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PMW-350 Aperture Correction

After completing the multi camera shootout at Visual Impact, one thing was bothering me about the pictures from the PMW-350 and that was the way the specular highlights in the tin foil were artificially enhanced. During the test the camera was set to factory defaults, which IMHO are too sharp, but the foil in particular looked nasty. Since then I have been further refining my paint settings for the 350 and looking at detail and aperture. Today I was replicating the tin foil test and looking at the aperture settings (not the knee aperture) and I noticed that turning aperture on and off had a very pronounced effect on highlights but a much smaller effect elsewhere in the image. Normally I would expect the aperture setting to act as a high frequency boost making subtle textures more or less enhanced, which it does, but the amount of enhancement appears to vary with the brightness of the image with specular highlights getting a really big hit of correction. If you look at the images to the left at the top you have aperture correction on at +99. There are big ugly black lines around the highlights on the foil and the texture of the carpet has been enhanced. To some degree this is the expected behaviour although I am surprised by how thick the edges around the highlights are, this looks more like detail correction (it could be “ringing”). The middle images are aperture off, not zero but actually off and you can see that the edges on the foil have gone and the carpet is no longer enhanced. The bottom picture though with aperture on at -99 though is very interesting as the carpet appears slightly softer than OFF, which is not unexpected while the foils is sharper than OFF and this is not expected. I don’t like this behaviour I’m afraid to say as a typical way to get a filmic look from a video camera is to turn the detail correction off to give a natural picture and then use Aperture correction to boost high frequencies to retain a sharp image. On the PMW-350 you can’t do this as this as a high Aperture setting will give you those nasty edges on highlights. So what can you do? Well the 350′s native, un-enhanced resolution is very high anyway so it doesn’t need a lot of correction or boosting. The default Detail and Aperture settings will give some really nasty highlight edges so you need to back things off. If your going for a filmic look I would turn OFF aperture correction altogether, for video work with pictures that have some subtle enhancement I would use Aperture at around -20, certainly never higher than -15 unless you like black lines around specular highlights.

My current prefered detail, aimed at giving a very slight, not obvious enhancement are are as follows:

Detail Level -12, H-V Ratio +15, Crispening 0, Frequency +30, White Limit +30, Black Limit +40 (all other detail settings at default)

Aperture OFF for filmic look, Aperture -20 for video look.

I have also made some changes to the Matrix settings. I have been finding the pictures from Sony cameras to be a little on the Green/Yellow side so I have tweaked things a little to remove the yellow cast and put in a bit of red, this is a subtle change but really helps with skin tones, stopping on screen talent from looking ill! These settings work in the PMW-350, EX1/3 and PDW-700.

On an EX1/EX3 this works best with the Standard Matrix, On a PMW-350 or PDW-700 you can use it on it’s own or mix it with one of the preset matrices as a modifier. User Matrix On, R-G 0, R-B +5, G-R -6, G-B +8, B-R -15, B-G -9

Have Fun!

UPDATE: You can download some frame grabs from the shoot-out by clicking here.

I just spent the day shooting the same scene with 6 different file based cameras. I am working with Visual Imapact to produce a series of DVD’s containing sample clips in their native format and file structure from a range of cameras. On the set today I had the following cameras: Sony PDW-700, Sony PMW-350, Sony EX3, Panasonic HPX3700, Panasonic HPX301 and a Panasonic HVX200. We also recorded the output from the PMW-350 on a NanoFlash and this footage will also be available within the DVD set. The idea is to provide people with a way to directly compare the image quality and workflow of all these cameras, in effect, side-by side.

In order to keep things fair each camera was set to it’s factory defaults. Now I know that with careful tweaking all the camera are capable of better pictures, but it was decided the fairest test was to present them in their default settings.

The scene used in the shoot comprised of a colorful Lego train on a small circle of track, some crumpled foil to give bright specular highlights, a chamois leather for natural texture along with a couple of rose blooms. A metal bodied torch and paint brush finished off the still life. In the background there is a sharpness chart and a color chart. All this was then placed on a chroma key green fabric covered table with a chroma key blue back drop.

The scene was shot at 3 different frame sizes in 1080P25, 1080i50 and where available 720P50 and SD. The scene was shot at 0db gain and also at +6db gain. It was exposed using a 50% grey card measured with a Hamlet Microflex scope to ensure matching exposures. A slate was used at the beginning of each shot to identify the camera, the frame rate, aperture and recording mode. The Panasonic P2 cameras were used in both AVC-I modes and DVCPROHD modes. All the 2/3″ cameras used the same Canon HJ14x4.3 lens but I did in addition use the kit lens on the PMW-350 for comparison as well as an SD lens on the PDW-700. The HPX301 and EX3 used their standard lenses.

I’ll be spending the next couple of days checking the footage and compiling the DVD’s, but hope to have the full set of disks available for purchase very soon.

