4/3 to m4/3 Speedbooster

Discussion in 'Adapted Lenses' started by OzRay, Mar 1, 2014.

  1. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    Would this be at all possible? It would certainly introduce some interesting possibilities, especially if fully coupled, which shouldn't be hard to do. It'd be great if M mount lenses could be speed boosted as well, but with the lens to sensor distance, it's probably impossible.
     
  2. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    Optically, I think a 4/3 to m4/3 SpeedBooster would be possible. The 4/3 flange distance is 38.67mm which is larger than the 37mm flange of the Alpa (not Alpha) mount that MetaBones makes SpeedBoosters for already (although only for Fuji X and Sony E mount at present). In short, there's space for the optics.

    One slight wrinkle is the electronics - since native 4/3 lenses are almost all focus-by-wire and the aperture is controlled electronically, a purely mechanical adapter wouldn't be very useful. Fortunately, various Chinese companies have already managed to clone the Olympus/Panasonic 4/3-m4/3 adapters, so clearly the electronics are out there - Metabones would just need to license them (or reverse engineer them).

    The bigger issue I think is the image circle. The 0.71x SpeedBooster basically requires the lens to cover a 40% larger image circle than the 4/3 sensor requires. While I suspect most lenses do indeed have that coverage, it's not clear how good the quality would be. I'm fairly certain the 7-14/4 and 9-18/4-5.6 will have issues with mechanical vignetting. The 11-22/2.8-3.5, 14-54/2.8-3.5 and 12-60/2.8-4.0 are likely to cover the sensor, but I'd have concerns about performance toward the edge of the frame, especially with the first two. The telephoto HG and SHG lenses should be fine in terms of coverage - the issue there would be whether or not the focal lengths are interesting. Usually people want more reach for their telephotos, not less.

    Still, I would be very interested if they could make such an item. Admittedly it's not that big a market, but I daresay there are enough crazy folks out there like us that it would still be profitable.
     
  3. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    A direct coupling probably wouldn't be such and issue, but the coverage yes. However, I think the 4/3 lenses do have a greater coverage of the sensor than many suspect. Obviously not as much as a 35mm or APS lens, but there is some leeway. I did some experiments quite a while back and the coverage is not limited to just the diagonal of the sensor. Whether it would be enough is another matter.
     
  4. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    There's a fairly easy way for anybody with a m4/3-Nikon mount or m4/3-Canon mount SpeedBooster to test coverage. Put the camera on a tripod with the SpeedBooster but no lens mounted, and then hold the lens in front of the SB and try taking a photo. It's probably most effective if you set the focus and aperture ahead of time on the lens. Obviously you won't have infinity focus due to the difference in flange distance (and the inability to mount it directly) but it should give some sense of whether the coverage is sufficient or not, and on wider lenses it will probably allow you to gauge edge sharpness as well.
     
  5. Andym72

    Andym72 Mu-43 Veteran

    330
    Mar 4, 2013
    Reading, UK
    Speedboosters work by taking the larger image circle and projecting it smaller, with the handy side effect that the same amount of light is squeezed into half the area, resulting in one stop faster f number.

    Four Thirds lenses don't have larger image circles than m43, so unless you want horrible vignetting, it's pointless.


    Sent from my iPhone using Tapatalk
     
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  6. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    If it's that simple, then you should be able to make a speedbooster for M mount lenses.
     
  7. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    Wrong. Four Thirds lenses are not required to have larger image circles than m4/3 lenses. But that doesn't mean they don't, and in fact we do know some cover a larger imaging circle. For example, the Olympus ZD 50/2 macro covers a diagonal of 40mm (well beyond both 4/3 and APS-C).

    Not with the current formula. The glass elements of the SpeedBooster have a certain thickness, and M mount doesn't leave enough space for them to be fitted in the adapter. Leica has a flange of around 27mm vs. 18mm for m4/3 meaning the optics in the SB adapter can't be thicker than 9mm. With 4/3 they have nearly 20mm to work with.
     
  8. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    I was being a tad sarcastic there; however, you never know what some smart cookie can come up with one day.
     
