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01-14-2013, 04:44 PM   #1
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New Pentax mirrorless concept - Adapts the Pentax 50/1.2 to be 35/0.95!!

I just read about this on RFF (rangefinderforum.com) while researching another mirrorless (Fuji X series) for use with my Pentax primes.

Sounds like a tele-converter in reverse, a 0.7x converter that takes advantage of the smaller flange distance of mirrorless bodies. I see that they have now done a press release and it is now on DPR: Metabones announces 'Speed Booster' lens adapter for mirrorless cameras: Digital Photography Review

Also what looks to be a pre-production review from a photo-blogger: philipbloom.net/2013/01/13/speedbooster/
I've yet to read through the white paper in detail but this is exciting news IMO. The physics of it appears to be legit and sound.

This probably would not be of use with the K-01 but I was always thinking that prior to release of the K-01 that the Pentax mirrorless "System" would comprise of such an adapter or adapters to allow usage of the legacy Pentax lenses on the Pentax mirrorless.
The system would comprise of the body with 2 adapters
- Adapter 1 would maintain the normal 35mm SLR flange distance, hence it would be mainly a spacer between the body and the legacy lens
- Adapter 2 would be this "speedbooster" adapter as detailed in the white paper, hence the 50mm K/M/A/DA lens would become a 35mm on this APS-C mirrorless thereby becoming a "52mm-E" again due to the 1.5x crop of the APS-C (50*0.7*1.5)

One question I have is that is it possible to just make a shorter adapter w/o any optics to get this "reducer" effect? Or do you need the optics to ensure the light ray traces reach the "film" or sensor plane properly?

What do you fellow Pentaxians think? too good to be true?

01-14-2013, 04:55 PM   #2
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I want to know how it is supposed to make a lens sharper, that just seems to be impossible.
01-14-2013, 05:01 PM   #3
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It's hard to see why this would have to be limited to FT MILCs, unless it's a limitation caused by the size of rear element requiring a crop. Even so, a FF lens on a APS-C body might not be limited that way, so I imagine it's a matter of individual lenses and bodies.

It's also hard to see why they'd be planning versions for Contax and even Alpa (!), and not Pentax.
01-14-2013, 05:06 PM   #4
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QuoteOriginally posted by elliott Quote
I want to know how it is supposed to make a lens sharper, that just seems to be impossible.
It's like zooming out of an image.

01-14-2013, 05:20 PM   #5
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QuoteOriginally posted by RobA_Oz Quote
snip......
It's also hard to see why they'd be planning versions for Contax and even Alpa (!), and not Pentax.
Couldn't agree more with you on this thought. Maybe they're going after the folks with expensive glass to justify the announced MSRP of $599, hence I could understand Leica, Contax, ALPA. But then again, Pentax glass isn't cheap either.
01-14-2013, 05:20 PM   #6
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This kind of device is called a "telecompressor" or "focal reducer" in astronomy circles, and has been around for a very long time in practical use, so the physics are sound. It focuses your lens into a smaller image circle, which *might* make it "sharper" but then you are also adding non-original glass to your optics, which isn't always a great idea. We've already discussed the possibility of something like this on the Pentax Q.
01-14-2013, 05:29 PM   #7
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QuoteOriginally posted by elliott Quote
I want to know how it is supposed to make a lens sharper, that just seems to be impossible.
You'd have to read and understand the white paper section 6 - "Its too good to be true! - Part 3, MTF is increased". I've skimmed through it but still don't understand it. My simple takeaway from it is that it is similar to looking at a reduced image size. Someone with better knowledge of the physics of this phenomena can probably explain this better for me. Quick look at the images appears that the images are somewhat sharper.
01-15-2013, 07:28 AM   #8
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QuoteOriginally posted by PentHassyKon Quote
You'd have to read and understand the white paper section 6 - "Its too good to be true! - Part 3, MTF is increased". I've skimmed through it but still don't understand it. My simple takeaway from it is that it is similar to looking at a reduced image size. Someone with better knowledge of the physics of this phenomena can probably explain this better for me. Quick look at the images appears that the images are somewhat sharper.
Circle of cofusion, google it.

The light points where the image is make off are getting smaller and with that resolution is increased.

