GH4 Super 16mm Lens Coverage Boost - GH4 & BMCC Coverage with Olympus MC-14 Teleconverter

J

Joshua Cadmium

Well-known member
Super 16mm Lens Coverage Boost - GH4 & BMCC Coverage with Olympus MC-14 Teleconverter

I've been waiting for a 1.4x teleconverter to come out for m4/3 for awhile now, mainly so that it could be used to increase the image circle of Super 16 and regular 16mm lenses. Good news - it does!

It increases the 16mm lens circle from 12.7mm to 17.78mm, which is more than enough for GH4 in UHD and C4K and just a hair under BMCC (although most lenses should cover just fine).

It increases the Super 16 lens circle from 14.54mm to 20.35mm, which is more than enough for 16x9 m4/3 coverage (which is 19.83mm).

The MC-14 does introduce a little chromatic aberration, but it's nothing too serious.

The only issue is that the MC-14 does have to be altered in order to work with any m4/3 lens. There's a piece of plastic which protrudes out (fitting into the Olympus 40-150mm) that needs to be cut off. I used a set of sprue cutters, which worked great, but I used them after disassembling the entire teleconverter, in order to have enough room. If you're careful, you shouldn't need to do that.

Also, some lenses protrude too far, making them incompatible with the teleconverter (the glass elements would hit.) For instance, the Angenieux 7-81mm fits without any alteration, the Zeiss 10-100mm T2 has to have it's rear plastic cover taken off in order to fit, and the Abakus 132 B4 to PL doesn't fit at all.

The MC-14 was almost perfectly parfocal, and it looks like you could shim the mount to make it absolutely perfect.

I'll have pictures up in a bit.

Yay!
 
Okay, below are some pictures. The first shows the aftermath of cutting off the tab (on the right):

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The next picture shows the Angenieux 7-81 at T4 on the lens (T5.6 with the adapter) on a DSC Labs 4K test chart. This was taken on a Panasonic G5 with the same 3.75 um pixel size of the GH4 and GH3. This is at the 1080P 19.83mm diagonal size. The image size is 4602 x 2592, or 4.5k, which is 44% more pixels than UHD.

uc




The final shows the Zeiss 10-100mm on the same chart at T8 on the lens or T11 with the adapter. This was taken at the same 19.83mm diagonal size, 4.5k resolution as the one above, as this lens has additional coverage as you zoom in. (Note that the framing is more zoomed in than for the Angenieux, so the numbers and lines are going to naturally appear sharper than the picture above, since they are magnified.)

uc




I've found the adapter to be basically parfocal. It's so close to perfect that you could consider it so. The 4 screws on the opposite end (not the side pictured above) each have two washers in place, one on top of the other, with one of the two being very thin (shim thickness thin.) I removed just the very thin washers on all 4 screws and the adapter became just a touch less parfocal. I'm guessing, therefore, that Olympus is using the washers to shim the mount. If you're adapter is off (after testing that the main lens and mount is perfectly shimmed) you could cut shims the size of the washers to make it perfect.


Here are links to the pictures so you can see them in a separate tab:

Angenieux 7-81mm: http://drive.google.com/uc?export=view&id=0BznQ3hfwYm4NQWFYcTRGV1Rhdzg

Zeiss 10-100mm: http://drive.google.com/uc?export=view&id=0BznQ3hfwYm4NMWNmUUJTcW53bUE
 
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Thanks for sharing.

Could you please update the pictures in the second post (they are gone)?
 
Ryan Patrick O'Hara said:
Very cool. So this is m4/3 to m4/3, and we can add our lens adapters to it like business as usual?
Click to expand...

Yep, you'd first adapt whatever you wanted to m4/3 (native PL mount, Arri Bayonet, Arri Standard, C Mount lenses, etc.) and then just stick the teleconverter on the end of that, as long as there was room to do so (some lenses will stick out too far.) That's it. :)
 
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