topic Re: 5D mkiii video focus issues in EOS DSLR & Mirrorless Cameras

5D mkiii video focus issues

conran — Tue, 30 Jun 2015 19:02:48 GMT

Hi everyone,

My first post and i'm hoping to find some help.

Recently i've been seeing issues with focus on my 5dmkiii. The image looks sharp on the LCD (at maximum zoom) but soft when i check the file on the desktop. It's across all lenses and all picture modes.

I've been using 5D's for a few years now but this has me stumped. Any help would be much appreciated.

thanks

Jamie

Re: 5D mkiii video focus issues

Peter — Wed, 01 Jul 2015 20:45:11 GMT

Video? You can´t zoom the video in your camera I suppose.

Re: 5D mkiii video focus issues

conran — Thu, 02 Jul 2015 08:09:07 GMT

Everything looks sharp on the LCD when magnified but the output file is still soft.

Re: 5D mkiii video focus issues

TTMartin — Thu, 02 Jul 2015 11:52:22 GMT

@conran wrote:

Everything looks sharp on the LCD when magnified but the output file is still soft.

Are you judging the sharpness on your computer monitor with the full image displayed, or are you zooming in on a portion of the frame?

Also what 'pcture style' are you using when shooting your video?

Re: 5D mkiii video focus issues

Peter — Thu, 02 Jul 2015 11:50:53 GMT

Any example?

Re: 5D mkiii video focus issues

conran — Thu, 02 Jul 2015 12:34:21 GMT

Looking at the file on desktop, the image is sharp on the camera.

Tried multiple picture styles/apertures/lenses etc and still the same result. Also had the same results in a studio set up with lots of lighting.

Here's a sample video vs low res jpg still.

Re: 5D mkiii video focus issues

TTMartin — Thu, 02 Jul 2015 14:12:46 GMT

@conran wrote:
Looking at the file on desktop, the image is sharp on the camera.

Tried multiple picture styles/apertures/lenses etc and still the same result. Also had the same results in a studio set up with lots of lighting.

Here's a sample video vs low res jpg still.

There is a difference between focus and resolution. The 5D Mk III uses pixel binning to reduce the sensor resolution down to video resolution. Video simply has less resolution. The thing to keep in mind, is that if nothing is sharp then it is not a focus issue.

Re: 5D mkiii video focus issues

conran — Thu, 02 Jul 2015 14:31:34 GMT

Thanks Martin, understand there's a difference betwen resolution and focus. I know the mkii requires sharpening in post, more so than the mkii etc but the quality of video has reduced considerably.

as i said, focus on the LCD is pin sharp (as sharp as it gets with a mkiii) but the output is unnaceptable even for a dslr video.

Tried it on my mkii as well and same issue. firmware is up to date etc, (this was happening before the update).

Only thing i can think of is somehow a card has corrupted both cameras but i'm just guessing really.

Too the cameras to a Canon specialist and they couldn't understand it either.

Re: 5D mkiii video focus issues

TCampbell — Thu, 02 Jul 2015 15:33:11 GMT

Or stated differently... in "still" mode it's a 22MP image. In "video" mode it's a 2MP image.

A 2MP image isn't going to have the detail-resolving capability to compete with a 22MP image.

Re: 5D mkiii video focus issues

conran — Thu, 02 Jul 2015 15:54:27 GMT

Thanks Tim, understand the difference in quality.

This isn't a comparison between still and video though. The video is out of focus, difference between 'in focus' on the LCD and what comes out of the camera is just night and day so to speak.

I've shot with both mkii and mkiii and had much sharper files in the past Tried clearing all camera settings etc and starting again but still the same issue.

Has me stumped.

Re: 5D mkiii video focus issues

TTMartin — Thu, 02 Jul 2015 16:16:12 GMT

@conran wrote:
Thanks Tim, understand the difference in quality.

This isn't a comparison between still and video though. The video is out of focus, difference between 'in focus' on the LCD and what comes out of the camera is just night and day so to speak.

I've shot with both mkii and mkiii and had much sharper files in the past Tried clearing all camera settings etc and starting again but still the same issue.

Has me stumped.

If NOTHING is sharp it is NOT focus.

Focus determines where the sharpest plane of an image is, not the ultimate sharpness.

You can be perfectly 'in focus' and have a completely blurred image due to other factors.

Re: 5D mkiii video focus issues

TCampbell — Thu, 02 Jul 2015 16:48:20 GMT

Without looking at your LCD image and comparing to our computer screen image it would be hard to say why this happens.

BUT... the LCD is small. Small images always tend to look sharper than large images. The 3.2" LCD screen is merely a 1MP display. Each single pixel of the LCD literally represents 22 pixel of image -- when you have to resample 22 pixels down to just 1 pixel it's difficult to use that to judge image quality.

Re: 5D mkiii video focus issues

conran — Thu, 02 Jul 2015 17:30:19 GMT

Cheers Tim, what could those other factors be?

It's been tested in studio conditions with lots of lights and in daylight too.

The shot shave DOF but the supposed point of focus is still soft.

Re: 5D mkiii video focus issues

TCampbell — Fri, 03 Jul 2015 16:28:51 GMT

Ordinally "other factors" might be blamed on issues with the lens' optical quality. But since you are satisified with the results from a still image, it's clearly not the optical quality.

If you still suspect the camera is missing focus then you'll need a better focus target. I use a Spyder LensCal. The device has a flat card with a high-contrast focus target. Adjacent to the target is a rule. But the rule is leaning back at a 45º angle. The 0 point on the rule is in the middle and this point is at the same distance as the face of the flat focusing target. Since the scale is leaning on a 45º angle, if the camera is either front-focusing or back-focusing then you would notice that some other point on the scale has better focus than the 0 point in the middle.

Here's the website with a picture of the card: http://spyder.datacolor.com/portfolio-view/spyderlenscal/

The other focus calibration tool I've seen is the LensAlign -- it's very similar to the Datacolor product in how it works.

The major purpose of both of these products is to provide a tool to help you perform auto-focus micro-adjust (on cameras that support it -- such as your 5D III. Although micro-adjust only applies to focus performed by phase-detect AF sensors... it is not used when using live-view or video since that uses contrast-detect AF.)

Since your focus target is a simple flat card, you cannot easily tell if there is some point in space closer than your card that had better focus... nor can you tell if there is some point in space behind your focus target that would have better focus. Although... in looking at your setup, it does appear to me that the focus target has better focus than other areas - it's just not possible to be precise.