Pam Chewning |
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diopters
I am comfused about which diopters and ring mounts to use on a Nikon D50. (52MM) I know this is not the best way to do Macro but this college student has limited funds. Any advice would be appreciated.
October 04, 2006
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robert G. Fately |
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Pam, diopters, or "close up lenses" as they're often called, come in different strengths (typically noted as +1, +2, etc.). The higher the number, the closer the main lens will be able to focus to the subject (what you lose is the ability to focus at infinity while the close-up lens is attached). Exactly how far from the subject you can get depends on the focal length of the lens you're attaching the close-up lens to - the longer the focal lenght of the main lens is, the further away from the subject you can be. This is all a matter of a few inches; it's not as though you can get a close-up of a butterfly from across the room in any event. The 52MM to which you refer is probably the diameter of the front of the main lens you have - this is the size of close-up lens you need to get. As you may know, the close-up lens attaches by screwing onto the front of the main lens, just like a filter. So the thing you want to do is get a close-up lens that's 52MM in size (or whatever your lens requires). I hope thathelps a bit...
October 04, 2006
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Pam Chewning |
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Thank you so much. There is so much information out there and every manufacturer says something different. Should I consider an extension tube to increase the focal length? Thanks again,
Pam
October 04, 2006
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robert G. Fately |
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Hi, Pam, Well, an extension tube is a different approach to getting close-up shots, instead of using a close-up lens. It does not increase the focal length of the lens you put on it, it's just a light-tight tube that moves the lens further away from the film (or chip). This, in turn, allows you to focus closer but, as with the diopter filters, eliminates the ability to focus at infinity while you are using it. Extension tubes (and their flexible cousins, bellows) are similar to the close-up filters in that if you use a longer lens on them, you get a greater "working distance". So with a 50MM lens you might have to be 3" from the subject (let's say a coin), while with a 200MM lens you can get back to 12" form that same coin and get the same-size image on the film/CCD. Longer working distance might come in handy for icky bugs or situations where you just can't get to within 3" away. Plus, it gives you more lighting options - the lens itself won't throw as much of a shadow if it's further away. With extension tubes, a longer tube is kind of like a stronger diopter value - it allows you to get closer. Unlike the close-up lenss, though, there is light loss with an extenstion tube, meaning that you'll need a slower shutter speed if you're using available light. Either way, be aware that in the world of close-up shooting, depth of field becomes very very shallow - you'll often want to use a small aperture just to get most of the subject in focus. If you want to see a bunch of my macro shots, I have them on a different site: www.yessy.com/f8lee - some of the flower shots were taken with macro lenses, some with bellows, some with extension tubes, and some with close-up filter/lenses. Virtually all of them were taken with a tripod, however, and many using flash, as I had to use small apertures to get what I wanted in focus.
October 04, 2006
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Pam Chewning |
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Thanks again. Pam
October 04, 2006
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Michael H. Cothran |
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Allow me to inject just a little more information for your consideration.
While it is true that you can get closer with either diopters OR extension tubes, their physics are totally different:
A diopter placed on any focal length lens will allow the lens to focus at the same distance. This becomes advantageous when mounted to longer lenses, as a 200mm lens focused @ x inches will produce a closer shot than the same distance with a 50mm lens and the same diopter.
With extension tubes, just the opposite happens. An extension tube looses its potency when mounted to a longer lens. Example (and FYI) - to achieve 1:1 magnification, a given lens needs to be extended its focal length distance. In other words, a 50mm lens requires an extension of 50mm to achieve 1:1 ratio. Add that same 50mm extension tube to a 100mm lens, and you'll only reach 1:2. Add the same 50mm extension tube to a 200mm lens, and now your maximum magnification is 1:4. So, the longer the lens, the more extension tubes you need in order to get closer.
A good plus for using extension tubes is that they contain NO glass, which means no loss of quality due to cheap glass found in some diopters.
My suggestion - if you can afford upwards to $100, I would strongly recommend you purchase Nikon's own pair of two-element diopters - the 3T and 4T. They only come in 52mm size, so would be ideal for you, and the quality you get is as good as it gets. You might find some used ones on Ebay. Nikon also makes similar diopters in 62mm size, labeled the 5T and 6T. I would buy the larger size, since these will fit more lenses than the 52mm size.
Most modern lenses are wider than 52mm.
Good luck.
Michael H. Cothran
October 05, 2006
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