ccaillouet
Member
I'm a video engineer who has been working in high definition since 1987. I have seen at least six generations of cameras with a variety of lenses come along before the introduction of the 1/3 inch models. Lately, I have been shooting some tests under various conditions in different formats and have noticed the following regarding sharp pictures with the HVX200. Much of it applies to any small camera. Jarred thought some of you might like to read my conclusions.
I hope this is helpful.
What have you noticed in your world?
cheers,
crc
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1) Regarding the small chip problem and aperture:
I find that i prefer the quality of the system around f4 - f5.6 because the farther open you get, the more you see chromatic aberrations, especially around the edges of the image. These show up as a red or blue fringe on edges. The diffraction limiting spoken about with 1/3 inch chips is not severe at these settings and the failure is a monochromatic softening of the image, which is the subject of this discussion in general and can be dealt with, to a certain extent. It's a balancing act to maximize sharpness and minimize artifacts, especially while trying to control depth of field. You have to decide which is more important for your application. Big screens blow up small artifacts but they also expose softness.
2) Focus:
Focus is the single biggest problem, especially at longer focal lengths. This lens is really pretty long for a 1/3 inch camera and focus can be an issue if the subject moves very much. An example is shooting animals from a distance. The low res viewfinder and LCD are limited, even with mono and EVF detail in the small one. You just have to keep checking to make sure focus is good. If you just blur one pixel into the next one, you have halved your highest resolution and it goes downhill from there, reducing detail contrast and apparent resolution.
3) Detail settings:
I usually like less detail in a camera but i find that the HVX needs detail set around "0". It is possible to shoot with a little less to minimize noise enhancement, and then to use the Unsharp Mask filter in FCP to bring it back. I use 50% at 2 pixels and a 5-10% threshold. For some reason, i found that the Luminosity check box (in the Unsharp Mask filter) needs to be off or the noise gets a little blocky. You can use variations of these settings to make some soft video "pop" a little. The bigger that you make the pixel value, the more of the "white edge" effect you may get. If you are shooting mattes, you want to minimize the Detail setting in the camera and do any sharpening after the matting process.
4) Gain:
Keep Gain at 0 to minimize noise enhancement. Detail enhancement aggravates noise. Noise uses bits in the compressor. Too few bits causes blocking artifacts to appear.
5) Record Format:
Don't bother with 1080i unless your client specifies it. The sensor arrangement and native resolution of this camera is well suited to 720P, which is also where the variable frame rates work, and the down-conversion to 720P has the effect of doing a little noise filtering in an area where there is little, if any, detail. You can shoot 1080 if you want to, but, in my opinion, it won't buy you anything except marketing advantage. And if you are shooting at 24PN, it makes a big difference in record time, AND transfer time per recorded minute. 1080i60/24P uses the same record resources as any other 1080i.
6) OIS:
Don't use the OIS unless you really need it. Use a heavier tripod. The OIS is good but it can cause small movements which can add just a little blur at normal shutter speeds. Remember, a one pixel blur can reduce the resolution by HALF and you don't need that. Also, using a wireless or wired remote will prevent bumps when recording still shots and helps when using the Pre-record feature - good for nature recording.
7) Exposure:
Work hard to use the bits that you have by using good exposure control. Unless you are looking for a special dark look, full exposure will usually work better for this camera. Sharpness is about contrast and is more important at lower resolution because the vision system is more sensitive to contrast at about 1/10 of the limiting resolution. So for most viewing distances and most scenes, good contrast at 200 lines will make a scene look sharper than limiting resolution at 1000 lines. Of course, more expensive cameras and lenses will give you more of both ends, but we are dealing with what we have available. Focus and exposure, along with lighting and subject content, determine contrast.
8) A few more words on noise:
Full exposure will also reduce the visibility of noise in the picture. Camera noise comes in different flavors. Some of the noise in the sensor does not vary with with the signal so a larger signal masks the noise while a darker signal looks noisier. The automatic gain functions in the eye/brain also kick in to pull the noise up in dark scenes. This is another reason to keep the signal higher if you can, while still getting the look that you want. Try using contrast within the scene to give the impression of darkness while keeping the eye from opening up, and to attract the eye where you want it. Also, playing with different gamma and pedestal settings can move the noise into an area that does not get amplified so much. The Normal HD gamma setting has a 4x amplification at the bottom few percent of the curve. That's how gamma works - darker signal, more gain - and the 4x limit is to keep the picture from getting even noisier. The CineLike settings have a toe that suppresses the black gain a little and might help you keep the noise down.
