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04-08-2009, 04:44 AM   #1
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Pentax DA 18-55 F40

Hello !
Recently i saw that the minimum aperture of my lens (DA 18-55) is not F38 anymore, but F40. Is this normal or there is a problem ? I'm using a K10d together with this lens with 1.30 firmware.

04-08-2009, 05:07 AM   #2
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http://www.dpreview.com/lensreviews/pentax_18-55_3p5-5p6_p15/page3.asp

I don't have the lens with me, but can it reach f 1:40 at 18 mm?
04-08-2009, 07:17 AM   #3
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QuoteOriginally posted by gabymarian Quote
Hello !
Recently i saw that the minimum aperture of my lens (DA 18-55) is not F38 anymore, but F40. Is this normal or there is a problem ? I'm using a K10d together with this lens with 1.30 firmware.

The mex it can go is F38, as far as i can tell . . .
04-08-2009, 08:11 AM   #4
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On an *ist D...

QuoteOriginally posted by gabymarian Quote
Hello !
Recently i saw that the minimum aperture of my lens (DA 18-55) is not F38 anymore, but F40. Is this normal or there is a problem ? I'm using a K10d together with this lens with 1.30 firmware.
mine goes from 3.5 at 18mm to 5.6 at 50 just as the title suggests. You haven't mentioned if it is the DA I or the II.

Cheers,
Cameron

04-08-2009, 08:18 AM   #5
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mine ( the II version) goes to f40, too.

did you, by any chance, change the ev steps from 1/2 to 1/3 ?
04-08-2009, 08:31 AM   #6
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QuoteOriginally posted by Cambo Quote
mine goes from 3.5 at 18mm to 5.6 at 50 just as the title suggests. You haven't mentioned if it is the DA I or the II.

Cheers,
Cameron
50????? Hmm, I doubt it
04-08-2009, 09:55 AM   #7
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QuoteOriginally posted by octavmandru Quote
50????? Hmm, I doubt it
That's about right. Might be somewhere between 45 and 50, but it's tough to say for sure since the EXIF seems to always report just approximations of the actual focal length.

Are you seeing something different?

Last edited by Marc Sabatella; 04-08-2009 at 03:25 PM.
04-08-2009, 10:05 AM   #8
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I meant 55...

QuoteOriginally posted by octavmandru Quote
50????? Hmm, I doubt it
picky, picky...

Cheers,
Cameron

04-08-2009, 03:55 PM   #9
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QuoteOriginally posted by Marc Sabatella Quote
That's about right. Might be somewhere between 45 and 50, but it's tough to say for sure since the EXIF seems to always report just approximations of the actual focal length.

Are you seeing something different?
QuoteOriginally posted by Cambo Quote
picky, picky...

Cheers,
Cameron
No guys, never meant to be picky.
The OP question was about the maximum f stop upper limit.
I suspect he noticed the upper limit to be f 1:38 at 18 mm, and it automatically increases at f 1:40, when extending the zoom at 55 mm.
He wanted to know if this is normal, or a malfunctioning of the lens.
Personally, I think is normal behavior. In the previously added link, DPreview is mentioning the f 1:40 as the top f stop.


BTW, what kind of info is sending the lens to the body about the f stops and focal length? Analogical, like a variable resistor? Does anyone know?
I have a malfunctioning Tamron 20-200 mm. Always is saying 200 mm in EXIF.

Last edited by octavmandru; 04-08-2009 at 04:05 PM.
04-08-2009, 06:03 PM   #10
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I'd taken a shot at f/40 at 55mm, just to get a 30sec exposure in inner Brisbane.
Was helpful then... and reasonably sharp too...

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