I’m doing a multi camera shoot out at Visual Impact tomorrow in order to put together a DVD of native clips from many of the currently available HD cameras. So far we have  the following cameras lined up for the test:

PDW-700, PMW-350, EX3, HPX-301 and HPX3700. Hopefully we will be able to include some JVC’s cameras in a future session. The idea is to compile a DVD of raw footage from all of these cameras under identical lighting situations to enable potential buyers to see for themselves the differences (or not) between the cameras and workflows. It is not going to be a “which is best” review or comparison as all the cameras have strengths and weaknesses. I’ll post details of how to get a copy of the DVD in due course.

OK, not very scientific I know, but for those that want to see how close the pictures from theses two cameras are I have shot a quick clip with each and put them in a 54mb zip file for download. The PMW-350 clip is a 35Mb/s MP4 and the PDW-700 clip is a 50Mb/s XDCAM MXF.

The cameras were both set up with similar paint settings using Hypergamma 4. The detail is backed off a bit from the factory settings on both and I used the same lens on both cameras which was the Fujinon 16×8 lens that comes with the PMW-350. The clips have not been adjusted in any way other than trimed in length, this is how they look out of the camera.

Both are remarkably similar. I can see that the 350 is more highly saturated and that you can just about make out the difference between 4:2:0 and 4:2:2. The interesting area is how the 350 handles the overexposed sky behind the trees, or rather the way the trees don’t appear to blur into the overexposure as with the PDW-700.

I have been giving a lot of thought to the PMW-350 and whether it fits in with what I do. I’m really, really torn. While I love my PDW-700 and the optical disc workflow I also really liked the PMW-350 package. Now to bring my PDW-700 up to a similar package would mean purchasing a colour viewfinder (C35W £6,500) and a new ALAC compatible HD lens (£8k +). The cost of these options is around the same price as a PMW-350 kit with lens. The 350 has a wonderful colour VF as standard and is very nice to use. It has much lower power consumption than the 700 and weighs a lot less, which would be very nice for me with all the traveling I do.

Convergent Design NanoFlash on Sony PMW-350

The downside to the PMW-350 is the 35 Mb/s data rate and the use of CMOS sensors. The 35 Mb/s issue is easy enough to get around as I have a couple of NanoFlashes which can record at higher bit rates, making the 350 suitable for HD broadcast without any issues. The CMOS sensors, for most people would not really be an issue, especially now Sony have incorporated flash band removal into the clip browser software, but for me it’s important because of the amount of lightning I shoot. Certainly I can get good results with my EX1 and EX3 but I really don’t know yet how the 350 will perform.

While thinking about all this, it occurred to me that the 350 would probably make a really good camera for Indie Films. The use of 2/3″ sensors means that it’s easier to get a reasonably shallow depth of field compared to 1/3″ or even 1/2″ cameras, without having to resort to 35mm lens adapters. The very high resolution images with very, very low noise would certainly look good projected on to a big screen. If you took the HDSDi output and record it on a NanoFlash at 100Mb/s or higher then it will grade very well. The lack of camera noise (59db) means that you can really push and pull the picture very hard during grading before it will degrade. Even if you only record at 35 Mb/s this low noise floor is going to help with grading as less noise means less stress on the codec in the first place. On top of all that the supurb sensitivity means that you will be able to use very minimal lighting rigs, perhaps just using practicals to light a scene, which should really give you more scope in your composition.

Further PMW-350 advantages include the use of Sony’s Hypergammas, step gamma and multi-matrix. These settings are normally only found right at the high end of the product range and give you excellent control of the look of your images. Add to that 24P (23.98P) and the ability to overcrank and undercrank and it all adds up to an extremely capable camera.

So, will I be getting a PMW-350? Well if I didn’t have my PDW-700 I would certainly be getting a 350. At the moment I’m still undecided….. if only I could work out a way to afford both.

OK, here’s my take on the situation.

If money is no problem then the safest bet is to purchase a good quality HD lens, expect to spend at least £8k.

If you budget is restricted then the situation is much less clear. There are now several low cost 2/3″ HD lenses designed for cameras such as the Panasonic HPX500. In my opinion these lenses are just not worth the money. They might be cheap (£4k ish) but the one’s I’ve played with have been pretty grim, suffering from lots of CA and soft corners.

If your on a tight budget the best thing you can do is take your camera to a good dealer and go through their second hand lenses, trying them on the camera. Check for resolution (use a chart), corner softness, CA and contrast. I did this and ended up with a Canon 16x8x2 IF lens. I found that lenses with lower zoom ratios tended to be better than those with higher ratios. I’m really pleased with my lens and when compared to the latest HD equivalents I can not tell the difference in real world use. It certainly outperforms all the budget HD lenses I’ve tried.

One interesting thing that I have discovered in my research into this subject is that Contrast is what makes the biggest difference in lens performance, not simply resolution as one might expect. Visually the next thing you notice is CA. This is a tough one as when you increase the resolution or sharpness of a lens you also tend to increase the CA.

Until lens manufacturers start to release MTF curves for their lenses the only thing we have as buyers to go on is the advertising blurb. It’s easy for a manufacturer to claim improved performance or new glass or other technology, but without accurate MTF curves it’s all pretty meaningless. You would only need the tiniest resolution improvement to be able to claim that you new HD lens range is sharper than your SD range, it could just be a fraction of a percent difference.

