Jump to content


  • Posts

  • Joined

  • Last visited

Posts posted by dr_jon

  1. Is this really the issue though, or does the CPU (presumably a SoC in reality) never get so unhappy it needs a heatsink (and they can run at 70C case temperature, 100C internally, probably way more than assorted other components in the camera body). (BTW 45C and above is not something you want to touch.)

    As there are YouTube videos showing you can record 4k HQ for 4 hours to an external recorder provided no cards are in the camera that suggests the issue is:
    (1) The super-whizzy cards get too hot and aren't rated to record reliably when hot, so the camera stops trying to record
    (2) The SoC gets a lot hotter when doing H.265 compression
    (3) Both

    Someone needs to record 4k HQ to a fast SD UHS II card with the other slot empty, IMHO...

  2. I don't know about 2.8k upscaled but I have seen "3480 to 3840" upscaling mentioned, which is a 10% stretch. Also the maths works great, as it's every other pixel.

    So I suspect they read all the pixels (as hard not to along a line) and scale them, they could read every other line but that would break bayer, so possibly the approach is that they read the whole (16:9 crop of the) sensor and just do the simplest scaling option of using 2x2 bayer blocks to make pixels and upscaling by 10-ish% to give 4k.

    Note the 16:9 crop is 6960 x 3904, making 2x2 pixels gives 3480 x 1952, which is about 10% off 3840 x 2160.

    Plus the sensor/processor combination in the M6II can do 30fps 18MP Raws with AF/AE until it runs out of buffer, so reading the whole 16:9 area at 30fps is certainly within the realm, or trivial if some video processing is done on-sensor, as is quite common (the 16:9 crop being 50% more pixels than 18MP).


  3. On 1/4/2019 at 11:44 PM, Kangaroo said:


    I'm currently using a 6d for both photo and video, nothing professional and I've found a very good deal on Gh3. The 6d would still be used for photos because it's all I need but the videos always feels a bit too mushy, I like the color and the FF look but in the last few years I've seen so many videos from other cameras that I would really love to have a clean and crisp image. I was considering the gx85 but I'll be shooting only 1080p and the gh3 should be better in this regard. So I was wondering if the gap would be actually huge or if it would just be a minor upgrade. I've seen a few samples from a guy on yt that is still using the gh3 and to me it's pretty amazing but maybe I should just work more with the camera that I have. 

    Also, the pre amp on the gh3 should be much better right? 

    I haven't read all 4 pages of replies, but have owned GH3, GH4, GH5 and 5D2 plus 5Dsr.

    What I will say about 1080p on the GH3 is it doesn't use all the pixels (it skips a bunch) which can lead to quite bad aliasing/moire on subjects that lead to that (the 5Dsr is actually a lot better and really doesn't do aliasing that I can detect). I would be tempted to look for deals on the Panasonic G80/85 (number depends on where you are in the World, it's the same camera, note G not GX) with the 12-60 kit lens (plus check you are happy with the viewfinder when panning).

    Another option if you have Canon glass is the EOS M50, which does a nice 1080p with Dual-Pixel AF (the 4k isn't as good) and can take your Canon lenses with an adaptor (which is sometimes thrown in).

  4. On 1/10/2019 at 11:07 PM, FoxAdriano said:

    Hello, the next months I will go to make a short documentary in the Coptic churches with poor light.The churches at night lit up little more than with candlelight of many faithful. Can anyone advise me how to configure the GH5 to get a good video inside the churches? I have the Leica 12-60mm f / 2.8 lens.
    Outside I want to film in 50p but maybe inside it would be better to film in 25p to get more light. Quite right? Thank you.

    Firstly if using the 12-60 Leica you'd want to keep to the wide end as the aperture falls rapidly...
    2.8 - 12mm up to...
    2.9 - 13mm
    3.0 - 15mm
    3.1 - 16mm
    3.2 - 18mm
    3.3 - 20mm
    3.4 - 23mm (tested twice)
    3.5 - 24mm (tested twice)
    3.6 - 27mm
    3.7 - 29mm
    3.8 - 32mm
    3.9 - 36mm
    4.0 - 52mm

    A brighter lens would be good but you need to check you get the DoF as it's no use if you don't have enough stuff in focus.

    Also you can try a longer exposure. Rather than 180 degrees (so 1/50th for 25fps) try shooting up to 360 degrees (i.e. 1/25th) if really dark. Note not so good with much movement or panning. Oh and yes, 25 fps not 50.