  9. mfj197

    mfj197 Mu-43 Regular

    80
    Aug 20, 2012
    Guildford, UK
    Michael
    Actually AndyM72 was quite right. The fact that some four this lenses may cover a larger image circle than they need to doesn't change the fact that the specification is for the same image circle. No point in creating a speedbooster that only works with lenses that are outside the specifications.

    Michael

    Sent from my Galaxy Note 3 via Tapatalk
     
  10. Pawel D.

    Pawel D. Mu-43 Regular

    45
    Jan 25, 2014
    Białystok, Poland
    Personally, I'd love that kind of speed booster/focal reducer. I have 2 Sigmas with 4/3 mount: 50/1.4 and 30/1.4 and having those with aperture control and AF plus specs: 35/1.0 and 21/1.0 would be a great thing to have :D This combination could be a kick-ass for some manual Noctons and similar. Well... image quality might not be as good, but still - a gear worth having :)

    I tried some on EF focal reducer with OM adapter and here are my results:
    - Sigma 50/1.4 - focuses for close-up only, no vignetting (originally designed for FF sensor)
    - Sigma 30/1.4 - focuses for close-up only, no vignetting
    - Zuiko Digital 14-45/3.5-5.6 - no vignette!!! a short FL eq. with FR is: 10/2.5 :) - it was a first 4/3 Oly KIT lens; no focusing without electronics
    - Zuiko Digital 40-150 - no vignette; no focusing without electronics
    - Zuiko Digital 12-60/2.8-4.0 - black corners on 12 mm FL :( pitty...
     
  11. wushumr2

    wushumr2 Mu-43 Regular

    137
    May 20, 2013
    Actually, if the speed booster worked with the super telephotos, that WOULD be a good thing. You'd maybe have something like a 125mm f1.4 or 60-200 f2...that'd be QUITE interesting...
     
  12. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    It depends. If there are only one or two lenses for which this is true, I'd tend to agree. But Olympus glass, especially SHG and HG glass, is notoriously over designed, so I wouldn't be surprised if there a significant number of 4/3 lenses for which a SpeedBooster would work. Note that a 4/3 SpeedBooster by virtue of its short flange would also be able to adapt virtually every other type of lens as well - Canon FD, Canon EF, Nikon F, Olympus OM, Pentax K, etc - just by inserting a small adapter. So it would sort of be an all-in-one solution.

    Thanks for sharing these. The Sigma's aren't too surprising as they are originally FF and APS-C designs respectively, and telephotos typically have coverage to spare. The 14-45 is an interesting surprise. Too bad about the 12-60 - how far do you have to zoom for the black corners to go away?

    Yes, 110/1.4 from the 150/2 and 65-180/2 from the 90-250/2.8. Still, those are awfully big lenses!

    You're making it sound as if lens designs are tailored to offer coverage as close as possible to the exact size of the sensor. I don't think that's really a safe assumption. Indeed, by far the easiest way to get good corner and edge performance from a design is simply to build it so that it covers significantly more of the sensor than just the imaging area. With telephotos there's also the fact that focal length and f/stop, rather than imaging circle, tends to be the determining factor on size. There are even some native 4/3 lenses, like Olympus's 300/2.8, that are in fact full frame designs.
     
  13. tjdean01

    tjdean01 Mu-43 Top Veteran

    842
    Feb 20, 2013
    If some of the 4/3s or m4/3s lenses actually do cover a image circle larger than our sensors it's a shame that they're not faster to begin with! I know the Sigma ones--since they were created for APS cameras--will have a larger image circle and that 60/2.8 being an appx 50/2.2 would be nice (but this would necessitate a lens redesign as that's a m4/3s lens and no room to stick any adapter in between.
     
  14. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    Gordon
    The f2 SHG lenses already have a speedbooster type group built in. Why do you think they're so friggin big ( and so sharp). For example the 35-100 is a 70-200 2.8 with a 1 stop boooster as the rear group.

    Gordon
     
  15. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    IIRC it is actually a 2 stop reducer (it's a 0.5x reducer on a 28-70/2.8 and 70-200/2.8 design), but they couldn't get it perform as desired wide open (at f1.4) so they limited the max. aperture to f/2.0. If they'd just waited a year or two, they could have used APS-C 17-50/2.8 and 50-135/2.8 designs and a 0.7x focal reducer, and gotten something just as fast, but dramatically lighter.