I’m off to Arizona on Thursday for a long weekend to shoot the monsoon thunderstorms. I had postponed this trip from earlier in the month when the weather just wasn’t right. This tim around the forecast is really good (for storms that is). I will be shooting with my PDW-700 and my EX1. I will also be giving the Nanoflash a shake down making good use of the cache function to capture what I hope will be some great lightning storms.
Anyone want to join me? I have a couple of spare seats in the car and motel rooms are peanuts.

The PDW-700 cameras are balanced for daylight optically and then corrected electronically for tungsten etc.

Traditionally cameras were balanced for Tungsten and then added colour correction optical filters to get to daylight. This was done as CC filters absorb light and thus make the camera less sensitive. Normally when shooting outdoors in daylight sensitivity is not an issue while shooting indoors under tungsten light you used to need every bit of sensitivity you could get.

The down side to this approach is that tungsten contains very little blue light so to get a natural picture the blue channel was often running at quite a high level of gain which increases noise in the blue channel and thus overall noise. In addition when you rotated in the CC filters to get to daylight the sensitivity of the camera was reduced, so you did not have constant gain.

With the PDW-700 (and also the F350 I believe) the cameras are essentially balanced for daylight, without the use of any CC filters, which helps reduce noise in the blue channel. Then for tungsten shooting you electronically re balance the camera. By doing this the overall sensitivity of the camera is constant whether shooting at 3.2K or 5.6K and you only get additional blue channel noise while shooting under tungsten. If you are worried by blue channel noise you can always correct from daylight down to tungsten with an optical CC filter (80A) and leave the camera set to daylight, although this will reduce the systems overall sensitivity by around 1 and a half stops.

Last weekend was the Royal International Air Tattoo. The largest military air show in the world. I’ve filmed this event many times and every year we try to do things a little differently to jazz things up. We have been shooting the show in HD for the past 3 years, this year it was entirely XDCAM with the exception of the minicams which were HXR-MC1P HD minicams. We had an EX1, EX3 and 3x PDW-700′s. As well as the usual extra long telephoto lenses we had a couple of gyro stabilized lenses including a schwem gyrozoom. While not an HD lens we found that the performance of the lens wasn’t too bad. There is no other lens that offers the degree of stabilization offered by the schwem so for the applications we were using it for we were happy to accept the slight softness in the corners. The application we had was to use it in one of the “Follow Me” vehicles used to marshall the aircraft around the airbase. The high point of this was doing a tracking shot of the recently restored Vulcan bomber landing at Fairford. To do this we drove along the taxiway parallel to the runway at high speed as the Vulcan came into land. Once it had landed we got some impressive shots as it taxied right behind us. The Vulcan is a huge aircraft and to have this bearing down on you as it taxies with all four engines running (they normally use only 2) is quite a rush! The Schewm is a long lens so the Vulcan completely filled the frame, despite this the gyro stabilisation kept the images rock steady. Over the weekend I shot aircraft startups and GV’s using an EX3, then the follow me stuff with the schwem and PDW-70 as well as flying and display footage using a PDW-700 and 42x Fujinon lens. The most reassuring thing is that as these are all XDCAM cameras we know they will all cut together well in the final edit.

The PDW-700 and F800′s are sold body only, so you have to choose which viewfinder you want. there are 3 choices. A cheap HDVF 200 mono CRT finder that is 480+ lines resolution, the mid range (top of the CRT range) HDVF-20A which is 500+ lines resolution and then there is the expensive colour HDVF-C35W.
I got the HDVF-20A. The viewfinder is a critical part of the package and I wanted a good viewfinder. For the past year my main camera has been my trusty EX3 which I love. This has a really good colour viewfinder with an excellent colour peaking function and image magnification. When I use my EX3 it is rare for me to not get my pictures pin sharp and spot on in focus. Plus I can frame my image taking into account both black and white contrast range and colour contrast. With the EX3 judging exposure is easy, you can see when your overexposing as you can see colours washing out. If I don’t want (or can’t) take a colour monitor on location then I really can light an interview or check colour balance without just using the EX3′s finder.
Now with the PDW-700 I am struggling. Going back to a mono CRT has been a bit of a shock, to be honest I am struggling with it. It’s not that there is anything wrong with the HDVF-20A but I have become used to working with a colour VF. I’m not sure I can live with the CRT VF for very long. I guess I am going to have to start saving my pennies as I think going back to a mono CRT is a retrograde step. I just wish the C35W was a little cheaper. Perhaps Sony could bring out a VF for the 700/F800 based on the rather good EX3 finder.
If I was making the purchase again I would opt for the more expensive C35W. I no longer see a colour VF as a luxury but more of an essential item. When you work with cameras day in – day out you want the tools that make your life as easy as possible and a good colour VF is one of them. On it’s own the C35W may seem expensive at £5.5k compared to the £3.5k of the 20A, but in terms of the total packing it’s another 10% to the cost but in retrospect I think it would have been worth it.