to have decent color correction and low distortion. Typically, the worst photographic lenses have 4 elements, and many have 6 or more. Photographic lenses are also usually coated to improve contrast and transmission, while loupes generally are not. These are some of the reasons photographic lenses cost much more than loupes.
A few folks have heard me, and have generally converted over to enlarging lenses for coin viewing. Enlarging lenses are very high quality, and available very cheaply on the used market. They are readily available in 50-135mm focal lengths, with a few types available in shorter or longer focal lengths. There is a simple formula that will convert "Focal Length" (FL) to "Magnification" (M)
M = 250/FL + 1
So a 50mm lens has a magnification of 6x, and a 125mm lens has magnification of 3x. These magnifications are great for viewing and grading coins, so the available range of lens focal lengths is very synergistic with our hobby.
But what about higher magnifications? Many folks use the B&L 14x and 20x Triplets for viewing and attributing varieties. I myself have these Triplet loupes, and used them for years before I got a stereo microscope. I was never happy with them, and was ecstatic when I got my stereoscope, but there is still a need for that "quick view", or to check for varieties at coin shows, etc. The 14x and 20x have been mainstays for this, though their image quality, contrast, field flatness, and field of view have always been limiting, even though they are the best available for this purpose. Or are they???
I've just run across a small supply of 13mm optical scanner lenses that were designed for microfiche viewing. They are a bit larger than the B&L 20x body, but have a bit higher magnification, a bit wider field of view, and are quite a bit sharper and more contrasty. I find that because of the better image quality, they are more comfortable to use as well as more revealing of variety details. They don't take the place of a good stereoscope, but if you don't have a stereoscope, you want the best quality loupe you can get.
Only disadvantage to these is they have no case/handle like the B&L's, so you end up simply holding the lens body. You will also need to store them in a place where they won't get dusty or scratched. Part of the price of the B&L's is their nice folding handle, but the most important thing about loupes is the image quality, not the nice mechanics, right?
I'm going to make these available to LCF folks for $10. I'd like to get them into a few folk's hands before trying to sell them in other places, so I'm making them available here exclusively for now.
For folks who have never owned or used a 20x B&L Triplet, please realize that these high power lenses are VERY SMALL. I personally was shocked when mine arrived (over 30 years ago!) and I started using it. You have to get very close to the coin, and get your eye very close to the lens, to view with them. So please be forewarned not to expect a big lens. To be specific, this lens is only about 1/2" in diameter and 1/2" long! It has a nice black aluminum body, and I will wrap the body with black friction tape if requested to improve the feel of the lens.
I can ship the lens for $5 so total with shipping (in the US) is $15. It seems retail price for the B&L 20x is ~$65, so this is quite a bargain IMO. I plan to sell these for probably $15-20 on other forums so get yours at this low price while you can!
A few folks have heard me, and have generally converted over to enlarging lenses for coin viewing. Enlarging lenses are very high quality, and available very cheaply on the used market. They are readily available in 50-135mm focal lengths, with a few types available in shorter or longer focal lengths. There is a simple formula that will convert "Focal Length" (FL) to "Magnification" (M)
M = 250/FL + 1
So a 50mm lens has a magnification of 6x, and a 125mm lens has magnification of 3x. These magnifications are great for viewing and grading coins, so the available range of lens focal lengths is very synergistic with our hobby.
But what about higher magnifications? Many folks use the B&L 14x and 20x Triplets for viewing and attributing varieties. I myself have these Triplet loupes, and used them for years before I got a stereo microscope. I was never happy with them, and was ecstatic when I got my stereoscope, but there is still a need for that "quick view", or to check for varieties at coin shows, etc. The 14x and 20x have been mainstays for this, though their image quality, contrast, field flatness, and field of view have always been limiting, even though they are the best available for this purpose. Or are they???
I've just run across a small supply of 13mm optical scanner lenses that were designed for microfiche viewing. They are a bit larger than the B&L 20x body, but have a bit higher magnification, a bit wider field of view, and are quite a bit sharper and more contrasty. I find that because of the better image quality, they are more comfortable to use as well as more revealing of variety details. They don't take the place of a good stereoscope, but if you don't have a stereoscope, you want the best quality loupe you can get.
Only disadvantage to these is they have no case/handle like the B&L's, so you end up simply holding the lens body. You will also need to store them in a place where they won't get dusty or scratched. Part of the price of the B&L's is their nice folding handle, but the most important thing about loupes is the image quality, not the nice mechanics, right?
I'm going to make these available to LCF folks for $10. I'd like to get them into a few folk's hands before trying to sell them in other places, so I'm making them available here exclusively for now.
For folks who have never owned or used a 20x B&L Triplet, please realize that these high power lenses are VERY SMALL. I personally was shocked when mine arrived (over 30 years ago!) and I started using it. You have to get very close to the coin, and get your eye very close to the lens, to view with them. So please be forewarned not to expect a big lens. To be specific, this lens is only about 1/2" in diameter and 1/2" long! It has a nice black aluminum body, and I will wrap the body with black friction tape if requested to improve the feel of the lens.
I can ship the lens for $5 so total with shipping (in the US) is $15. It seems retail price for the B&L 20x is ~$65, so this is quite a bargain IMO. I plan to sell these for probably $15-20 on other forums so get yours at this low price while you can!