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$199 focal reducer speed booster adapter Pentax PK K to Sony NEX
Posted By: jogiba, 05-08-2013, 05:10 PM

QuoteQuote:
Focal reducer/Speed booster adapter

for/Pentax PK K bayonet lens to Sony NEX mount 5 6 7 camera FS700 FS100

All metal structure, with excellent opticals (4 elements/2 groups, super multi-coated)
what it does:


reduce the focal length (by 0.72x wider)


Ex. 50mm lens on NEX with the adpater, eff. focal length is 50mm x 1.5(crop) x 0.72 = 54mm

 

effectively increases the maximum aperture of the lens by 1 stop




(in other words, under the same aperture, you can use faster shutter speed (by 1 stop).

  what it does not:
there is no electronic integration, no auto fucusing

(you still need to manually focus your lens and aperture, etc.)
Focal Reducer Speed Booster Adapter Pentax PK K to Sony NEX 3 5 6 7 FS700 FS100 | eBay




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06-28-2013, 10:25 PM   #91
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QuoteOriginally posted by rparmar Quote
PP is not the issue. These shots are poor under any circumstances. Researching further I have found side-by-side tests that confirm that these knock-off adapters are quite bad optically. I guess I'll wait for Metabones to bring out a K adapter. That'll give me more time to save my pennies.
Oh well to each their own, save your pennies and cross your fingers..

06-28-2013, 11:36 PM   #92
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here's my pentax k 1.8/55mm at f5.6 sharpness sample no pp sharpening full size
peep away
Link to Original click

100% crop

Last edited by Sliver-Surfer; 06-28-2013 at 11:51 PM.
12-04-2014, 01:01 PM   #93
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Can someone explain what this adapter actually does and the difference between this one and one that has no glass at all and which one is better or worse? Thank you!
12-04-2014, 01:07 PM   #94
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QuoteOriginally posted by DavidSKAF3 Quote
Can someone explain what this adapter actually does and the difference between this one and one that has no glass at all and which one is better or worse? Thank you!
It's like an inverted teleconverter that makes the focal length shorter and aperture wider. Note that you need a lens that projects a bigger circle natively than you r sensor.

12-04-2014, 01:13 PM   #95
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QuoteOriginally posted by DavidSKAF3 Quote
Can someone explain what this adapter actually does and the difference between this one and one that has no glass at all and which one is better or worse? Thank you!
Zhongyi Is my favorite. all the other info is in the first page of this thread.
Also funny you rehashed this thread I discovered yesterday that some of my Pentax lenses cover the sensor on my A7 fairly well which would make for super panoramic shots (pentax-m 3.5/28mm in particular) also m-2.8/40mm m-1.7/50mm m-2.8/28mm
12-07-2014, 07:14 AM   #96
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QuoteOriginally posted by Sliver-Surfer Quote
Zhongyi Is my favorite. all the other info is in the first page of this thread.
Also funny you rehashed this thread I discovered yesterday that some of my Pentax lenses cover the sensor on my A7 fairly well which would make for super panoramic shots (pentax-m 3.5/28mm in particular) also m-2.8/40mm m-1.7/50mm m-2.8/28mm
Perhaps I misunderstand. Are you saying that the focal reducer is useful on the A7? I thought it only did anything on crop sensors.
12-07-2014, 08:25 AM   #97
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QuoteOriginally posted by Mikesul Quote
Perhaps I misunderstand. Are you saying that the focal reducer is useful on the A7? I thought it only did anything on crop sensors.
I am trying to discover whether it is, and which lenses work best . So far it seems more pancake like the lens is the better so Pentax-M have an advantage, I think. I haven't thrown any m42s on it yet. Here are some advantages I see so far.
1.Panoramic crops( distortion to the left and right)
2.Square crops(no issues..top and bottom nearly perfect)
3 Increase light sensitivity
disadvantages
1.distortion on sides
2.dark vignettes(need to be cropped)
these are on -m 3.5/28mm


The samples images I gave are not the best example because the bright chandleirs cast the dreaded blue circle and bight light reflection
12-07-2014, 09:09 AM   #98
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QuoteOriginally posted by Sliver-Surfer Quote
I am trying to discover whether it is, and which lenses work best . So far it seems more pancake like the lens is the better so Pentax-M have an advantage, I think. I haven't thrown any m42s on it yet. Here are some advantages I see so far.
1.Panoramic crops( distortion to the left and right)
2.Square crops(no issues..top and bottom nearly perfect)
3 Increase light sensitivity
disadvantages
1.distortion on sides
2.dark vignettes(need to be cropped)
these are on -m 3.5/28mm


The samples images I gave are not the best example because the bright chandleirs cast the dreaded blue circle and bight light reflection
Is there some reason you do not just use one of the standard adapters for legacy full frame lenses on the FF camera?

12-07-2014, 09:19 AM   #99
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QuoteOriginally posted by Mikesul Quote
Is there some reason you do not just use one of the standard adapters for legacy full frame lenses on the FF camera?
I do use them Im just doing some experimenting with the turbo because I shot a rock concert the other night with a Zoom lens(Adaptall 35-80mm) that I hadn't used on my a7 but I used it on my nex 5n with a turbo booster last year and it was bit slower on the A7. So It got me thinking if there might be some lenses that may work better than others on the A7.
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