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12-25-2012, 03:32 AM   #1
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What is Focal Length of Fotodiox Q to K adapter?

Just got one and I don't know what the focal length is. Focal length is needed for firmware 1.10 and must be set manually for functions
such as Shake Reduction to work.


Somebody know this? How can I figure it out?

12-25-2012, 07:57 AM   #2
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QuoteOriginally posted by SonDa5 Quote
Just got one and I don't know what the focal length is. Focal length is needed for firmware 1.10 and must be set manually for functions
such as Shake Reduction to work.


Somebody know this? How can I figure it out?
Type in what it says on the lens. So if it's a 50mm lens, type in 50mm, if it's a 70-210mm lens, type in the lower end of the zoom range or wherever you plan on shooting the most.

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12-25-2012, 12:09 PM   #3
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Thanks.

I wasn't sure if the adapter offset distance would effect over all focal length.
12-25-2012, 02:57 PM   #4
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Hi SonDA5,

I'll give you a bit more information of what the K to Q lens adapter does, if you're interested.

For any interchangeable lens camera, all the lenses need to be designed so they can focus the image on the sensor (film) throughout their entire focusing range. To do this, they need to have a set lens mount flange to sensor plane (register) distance. For the K mount it's precisely 45.46mm. The Q, because it was designed to not need the mirror of an SLR, and because they wanted it to be very compact, uses a 9.2mm (?) register distance. To make K mount lenses focus to their designed ranges, an adapter is needed to move them out so their flanges will be 45.46mm from the Q's sensor plane, so essentially the adapter is a 36.26mm spacer with a Q mount on one side and a K mount on the other. The adapter does not effect the lens' characteristics, just allows the lens to focus throughout its range as it was originally designed to do.

Pentax's K mount is AFAIK, the only DSLR mount that currently uses a mechanical aperture actuating mechanism, so any adapter for the K mount must have a mechanical aperture adjustment linkage to change apertures in lenses that don't have their own aperture ring.

The Q does not have a mechanical shutter in the camera body. Only the 01 prime, 02 kit zoom, and the 06 tele zoom have mechanical leaf shutters built into the lenses. The 03 FE and 04 and 05 toy lenses, as well as any of the 3rd party lens adapters for any mount all use just the electronic shutter in the Q's sensor.

The Pentax K to Q lens adapter has a both a mechanical leaf shutter and a stopless aperture control ring built into it.

Scott

12-25-2012, 03:11 PM   #5
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Thanks Scott.


The cheapy fotodiox works fine for manual focusing and has and adjustable aperture ring built into it. Flash offset control can manually be set as well. I might get the Pentax adapter when the price comes down but for now the cheapy fotodiox is working great for me.
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