Power of 250d &500d diopter lens?

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I am having trouble comparing the power of Canon diopters to other brands, I have found other diopters listed as + 1 , + 1.5 , +3.0 , etc. What power is the Canon 250D andthe 500D ? (for the lens, not viewfinder)

Thanks for help on clearing this up!

D.C.

-- D.C. (cyberern@wctc.net), November 19, 2000

Answers

I would also like to know if these diopters will give sharp results in the Canon 28-105mm macro, and the 100-300mm (both usm) or are these diopters targeted for a 50mm prime??

-- D.C. (cyberern@wctc.net), November 19, 2000.

Anything you put on the front of your lens will reduce the quality of the image, even a filter, but you'd rarely see the difference. Diopters on the front of camera lenses usually cause the corners to go visibly soft. If you're taking pictures of flowers & bugs that probably wont matter. A stamp collection or other flat stuff would be a problem. The "D" series Canon's use a double lens design that greatly reduces the problems usually seen with these types of close up lenses, but they aren't perfect. I've heard from several people that use them on Canon zooms as well as primes with good results.

As I understand it, the 500 forces any lens to focus at .5 meters when the lens is set at infinity, so that would make it a +2 diopter (1 meter would be +1 diopter). The 250 restricts maximum distance to .25 meters, so it would be a +4 diopter. I've never used these but this is what I've heard from a combination of other sources.

BTW Nikon has a line of these double lens close ups (T-something or other I believe) that are just as good and cost half as much. I don't think they make them in a 58mm though so you'd have to get a step up ring & use their 62mm for the 28-105 USM. Still substantially cheaper.

-- Jim Strutz (jimstrutz@juno.com), November 19, 2000.


D.C.,

The previous post pretty much covered it but for one fact. The Nikor (3T, 4T, 5T and 6T) and Canon (250D, 500, 500D) plus diopters are all optimized for telephoto lenses. I use both the Nikor and Canon diopters and can't say I see any difference.

The Canons are available in more sizes however. The Nikor 3T and 4T are 52mm diameter and the 5T and 6T are 62mm. The Canons are available in sizes up to 77mm.

As far as corner sharpness is concerned the two element design (everything under discussion but the Canon 500) greatly improves edge to edge sharpness but if you are doing critical work a true macro lens would be noticeably better.

I use the Nikor 5T and 6T with the 28-105 USM and the 100-300 USM with excellent results. I also have a 500D 77mm that I use on the 70-200 mm USM and 300 mm USM. Wisdom would indicate that this combination should be better but I've never made any kind of direct comparison. Perhaps I shall sometime but right now I'm just too busy shooting and having fun to worry about it.

Joe Dickerson

-- Jospeh A. Dickerson (jadphoto@aol.com), November 20, 2000.


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