    I like to shoot in VLogL (which is a paid-for upgrade and needs practising before using, also setting a viewfinder LUT which is a built-in option) when it's dark as it gives me the most flexibility on setting the light level I want in editing and not falling off a cliff, but that's for when I don't want a "standard exposure" but want the scene to look somewhat dark. The in-viewfinder histogram can be useful (once moved to a corner).

    If you want a zoom and don't mind manual focus you could consider using a f2.8 FF lens with a SpeedBooster, if you can rent them from somewhere (e.g. 16-35). Or just rent/buy a f1.2 (or faster) m43 lens. However you might find a Panasonic lens with OIS that supports Dual-IS2 is really useful (I tend to do that when hand-holding over a slightly faster lens with less good stabilisation).

    Do note that wanting a dark scene to look somewhat dark, rather than fully lit, will help with noise etc.

    Hope something there helps!


  5. 20 hours ago, jonpais said:

    Not necessarily. The Canon EF 50mm f/1.2L USM has a T stop of 1.5. Likewise the Canon EF 85mm f/1.2L II USM.


    This really depends on the sensor and how well it copes with light coming in at very wide-angles. They are T1.3 with film. With the lower angles from the RF mount they should be somewhere in-between film and EF sensors.

    1 hour ago, mercer said:

    The fact of the matter is this... 95% of the people who will buy this camera are still shooters. If they shoot any video, it will be 1080p and they’ll use iMovie to edit it.

    Half of the remaining 5% will be vloggers and only half of them will shoot in 4K.

    The remaining 2.5% are video enthusiasts that shoot family videos or clips documenting their hobby and only half of them will shoot in 4K.

    But for a fair guesstimate let’s overestimate and say 5% or less  of the actual customers will shoot in 4K.

    I fit square in the middle of video hobbyist/enthusiast and if I ever buy the camera, I would guess I’ll shoot 75% of my stuff in 1080p.

    So yes, the 4K Crop sucks, nobody is denying that, but as a company, Canon understands their market and when you honestly look at the market, no wonder Canon is number 1.

    Surely all Canon need to do is make a fourth EF-RF adaptor that has Speed-Booster style optics for 4k. They could label it as a Cinema lens thingy to avoid confusing people. If the adaptor electronics is pass-thought I'd assume metabones and the others will have devices really rather soon.

  6. On 07/06/2017 at 0:08 AM, BTM_Pix said:

    If you could find a GH4 that hasn't been upgraded then what I would be tempted to try is do the initial octopus boot up sequence and then go to the ROM backup menu that appears when you do this and do the backup to SD function.

    Then get your updated GH4 and do the same and back its ROM up to SD.

    These are plain text files though ideally you would open them both in a hex editor and do a compare between the old one and your upgraded one.

    There might be a clue in there as to how you could do something that would allow the old firmware to be put on the GH4 with the newer one.....

    Please note that I'm not in any way telling you to be brave and just go into the ROM backup menu and then load the file from the older version onto the GH4.

    Its precisely the sort of reckless thing I would do of course ;)

    As an aside I have a fairly early GH4 and when I sent it in for the Audio fix (which wasn't, BTW) they just changed the main board and I got it back with an earlier firmware version than it had when I sent it off (which had been 2.3)...

    P.S. I should say I don't think VLogL is a good idea with internal recording (I like CineD BTW), as it only uses 160 levels so you tend to get posterisation on areas of flat colour, like the sky for example. Presumably external recording won't help if you don't have 10-bit output.

  7. I struggle to see how splitting the Micro Four Thirds cameras off from the Professional Video Division (which seems an ideal fit, except the latter is profitable and the former not-so-much) and making people redundant is quite such a positive as they are trying to spin it... It will be interesting to see what happens, but IMHO "redoubled" seems like marketing spin to keep people buying the products. Not that I'm suggesting cameras are doomed, but I think the ILCs will get trimmed somewhat along the way...

  8. I have a suggestion for how you might do a 6k photo mode... if You're using an anamorphic lens maybe it can extract stills from video and stretch them horizontally to make a "correct" picture with the same image height.

  9. Quite interestingly LensRentals say the metabones products are not reliable enough for professional use...
    "The Metabones adapters give a tempting promise of being able to use the larger Canon, Nikon, and Sony A- mount on smaller mounts like the micro 4/3 and Sony E-mount. Many times they work and provide aperture control and support image stabilization, but we have routine problems with these adapters that can be quite frustrating. The most common being a loss or lack of electronic connection between lens and camera, sometimes creating errors and freezing in the camera. The adapters also regularly have screws coming loose and other functional issues. We state a warning to customers on the individual product pages discouraging against relying on the adapter for the success of the shoot."


