Blackmagic Forum

Hello all,

Thank you for allowing me into the community. I am sorry that I have not found the answer to my very basic problem in the forum, and I thank you with your patience with my issue. 

I heard so many good things about blackmagic, I must be doing something wrong with my setup, as I am really disappointed in the results I am getting. 

My shots a really blurry, when compared to my much cheaper action cameras, and I was hoping for crystal clear 4K shots. What am I missing?

Sample video below, details below. Thank you for any tips! 



Kit
Black magic Pocket Cinema Camera 4K 
Laowa Lens 7.5mm f2.0 Micro Four Third C-Dreamer
46mm-55mm Step Up Ring Adapter
K&F Concept 55mm UV Filter Ultra Slim Japan Optics

Shooting in 
4K DCI 4096 x 2160 at 59.94fps 
Black magic Raw Constant Quality Q5
Native ISO 400 (or 3200)
Shot with f.stop 16, sharpness assist lines were all clear blue 

Adjusting in Davinci Colour Tab to 
Mid tones detail 0.25 
Sharpness Radius RBG 0.47, scale 0.5

Don’t shoot with such a small aperture. Use T4 or T5.6.

Try less compression such as Q1.

Your focus assist may be deceptive so set to 25% assist strength to get a more precise reading. Don’t use blue as your colour, try green (or red).


There may be other things to change but try these to see if they help.

You need to up your aperture and use NDs.

rick.lang wrote:Don’t shoot with such a small aperture. Use T4 or T5.6.

Try less compression such as Q1.

Your focus assist may be deceptive so set to 25% assist strength to get a more precise reading. Don’t use blue as your colour, try green (or red).

Thank you for taking the time to give me advice. The compression made no difference, I should have said so in my original post.

I thought aperture would have a higher depth of field the smaller the aperture, but will try setting at 4 and 5.6.

I was thinking about the aperture assist, but trying to cycle through the full focus range, and never got a sharp picture.

Did you have a chance to look at the YouTube video above? Maybe my expectations are too high, and action cam footage is artificially sharpened...

Really need to define what "blurry means to you. Blur usually is associated with motion (of the subject or camera.) This is typically controlled with shutter speed (shutter angle) or stabilization (tripod; stabilization device or procedure.) Blur is typically directional but can be multi directional or even radial as when zooming (or moving camera toward or away from subject.)

Sharpness (or softness) usually is associated with focus or resolving power. Yes, it can be confusing as sometimes this is sometimes called blur. Sharpness can be so fine as to be limited by grain or noise and so soft so as to be the creaminess smoothness (maximum bokeh.)

In your particular example I would suggest to first investigate the aperture. An article (one of many) describing sharpness vs aperture for various sensor photo sight sizes can be found at this link:
https://www.cambridgeincolour.com/tutor ... graphy.htm
From this article you should be able to discover that for the Pocket 4K an aperture of f5.6 or wider would produce the greatest sharpness. Remember also that different lenses will likely have different sharpness (resolving power) and contrast (contrast will affect the apparent sharpness.)

Some of the other suggestions can help as well, maybe to a lesser extent than aperture.

Keep in mind that something done in post can influence an issue so best to evaluate with a basic color management first without any tweaks.

Some additional advice (although not concerning the sharpness issue) would be that unless your delivery is to be broadcast (of which very little is done today) do not use fractional frame rates. Use progressive rates like 24, 25, 30, 60. Fractional rates (as well as interlacing) are used when broadcasting analog signals. With digital streaming (and digital projection) and such (what are commonly used today) whole progressive frame rates are used. This will help keep things more simple.

Thoughtful post, Jeffrey.

Thank you very much for your detailed and thoughtful responses, I learnt a lot only from those contributions. 


This is clearly a welcoming and supportive forum, I should have left Facebook ages ago and go to where the experts hang out. 


I always thought that a large aperture would lead to a shallow depth of field, which it does, but I did not appreciate its impact on softness. I also was not aware that I could and should go to 60 and 30 frames per second.


And you are correct, I did mean softness and not blur, another thing I have learnt. In terms of shutter speed, it is not the cause of blur, with being 1/300 - 1/1000. 


