Buy APS-C sensor glass, or Metabones Speedbooster?

[Zexun Tan]

Hey guys, so I've got a question here...

I bought my FS700 in November last year and couldn't love it more - my production value has upped quite a bit in terms of my workflow, 50/60p slowmo and then the SSM.

One thing though - I came over from the Canon 5D2, a full frame sensor, and am very used to how the glass looked on that sensor. On the FS700, I use Metabones' Smart Adapter II (EF to NEX).

Now the question is that I need an ultra-wide, which most people would recommend the Tokina 11-16. I've worked with that many times and I'm completely comfortable with it should I decide to own one myself.

Now the other thing I can do is buy a Metabones speedbooster and have my own Tokina 16-28mm perform similarly to the 11-16, with the addition of getting all my other lenses looking as if they're on the 5D2. The issue here is that... there seems to be quite a distinct barrel distortion and chromatic abberation at the corners of the images in tests done by people like LensRentals.

Both the Tokina 11-16 and Metabones Speedbooster cost the same over here in Singapore. Which would be a better option?

Cheers,
Zexun

[Tim Dashwood]

If you already have full-frame glass then I would definitely get the Speedbooster. It will put you back in your comfort zone for field-of-view and you will gain a stop of transmittance. If your glass shows chromatic abberation in your own tests then it might be something you will have to fix in post. The corners will always have issues on very wide lenses and the benefit in some ways of using a slightly smaller sensor is that your are using the image from closer to the centre of the lens. The Speedbooster may magnify some issues in the corners, but all you can really do is test your specific lens and see if it has the same flaws as the LensRentals tests.

[Eric Darling]

Maybe I got a bad copy, but my speedbooster's back focus is completely off. Zoom in, focus, zoom out, and the image goes soft. Rack it to focus, zoom back in, image goes soft again!

I'm going to get mine RMA'd by since there is no adjustment to be made for back foucs, I believe it could be a design flaw.

I'm using mine with Canon L series zoom lenses, and the problem exists with each one of the lenses.

[Sami Sanpakkila]

That's interesting Eric. I've read conflicting reports about which Canon Zooms are parafocal and wich are not. (Canon has never officially made this info public).

Here's one unofficial list I found online Doug Chinnery Photography: Canon Parfocal Lenses

I went to a local shop here and tested the EF 28-70mm f/2.8L USM and EF 70-200mm f/2.8L USM with my FS700 and speed booster. Both of them didnt seem to hold focus but the guy at the photoshop claimed them to be parafocal....

So I'm interested in hearing out if it indeed is the Speed Booster that is causing an issue.

[Eric Darling]

I've got a message into Metabones last night. No reply today. I'll give it one more day before I start to really complain.

[Sami Sanpakkila]

I just got bought a second hand Canon 24-105 L IS f4 lens today and that works well with the speed booster.

I can zoom in, focus and zoom out and it keeps focus (is this what you call rack focus?). So this lens seems to work for my intended purposes, ie. I can do zooms with it!

With the Speed Booster it reads as 2.8 and I can shoot with it at relatively dimly lit room at dusk. So very happy considering it's such a cheap lens.

Sami

[Eric Darling]

Very glad to hear it's working for you with your setup, Sami. Day three, and Metabones has yet to even acknowledge receipt of my two emails to them. So, hopefully someone picks up the slack and gets back to me before I start to worry that I'm not going to get any support from them.

[Eric Darling]

Finally got an answer three days later... Here's the link that helps:
Metabones - Infinity adjustment (Speed Booster? only)

[Sami Sanpakkila]

Hi Eric,

I had the EXACT same problem with my Speed Booster when it arrived.

Does back focus mean the same thing as infinity focus being off? (Im not native english speaker so some terms are not that familiar to me).

Not the best quality control if they're letting so many of the adapters slip by like that!

Sami

[Eric Darling]

In traditional broadcast lenses, there is an adjustment for back focus right where the lens hits the mount. This allows for some adjustments with various lenses.

For all intents and purposes, it's the same thing on the Speed Booster. I didn't realize there was an adjustment, as it's buried in that obscure link they eventually provided to me. But, I guess it makes sense in order for them to accommodate as many lens options as possible. The screw is tiny, and I guess it comes loose easily or something, as my lenses are all top of the line and newer than the 2006 date they specify in the online document.

The one thing that's really tough to gauge for me is the exact spot that nails critical focus. I guess I need to get out my old back focus chart and hook up to a big and high resolution monitor. But, it definitely will be adjusted, and that's good to know, as I was beginning to worry that I was stuck with a bum piece of gear and no support. They have no U.S. telephone number, so everything is via email. It feels a little isolating when you really need support, and it takes three days to get it!

[Sami Sanpakkila]

Hehe, in Finland the whole idea of phone support is still quite foreign!

That's the link they emailed me as well. What I noticed when I got the shipment was that something was ratling inside the box. It was the glass inside the adapter that was completely loose and spinning. I hadn't even noticed the back focus was off before I wrote them about the problem

I fiddled with the infinity focus until I felt it was in focus. I need to wait for a clear night sky to check it on the moon and stars to see if it holds up. So far the fartest I've been able to test in the city is about 500-700 meters. The rack focus seems to work with the 24-105 so thats positive!