  10. 53 minutes ago, Nathan Gabriel said:

    I'm just wondering about your chart because I don't understand these things at all. Is the diffraction inherent in the optics out is it possible some new sensor technology can give better results?

    Diffraction is an inherent property of light passing through an aperture. What you end up with is each part of the light turns into an Airy Disc with particular physical properties. The diameter of the disc only depends on the f-stop, nothing else. Hence the smaller the pixels the more of an issue it is. This is worth a read and includes a calculator (just ignore the camera section in the lower half):
    (Astronomers are even more interested, as stars, being point light sources, really show the effect.)

    Generally (IMHO) diffraction blurring starts to become an issue at the pixel level when it hits two pixel widths and gets worse at three widths. Exactly how bad it is depends on stuff like the strength of the anti-aliasing filter (if any) and how much blurring the de-bayering algorithm adds (which is always some). It isn't a hard limit, it's always there and just gets worse, so people have to define the point they start to care about it, which varies somewhat depending on who you read. For still photography it has been taken, for a fair while now, that a 30um blur on a FF sensor (divide by crop factor for others) is the limit for good sharpness of uncropped still images (which comes from lots of perceptual testing of people and a bunch of assumptions, like using 8"x10" images at a particular viewing distance). At the pixel level the 2-3 pixel widths seems to be where people are. I personally think if you are at 2 pixels or less you can ignore diffraction effects at the pixel level (compared to other factors).

    (Edit) P.S. reverse engineering the graph on the previous page gives about 4.4um as the diffraction limit for f8 (10.7um Airy disc), which is 2.43 pixels and 5.8um for f11 (14.7um Airy disc), which is 2.53 pixels, so I suspect they used 2.5 pixels as their limit. It doesn't magically get really bad at this point, just gradually worse.

    P.P.S. Also remember as you move away from the plane of focus the image gets gradually blurrier, this is where the 30um value is most often used, as the limits of the depth of field. Diffraction softening just adds to this.


  11. 1 hour ago, berkenboom said:

    8MP is 4k indeed. But if Panasonic wants to do 6k readout, or even 8k(~34MP) in the future,the diffraction starts at f4.5, which is limited.
    Though looking at the chart again the diffraction is less than I expected, my bad.


    Hey, I swapped f2.8 and f1.4 in one of my posts (although no-one noticed, not that it stopped me going "Duh!" as I spotted it just outside the edit window), so I think I beat you ;-)

    Here you go, for people to read and laugh at my ability to go from brain to keyboard...

    "Not really, the light per unit area (which is what the f-stop is) will be 2 stops less, but there is 4x (i.e. 2 stops) the area at that illumination level, so the amount of light captured to make the image is the same between the f2.8 on m43 and f1.4 on FF. Also the noise in the light depends on the amount of light you capture, so will also be the same."

  12. 56 minutes ago, araucaria said:


    58 minutes ago, k-robert said:


    1,4 ≠ 2,8

    Photography is a lot more than DoF...


    But they are. A FF f2.8 lens will capture the same amount of light over the image as a m43 f1.4 lens (both wide-open). That also means you get the same shot noise (which is most of the noise in the image). You need to increase the ISO on the FF camera by 2 stops to get the same exposure. However that doesn't affect the noise as (i) most of the noise is in the light and changing the ISO won't change that and (ii) the sensor read noise will usually fall a bit with increasing ISO, so the total noise will be lower if anything. (Think of it this way... at the same illumination level if a f1.4 lens puts 1M photons onto a m43 sensor then a f2.8 lens will put 1M photons onto a FF sensor. Of those photons on average 1,000 will be the shot noise, in both cases.)

    Increasing the ISO isn't a problem as the FF sensor will be able to capture around 4x the electrons of the m43 sensor due to its greater size. Increasing ISO by two stops knocks about a factor of 4 off that so it will be about the same as the m43 sensor and not saturate if the m43 sensor doesn't.

    Also remember a 50mm f2.8 lens has the same diameter entrance pupil as a 25mm f1.4 lens (17.86mm) so the DoF will be the same at the widest aperture. The FoV will also be the same. Diffraction softening will also occur at the same DoF (it goes with DoF, regardless of format). Hence the minimum and maximum amounts of available DoF are the same.

