FPS Meter?

ric1 · March 14, 2016

Hi,

Am filming with a Bolex H16 with a Pan Cinor zoom on it, very difficult to get the correct aperture for the speed I shoot at which is 16&2/3rd fps. My film is Fomapan asa 100. Have been using a Gossen 6 as a meter but the exact speed I film at is an in-between value, and it's often a problem to read off the correct aperture I need, especially in challenging situations.

I was wondering if there is a digital reflective light meter that I could set the fps into, and get an aperture reading that way please? I was looking at the Sekonic 308DC meter but I don't know if it would accept an in-between fps rate? Useless if not, I'd be back to guesstimating between f-stops again.

Advice appreciated :)

Thanks

Charles_Webster · March 14, 2016

Why do you use 16-2/3 fps? Any setting within 1/3-1/2 stop will be close enough. You can't see 1/3 stop difference in exposure anyway, and your film should have enough latitude that even a full stop should not have much effect.

Oh, and even if you could find a meter with FPS settings, you won't find 16-2/3 on it. Silent speed was 16 fps, sound speed was traditionally 24 fps (US) and video is 29.9 or 30.

craig_shearman1 · March 14, 2016

The H16 does not have 16 2/3 as one of its standard speeds. Are you using an external motor that lets you set that speed? And why are you shooting at that speed -- it is compatible with absolutely nothing. 16mm is normally shot at 24 fps (or 25fps in Europe for PAL TV) and everything is set up for that whether you are finishing on film or video. I could see 30 maybe for video transfer, but not aware of anything that runs at 16 2/3 or even normal 16. Charles is correct that the setting you would use for 16 will be close enough. And cine meter will work, and most digital meters have cine settings. If you don't have cine settings, look in your Bolex manual -- it will tell you the shutter speed for any given combination of variable shutter angle and fps.

Charles_Webster · March 14, 2016

Craig, I could not remember if my H16Rx ran at 16 fps or not. I imagine the "wild" motor could be set to run at almost any speed that the camera would transport film.

I always shot with the Sync Motor so never encountered this issue.

AJG · March 14, 2016

If you're trying to compensate for the different shutter speed that the Bolex has compared to standard cine cameras, you can try setting a lower ASA/ISO on your meter. As I recall, the shutter speeds are faster by about 2/3 of a stop due to the narrower shutter opening and the light taken by the beam splitter for the viewfinder.

Charles_Webster · March 14, 2016

The beam splitter loss is applicable only to the H16Rx model. The others do not have the through the lens viewfinder.

craig_shearman1 · March 15, 2016

Is 16 2/3 a European thing? If you did a telecine transfer with a projector that had a standard three-bladed shutter, that would produce 50 images a second, which would transfer evenly into 25 fps for European TV. That would be similar to the concept in the U.S. of shooting 24 fps and transferring on a projector with a special five-blade shutter to get 120 images per second, which transfers evently into the 30 fps of U.S. TV. But 1) does anybody still transfer with a projector anymore instead of more sophisticated digital technology 2) is European TV still 25 fps with HD and digital and 3) the standard solution was always to shoot and transfer at 25 fps when shooting film for European TV, or you could just shoot normal 24 and let it be speeded up by 1 fps. As for shutter speed, a movie camera with a standard 180 degree shutter has a shutter speed of 1/48 of a second at 24 fps. The H-16 I believe had a 130 degree shutter, which means 1/65. If my understandint is right, the formula is fps x 360/shutter opening. I think that results in 1/46th for 16 2/3 and a 130 degree shutter. Short answer: use what a standard cine meter says to use for 24 fps. But double check my math. :)

ric1 · March 15, 2016

Thanks. Yes, I shoot at 16&2/3rds to synch with my dv cam which runs at 50fps and I have a 3 blade projector, so I set the H16 Reflex at just over 16fps. But my Gossen is marked from 9 to 18fps with a tiny dot inbetween, the dial detail is so minute here that I cannot really tell what the dot signifies. But I haven't even got '16' to aim at when I'm filming, and on a difficult shoot it becomes nigh impossible to work out what's going on. The H16 has tended to under expose recently.

The lens is challenging as well, it swallows over a stop of light, that took some getting used to. It's an early model so it has no shutter angle control, I can only fade in and out with a variable ND filter. Add all that to a light meter which has no clear read out for the speed I shoot at and you have a recipe for a nervous disorder by the end of the day.

