Happy turbo boosting(?), also: M42 on Pentax K on Fuji X

[Casa]

I'm currently looking forward to seeing a Lens Turbo II Pentax K adapter from Zhong Yi (Mitakon), it's announced but already very late. It'd be a great addition to my system because my Cupboard is full of old K lenses... However, my current always-on for portraits is a Helios 44 (M42), so my first question: Does anyone have experience with using an M42-Pentax K adapter on a Lens Turbo/Speed booster for Pentax K/Fuji X? Does it even work? Zhong Yi already offers a M42-Fuji adapter, but given the amount of K lenses I have I'd rather go with the upcoming Pentax K option, and given my limited funds not buy both. 

 

Other than that, how's the general experience and satisfaction with Lens Turbo or similar adapters? I'm quite aware they're not nearly as sharp as the unadapted lens or the Metabones stuff, but I'm not looking for perfect sharpness in my photos anyway, more for pleasing portraits with nice backgrounds. Also, that extra stop of light would be amazing for using my favorite portrait lenses in low light situations. 

[heliosfan]

Hmm....since flange distance is the same for M42 and Pentax-K (45.46 mm) I don't think you will find an adapter that will work with both (you will at least lose infinity focus).

Personally, I would go for the SpeedBooster with the shortest available flange distance (which currently is the Canon EF version - flange distance 44 mm). That way you can adapt all your lenses (and most future ones) by using cheap M42->EF, Pentax-K->EF etc "dumb" adapters (which are basically washers of 1.46 mm thickness). I know, it sounds like a bit of a hack, but it would barely be noticable on the camera.

 

Canon DSLRs are the most "adaptable" of the big brands, and in my Canon days I used this all the time for my Pentax/Takumar lenses. They are so cheap you can just keep them permanently on the lenses. It also has the advantage of being faster to attach than the M42 screwmount.

 

However, I have not tried the SpeedBooster (but want to!). Sharpness is, from what I have heard, equal to the unadapted lenses, with exception of the corners. In fact, the extra stop of light and that full frame depth-of-field is probably too tempting to resist for me in the long run.... 

You can read about version 1 adapted with a Helios here (MD version of SpeedBooster w/M42->MD adapter):

http://jonasraskphotography.com/2014/05/26/helios-turborized-the-helios-44m-4-w-mitakon-lens-turbo-review/

[Casa]

The more I think about it the more you're making real sense there. I'm really considering doing exactly that, which would also mean no more waiting for the PK adapter release. Keeping infinity and being able to adapt 3 different systems sounds too good.

[NeddyN]

Casa I am dealing with the same issue as you. Plan to use Pentax K and Pentax M42 on my XT-1 with a speed booster and wondered if you took the above advice and are going: Lens Turbo EF-X plus an M42-EF cheap adapter? And/or Lens Turbo EF-X plus an K-EF cheap adapter? Any feedback from folks in a similar situation would be very helpful! Thanks!