  13. 19 minutes ago, berkenboom said:

    Here is a graph a made once on the left there is the pixel size.
    the dotted lines are the f numbers.
    10 um doest leave much room for sharpness (less then 2MP for m43)


    Am I reading this incorrectly? It seems to agree with me to a decent approximation. The f8 and m43 lines intersect at about 13MP, which is about the 8MP (in a 16:9 crop) needed for 4k.

  14. 10 minutes ago, berkenboom said:

    I agree that Super 35mm/APS-C is the way to go for 6/8K. Diffraction would kill the sharpness if Panasonic would stay at 4/3.

    But for me the real question is: will the Super 35mm have a 4:3 aspect ratio, or a more video friendly 3:2 ratio?

    If you're delivering a 4k image, as the article suggested (downscaling 6k, not producing 6k) diffraction isn't that much of a problem. At f8 (so equivalent to f16 DoF on FF - that's plenty, yes?) the blur caused by diffraction will be 10.7um diameter (regardless of format, plus generally, although not evenly, declining towards the edges). This will begin to get noticeable at pixel sizes under about 5.35um, but will only increase slowly (it'll be worse under 3.5um). Taking 4k from a 17.3mm wide (m43) sensor means each video pixel is effectively 4.2um wide. You'll see some diffraction softening, but not much - and that's with a lot of DoF. (You get more softening from debayering the sensor than minor amounts of diffraction.)

  15. 4 hours ago, TheRenaissanceMan said:

    No, a 50mm f/2.8 will be two stops darker than a 25mm f/1.4. Same depth of field, but that's it. 


    Not really, the light per unit area (which is what the f-stop is) will be 2 stops less, but there is 4x (i.e. 2 stops) the area at that illumination level, so the amount of light captured to make the image is the same between the f2.8 on m43 and f1.4 on FF. Also the noise in the light depends on the amount of light you capture, so will also be the same.

  16. 2 hours ago, Andrew Reid said:


    This thread has been an interesting marketing lesson for Panasonic!

    It shows that if they put an over-sized sensor in there then the perception will be that they are dumping Micro Four Thirds standard, even if per my article (which nobody read) they are actually keeping it.

    Panasonic are in a perfect place to introduce two lens line-ups to one camera system.

    A dual 2x crop and 1.5x crop system. Small portable M43 lenses and larger coverage S35 glass.

    If not then we can just sit here and watch Micro Four Thirds die in a market place where you can buy a full frame camera for under $900 with lenses as small as the FE 55mm.

    Also the RX1R II's optics matched with sensor proves that full frame does not automatically mean massive lenses. The lens on that camera is smaller than most Micro Four Thirds primes.

    The fact is it is the 2x crop which hurts the GH4 most on the market where it competes with full frame and APS-C Sony cameras, also it is sold into a filmmaking would where 2x crop is a compete NON-STANDARD and Super 35mm is a match for APS-C. Sorry but that makes no sense, Panasonic.

    I'm afraid I struggle to see the business case here. Panasonic aren't doing that well selling cameras (in Japan they are now selling less mirrorless than Canon) and new lenses just trickle out. I doubt anyone inside Panasonic sees throwing lots of money into an all-new camera system as likely to be a winner, especially in a generally declining market. I think they only sell a decent number of GH4s as it offers a lot for the money and is stills and video. No way will videographer sales (if they effectively ditch the stills side by only having 8MP with m43 lenses) get them back that money at similar prices on a new format. I think if they go to a different sensor size they will have to use 3rd party lenses (developing their own being an unlikely investment), so whose mount would be possible - Canon EF maybe using the V35 sensor (4096x2160)? Won't be any good for stills. Plus sounds tricky to avoid damaging higher-margin V35 LT sales... I can't see it. To do your suggestion at a minimum they'll need someone else to have designed a sensor just for this camera and to be happy about low sales volumes for that sensor (which usually means prices that drive 5-figure camera pricing, so they've pretty much just designed the V35 LT again).

    P.S. I read your whole article before coming to the forum for my first post on the subject.

