Apefos Adapter
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GH2 TUTORIAL How To Improve Image Quality From Soft Lenses (on Vimeo)
http://vimeo.com/34423217
The challenge: to use the lenses wide open to get the most shallow dof in GH2. But this makes the image soft because almost all lenses are soft wide open. So what is the solution?
Go on reading and see the video...
When you read the word "IMPROVED" in top right corner of video it means the image was graded in post-production to correct softness with these settings: sharpen 20, gamma correction 11, brightness -3, contrast 2.
Instead of Sharpen 20 you can apply Sharpen 10 plus Unsharp Mask 80 / 1,2 / 0. Of course the amount must change due to more or less softness.
I used the same post-production settings for all lenses and all fstops to get some kind of comparison.
GH2 was set to Cinema, Contrast 0, Sharpness -2, Saturation +2, Noise Reduction -2, Hacked 40Mbps, 24p 1920 x 1080.
The conclusions:
It is possible to use the lenses wide open and correct softness in post production.
Stopping down 1 fstop from the widest aperture helps a lot to avoid softness in all lenses and keeps the shallow dof almost the same.
The way to go: Stop down 1 fstop from the widest aperture and do a softness correction in post production using settings similar to described above to improve image quality.
If you can, stop down 2 fstops from the widest aperture. The image will be even better. f2.8 is a good aperture to get a decent shallow dof in GH2. So if you have a fast lens stop it down to 2.8 and try what you get.
Never let the image gets overexposed. This will make the image quality very bad, a lot more soft, dificult to correct in post production. When using a third part lens in GH2 with an adapter, set the metering to SPOT and use a 18% grey card. In this video I measured light in person face using the spot meter in GH2, but the image got overexposed 1/3 fstop. You can see when the image is correct exposed in LCD or viewfinder, you just need to train your eyes.
Lenses in this test:
The Lumix 14-42mm 3.5-5.6 is the reference lens. It is tack sharp and a nice contrast lens.
Sigma 20mm 1.8
Canon FD 24mm 1.4
Vivitar 28mm 1.9
Nikon 35mm 1.4
Olympus PenF 40mm 1.4
Minolta 45mm 2
Nikon 50mm 1.4
Nikon 55mm 1.2
Minolta 58mm 1.4
Tokina 35-70mm 2.8
Nikon 85mm 2
____
FAST LENS REVIEW - Nikon, Canon FD, Minolta, Olympus PenF, Sigma, Tokina, Vivitar
I am doing a exaustive test with many lenses and will share the results.
First impressions:
All the lenses are very soft wide open, I mean you cannot seriously use the widest aperture.
To get a good quality picture, good contrast and shapnees you need to stop down 1 or even 2 ftops.
This makes all lenses usefull at f2.8 and crap from f1.2 to f2 when used in GH2.
So, if you are hungry for a shallow depth of field, to blur the background when the backgroud are near the talent, for example inside a house or office, or if you want to blur the background when shotting two or tree persons, or one person NOT in a close up, it seems the GH2 is not the best choice. Also, the T2i, T3i, 7D, 60D, D3100, D5100, D7000, Nex5, Nex7, VG20, FS100, C300, and so on would not be the best choice. Why? Because crop sensors just uses a small part of the image from a full frame lens and doing this it will amplify the softness and you will need to stop down the lens loosing its power to do shallow depth of field. All these cameras can give you a shallow depth of field at f2.8 when you shot people from chest to head and when the background is far away. But the problem to get the shallow depth of field at f2.8 is when the background is near or when you want to open the angle of view.
If you are hungry for shallow depth of field the only options would be the Full Frame cameras like the 5D and 1DX, this way you can stop down the lenses to f2.8 to avoid softness and keep the shallow depth of field because Full Frame sensors are powerfull to do this. Also you can use some lenses wide open because full frame sensors does not amplify the center of image, it will use all the image projected by the lens and it will not amplify the softness.
GH2 is 2x crop factor so I did a 50% downsize in image to simulate the lens in a full frame camera and the in some lenses widest apertures became useable. If not so useable stop down just 1 fstop solves the softness for a full frame camera. Do not need to stop down 2 fstops as in GH2.
I will list the lenses being tested and say the results for each fstop from wide open to some stop down until image be good.
More to come...
http://vimeo.com/34423217
The challenge: to use the lenses wide open to get the most shallow dof in GH2. But this makes the image soft because almost all lenses are soft wide open. So what is the solution?