I hope this is helpful.
What have you noticed in your world?
cheers,
crc
--------------
1) Regarding the small chip problem and aperture:
I find that i prefer the quality of the system around f4 - f5.6 because the farther open you get, the more you see chromatic aberrations, especially around the edges of the image. These show up as a red or blue fringe on edges. The diffraction limiting spoken about with 1/3 inch chips is not severe at these settings and the failure is a monochromatic softening of the image, which is the subject of this discussion in general and can be dealt with, to a certain extent. It's a balancing act to maximize sharpness and minimize artifacts, especially while trying to control depth of field. You have to decide which is more important for your application. Big screens blow up small artifacts but they also expose softness.
2) Focus:
Focus is the single biggest problem, especially at longer focal lengths. This lens is really pretty long for a 1/3 inch camera and focus can be an issue if the subject moves very much. An example is shooting animals from a distance. The low res viewfinder and LCD are limited, even with mono and EVF detail in the small one. You just have to keep checking to make sure focus is good. If you just blur one pixel into the next one, you have halved your highest resolution and it goes downhill from there, reducing detail contrast and apparent resolution.
3) Detail settings:
I usually like less detail in a camera but i find that the HVX needs detail set around "0". It is possible to shoot with a little less to minimize noise enhancement, and then to use the Unsharp Mask filter in FCP to bring it back. I use 50% at 2 pixels and a 5-10% threshold. For some reason, i found that the Luminosity check box (in the Unsharp Mask filter) needs to be off or the noise gets a little blocky. You can use variations of these settings to make some soft video "pop" a little. The bigger that you make the pixel value, the more of the "white edge" effect you may get. If you are shooting mattes, you want to minimize the Detail setting in the camera and do any sharpening after the matting process.
4) Gain:
Keep Gain at 0 to minimize noise enhancement. Detail enhancement aggravates noise. Noise uses bits in the compressor. Too few bits causes blocking artifacts to appear.
5) Record Format:
Don't bother with 1080i unless your client specifies it. The sensor arrangement and native resolution of this camera is well suited to 720P, which is also where the variable frame rates work, and the down-conversion to 720P has the effect of doing a little noise filtering in an area where there is little, if any, detail. You can shoot 1080 if you want to, but, in my opinion, it won't buy you anything except marketing advantage. And if you are shooting at 24PN, it makes a big difference in record time, AND transfer time per recorded minute. 1080i60/24P uses the same record resources as any other 1080i.
6) OIS:
Don't use the OIS unless you really need it. Use a heavier tripod. The OIS is good but it can cause small movements which can add just a little blur at normal shutter speeds. Remember, a one pixel blur can reduce the resolution by HALF and you don't need that. Also, using a wireless or wired remote will prevent bumps when recording still shots and helps when using the Pre-record feature - good for nature recording.
7) Exposure:
Work hard to use the bits that you have by using good exposure control. Unless you are looking for a special dark look, full exposure will usually work better for this camera. Sharpness is about contrast and is more important at lower resolution because the vision system is more sensitive to contrast at about 1/10 of the limiting resolution. So for most viewing distances and most scenes, good contrast at 200 lines will make a scene look sharper than limiting resolution at 1000 lines. Of course, more expensive cameras and lenses will give you more of both ends, but we are dealing with what we have available. Focus and exposure, along with lighting and subject content, determine contrast.
8) A few more words on noise:
Full exposure will also reduce the visibility of noise in the picture. Camera noise comes in different flavors. Some of the noise in the sensor does not vary with with the signal so a larger signal masks the noise while a darker signal looks noisier. The automatic gain functions in the eye/brain also kick in to pull the noise up in dark scenes. This is another reason to keep the signal higher if you can, while still getting the look that you want. Try using contrast within the scene to give the impression of darkness while keeping the eye from opening up, and to attract the eye where you want it. Also, playing with different gamma and pedestal settings can move the noise into an area that does not get amplified so much. The Normal HD gamma setting has a 4x amplification at the bottom few percent of the curve. That's how gamma works - darker signal, more gain - and the 4x limit is to keep the picture from getting even noisier. The CineLike settings have a toe that suppresses the black gain a little and might help you keep the noise down.
