The sharpest image

[Eugene Lehnert]

Hello-

I am looking for some advice regarding achieving the sharpest image I can in 4K on the Scarlet camera. I have a set of old Nikon still film lenses with Canon adapters that I typically use for most of my productions. Typically what I do is always downconverted to HD. I had a client that is looking for true 4K content. I rented Zeiss ZE prime lenses with Canon mounts and I found that they had trouble focusing at infinity. My old Nikon still lenses were able to achieve better focus. Is this a back focus issue?

Thanks,

Eugene

 

[Maz Mawlawi]

So far the the sharpest photo lenses I have used on Epic for 4K delivery are the Zeiss ZE and the sigma Art lenses. You may have had a bad back focus on your scarlet. While I like the vintage Nikon organic look they are a little too soft in 4K for my taste. (I guess it depends how well those lenses are maintained)

 

[Jeffery Anderson]

Focusing to Infinity:
That's a problem with your Lens Adapter, they make Zeiss in the Canon Mount, they even make a Nikon Mount for the Red DSMC.

Can't backfocus a Prime Lens, if the # are off, you have to shim or shave... but that's cinema lenses. Anyways, you have a cheap adapter.

Best Lens available, for Canon or Nikon Mount is Zeiss Otus

Nikon Mount

Cheap Mounts on Ebay

if you own a bunch of Nikon Mount Zeiss Lenses, I would probably just buy the Red DSMC mount and sell the Canon one.

 

[Dr. Sassi]

If the lens is "sharp" while in mid distance but not in infinity, you need to set the back-focus. Make first certain that the lens is OK, perhaps test it on a DSLR body. If both bodies show the same problem, you know it is the lens, most likely not, though.

Find something really far away with a good contrast. This should be your reference point.

The procedure is in the Manual (well for PL) but for still glass it is not that difficult, -- check back with the support -- if in doubt. After you have set the back-focus newly, check the lens for the close and fare distance.

(For professional back-focusing you want to get the markings on the lens correct as well, but I guess that is here a secondary concern)

For shooting: Find the sweet-spot on the lens, most likely around 5.6 +/- and expose as precise as you can: noise-reduction eats sharpness. Wide open or nearly closed will not deliver the sharpest image.

If you like 4K as deliverable, to shot in 4K might be not enough. You have no tolerance for errors if the pixels go out 1:1, though de-bayered and de-noised... and somewhat sharpened I guess, sounds like a challenge.

Sharpness (Cognitive) is normally defined as mixture out of contrast and resolving power of the lens (considering the sensor can keep up with the lens). What helps is normally some kind of soft background, so the "visual contrast" to the sharper parts is greater.

 

[Ben Scott]

£250 Contax Zeiss 35mm f2.8 at anything past f4.

If you can't get sharp enough to take someone's head off with that, you're doing shoot wrong.

 

[Eugene Lehnert]

The Nikon lenses use the adapters. The Zeiss ZE lenses are built with the Canon mounts and they are the softer lenses.

Focusing to Infinity:
That's a problem with your Lens Adapter, they make Zeiss in the Canon Mount, they even make a Nikon Mount for the Red DSMC.

Can't backfocus a Prime Lens, if the # are off, you have to shim or shave... but that's cinema lenses. Anyways, you have a cheap adapter.

Best Lens available, for Canon or Nikon Mount is Zeiss Otus

Nikon Mount

Cheap Mounts on Ebay

if you own a bunch of Nikon Mount Zeiss Lenses, I would probably just buy the Red DSMC mount and sell the Canon one.

 

[D Fuller]

The Nikon lenses use the adapters. The Zeiss ZE lenses are built with the Canon mounts and they are the softer lenses.

It is unlikely that the Zeiss lenses with factory Canon mounts are off, but it's quite ikely that your Nikons with the adapters are off. But if they are all the same brand of adapter, it's quite possible that they are all off the same. And if your back focus is set for them, and the Ziess are different, the Ziess would all be soft at infinity. Check the back focus. It'll solve your problem.

FWIW, this is not as uncommon a problem as you might think. Last year I had a shoot for which I rented lenses from two different rental houses, and they were collimated differently, so we had to choose which set we'd have perfect back focus for. These were all PL mount cine glass maintained by good rental houses, so it's not hard to believe that the adapters on your Nikons aren't perfect.