Look at you monitor, now move close so your nose is thouching... you see the pixels right so it's not sharp.
Now move away few feet, much sharper image right

Condenser does the same thing, it moves the image away, making it appear smaller and therefore sharper.

01-15-2013, 08:03 AM   #9
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QuoteOriginally posted by PentHassyKon Quote
This probably would not be of use with the K-01 but I was always thinking that prior to release of the K-01 that the Pentax mirrorless "System" would comprise of such an adapter or adapters to allow usage of the legacy Pentax lenses on the Pentax mirrorless.
The system would comprise of the body with 2 adapters
- Adapter 1 would maintain the normal 35mm SLR flange distance, hence it would be mainly a spacer between the body and the legacy lens
- Adapter 2 would be this "speedbooster" adapter as detailed in the white paper, hence the 50mm K/M/A/DA lens would become a 35mm on this APS-C mirrorless thereby becoming a "52mm-E" again due to the 1.5x crop of the APS-C (50*0.7*1.5)
In answer to your original query... yes, I think this would be a good idea, and one that Pentax is quite able to accomplish, but it is highly unlikely for basic business reasons: it would mean creating those two adapters to go on yet another lensmount type with the reduced flange distance and all the adaptable lens mechanics (K, Q, and then a new mirrorless APS-C called, maybe, P for Prince?); either that, or make something similar to a K-01 (mirrorless K-mount) that has the focal-reducer built in... but that could only use FA or earlier 135 lenses, which won't help modern lens sales at all (making the marketing very difficult). Perhaps some way to "insert" an optical adapter in front of the APS-C sensor, but inside the lensmount? Having end-users stuff items inside the (mirrorless) mirrorbox is a risky proposition for a mass-market consumer good.

That EF-NEX focal reducer is the product of an optical company and the Conurus adapter company, and marketed by Metabones. In other words, for something like this to come out for Pentax, we'd need to gather optical engineers, someone who has decoded the electronics of modern Pentax lensmounts (like Conurus did with the EF mount when they started converting Contax G-lenses to EF), and folks who are knowledgeable about the production of this kind of complex device. More likely that an NEX, the new adapter, and some EF-mount lenses would be cheaper and more immediate for most folks...

Last edited by panoguy; 01-15-2013 at 08:10 AM.
01-17-2013, 09:10 PM   #10
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i would love something like this for the k-01 :/
01-18-2013, 05:31 AM   #11
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Even if they did one for the Q $599 is just too much for me.
01-18-2013, 05:41 AM   #12
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How is this a "New Pentax mirrorless concept" that the blog title is referring to? The Metabones Speedbooster is a third party adapter.
01-18-2013, 12:25 PM   #13
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QuoteOriginally posted by Clavius Quote
How is this a "New Pentax mirrorless concept" that the blog title is referring to? The Metabones Speedbooster is a third party adapter.
Two corrections: this is a forum thread, not a blog and the OP wrote this:

QuoteOriginally posted by PentHassyKon Quote
I was always thinking that prior to release of the K-01 that the Pentax mirrorless "System" would comprise of such an adapter or adapters to allow usage of the legacy Pentax lenses on the Pentax mirrorless.
The system would comprise of the body with 2 adapters
...
Clearly this is not a mirrorless concept by Pentax, but rather by the OP.
01-20-2013, 02:07 PM   #14
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We use these types of devices in telescope for astrophotography where a fast f-ratio is desired in long focal length instruments. We call it a tele-compressor or focal reducer / corrector. The concept is to add a positive element to reduce the effective focal length, thereby decreasing the focal ratio, typically by 50%. Normally such a device is made knowing which optical configuration it is to be matched with to ensure minimal distortion or even correction of known optical defects of the full aperture optic.

My guess is that it would work well with medium focal length lenses, but vignetting could be an issue.
01-26-2013, 07:55 PM   #15
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Photomicrography (or just regular microscopy) also uses auxiliary lenses that increase focal length (such as a 0.7x). The result in stereo microscopy, beyond the primary function as a focal length reducer--is often a "speed" boost-- only in the sense that with a longer working distance from your main objective to your subject you often need less light to resolve the same image.
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