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07-14-2008, 08:04 AM   #1
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Q about fisheye lens attachments (the cheap kind)

hey everyone - i was thinking of what to do with my 18-55 kit lens now that i have upgraded to cover that focal length, and i thought why not get one of those cheap fisheye screw-ons to get both full frame and circular fisheye capability.

my Q is:

there seems to be a conversion factor involved. the attachments all note numbers ranging from 0.25 to 0.75. i can't correlate higher / lower numbers to prices (they seem to be arbitrary on ebay) ... what do those numbers mean???

07-14-2008, 09:00 AM   #2
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I have no experience with the use or quality of fisheye converters, but those numbers are used to describe how the converter will change the field of view.

So if it's a 0.75x converter, at 18mm, the lens will behave like a 13.5mm lens. At 55mm, 41.24mm.
07-14-2008, 09:01 AM   #3
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The numbers refer to the magnification factor. If the number is smaller than 1, it converts the lens to wide angle, if it's greater than 1, it converts to telephoto.

You take the current focal length, and multiply it by the x number. IE 18mm x .25 = 4.5mm.

The thing about most of these lenses is that they are awful in the corners. Very soft with distortion. You'll lose about 1 stop as well.

It's not a bad deal to play around with for only $30, but don't expect great quality.

They screw into the filter threads on the front of the lens. Usually, they are two part lenses, with a magnifier piece in back with the larger front piece. The one I have has a 10x magnifier that can be useful if you can live with the distortion.
07-14-2008, 09:38 AM   #4
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thanks for that info, very helpful!

i'm aware of the quality issue, but i thought for $30 screwed on to a lens i never use anymore, why not.

i have used a zenitar in the past, but wanted to experiment with a fisheye that could do both circular and full frame.

07-14-2008, 10:40 PM   #5
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QuoteQuote:

i'm aware of the quality issue, but i thought for $30 screwed on to a lens i never use anymore, why not.

You'll have a second reason not to use that lens anymore, and be out $30.
07-15-2008, 02:23 AM   #6
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I don't see anything wrong if you have the lens in not trying it.

I have a wide angle adaptor 0.45X for my Kodak P&S. It has a 58 mm thread, so I have put it, from time to time on my old Tamron Adaptall II 24mm F2.5 and get the net result of a semi fisheye at 11mm.

It works and the quality is suprisingly good. Is it a 10-17 fisheye, NO, but for the value, it is not bad at all.
07-15-2008, 06:01 AM   #7
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My boss used one on his EOS 350D with a kit lens. It was calle Cristavision PRO and even thou it added considerable weight to the camera the results were horrible. If I had to take pics with that camera the first thing I did was take of the bottle bottom.

Here's a 50% resized sample pic at f9!!
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