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06-21-2015, 08:21 PM   #1
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Has anyone tried fitting a speed booster between a Q and a k-mount lens?

I'm actually really curious; I know I can get my hands on a m43 to Q adapter, and then something like the Roxsen, Metabones or Mitakon booster for k to m43. Seeing that the Q suffers from the tiny sensor, would the focal reducer help it when mounting K lenses? We'd lose a chunk of the crop, but it would give a stop of speed, and I'm wondering if the trade would be worth it. Any mad science people here who have already had this thought?

06-21-2015, 08:58 PM   #2
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The Q does not "suffer", but it would be interesting to try, especially with a fast lens...
06-22-2015, 07:43 AM   #3
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QuoteOriginally posted by Mothballs Quote
I'm actually really curious; I know I can get my hands on a m43 to Q adapter, and then something like the Roxsen, Metabones or Mitakon booster for k to m43. Seeing that the Q suffers from the tiny sensor, would the focal reducer help it when mounting K lenses? We'd lose a chunk of the crop, but it would give a stop of speed, and I'm wondering if the trade would be worth it. Any mad science people here who have already had this thought?
Typically, small sensor issues involve traits such as dynamic range, and I don't see how a booster would help at at with that; it would help with the fact that using only part of the light coming through the lens means that you lose sharpness. However, my primary reason for using adapted lenses on my Q is to gain "super telephoto" power, and a booster would completely reverse that gain. Native Q-mount lenses provide all the capability I want apart from the birding "super telephoto" uses, so in my particular case I can't think of any advantage to me personally of using a booster.
06-22-2015, 05:26 PM   #4
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QuoteOriginally posted by reh321 Quote
Typically, small sensor issues involve traits such as dynamic range, and I don't see how a booster would help at at with that; it would help with the fact that using only part of the light coming through the lens means that you lose sharpness. However, my primary reason for using adapted lenses on my Q is to gain "super telephoto" power, and a booster would completely reverse that gain. Native Q-mount lenses provide all the capability I want apart from the birding "super telephoto" uses, so in my particular case I can't think of any advantage to me personally of using a booster.
I am also in the same boat, to be honest; its more that there are not many good choices for super telephoto capability. even with the speedbooster on there, you'd still be hitting decent crop factor, and it would theoretically give a better image quality and a bit better low light capability (partly i'm greedy and want to shove it on an f2.8 300mm though...)

06-22-2015, 10:34 PM   #5
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pentax should make a q-mount to m42 10mm-20mm(range) helicoid with integrated 2X speedbooster + leaf shutter. then u all of the m42 adapters for every lens in existence become much more versatile. i dare pentax to be so bold ^^ (the optical group would probably have to move with the helicoid.)

starting with m4/3 then Robot & Leica etc.

back to the subject at hand. u would have to buy a speed booster in the first place lets say nex pk booster... measure the distance from the back end of the optical group to the nex mount. add the nex flange focal distance to that number and thats how far the back of the optical group has to be from the Q sensor. 8.8mm difference between q and nex FFD. (if im correct)

also u have to keep in mind the pk flange focal distance as well--unless speed boosters negate that number. if they do not then u would be required to match the pk mount flange focal distance overall total distance + on top of the nex booster + nex flange focal distance. yeah...

get all that right then glue a sanded pk cap to a reamed out d-mount adapter(for image circle) and redo all ur math with that in mind as well. HAH!!

Last edited by xerxal; 06-22-2015 at 11:31 PM.
06-23-2015, 07:13 AM   #6
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QuoteOriginally posted by Mothballs Quote
I'm actually really curious; I know I can get my hands on a m43 to Q adapter, and then something like the Roxsen, Metabones or Mitakon booster for k to m43. Seeing that the Q suffers from the tiny sensor, would the focal reducer help it when mounting K lenses? We'd lose a chunk of the crop, but it would give a stop of speed, and I'm wondering if the trade would be worth it. Any mad science people here who have already had this thought?
I've not tried a focal reducer with a Q, but I have one for my a6000 and I do not use it because it loses corner sharpness and increases aberrations compared to a native lens. I don't find I get a whole extra stop either, it ranges from 1/2 to 2/3 stop for a given scene. The extra light is not a worthwhile trade for the compromises introduced by a focal reducer, IMO.

When I use a FF lens on my a6000, I want to stop down for improved IQ, which swamps the advantage of more light. If it gives you a focal length you want and don't have, that could be an advantage.
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