@Boncrek For what its worth, I have the 2nd version, the one that came with the tripod foot, and I see it a little bit. Its not bad, but Ill see it if I look for it.

@Vitaliy_Kiselev I did read it and only some persons mentioned it while others say they didn't see it at all. So I decided to ask.

This is a question for owners of the Version 1 of the Lens Turbo (the one without the tripod foot): Does your copy of the lens turbo suffer from the blue dot problem when looking into bright light sources while stopped down?

@konjow I measured mine and I'm pretty sure it is at least 21mm on the thinnest part of the curve.

I've gotten the Nikon (F/G) to M43 one, because the newschool Tokina 11-16mm f/2.8 and Sigma ART 18-35mm f/1.8 give you a very nice ability to shoot wide and in somewhat lowlight conditions. Especially with the rather small crop sensor of the GH4/BMPCC, I find it really convenient to be able to use these lenses and use a focal reducer in combination with 'em. Pretty sure 'new' refers only to the addition of the adapter's collar / tripod mount. It's a rather nice addition though, certainly if you're working with some heavier/bigger glass.

Just got back from a trip to China (I took the FZ1000 with me to keep travelling light) and have some days off now to fully test the RJ Lens Turbo out (if weather permits to go out and shoot some).

Is there any reason stacking a dumb adapter on this would lower IQ?

Because adapters are not ideal things :-) But for video tasks if additional adapter is not faulty you are usually ok.

Ah! It took a while to get here. But in the end it was worth the wait. Own fault for wanting the free shipping (no import charges, yay!). Free shipping is not so quick. Easy peasy put together. Lens turns on smoothly; in turn the adapter attaches smoothly to the GH4 as well (maybe some added markings on the tripod collar and lens turbo would've been nice for easier alignment of the two in order to get the tripod base exactly level). So far, so good. Happy camper here. Thanks Vitaliy & RJ!

Now just gotta find some time for some vigorous testing. Unfortunately a couple of long days work ahead of me first.

Have there been any side-by-side comparisons between the different focal reducers? I'm especially interested in any image quality differences between this, and Metabones.

Also, do we know if they are working on anything stronger than 0.72x? Maybe something better suited for the GH4?

How do I know if it's the older adapter the one I have ?

@Vitaly,

First suggestion: write apperture mesures/marks on the adapter so we can have more controls on the apperture wheel, especially if the lens used lacks one. See this for exemple: http://www.bhphotovideo.com/c/product/1002612-REG/metabones_mb_nfg_m43_bm1_nikon_g_mount_lens.html

About the mount ring, I was wondering if it was possible to get one without the adapter since the first time I bought the one for nikon mount I didn't think I would need one.

Other suggestions might follows, but I thing that gonna be all for now.

@Vitaly, Is the RJ Manufacturer/builder open to some suggestions like light modifications on their adapters speedbooster ?

Also, do thew still offer the tripod mound ring ?

Thanks to answer

I've heard from someone that it's a stereoscopic fisheye, and I had no idea what the hell they meant by that as I had assumed that all fisheyes had been using one perspective. I think that might be one reason behind the 6.5, or it could be 8mm as several have argued :) Refer to http://en.wikipedia.org/wiki/Fisheye_lens#Mapping_function for those who've no idea what I meant.

From the research I recall, I couldn't find any mention or examples of it. One of the reasons I'm so interested too. I can't really imagine what they'd look like though, sounds like it'd give crazy results.