 Alethea Hawley |
What extended zoom? Im looking for a powerful zoom for my Canon EOS 300 film slr camera. Does anyone know anything about Opteka? Also what does mirror lens mean? They do a 500mm fixed? mirror lens which is much much cheaper than buying something like a Canon 100-500mm zoom. Any advice?
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Jon Close |
A mirror lens (aka "reflex" or "catadioptric" or "Cassegrain") is a very economical way to get very long focal lengths. The design uses 2 mirrors to "fold" the light path, making it very compact and lightweight. The design has several short comings. It can only have a single aperture setting, usually a relatively slow f/8. It is manual focus (though Minolta did make an autofocus 500 f/8 Reflex for its Maxxum/Dynax cameras). And because there is a secondary mirror in the middle of the lens opening, the design has lower contrast than conventional lens designs, and produces pecular doughnut shaped out-of-focus background highlights. On EOS camera bodies these lenses can only be used in M and Av exposure modes. Despite this, they are quite usable and can give satisfactory results for someone on a very limited budget. I have and use a Russian-made MC (Maksutov-Cassegrain) Rubinar 500 f/5.6. Opteka also makes a cheap conventional 500mm f/8 lens. It is also manual focus, but the aperture is adjustable (f/8 to f/32). Like the mirror lens, it can only be used in the M and Av exposure modes. Its major drawback is that its minimum focus distance is 10m (33 ft.). Again, it's usable if you don't expect too much from this $110 lens. It's not going to be as sharp as $1000-$5000 500mm lenses. Other inexpensive alternatives include using a 1.4x or 2x teleconverter with your 70-300 f/4-5.6 lens. Kenko and Tamron make decent ones that will work. Canon's and Sigma's are specially designed to fit only a select few of their lenses and won't fit yours. You'll be able to shoot in any of the cameras exposure modes. With a 1.4x you'll have 98-420 f/5.6-8, with a 2x you'll get 140-300 f/8-11. The EOS cameras generally need f/5.6 or wider aperture to autofocus. In bright light you may be able to autofocus using the teleconverter, but count on being limited to manual focus. Otherwise, there is a major step up in cost to get to 500mm and still have autofocus and all exposure modes:
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Jon Close |
Oops, slight correction. The last lens, Sigma 50-500, should be f/4-6.3.
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Alan N. Marcus |
Well spoken Jon, a tip of the hat. Alan Marcus
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Alethea Hawley |
Once again, thanks John, that was really helpful. Alethea
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Jon Close |
d'oh! I need a proofreader. ;-) "with a 2x you'll get 140-300 f/8-11" should be 140-600.
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David A. Bliss |
I completely understand wanting certain focal length lenses, but not having the money to get "good" glass. I am actually still in that boat. I am in the same position as you are, needing a longer focal length lens. I went the fairly cheap route early on. Looking back on it, I regret it. I have a number of photos that I shot in the first few years that would be very good pictures, if I had been using better glass. I know it's an old adage, but you do get what you pay for. Does that mean you need to mortgage the house for a Canon 600mm f/4? No, there are absolutely ways to go that won't cost the same as a used car, but going with the absolute cheapest lens will probably just be frustrating for you in the long run. Right now I am saving up for a new zoom combo. After doing a lot of research, I have decided on the Sigma 120-300 f/2.8, with 1.4x and 2x teleconverters. This lens has been rated very high by independent reviewers (ones I trust), as high or higher than any of the Canon zooms. It went from excellent to great with the 1.4x, and very good with the 2x. This will give you an effective focal range of 120mm at 2.8 to 600mm at 5.6. The entire combo should cost around $2500. I know that seems like a lot of money, but try getting that kind of focal range on Canon glass for less than $4000 or $5000 (or more!) It is going to take me about 6 months to get all of my finances in enough order to pull the trigger on this purchase (I could go into debt, but I have also learned my lesson about that!), but it will be worth it in the long run for me.
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Alethea Hawley |
Hi Jon, thanks for the correction, I worked it out though. And David, thank you too, excellent information. I'm so impressed with this site, and having access to this wealth of information. I'll probably do the same as you and save up for a Sigma or a Canon, makes sense. But I'll buy on ebay as the savings can be superb. If either of you are interested, check my images on flickr, link is http://www.flickr.com/photos/88979864@N00/ Cheers Alethea
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