Go on reading and see the video...
When you read the word "IMPROVED" in top right corner of video it means the image was graded in post-production to correct softness with these settings: sharpen 20, gamma correction 11, brightness -3, contrast 2.
Instead of Sharpen 20 you can apply Sharpen 10 plus Unsharp Mask 80 / 1,2 / 0. Of course the amount must change due to more or less softness.
I used the same post-production settings for all lenses and all fstops to get some kind of comparison.
GH2 was set to Cinema, Contrast 0, Sharpness -2, Saturation +2, Noise Reduction -2, Hacked 40Mbps, 24p 1920 x 1080.
The conclusions:
It is possible to use the lenses wide open and correct softness in post production.
Stopping down 1 fstop from the widest aperture helps a lot to avoid softness in all lenses and keeps the shallow dof almost the same.
The way to go: Stop down 1 fstop from the widest aperture and do a softness correction in post production using settings similar to described above to improve image quality.
If you can, stop down 2 fstops from the widest aperture. The image will be even better. f2.8 is a good aperture to get a decent shallow dof in GH2. So if you have a fast lens stop it down to 2.8 and try what you get.
Never let the image gets overexposed. This will make the image quality very bad, a lot more soft, dificult to correct in post production. When using a third part lens in GH2 with an adapter, set the metering to SPOT and use a 18% grey card. In this video I measured light in person face using the spot meter in GH2, but the image got overexposed 1/3 fstop. You can see when the image is correct exposed in LCD or viewfinder, you just need to train your eyes.
Lenses in this test:
The Lumix 14-42mm 3.5-5.6 is the reference lens. It is tack sharp and a nice contrast lens.
Sigma 20mm 1.8
Canon FD 24mm 1.4
Vivitar 28mm 1.9
Nikon 35mm 1.4
Olympus PenF 40mm 1.4
Minolta 45mm 2
Nikon 50mm 1.4
Nikon 55mm 1.2
Minolta 58mm 1.4
Tokina 35-70mm 2.8
Nikon 85mm 2
____
FAST LENS REVIEW - Nikon, Canon FD, Minolta, Olympus PenF, Sigma, Tokina, Vivitar
I am doing a exaustive test with many lenses and will share the results.
First impressions:
All the lenses are very soft wide open, I mean you cannot seriously use the widest aperture.
To get a good quality picture, good contrast and shapnees you need to stop down 1 or even 2 ftops.
This makes all lenses usefull at f2.8 and crap from f1.2 to f2 when used in GH2.
So, if you are hungry for a shallow depth of field, to blur the background when the backgroud are near the talent, for example inside a house or office, or if you want to blur the background when shotting two or tree persons, or one person NOT in a close up, it seems the GH2 is not the best choice. Also, the T2i, T3i, 7D, 60D, D3100, D5100, D7000, Nex5, Nex7, VG20, FS100, C300, and so on would not be the best choice. Why? Because crop sensors just uses a small part of the image from a full frame lens and doing this it will amplify the softness and you will need to stop down the lens loosing its power to do shallow depth of field. All these cameras can give you a shallow depth of field at f2.8 when you shot people from chest to head and when the background is far away. But the problem to get the shallow depth of field at f2.8 is when the background is near or when you want to open the angle of view.
If you are hungry for shallow depth of field the only options would be the Full Frame cameras like the 5D and 1DX, this way you can stop down the lenses to f2.8 to avoid softness and keep the shallow depth of field because Full Frame sensors are powerfull to do this. Also you can use some lenses wide open because full frame sensors does not amplify the center of image, it will use all the image projected by the lens and it will not amplify the softness.
GH2 is 2x crop factor so I did a 50% downsize in image to simulate the lens in a full frame camera and the in some lenses widest apertures became useable. If not so useable stop down just 1 fstop solves the softness for a full frame camera. Do not need to stop down 2 fstops as in GH2.
I will list the lenses being tested and say the results for each fstop from wide open to some stop down until image be good.
More to come...
Last edited by a moderator:
I picked up a Sigma 28mm f1.8 for £38 ($58 or so), and it's plenty sharp enough wide open (sharpness doesn't really change vs smaller apertures), and it allows some really good background separation, due to its focal length and relative speed. I honestly think it's the sweet spot for shallow dof at a reasonable field of view (not far off 50mm equiv). 
