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Old May 9, 2003, 6:29 PM   #11
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Hi Lin,

Just want to share with you one more result showing that lens size is not a problem that causes vignetting. I forgot I had a page at my 950/990/995/4500 user guide that serves this purpose. Here is Kenko KUT 500 5X teleconverter mounted on a Coolpix 4500:

http://www.cs.mtu.edu/~shene/FORUM/K...X-4500-400.jpg

The 4500 has a small lens of 28mm thread size, and the Kenko 5X has 37mm rear thread size. A 28mm-37mm step-up ring is required. The rear element of the Kenko is slightly smaller than that of the CrystalVue 8X. Due to its optical design, the Kenko 5X causes serious vignetting on a Coolpix 990. The following is an example:

http://www.cs.mtu.edu/~shene/FORUM/K...vignetting.jpg

However, if the Kenko is mounted on a Sony Digital8 camcorder (see below) which has a larger front element and larger thread size, there is no vignetting (or vignetting is at least not as bad as the 990):

http://www.cs.mtu.edu/~shene/FORUM/K...X-Sony-400.jpg

How can the same lens mounted on a larger lens has a vignetting problem much less than when it is mounted on a smaller lens? A good explanation is that the optical formula used in a 990 is different from that used in the Sony. The lens of 950/990/995/4500 is deeply recessed into the lens chamber, which means the distance between the rear element of the Kenko and the front lens element of the 990 is too large such that the FOV of the Kenko does not contain that of the 990.

Hope this helps.

CK
http://www.cs.mtu.edu/~shene/DigiCam
Nikon Coolpix 950/990/995/2500/4500 user guide[/quote]
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Old May 9, 2003, 9:58 PM   #12
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Hi Shene,

Yes, but remember I didn't say that large lenses "caused" the vignetting, I said that the 5x and above tele converters and monoculars will not work well with any currently manufactured fixed lens digicams which "have" large lenses.

Actually what I said exactly was:

"The OpticZoom 5x isn't a good match for the Canon. Large lens cameras in general don't do well with higher powered teleconverters like the 5x. There will be significant vignetting (black fringe around the periphery) even at full zoom."

I think from your very first post that you jumped to the conclusion of implied causality. Your response:

"Well, this is actually not exactly the reason."

I didn't imply that it was a "reason," simply stated the fact that large lenses in general don't do well with the 5x & so on.... The "cause" really isn't important to the user, only the "effect."

Best regards,

Lin
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Old Aug 20, 2003, 1:44 PM   #13
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So only testing counts?? So, which one is good for my Panasonic DMC FZ1?
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Old Aug 20, 2003, 3:13 PM   #14
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Quote:
So only testing counts?? So, which one is good for my Panasonic DMC FZ1?
I really don't know any other way to determine how a lens might work other than by trying it - especially since there are so many different manufacturers and lens configurations.

I haven't tried the DMC FZ1 with any of the telephoto lenses, but because it has a super large zoom, it would not be likely to work with anything over about 2x. The Olympus TCON-17 or the nearly identical Olympus B-300 would be most likely to be compatible at the telephoto end.

Lin
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Old Aug 20, 2003, 3:30 PM   #15
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Well it's not hard to confuse a newbie. Why am I confused? You said that nothing over 2 will work. Why? I read some other posts which say that for 5 tconverter you need at least 5 zoom or sth similar (I don't know the exact number). Now I really don't get it. As we see here:

http://www.eagleeyeuk.com/Main_Image...ple_photos.htm

the photos aren't bad and it's possible that FZ1 works even better.
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Old Aug 20, 2003, 5:18 PM   #16
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Pay particular attention to the corners on all 5x shots with OpticZoom and C2100UZ where you will see significant vignetting (shadowing in the corners).

If you don't mind the vignetting, that's probably about what you can expect with your camera and a 5x.

With a 1.7x tele, you should have no vignetting at full zoom with progressivly more vignetting as you zoom back.

Lin
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Old Aug 21, 2003, 1:06 PM   #17
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Unfortunatelly David Elson has the FZ1 and 5 EE and he says the vignetting is just too heavy. I'll have to find a converter with larger diameter, I suppose. But the first choice is still TCON17 or similar, as you said.
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