The Gossen is great, it works a treat, but the speed I am filming at makes using it extremely awkward, that's why I wondered if some of the more recent reflected light meters would allow me to focus on a defined fps - the Sekonic 308DC has a 16fps frame rate setting for example, that might make my life a bit easier?

Thanks again

Charles_Webster · March 15, 2016

I would suggest that the underexposure is because of the 2/3 stop light loss in the reflex viewfinder beam splitter. I thought all H16RX had a variable shutter. Mine was vintage 1970 and certainly did.

As I said earlier, your film latitude should all you to be +/- 1 stop without much effect.

Is there a reason you aren't using an incident light meter? They are more appropriate and common for cine work.

AJG · March 15, 2016

According to the Bolex manual I found on line, your effective shutter speed at 16 FPS would be 1/55. since you're going slightly faster, then setting your meter for a shutter speed of 1/60 ought to do it. I would ignore the FPS settings on the meter and use it in shutter priority mode (easy to do on the Sekonic 308 plain vanilla version). B&W reversal needs careful exposure for the best results, but that should be close enough given the limits of accuracy in setting a clockwork motor like the one on the Bolex.

ric1 · March 16, 2016

Thanks, apologies I'm a bit lost here. I used the Gossen as a reflected light ['spot'?] meter because I started out on Super 8 cameras which all worked that way. Are we now suggesting I go ahead and acquire the Sekonic 308 please? In which case I can begin to explore Andrew's suggestions for metering. It will be interesting to compare the Sekonic to the Gossen however the Gossen cine dial is near the centre of the circular display so the intervals are tiny, you could only easily use it for standard speeds like 18, 24 and so forth, which are clearly marked.

AJG · March 16, 2016

The Sekonic 308 is a great meter, but it is primarily intended to be an incident meter and is somewhat inconvenient to use in reflected mode since you can't see the readout when you are metering. A Sekonic 358 (discontinued, but available used) would be a much better choice since the meter cell can be pointed toward the subject in reflected mode while you can still see the readout. The current L 478 would also work if the $265 price (B&H) is within your budget. Both of these meters would give you the option of incident metering if you ever choose to go that way, and I find that very useful in studio/artificial lighting situations.

ric1 · March 16, 2016

Thanks, I primarily film landscapes - woah - had no idea metering the H16 was going to be such a learning curve, I had better results with the turret arrangement but then you can't easily use TTL viewfinding. The dog leg lens I now use is a dream for composing shots but the metering is still work in progress ;)

I don't understand why you say the Sekonic 358 can be used to point at the subject then read off the values - unless the 'head' of the unit can be revolved through 180 degrees, so that you are facing the subject and reading off values at the same time please?

ric1 · March 16, 2016

This image shows a revolving head - there is no mention of this in the 358 pdf manual though. https://upload.wikimedia.org/wikipedia/commons/5/5f/Sekonic_L-358_Flash_Master.jpg<img src="https://upload.wikimedia.org/wikipedia/commons/5/5f/Sekonic_L-358_Flash_Master.jpg" alt="" />

AJG · March 16, 2016

The Sekonic 358 metering head will revolve 180 degrees so that your reflected readings can happen while you can see the readout. Without other attachments, these Sekonic meters take in a fairly wide angle for their readings, probably similar to your current Gossen. For spot metering, there are other Sekonic meters and attachments for the 358 and 478 models. Unless you're into ultra precision Zone System type metering, I would skip the spot meter for film making purposes. When I worked on documentary films a long time ago we only used incident readings since they were a much faster way of getting an accurate exposure for the narrow latitude color reversal films that we were shooting.

AJG · March 16, 2016

A further clarification--the incident dome will come out and be swapped with a reflected attachment for reflected readings. If you buy a used meter, make sure that this is included. It is a small part and easily lost if someone doesn't use the meter in reflected mode very often.