Q1 to Q5 settings so not really make a difference to softness. Changing to prores 422 improves it a bit. 


Do you use the inbuilt details sharpening setting? It does not seem to make much difference to the outcome either. 


Is there a way to read up as to how soft my lens should be? Am I better off buying a speed booster for my existing canon lenses? Originally I bought the lens for its wide angle for drone photography, so I can't expect too much...

Hello team, I am really sorry to have to admit that the issue was not the Laowa Lens, but the fact that I had not notived that Davinci Resolve had auto-adjusted the timeline settings to 1920x1080p. Of course this meant that on my 4K monitor the image looked softened.
I feel like a prize idiot, but it was an honest mistake, as I am just getting familiar with both BMPCC4K and Resolve 19.

I did, however, learn a lot, not only about your welcoming forum, but also about frame rates, quality settings, aperture and more. Thanks again!

Stopping down an aperture too much, while beneficial for some reasons, can also lead to an increase in diffraction, which can reduce image sharpness, especially on high-resolution sensors. This is because when the aperture is very small, light waves diffract around the edges of the aperture, spreading out and causing a loss of focus.

reinkeb wrote:... In terms of shutter speed, it is not the cause of blur, with being 1/300 - 1/1000.

If you are using shutter speed to control the duration of your exposure, you might consider using shutter angle which is more of the standard approach shooting with a cinema camera where a standard is a 180 degree shutter angle. That tends to give a natural look to your motion. 180 degrees with a frame rate of 30 fps gives you a 1/60 sec exposure.

Should you change frame rates to 60 fps for example, there is no need to change the shutter angle but it will now result in a 1/120 sec exposure. So it’s simple to keep natural motion regardless of frame rate. Using a small shutter angle like 11 degrees can give your motion a strobe-like effect which isn’t always what you want to see.

I often shoot 360 degrees shutter angle at 30 frames per second so the duration is about 1/30 sec that can add a dreamy look to motion. If you decide to record at 60 fps off-speed for playback at a project frame of 30 fps, you should set the shutter angle to 360 degrees which will look ‘normal’ when you playback.

Q1 to Q5 settings so not really make a difference to softness…

All constant quality settings are considered visually lossless but of course that’s not exactly true as the data rates are considerably different. That said Q5 may give you good results with relatively small media usage. Q0 will provide you the most detail in shots where that is more important or challenging. Q1 and Q3 also reduce your data rates. Play with the different settings on a very detailed scene and you may see a difference, but for many shots without a lot of detail, you may not see any difference and go with Q5.

Do you use the inbuilt details sharpening setting? It does not seem to make much difference to the outcome either...

Generally only use modest sharpening in-camera if you are providing a live broadcast feed. The setting isn’t usually used if you’re shooting for normal video processing. In post you might add modest sharpening but be careful as strong sharpening will often ruin the shot.

rick.lang wrote:... In post you might add modest sharpening but be careful as strong sharpening will often ruin the shot.

Following up on what Rick says: Sometimes instead of sharpness what is really desired is contrast.

This can be seen in lenses where a sharper lens may not look as sharp as a lens with more contrast.

That’s an excellent observation, Jeffrey. I usually don’t adjust contrast or only apply a modest contrast in my videos, but in doing my stills work for clients, adding contrast often makes the shot.

reinkeb wrote:Hello team, I am really sorry to have to admit that the issue was not the Laowa Lens, but the fact that I had not notived that Davinci Resolve had auto-adjusted the timeline settings to 1920x1080p. Of course this meant that on my 4K monitor the image looked softened.
I feel like a prize idiot, but it was an honest mistake, as I am just getting familiar with both BMPCC4K and Resolve 19.

I did, however, learn a lot, not only about your welcoming forum, but also about frame rates, quality settings, aperture and more. Thanks again!

I was thinking this, given the video sample you uploaded was 1080P as well.

So because the pocket 4K has a small-ish sensor, it sets a higher requirement for the lens sharpness, CA etc. So you really want to study in detail what lenses you are using.

Contrast can also be manipulated at various frequencies (often done in beauty work) for even more control.