Hi all,
I've just received a Camdiox branded focal reducer for Pentax PK mount to m43 and thought I'd give a quick review as there isn't a whole load of info out there on this particular brand of focal reducers. If you want a focal reducer / speed booster for PK lenses you don't have too many options either!
I paid £72 for my copy from eBay (shipped within UK), so considerably cheaper than a Metabones and also a bit cheaper than a Lens Turbo in the UK. I'm not sure about availability of Camdiox items outside Europe; they are apparently 'designed and tested' in Germany but I imagine manufactured in China. I guess they are probably available elsewhere under a different brand name.
On first impressions the design and build quality of the focal reducer is good for an inexpensive adapter; it has a decent weight to it and the construction is solid, no loose parts or manufacturing defects visible. The lens elements are bright and spotless, they have a slight blue/purple coating. I mounted a few different lenses and all locked in tight, there is no play at all between the adapter and the lens or the camera body.
I tested my fastest PK lens out first which is a Pentax SMC-M 50mm f1.7. With a normal tube adapter this lens is soft at f1.7 and has a fair bit of glow to bright areas and noticeable purple fringing, it gets considerably better at f2.8 and delivers an excellent, tack sharp image at f5.6.
With this lens mounted on the Camdiox I gained about a stop of light and a wider field of view as expected. At f1.7 the resulting image is noticeably softer at the corners than with a normal tube adapter but the glow and purple fringing disappears which was a pleasant surprise. At f2.8 the Camdiox still produced a softer image but the corners are much improved. By f5.6 there is little difference in sharpness between the two adapters.
I tried to get the 'blue spot' to appear by pointing the adapter directly at a light source but only got the usual flares I expect with this lens. The eBay seller did warn about the 'blue spot' though so I doubt the Camdiox is impervious to it, I just haven't found the right situation to get it to appear yet.
Overall I am quite happy with the Camdiox, I bought it primarily to help mitigate the crop factor on the GH4 and in this regard it works as expected, according to the seller you gain a wider image by 0.72x which looks about right to me. Gaining a stop of light is always a bonus and once stopped down the Camdiox makes the image negligibly softer. If you wanted to use this adapter to get even more light at the fastest apertures I could not really recommend it as it does make the image much softer in the corners when wide open.
Here is a very quick album I put together of 100% JPEG crops of a barcode at the very top right corner of an image with both the Camdiox and the normal tube adapter:
Camdiox PK-m43 Focal Reducer Corner Sharpness
I might update with some more images once I have a chance to use the focal reducer shooting real subjects.
I've just received a Camdiox branded focal reducer for Pentax PK mount to m43 and thought I'd give a quick review as there isn't a whole load of info out there on this particular brand of focal reducers. If you want a focal reducer / speed booster for PK lenses you don't have too many options either!
I paid £72 for my copy from eBay (shipped within UK), so considerably cheaper than a Metabones and also a bit cheaper than a Lens Turbo in the UK. I'm not sure about availability of Camdiox items outside Europe; they are apparently 'designed and tested' in Germany but I imagine manufactured in China. I guess they are probably available elsewhere under a different brand name.
On first impressions the design and build quality of the focal reducer is good for an inexpensive adapter; it has a decent weight to it and the construction is solid, no loose parts or manufacturing defects visible. The lens elements are bright and spotless, they have a slight blue/purple coating. I mounted a few different lenses and all locked in tight, there is no play at all between the adapter and the lens or the camera body.
I tested my fastest PK lens out first which is a Pentax SMC-M 50mm f1.7. With a normal tube adapter this lens is soft at f1.7 and has a fair bit of glow to bright areas and noticeable purple fringing, it gets considerably better at f2.8 and delivers an excellent, tack sharp image at f5.6.
With this lens mounted on the Camdiox I gained about a stop of light and a wider field of view as expected. At f1.7 the resulting image is noticeably softer at the corners than with a normal tube adapter but the glow and purple fringing disappears which was a pleasant surprise. At f2.8 the Camdiox still produced a softer image but the corners are much improved. By f5.6 there is little difference in sharpness between the two adapters.
I tried to get the 'blue spot' to appear by pointing the adapter directly at a light source but only got the usual flares I expect with this lens. The eBay seller did warn about the 'blue spot' though so I doubt the Camdiox is impervious to it, I just haven't found the right situation to get it to appear yet.
Overall I am quite happy with the Camdiox, I bought it primarily to help mitigate the crop factor on the GH4 and in this regard it works as expected, according to the seller you gain a wider image by 0.72x which looks about right to me. Gaining a stop of light is always a bonus and once stopped down the Camdiox makes the image negligibly softer. If you wanted to use this adapter to get even more light at the fastest apertures I could not really recommend it as it does make the image much softer in the corners when wide open.
Here is a very quick album I put together of 100% JPEG crops of a barcode at the very top right corner of an image with both the Camdiox and the normal tube adapter:
Camdiox PK-m43 Focal Reducer Corner Sharpness
I might update with some more images once I have a chance to use the focal reducer shooting real subjects.