Camcorders: An unplanned change from Sony FDR-AX53 to Panasonic HC-VXF1

After using my Sony AX33 for several years in the wild, I was frustrated by the limited focal length compared with the later model, the AX53. After putting off a decision in the expectation that Sony would soon replace the AX53 (first on sale in 2016) I finally bought, from Amazon, the AX53 in May, a few weeks before a long trip. I was very pleased, as with the AX33, with the video quality. However, the longer maximum focal length came with what seemed to be more movement of the optical stabilisation system (BOSS) before settling down and a difference in the way the autofocus seemed to operate. Objects in the centre of the viewfinder only a little darker than the surroundings were sometimes ignored while higher contrast objects in the background were brought into focus; this was particularly evident in low light, but not exclusively so. The old annoyance of the electronic viewfinder in the AX33 was still there—no control over brightness. However, no camera is perfect for every job thrown at it and it did a very good job in terms of quality of output, on land, sea and air.

A fellow traveller had a new Panasonic camcorder (VXF1) and asked me to take some footage with her in it. The controls were virtually identical but I was impressed by the ergonomics of the viewfinder display, the speed and accuracy of autofocus and the stabilisation. Overall, I liked its handling a little more than my Sony.

After I had edited and stored the footage, I was clearing the cards when suddenly the Sony failed to start up. A camcorder logo appeared on the screen and I could hear the  sound of a motor near the front but then nothing. I did all the usual checks (battery out for half an hour, tried the mains adapter etc) but still nothing. The camcorder was dead—an ex-camcorder. Having struggled to find what to do with a broken-down Sony camcorder still within warranty, I decided to contact Amazon support. After a quick web-chat, the excellent assistant realised that it was a hardware failure and within minutes had sent me labels for it to be picked up by courier the next day for a full refund (it was outside the period for a normal return). The offending AX53 was soon back in its box and on its way.

Thinking back this was my second camcorder to die. The first was an early 1990s Sony Hi8. With that one I was lucky. I had just used it to play the last of my stored Hi8 video tapes onto a dvd, I think it was, via a PC, when it too refused to start. That was in the days when there were were magazines dedicated to camcorders and pages and pages dealing with the then common hardware failures.

How was I going to replace the Sony AX53; like-for-like or go for something different? Remembering the Panasonic VXF1, I started to look up reviews. However, I found surprisingly few. Camcorders are completely out of favour to capture video and new models do not get the coverage they once had. Nevertheless, the few reviews that have been written or shown on YouTube did prefer the newer VXF1 over the Sony AX53. I was also rather reluctant to trust another AX53; once bitten twice shy.

I should explain again that I prefer a camcorder with a small sensor. Unlike a film maker seeking narrow depth-of-field, I need a wider depth of field for wildlife that is often being filmed at maximum range and maximum aperture, and is often surrounded by vegetation. Much as I would like to carry a camera/camcorder with a larger sensor as well, for those other shots, there is only so much my back will carry. Better to get a small bird in focus, even if some of the background is also sharp, than get a fuzzy bird, is my motto. I should also explain that I prefer the ergonomics of a camcorder to that of a stills/video camera. I find I can hold a camcorder still for longer using one hand and arm locked into position than I can a conventional slr-style or ‘compact’ camera. I also do not have to think about using an external microphone since the for most of my purposes the built-in microphones for ambient sound are fine.

I decided to go with the 2018 Panasonic VXF1 rather than the 2016 Sony AX53 again, even though I had to re-equip with spare batteries and it was more expensive. I have done some trials. Video (4K) is excellent. The lens seems a little better especially the edge definition. I checked that the sharp video is not the result of oversharpening. Focus seems faster. The stabilisation system does not go wandering off all by itself. The viewfinder is better. The menu system is far superior to the Sony. There are programmable function buttons. The viewfinder is supplied with a rubber hood. The level indicator works well. It has infrared night vision (which I sometimes use and which once differentiated Sony from the competition). I was also surprised by the build quality. In my long line of camcorders starting with Hi8, I have had one previous Panasonic; the build quality of that was not impressive. My overall impression is that it is as if Pansonic looked at all the annoying features of the Sony and tried to come up with something better, even if a little more expensive.

Of course there are features I would like that aren’t there (a log profile video option, 50(60) fps 4K, GPS); but, my verdict on the Panasonic VXF1: so far so good.

