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02-08-2013, 09:33 AM   #1
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Possible C-mount fisheye - thoughts?

Found this lens for $30. Haven't bought it yet:

http://www.sec-op.com/downloads/SO-21CC.pdf

The 03 fisheye has a 160 degree angle of view. The one above is listed as 160, 130. Not sure what that second number is, unless it's 160 degrees wide & 130 degrees high.

Fixed aperture is f:2. Too fast for decent IQ?

Thoughts, anyone?

Cheers,
Bob :-)

02-08-2013, 11:07 AM   #2
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QuoteOriginally posted by GibbyTheMole Quote
Found this lens for $30. Haven't bought it yet:

http://www.sec-op.com/downloads/SO-21CC.pdf

The 03 fisheye has a 160 degree angle of view. The one above is listed as 160, 130. Not sure what that second number is, unless it's 160 degrees wide & 130 degrees high.

Fixed aperture is f:2. Too fast for decent IQ?

Thoughts, anyone?

Cheers,
Bob :-)
They listed both 1/3" and 1/4" sensor size so I suppose 160 and 130 degrees are for those two sensor sizes. Q has a 1/2,33" sensor so this lens is probably not usable any way.
02-08-2013, 12:16 PM   #3
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QuoteOriginally posted by StigVidar Quote
They listed both 1/3" and 1/4" sensor size so I suppose 160 and 130 degrees are for those two sensor sizes. Q has a 1/2,33" sensor so this lens is probably not usable any way.
Ah... I see. Thanks for the info. :-)
02-08-2013, 01:26 PM   #4
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QuoteOriginally posted by GibbyTheMole Quote
Found this lens for $30. Haven't bought it yet:

http://www.sec-op.com/downloads/SO-21CC.pdf

The 03 fisheye has a 160 degree angle of view. The one above is listed as 160, 130. Not sure what that second number is, unless it's 160 degrees wide & 130 degrees high.
As StigVidar says, for different sensor sizes. Unlike what he says though this doesn't make it unusable on the Q, you just won't be using the whole sensor.

QuoteOriginally posted by GibbyTheMole Quote
Fixed aperture is f:2. Too fast for decent IQ?
Not as such (the 01 prime is fine wide open), but I doubt this is any good. Quite possibly the same optics as my lens with the same specs, just a more convenient mount. (Mine is "board mount", 12mm screw.) I haven't managed to mount it properly, but so far my testing suggests it is terrible.

02-08-2013, 01:39 PM   #5
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QuoteOriginally posted by drougge Quote
I haven't managed to mount it properly, but so far my testing suggests it is terrible.
LOL... I had my suspicions. Ah well... Had to give a cheapie one more try before going for the 03 FE.
02-08-2013, 02:35 PM   #6
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It looks a lot like my 4.3mm cctv lens based on the dimensions and that works fine as does my 2.5 CS mount lens. The C mount adapter will provide the correct standoff for the lens regardless of the sensor it was designed for. As the 1/2.3 sensor is larger than 1/4 or 1/3 I believe the lens will just project a round image on the Q sensor. I know my 2.5mm lens shows the corners rounded off to almost a round image. Isn't that what a true fisheye does. I would try it.

Hans
02-08-2013, 03:10 PM   #7
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QuoteOriginally posted by hnikesch Quote
I know my 2.5mm lens shows the corners rounded off to almost a round image. Isn't that what a true fisheye does. I would try it.
How's the IQ on the 2.5mm? Got any samples? - Bob :-)

02-08-2013, 03:27 PM   #8
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I went ahead & ordered it. There's a 14 day money back period if it sucks, so no biggie. If it works out (which is doubtful), I'll let you guys know. - Bob :-)
02-08-2013, 03:57 PM   #9
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QuoteOriginally posted by GibbyTheMole Quote
How's the IQ on the 2.5mm? Got any samples? - Bob :-)
I posted both in Larry's database

https://www.pentaxforums.com/forums/pentax-q/211126-cctv-2-5mm-cs.html#post2231522

https://www.pentaxforums.com/forums/pentax-q/209474-adapted-lenses-tested-q-r...ml#post2220510

I sharpened the 2.5mm but no PP on the 4.3mm

Hans
02-08-2013, 05:07 PM   #10
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QuoteOriginally posted by hnikesch Quote
I posted both in Larry's database
Thanks for pointing me to the thread. The 4mm one looks pretty good! I may have to pick one of those up. :-)

The 2.5mm looks serviceable. Worth taking a chance on.

Cheers,
Bob
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