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Jay Turberville

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  1. Somethng worth thinking about with raw from a CFA sensor is that while the demosaiced files may well be 4:4:4, the data contained within is not that good. Every four pixels only gets one red, one blue and two green pixels. So for green screen work the real data density is pretty similar to 4:2:2. (I say "similar' because the green in your screen isn't an exact match for the green filter on the sensor pixels - also, I think the green filters on the sensor pixels of CFA sensors tend to be fairly broad spectrum and more green/yellow - though that may vary from camera to camera.) If you use a b
  2. Yes. That's exactly the way I was using the term "sensor." My point is/was that 4/3s and m4/3s cameras are different. The SSWF on 4/3s and m4/3s camera is a very thin membrane or piece of glass that sits above the sensor. There's an air gap between the sensor/filter sandwich (aka "sensor") and the SSWF with no physical support.between. This is what allows that surface to vibrate effectively at the high frequencies that will pop dust off of the surface. Furthermore, I think the actual mounting of the SSWF isn't particularly robust either. So I suggest looking into the manufacturer recom
  3. Keep in mind that you can't clean the sensor on a GH4. You can only clean the SSWF that sits in front of the sensor. I believe that this is a very thin item and I recommend being very careful with it. You might want to investigate further and get more detailed info. I've had 4/3s or m4/3s cameras for quite a few years now and have never tried cleaning the SSWF. As a practical matter debri that the SSWF can't dislodge has always been insignificant at practical apertures (f/11 and below IMO).
  4. Part of the reason is that you have to establish some standard threshold for noise in the darker tones. And this threshold is somewhat subjective. I did a lot of DR testing using Imatest and the software gave multiple results for different noise thresholds. It is up to the user to decide which threshold is appropriate. This is one reason why you should be VERY careful about drawing conclusions about DR when the results come from different sources. One of the big values of DxO testing is that the testing schemes are very consistent. But as mentioned previously, those results can only be c
  5. Right - unless the previous firmware was significantly faulty. S-Log shouldn't affect DR results either. What can affect results is noise reduction because it lowers the apparent noise threshold in the darker tones. But that is misleading since it reduces resolution/detail as well.
  6. The lugs for the strap rattle far more noticablely than the the lens. As for the original usability question, I just mouned it to the GH4 and: 1) No AFC. AFS only. 2) AFS is not very fast. The lens hunts back and forth and finally settles in. For the most part I'd consider this to be a manual focus lens on the GH4.
  7. OK. I'm confused. First the camera is too crisp, then the camera forces you to shoot wide open resulting in images that show all the flaws of the fast lenses that you are using. In other words, the image is too flawed/fuzzy. So which is it? Too crisp, or too fuzzy? From where I sit is seems like you have more of an issue with lens selection than anything else. Theyve been complaining about the 4/3s sensors having less DoF vs. full frame sensors for years now in the stills community. Bottom line is that 4/3s simply generally has less DoF range (less true now with affordable focal len
  8. Yes, the rattling is from the IS element - though on my lens it is a very dull and hard to notice rattle. When the camera is on and IS is enable there is no rattling. For a GH4, the lens is rather large. This is partly because it is moderately fast for this range, but I'd bet mostly because it was designed for the backfocus of a 4/3s camera. I suspect that a made for m4/3 lens of similar focal and aperture range would be significantly smaller. Optically the lens has an excellent reputation. I like mine a lot. I've read other videographers who hold this lens in moderately high regard
  9. No, you can trade resolution for levels of tonal gradation. The simple proof of this is in every B&W halftone image you've ever seen printed. And actually, that's true for every B&W photo as well. A B&W negative is fundamentally not continuous tone, but instead is a fine distribution of opaque silver clumps and clear emulsion. The appearance of tonal gradation comes from the size and distribution density of the film grain. The same is true for prints except that there is an opaque base underneath the emulsion. Saying that "all that's going to happen is a low pass filter filt
  10. That might be logical if you are going to display the image at the same final per pixel magnification and view it from the same distance. In other words, if you were going to display it at twice the width and height of the 1080p image. But we know that's not how videos/movies are typically viewed. So no, it really isn't logical. The practical reality is that an image with higher pixel count can tolerate more compression because each pixel and the resulting artifacts from noise and compression is visually smaller. If we want to get into pixel peeping, we need to consider question of the
  11. You must set the camera frequency to 24hz and then restart the camera. It will then output a 24hz HDMI signal. I just did this yesterday. My Vizio TV would not play the signal. It simply reported a non supported signal. Our larger Samsun plasma screen played the video back fine and also showed 1080p 24hz on the display for a few moments once communications were established.
  12. My second edit system is a six core AMD with a fairly low end GPU. I think has something like 130 Cuda cores. That machine plays the clip fine in Adobe Premiere 5.0. But I've got Premiere "hacked" (not much of a hack really) to use the Cuda cores on the non-approved card and this seems to be enough to let the clip be played back OK. Keep in mind that when playing 4K 24p files you are dealing with a number of possibilities. 1) If your display is less than 4K, then a very large image must be re-scaled 24 times a second and get rescaled. Cuda cores are great for that, but if your player
  13. No need to justify your preference for 24 fps. Many agree with you. I only bring it up because I'm particularly bothered by judder and it isn't bothering me in you clip. I just don't see it. I am bothered by the "shaky cam" a bit. But I'm not seeing anything like the "judder" we often see in 24 fps pans. I'll play your clip on a larger monitor this weekend and see if that makes a difference in what I perceive. What I do notice with the GH4 at 30 or 24 fps is that the rolling shutter effect is more pronounced - which I also don't like.
  14. There isn't much panning in your shot and hence not much there to cause juddering. When I play that clip on a Premiere timeline, it seems just fine to me - and I happen to be one of those guys who dislikes judder and have been critical of the look given by 24fps that so many film makers seem so happy with. I find it distracting. My guess is that your display was dropping frames. What did you use to play back the video?
  15. In fact, it is more than just an 8MP moving image. In 4K mode, the effective sensor size is reduced ("crop factor" is changed). That changes the FoV and perhaps for him the usability/desirability of a 14mm lens. BTW, some wide angle adapters that were designed for use on higher end compact digitals work quite well on some micro 4/3s lenses. My WC E68 Nikon adapter works very nicely on my 14-42mm MSC II Olympus lens that I modified to accept 52mm filters. It becomes a 9.5mm - 28.5mm lens with the addition (the adapter works vignette free through the entire zoom range. Image quality seem
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