Speed-Booster focus shift?

O

orfeas76

Member
I just tested the NikonG to NEX Metabones SpeedBooster on my NEX-EA50
I tested it with several lenses including 24mm f/2, 35mm f/1.4, 85mm f/1.4
All lenses produced a noticeable focus shift. The lens mark is at infinity when the real focus is at about 5 m.
Real focus at infinity is not possible, except if I close down the aperture, enlarging the depth of field.

I also tested the simple NikonG to NEX adapter and showed no focus shift.

Is this a known limitation of SpeedBooster or did I get a faulty product (longer tube than optimal)
 
That's the problem with using Adapters is the manufacture has to shift the infinity mark in-order to accommodate the huge range of lenses.

I talked with the tech guy at Fotodiox who makes the excellent Nikon to Canon Fotodiox Pro adapter. He said, they have to have infinity focus come slightly before the mark because of the huge variation of lenses out there, so it gives it some leeway, otherwise, some lenses might not be able to achieve infinity focus.

For me, I notice that with the regular Canon Metabones, infinity focus comes a little before the mark, but with the Canon Speed Booster, it hits infinity right on the mark. At least on the Canon Metabones, you can manually adjust where infinity focus falls on the adapter. It's tricky though so be careful. Metabones has instructions on their website.

In actually, many modern lenses (such as my Tokina 11-16) cannot even hit the infinity mark even without the adapter.
 
My issue is when I go to focus the lens, it rotates in the metabones adapter causes the aperture to change. So I get little bumps of exposure difference. So annoying.
 
* Marks in stills lenses are not accurate at all, I wouldn't trust them even without an adapter (for a start, if it's a zoom and it's not parfocal, they just can't be accurate at all focal lengths, there's no way around it)
* Unlike no-glass adapters, the speedbooster has an adjustment that can make them more accurate. It's a screw on the back side that allows you to rotate the back element. Don't play with it unless you really need to.

* that focus-and-aperture-changes thing is WEIRD
 
Chris Langer said:
My issue is when I go to focus the lens, it rotates in the metabones adapter causes the aperture to change. So I get little bumps of exposure difference. So annoying.
Click to expand...

Yikes! I haven't seen that. I've only tested with the speed booster. Heck, I'll leave it in the case and stick with the Novoflex if that's the case. Thanks for the heads up. I have to test that out before a long day tomorrow. Jeez!
 
It appears my lens doesn't mount fully on and wiggles if you move the lens. Since the aperture is so sensitive to movement, it becomes really easy to budge when focusing, hence the little bumps in exposure.
 
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