No shallow DoF on the 'tiny' GH2 sensor?

iHartVideo

iHartVideo

Well-known member
From my blog:

I've read so many posts on different forums saying that the GH2 sensor is too small to get nice, shallow Depth of Field (DoF).

I don't know how thin you need it but the shot below (from a recent interview piece) is as thin as I would want to go... focusing can get extremely difficult at these shallow DoF's. You can clearly see his hair is blurred out while his eye/nose area is sharp. This was shot on a GH2 with an older Nikon 50mm f1.4 at f1.4.

GH2-DOF.jpg.scaled1000.jpg
 
You can get great shots with the Gh2, it's fine.

However, one thing to worry about is...

Full Frame - SO out of focus it looks artfull and on purpose
GH1/GH2 - "bokeh" can be ENOUGH in focus that it makes the image look soft.

In that vidcap, sure his nose is sharp, but not really a DOF effect people want. It just looks like the lens isn't sharp on the rest of his face.
 
With respect to your seniority on this forum I do not see how the m4/3 sensor has anything to do with bokeh.
It is a property of the lens. Crop factor has nothing to do with the amount of bokeh you get on the lens.
For example my 50mm canon F1.2L has exactly the same amount of bokeh on the gh2 and the 5dII.
Lenses work the same regardless of the crop factor.
You can get better bokeh if you background is far away from the DOF and you are shooting wide open.
 
kurth said:
jeez - what ? dof is fundamentally affected by the size of the imager
Click to expand...

nope. just aperture and focal length, but you do have to use a wider focal length to get the same field of view as you would on a larger sensor. DOF with a 50 1.4 would be the same on a GH2 as it would on a 5D mark II, but in order to get the same field of view, the GH2 would need a 25mm, which has much deeper DOF. so i guess sensor size indirectly affects DOF, due to entirely differences in lens choice.
 
The size of the imager affects the field of view, but not the DOF. As dust'n said, the lens sets the FOV, and sensor size influences which lens you'll choose for any specific purpose, so sensor size is related to DOF but is not an actual factor in changing the DOF. DOF is set by the lens.
 
If anything I am very unhappy with how much DOF my 20mm 1.7 lens have.
I tested it yesterday an it has A LOT of DOF at wide open.
pretty annoying and hard to follow focus somebody indoors.
 
It's a wide lens on the 4/3 sensor. That's to be expected. It'll see great in the dark....but if you want Shallow DOF then get the V. 0.95 / 25mm.
 
hazna said:
If anything I am very unhappy with how much DOF my 20mm 1.7 lens have.
I tested it yesterday an it has A LOT of DOF at wide open.
pretty annoying and hard to follow focus somebody indoors.
Click to expand...

I like the shallow dof of the 20mm f1.7, but for scenes where I would need a shallow dof look I would use a proper follow focus setup with a friction follow focus setup. if not, I would just shoot at a deeper dof like f2.8 or 4.
 
Sure Barry, so expressing it yet another way, shooting a face like the original post photo with say a 50 f1.4 on both a 5D and a GH2 would give different dof, on account of the distance to subject to achieve the same framing.
 
hazna said:
If anything I am very unhappy with how much DOF my 20mm 1.7 lens have.
I tested it yesterday an it has A LOT of DOF at wide open.
pretty annoying and hard to follow focus somebody indoors.
Click to expand...

If you're unhappy with it, you are experiencing exactly the kind of lens speed the greatest film-makers of all time have experienced, and still experience on most feature films, if that's any consolation. Your only options are to remember the rules of short dof:

longer lens (easy)
wider aperture (Voigtlander 0.95 25mm as already suggested, but v. pricey!)
bigger sensor (Canon 5d - I wouldn't!)
closer subject (free)

Take your pick!
 
1. Defeats the purpose.
2.I would not touch the Voigtlander. Too soft and to much vignetting.
3. Have the 5dII and I like everything about it but the s**tty resolution videos "compared to the panasonic"
4. That doesn't even makes sense.
 
hazna said:
1. Defeats the purpose.
2.I would not touch the Voigtlander. Too soft and to much vignetting.
3. Have the 5dII and I like everything about it but the s**tty resolution videos "compared to the panasonic"
4. That doesn't even makes sense.
Click to expand...

Me thinks you are very mistaken about #2. :Drogar-Shock(DBG):
 
hazna said:
With respect to your seniority on this forum I do not see how the m4/3 sensor has anything to do with bokeh.
It is a property of the lens. Crop factor has nothing to do with the amount of bokeh you get on the lens.
For example my 50mm canon F1.2L has exactly the same amount of bokeh on the gh2 and the 5dII.
Lenses work the same regardless of the crop factor.
You can get better bokeh if you background is far away from the DOF and you are shooting wide open.
Click to expand...
Smaller sensors have greater DOF, but the crop factor, of course, makes the lens longer, so it's not the same frame size and comparing apples to oranges in some was. IE - 50mm = 25mm on a GH1, and even though they're equivalent framing wise, a 50mm lens on a Mark ii will have more bokeh than 25mm on a GH1 at the same aperture giving the same frame/distance.

The sensor size matters, but again, your 1/3 inch chip HDV cameras have more in focus since the lens is ultra wide to make up for the small sensor, so it's an indirect factor
 
hazna said:
If anything I am very unhappy with how much DOF my 20mm 1.7 lens have.
I tested it yesterday an it has A LOT of DOF at wide open.
pretty annoying and hard to follow focus somebody indoors.
Click to expand...

You mean to say it has not a lot of DOF wide open. A lot of DOF would mean a lot of things in focus.
 
Ben_B said:
You mean to say it has not a lot of DOF wide open. A lot of DOF would mean a lot of things in focus.
Click to expand...
Sorry my bad.
The DOF is very narrow.
My friend was making a coffee and only 1 inch move of his head takes him out of focus.
 
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