Out goes the failed Sony AX53

In comes the Panasonic VXF1

Variable Neutral Density Filters: Why are they not calibrated for photography or videography?

Variable neutral density filters are useful for video or time-lapse work. However, they are infuriating—as I pointed out in my review here—because they are not calibrated in stops or Exposure Values (EVs). Instead, all that I have found for sale have a linear scale corresponding to the change of angle of rotation.

Here is the scale on a variable neutral density filter made by Gobe:

Variable neutral density filters comprise two sheets of polaroid material, one rotating on top of the other. When the angle of polarisation of one sheet is identical to that of the other, there is no reduction in the amount of light passing through (other than the basic reduction caused by the material itself). As the angle is increased up to 90 degrees, the amount of light transmitted is decreased until, with two ideal polarisers, no light is transmitted at all. Although polaroid material is not an ideal in terms of a perfect optical polarising material, it does follow pretty well the Law of Malus. The intensity of light transmitted by the filter can be calculated from the angle of rotation of one sheet with respect to the other. I have actually checked experimentally using an ordinary cheap variable neutral density filter (i.e. made of polaroid material) that there is close agreement between the actual curve of intensity against angle of rotation and the theoretical curve calculated from the Law of Malus.

The problem for photographers is that we do not work with a linear scale of light intensity. We work with stops or Exposure Values, a base-2 logarithmic scale. In other words, halving the light intensity is 1 EV (stop) difference; halve it again, 2EV differences and so on. If we look at the graph calculated from the Law of Malus, we can see that the angle of rotation between the two polaroid sheets needs to reach approximately 45 degrees for the light intensity to be reduced by half, i.e. 1 EV or stop. With a scale of say 14 steps on the rim of the variable ND filter, we have to get to number 7 just to get a 1 stop reduction in light transmitted over and above that caused by the material itself. Minus 2 EVs is reached at 60 degrees but then smaller and smaller changes in angle are needed to achieve a change in EV.

This diagram shows the reduction in transmitted intensity with change of rotational angle (calculated from the Law of Malus). Also shown are where changes in EV fall on the line.

So we know that moving the rotation by one point at one end of the scale does not have the same effect as rotating the upper layer by one point at the other end of the scale. Quite simply the photographer does not know which graduation to use to achieve a reduction of light transmission by, say, 4 EVs or stops.

This graph shows the calibration of a variable neutral density filter in photographic terms, i.e. in stops or EVs. This one (made by Gobe has a scale marked with 14 points together with ‘min’ and ‘max’ marked as bands placed non-linearly:

This graph shows the effect of the setting on the rim of a Gobe variable neutral density filter
on the decrease in Exposure Value (EV) (stops). EVs were measured to the nearest 1/3rd
of a stop. A was the arrow on the side of the 'Max' mark nearest the scale. The graph
serves as a calibration curve for the filter.

My simple question is: why do manufacturers of variable neutral density filters not calibrate their filters with decrease in EV? Is it because the calibrations would all be close together on the rim? Or that it would be difficult to engrave a marking that sits precisely on an EV difference? In that case simple markings for, say, 5 or 6 EVs should not be too difficult even if only one or two of the marks had values attached. Or have manufacturers not done so because variable neutral density filters were traditionally marked by and physicists, with the graduations indicating simply the change in rotation? The very least manufacturers could do would be start the markings at a point where there is a decrease of 1 EV beyond the basic decrease (of approximately 2 stops) produced by having the filter in place.

There is actually plenty of room on the rim for two scales. Since the rotational angles cover 0-90 degrees, there is the rest of the rim on which EVs could be marked.

I wondered if more expensive filters had markings in EV. It would appear not. I found the instructions for Tiffen:

The Tiffen Variable ND filter operates on the same principle as a Circular Polarizer [erm, no it doesn’t] – rotate until you reach your desired effect and shoot. It allows you to have continuous control over the amount of light coming through your lens in an approximate range of 2 (ND 0.6) to 8 (ND 2.4) stops – while maintaining the integrity of your image. Note: The evenly spaced indexing marks between MIN and MAX do not represent calibrated stops. They are for reference only, to be used as a density bench-mark to return to a previous setting.

What would a variable ND filter look like when calibrated for photographic use? Here is the same photograph as above but the upper one this time has marks added in Photoshop to indicate a scale marked in EVs:

A big improvement, I would submit.