GH4 Will an adapted FF Nikon g lens be less sharp than the Lumix 12-35 zoom, in 4K?

T

twalp

Member
Doing some pre-purchase research about a "B" UHD video camera.

The prolific author at the "A Suggestion of Motion" site has written a lot about employing adapters to use a full-frame lens with the GH4, all of it positive. E.g. this.

The author of this video flatly states that using an adapted lens is a bad idea because the significant cropping of a full-frame lens results in loss of sharpness.

I've got several high-end Nikkor G zoom lenses, and using them with the GH4 seems attractive. I'm not worried about light loss because there's usually plenty of light available, and a decreased FOV doesn't seem a problem because of my lens assortment. So I don't see the need for a speedbooster.

What's reality in actual practice?
 
Using a FF lens WITHOUT a Speedbooster adapter will greatly reduce the sharpness of the lens, but WITH a Speedbooster it's a very nice combo. It's not as sharp as Olympus / Panasonic Micro 4/3 lenses, but this is a good thing for me because I often find dedicated Micro 4/3 lenses too sharp. I own eight Nikon AI-S lenses that I use with my GH4 specifically to get a softer looking image, and I also own a few Micro 4/3 lenses like the 12-35mm f/2.8 lens that I use for hand-held shooting because of the built-in OIS. ( and when I want AF for still photography )
 
The lens is a lens.

Sharpness.. a nikkor may resolve say 6k (for example) across the fullframe sensor area.

Over 1/4 of that area it will resolve 6/4 which is 1.5k

Does the gh4 sensor resolve more than 1.5k. with huge compression? probably not

A dx nikkor is designed to resolve between 4 and 6k over an area only twice the size of the GH4 sensor so. 2-3k.. plenty.


this is simple maths
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with a speed booster that 6k resolution gets projected onto the chip area, but the booster itself softens (more elements)

so with a booster your 6k lens might go to 5.5k but all of that information is projected on to the sensor.

more simple maths

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another element is sweet spot.. so the resolution of the lens changes over the projection area (it is soft in the corners) when only using the centre of the image circle one gets higher resolution.

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Conclusion..
-test you self
-a FF lens with no booster is probably a bit compromised.
 
Dude...
Homie....
Mate...

If you already have the Nikkor lenses you should ABSOLUTELY get the Metabones Nikon-to-MFT speedbooster.

The list of reasons FOR it is long, but I'll say that just like David Jones just said, I use the Speedbooster about 98% of the time on ALL my MFT cameras and I strongly prefer the resulting image quality.
I also use many Nikkor lenes - both primes and zooms.
 
Panasonic Lumix lenses (with the exception of Leica-branded Lumix) aren't really sharp, they're sharpened by the camera's distortion-correction software. Check out unsharpened RAW photos from a Lumix lens and you'll see that the corners are noticeably soft and the frame is curved. A center crop of virtually any full-frame prime lens easily beats the artificial edge enhancement of a non-Leica Lumix lens.
 
Listened to Northrup's argument about lens sharpness again and I don't buy it all.

He claims: "Because you're using such a small portion of the lens, the lens sharpness goes way, way down."

Not so. The image projected by the lens on the focal plane of the sensor is exactly the same, regardless of whether the camera has a full frame or cropped sensor.

The only difference is how much of the frame is cropped by the sensor. That's why a 50mm lens on a GH4 has half the FOV of the same lens on a full frame camera. To produce the same 1080p image size, the GH4 magnifies its cropped sensor's frame by 2X. The sharpness of that image is primarily determined by the 1080p resolution of the GH4. Since the lens was designed for the much higher resolution of still photography, cutting its resolution in half with the 2X magnification has little or no perceptible effect on the 1080p image.
 
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