GH4 GH4 Everything in Focus without losing quality?

J

Jason Rae

Well-known member
What you would guys suggest the maximum f stop you would use when trying to get everything in focus without losing image quality. I have a 12-35 2.8 and a metabones 18-35 sigma. Does it depend on the lens we are using or sensor for this. I know when we shot with out 5d Mark III anything over F11 was mush. I know its mush compared to the gh4 regardless of F stop but just wanted to get any advice on this.

Our last shot we used f10 and it was good looking footage and even the trees 40 feet behind me where in focus... lol But again just wondering what yalls thoughts are on this...

Thanks for the input as always.
 
Depth of field is a function of sensor size, lens focal length, and aperture. The smaller the sensor, the longer the depth of field. The wider the lens, the longer the depth of field. There are several DOF calculators online and for your phone. They are helpful in determining the range of acceptable focus for any sensor/lens/aperture combination.
 
FWIW. With an Olympus 12-40 on the GH4, I've found that max detail occurred at f8 with f5.6 almost as good and gradual roll off to 2.8. Going the other way was like stepping off a cliff. F11 was much worse on fine low contrast detail and, of course, f16 even more so. This was when pixel peeping in the center of 4k frames. If I want max detail for a nature shot of grass, trees, etc. then I stick with f8. Whether all this would matter much when scaled to HD and viewed on the web after compression, probably not. I've yet to check it out on a large screen tv to see if it makes much difference there.
 
Not directly related to the question at hand, but worth keeping in mind when trying to achieve deep depth of field with very little diffraction.

The most important factor in DOF is distance to the subject not aperture or focal length. The closer the subject is to infinity the deeper the depth of field. Regardless of the lens or aperture, keeping the subject a bit further away will increase the depth of field significantly.

Anyway, just another tool to keep in the bag.

Cheers,
Pete
 
Larry McKee said:
Depth of field is a function of sensor size, lens focal length, and aperture. The smaller the sensor, the longer the depth of field. The wider the lens, the longer the depth of field. There are several DOF calculators online and for your phone. They are helpful in determining the range of acceptable focus for any sensor/lens/aperture combination.
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Also, focal distance. You can achieve a shallow DOF on an iPhone if the focal distance is applicable.
 
Jason Rae said:
What you would guys suggest the maximum f stop you would use when trying to get everything in focus without losing image quality.
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I would start at f4 (which has the least diffraction for this lens) then stop down until you get the needed DOF. Since MTF and DOF are mutually exclusive, it just depends on how much diffraction loss you're willing to accept for DOF. Scenes requiring a lot of DOF will end up less sharp. I like Photozone's lens charts anyway...

http://www.photozone.de/m43/766_pana1235f28?start=1
 
A 50mm is a 50mm and a 12mm is a 12mm, regardless of the camera in terms of DOF. If you mount a 50mm on a Nikon FF and then on the Gh4, take a shot from the same position on both cameras at F5.6, the DOF will be exactly the same. What won't be the same if the field of view. Not if you stepped back with the Gh4 and matched the field of view to the Nikon FF at the same Fstop, you would be changing the focus point, which then changes the DOF (because you are further away from the subject on the Gh4 with the 50mm). Now if you set cameras in the same place with a 100mm on the FF camera and a 50mm on the Gh4 to get the same FOV and have the exact same settings on the lens with aperture, it's the 100mm vrs the 50mm creating the DOF difference. So the sensor is not creating more DOF. It's the lens used to get the same FOV as the between the formats. Focus at 10ft. on the 100mm and 10ft. on the 50mm at the same Fstop, the lens is dictating the DOF.
 
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I just meant that since higher apertures increase DOF resolution but decrease the maximum overall resolution (or MTF) the trade-off is kind of a subjective thing. My take on it anyway.
 
CustomerGH4 said:
With the Leica 25mm, I got beautiful shots even in the F16 range.
PS, as they say "smaller the hole, better the quality;)"
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Please don't spread stuff like that; at f/16 you're past diffraction and I really didn't like what I saw, given as someone who usually doesn't mind going a little past diffraction limits.
 
ralfmouth said:
I just meant that since higher apertures increase DOF resolution but decrease the maximum overall resolution (or MTF) the trade-off is kind of a subjective thing.
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...But this is true of every camera, especially FF cameras as most of their lenses are very soft wide open. The typical rule of thumb for FF lenses is to close down at least 2 F-stops to clear up coma, chromatic-aberration, and increase resolution.

The new Zeiss OTIS and Sigma ART FF lenses are extremely sharp at full aperture, as are some of the Olympus and Panasonic Micro 4/3 lenses, so with these lenses you can shoot wide open. ( where the DOF might be too shallow for the FF lenses, but just fine for the Micro 4/3 lenses )
 
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