    But yes, the 14-35/2 definitely won't work, as Lloyd Chambers showed. Probably the 35-100/2 as well, though telephotos tend to be less restrictive.
     
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  16. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    If there's no vignetting at 14mm, then that's pretty good. My 14-35mm f2 would become a 10-25mm f1.4 and the 35-100mm f2 would become a 25-70mm f1.4. I could live with that. The electronics, I think, could be easily overcome, as the tele-extenders and macro tubes don't require all that much. And if a licence is required, I'm sure that Olympus would gladly give one, as they seem to promote products such as Voigtlander, as it just adds to the lens collection.
     
  17. I tried some "free-lensing" on my NX300 last night with some Four Thirds lenses. It's a bit hard to establish exactly where the correct flange distance is, but regardless of where I held it the 50-200mm provided enough coverage for the APS-C sensor. The two PanaLeica zoom twins (14-50mm and 14-150mm) both showed hard mechanical vignetting at all focal lengths which indicates that rather than being over designed, these two lenses are simply well designed.

    I suspect that the reason the 14-45mm displayed no vignetting in this scenario compared to the 12-60mm is because the former is less telecentric than the latter. The OM mount has a flange distance over 9mm greater than Four Thirds so placing the 14-45mm lens on the OM mount puts it further away from the sensor and increases the size of the image circle it projects. The image circle of a more telecentric lens won't increase in area as much when the lens is mounted further away from the sensor.
     
  18. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    That makes sense. It's the same story with APS-C lenses on full-frame - most of the zooms that go to 28mm EFL or wider don't cover the whole sensor. If I get a chance, I'll try to see where my 50-200 fits in the whole scheme of things.
     
  19. RDM

    RDM Mu-43 All-Pro

    Just wait till they come out with the Konica AR mount boosters, then you just buy some Generic 4/3 to µ4/3 adapter off ebay and put its guts in there. :smile:
    (don't know if that will ever happen tho)

    But I like the Idea for a booster such as this for use with the the Sigma 4/3 lenses. For example , If someone has a 10-20mm Sigma, they can use it instead of having to sell it, & buy a canon EF version and then the EF speed booster. Heck, Sigma should have made and sold this adapter.
     
  20. eteless

    eteless Mu-43 All-Pro

    Jun 20, 2014
    I hacked one together using a the optics from a mitakon adapter and a half dead MMF-3 and lots of hot glue to test it out a few weeks ago.

    The 35-100mm f2.0 worked well from about 80-100mm, below that it didn't cover the entire sensor however it was STUPIDLY bright, almost unusable in daylight, TTL flash didn't seem to work.

    The other *huge* problem I had was stabilization didn't function at all, it was worse with it on than off. Due to the fact that you were using a shorter focal length than what the camera saw attached to the camera it would massively over correct any movement and you had thus juddering mess in the viewfinder as it attempted to stabilize it, not to mention the noise it made.

    I only currently have one legacy 4/3 lens to test (35-100), I've sold off all the equipment I haven't been using. I did it more of a test to see if something like the sigma 30mm f1.4 would work, however my experience with the stabilization has shown me that a purely dumb adapter is useless, you need one which communicates the real lens focal length.

    I can post pictures of the adapter if people want, but it's not pretty. It currently has the optics taken out as I'm using them in something else, however you can see the basics behind it. I shortened the plastic case between the metal mounts by around 6mm (I have the exact figure written down... somewhere). I wasn't after accuracy and was just testing to see if it would work, I just cut it off square with a grinding wheel. It's accurate to within .01mm using calipers but it wouldn't be anywhere near as precise as if done using a lathe, as I would have done using a metal blank had it worked. One of the bigger problems was I had to machine one of the faces of the optic group to allow it past the electronic connectors inside the bayonet fitting, it wouldn't be a problem for something designed specifically for this purpose like the metabones adapter however.

    I should mention that the m43-43 adapter isn't smart at all, anyone can make one. It doesn't actually tell the camera anything at all, it just connects the pins up, there are two pins unused as they were not part of the 4/3 standard, and there is one wire which is attached to an internal switch on the MMF3 which tells the camera that you're disconnecting the lens and forces it to cut power to the lens preventing short circuit.
     
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