  17. 1 hour ago, Jaime Valles said:

    So... are you saying a GH5 with a Micro 4/3 sensor can't have better ISO performance than a GH4? :)

    It's a tricky one. They can improve the DR by lowering the read noise and 3.1 electrons is a fair bit these days. To reduce the shot noise they need to capture more Photons, but the lens f-ratio controls how many fall on the sensor - same lens, same number of Photons. You can improve the Quantum Efficiency, but 58% is really good. You can weaken the colour filters to let a bit more of other colours through. However if you make more electrons you need to make a bigger pixel to store them, which gets harder for the same surface area. I can see them improving the DR (but I don't think they will, as they will want 50p/60p which mean running it faster, which means more noise, so other improvements will get eaten up), but I think for overall noise all they can do is what people have mostly been doing, which is implement ever cleverer noise reduction in their processor. It's doable, but I don't think it'll get you to where Neat Video can get you now. Just my opinion though. Well, except the physics bits.

    (Edit) Should have said, they can maybe improve the DR a bit if they use the Arri/Canon way of splitting the pixels up, although I suspect that would run into a lot of patents.

  18. 33 minutes ago, cantsin said:

    Thinking about it more: It would make a lot of sense for Panasonic to introduce a Full Frame camera with an 8K sensor and 8K video recording. 8K is about to become standard in Japan anyway, and such a camera would give Panasonic the same competitive edge with higher video resolution on a consumer mirrorless camera as the GH4 did when it was introduced. Panasonic could make MFT lenses fully adaptable to the full frame camera and offer 4K recording in MFT crop mode. Since MFT has exactly 50% horizontal coverage of full frame, this would result in a clean 4K image.

    Provided someone designed a 32MP FFs sensor that is fast enough to shoot 8k video (which is very fast indeed). I find it hard to see how they would make their money back as lots of the people shooting 8k are also the people using cine lenses that generally don't have an FF image circle. Sony might, but it would be hard to keep cool.

    12 minutes ago, Jaime Valles said:

    Sensor size is not the only factor that determines noise in the image. The GH4 has a smaller sensor than the GH2, yet it has better performance at the same ISO. ISO 3200 is only 2 stops higher sensitivity than ISO 800. I don't think it's unreasonable to expect better ISO performance from the GH5 using a Micro 4/3 sensor.

    Also, I forgot to add to my list that I want the GH5 should have 5-axis in-built image stabilizer, as long as the camera doesn't overheat like the Sony cameras. I need to be able to shoot continuous footage (not limited to 30 minutes) so if IBIS causes short record times then no thanks.

    At ISO 800 a GH4 pixel can hold 5091 electrons and has a read noise of 3.1 electrons. That means the noise in the light will exceed the read noise once you get to about 17 electrons (it's 56% efficient converting photons to electrons and the noise in light is the square root of the number of photons). So anytime the pixel is much more than 3.3% illuminated the sensor read noise isn't that big a thing. For example at 10% illumination (509 electrons) you have on average 17 electrons of noise and the rest is signal. Even if you go from 3.1 electrons of read noise to 0.5 it isn't making a significant difference (btw noise combines as less than straight addition).

  19. 1 minute ago, Jaime Valles said:

    No, no, no. I don't want a Super 35 sensor in a GH5. I REALY LIKE the Micro 4/3 size sensor. It makes focusing easier than S35, yet still has enough shallow depth of field to look cinematic. I don't care for Speedboosters. I love using my Voigtlander and Lumix lenses on my GH4, and would want the GH5 to shoot on a 5K or 6K m4/3 sensor downsampled to 4K in camera. 10-bit 4:2:2 internal 4K would be an incredible way for the GH5 to separate itself from everything else in the market.

    I don't want to use S35 or FF lenses. I WANT my lenses to remain small. I want my whole kit to remain small. There are tons of other cameras out there right now that use S35 or FF sensors. I don't want to pay for a large sensor if I'm just going to use a 4K crop from it because of all my m4/3 lenses. If you want S35 or FF, buy a different camera. Get the Sony A6300 or something else. Leave the GH series Micro 4/3 sensor, because there are a lot of us that find it the perfect size sensor.


    What I want in a GH5 (in order of importance to me):

    • Micro 4/3 sensor
    • Internal 10-bit 4:2:2 4K
    • ISO 3200 as good as the current ISO 800 of the GH4
    • 4K 60p
    • No lag on the HDMI output
    • V-Log included
    • Keep the same style body & battery so all GH4 accessories work

    I can't see you getting ISO 3200 as good as the GH4's 800 unless it's by more noise reduction, as it's a sensor area issue, most of the noise coming in with the light rather than being due to the sensor. I don't know if you'll get 10-bit but it's a definite maybe. I think the rest looks likely. I'd also like FHD modes that don't skip 30% of the pixels, so the aliasing/moire goes away. I suspect they will try to be close to the Ultra HD Blu-ray spec, including gamut.

  • Create New...