BMPCC with Speed Booster (BMPCC Version) and Tokina 11-16

[pH0u57]

I shot this after my BMPCC Speed Booster finally arrived. When I mount the Tokina 11-16 f2.8 DX2 to it, I can notice a big problem with sharpness in the center, especially when wide open. The corners, ironically, seem to be way better. Even when stepped down, the sharpness is not really good. Does anyone else have that problem and/or a solution for it?

[Axel]

On the phone here, I don't have my bookmarks. What you probably need to do is calibrate the Metabones' backfocus. This is delicate (you need to fix a screw or so to "infinity". If it is sharp at infinity, it wasn't the backfocus) but technically not too complicated. I think there was an official Metabones instruction on the net > Google.

[Axel]

Here is the instruction. 

However, now that I saw your clip on the big monitor, I'm not sure about the nature of the problem. Please don't be angry, if I do you wrong. How did you focus? The sharpness improved when you stopped down on the TV set (as it would even if not focussed correctly), but the other shots just look out of focus. Again, no offense intended, but did you try to shoot from a tripod, focus with peaking and magnification? Focussing is the toughest job with the BMPCC. You do know that the FOCUS button doesn't work with the Speedbooster (sorry if that sounds like check the plug)?

 

Also, as Andrew Reid reported here, your Tokina has a focus problem in the corners:

 

 

The Tokina 11-16mm at the wide end does appear to have very soft corners though.

 

You can have either the center sharp, but the corners not - or the other way around. Or nothing.

[pH0u57]

No offense taken. I used peaking and focused it on minimum (0,3m) when I tried to get in close. The ones that are supposed to be completely in focus are shown focused in peaking, though, on a large screen, they still look soft.

 

I know about the corner-issue though, it seems to be the other way round with me. This is why I think it's not a back-focus problem either. Though, I stand to be corrected. ;)

[Axel]

Maybe this lens is not good for the SB-Pocket-combo. Perhaps you should sell it and buy something like that for wide angle (there is a 6mm too, giving you the same parameters as your current setup). I didn't realize the lens you used in Brazil, but if that's your 'allrounder', you could then sell the Speedbooster too. I sold all my MFT lenses, because I use the Sigma 18-35 with SB and Novoflex adapter, which gives me a range of 61° - 19° angle of view (or, for anyone not used to this terminology, 30-105 mm full frame equivalent) at f1.0 (or, with Novoflex, f1.8, which is still insanely fast). Now I know the SB-Tokina gives you an extreme angle of ~ 97° AOV, but the downside is a too heavily curved focal pane (or rather focal curve). That's why there are only few fast extreme wide angle lenses. And they are usually very expensive. 

 

My favourite country for vacation is also Brazil. That the color washes off the buttons is really tough. There are so many different climate zones in Brazil, you didn't say where you stayed. 30°C in Manaus will mean 99% humidity, 30°C in Bahia salt in the wind ...

[pH0u57]

No no, I use different lenses as allrounders. ;)

I have both Vario X lenses (12-35 & 35-100 f2.8) and they work superb. I want to use the SB-Tokina combo for small, darker spaces like rooms and so on. Andrew used that combo in one of his tests and his pictures were pretty great IMO.

 

I tried the lens on a Nikon today and since the focus is not perfect, it's way better than on the SB. Might have to get the lens checked, too, though. Then I tried another Nikon (or Sigma in that case) lens on the SB and I had another weird problem. On 12mm, the background is sharp when focused to 0,3, but when I focus to infinity the whole picture blurs. On 35mm though, I could focus really close and shift it to the background without a problem, even on wide open. The image is sharp and very nice. Do I still need to try to adjust the Speed Booster or will I have to send it in?

 

 

It wasn't a vacation, but yeah, it's a great country. Seen much dark stuff, but also a lot of cool things. The button-thing started in Rio, no excessive heat or humidity there at that time.

 

 

 

***UPDATE***

 

Adjusted the SB myself and though it's still not perfect on infinity (especially after 3-5 meters), it's WAAY better now. Thanks for your help.

[sir_danish]

I have a similar problem, but I use my BMPCC with the speed booster and a Sigma 18-35. What I noticed is that I can´t get the center and the corners in focus at the same time. As if the focus plane was concave, no matter the the focal distance...

Additionally, the left side of the image is always softer than the right side. That makes focussing really tought with the lens wide open.

If the left side is in focus, the center is completely soft and the right side somewhat soft too. If the center is in focus, the right side is quite sharp too but the left side is completely soft...

 

This shot was taken with the lens wide open and set to infinity.

Notice how the right side is quite sharp, while the left side is very soft.

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Can anyone confirm, that this is a common issue when using the BMPCC speed booster with the Sigma 18-35?

I would be happy if someone with a BMPCC + SB +  Sigma 18-35 could do a test with the lens wide open and set to infinity. I´ve already replaced the SB and the lens, yet everything looks the same.