craig_shearman1 · March 16, 2016

There are many, many light meters that can do fps, including my Sekonic L-718 that I just played with a few minutes ago. In my experience with movie film (two years of film school at NYU and years of shooting off and on before and after), incident meters are the standard. You stand as close to where the subject is (or at least in the same light) and point the dome back at the camera. Correct exposure might not be guarantted but it's as good as you are going to get. Reflected meters are rare in film work, at least in my experience, and there is no such thing as the zone system in movies. Keep it simple. Whichever meter you use, the 16 fps setting is close enough -- the 2/3 of one fps just isnt' enough to matter. The trick though, is knowing a couple of things -- what is the actual shutter speed on your camera? Different models of the Bolex H16 had different shutter angles and generally narrower than on something like an Arriflex, so you have to do the math to find what the the actual shutter speed is. Secondly, you have to know how much light is being lost by the viewing system. Are you using an H16 reflex model? If so, the beamsplitter siphons off maybe two-third of a stop. or are you using a non-reflex model but using the Pan Cinor with the dog-leg finder, which also siphons off light? Or are you using a normal Pan Cinor on a non-reflex body? If your camera is old enough that it does not have a variable shutter, is is probably old enough that it is not reflex. Are you acually shooting at 16 2/3? The spring would motor in an H16 doesnt' have that setting, so you would have to be using an external electric motor that does. And if you are transferring on a projector at 16 2/3, how are you getting that speed? Most projectors run at either 16 or 24, but there are some with variable speed and you could reach 16 and 2/3 by adjusting the speed while watching the image in your video camera until the roll bars go away. Honestly, your life would be much, much simpler if you shoot at 24 fps and have the film transferrred at a lab. "I started out on Super 8 cameras which all worked that way" I've shot both Super 8 and 16. As much fun as Super 8 is, 16 is very, very different.

ric1 · March 16, 2016

Here is the H16, I worked out from the serial number that it weighed in at about 1958.

If you film at 16&2/3 it syncs with 50fps because the camera speed divides exactly into 50. You will note that the H16 has no lever down its side for shutter blade angle. I don't know what the set shutter angle is for this camera, 180 degrees? My projector has variable speed control. I am critical of lab transfers / telecine because the results are so often like video, you lose the inherent 'shake' of the film (especially Super 8) as the software stabilises everything to the nth degree.

The fact you can rotate that light meter head is good news but it looks like I am going to have to learn incident light reading, something I have been long curious about but never tried.

The dog leg lens is a Pan Cinor F2 17-85mm. The black cowling supports an additional thread enabling the use of filters - was unable to match the native thread dimension. The lens is covered with elastic bands to hold the multiple lens caps in place because it turned up with most missing. Oh how I wish I could replace those missing caps. Both camera and lens have been serviced.

How is this so far please?

craig_shearman1 · March 16, 2016

Thanks for the pictures. Bring back lots of memories. Looks like you might have the 1956 H-16 Reflex. That model had a 144 degree shutter, so at 16 fps your shutter speed is 1/40. You don't need to use a dogleg lens since this is an actual reflex camera. Does the Pan Cinor have any way to flip its viewing mirror out of the way? Otherwise you are losing light to it and again to the viewing mirror inside the camera. Here is a link to the Bolex Collector page on this camera. They also have a lot of other information. <a href="http://www.bolexcollector.com/cameras/h16reflex.html">http://www.bolexcollector.com/cameras/h16reflex.html</a> "I am critical of lab transfers / telecine because the results are so often like video, you lose the inherent 'shake' of the film (especially Super 8) as the software stabilises everything to the nth degree." Film isn't supposed to have any shake unless there's something wrong with your camera/projector. Super 8 would have it the worst since it's a very small format and there's no registration pin and the cameras were mostly intended for the consumer market. A Bolex does not have a registration pin, but I believe they claimed that the claw stayed in position on each stroke and provided good registration during exposure. An Arriflex and other more expensive cameras have registration pins, so steadiness is rock solid. That said, if you're happy with doing your own transfers, nothing wrong with that. And 16 fps can save you significant money on film stock. Incident light reading is much, much easier than reflected. It eliminates the guesswork from a reflected meter pointing at something dark in one shot, something light in another shot or taking in too much or too little of what you're trying to meter.

ric1 · March 16, 2016

Thanks Craig, you said:

"Looks like you might have the 1956 H-16 Reflex. That model had a 144 degree shutter, so at 16 fps your shutter speed is 1/40. You don't need to use a dogleg lens since this is an actual reflex camera. Does the Pan Cinor have any way to flip its viewing mirror out of the way? Otherwise you are losing light to it and again to the viewing mirror inside the camera."

Sadly this will might to wait, the Bolex is back-wound for double exposure right now and I don't want to compromise the film. It would be great if you were right, back when I used the turret lenses the prism directed my line of sight through the diaphragm, so that below maximum aperture all you saw through the viewfinder was slate black, that's why I went for the dog's leg. Yes, it would be a 58 issue of the 56 model.

How is the 144 degree shutter going to affect metering at 16fps please? I am shooting asa 100 film with a ND2 filter on the lens. I removed a second ND2 filter from the fillter tray because of under exposure. I dropped the asa on the Gossen from 50 to 25 to allow more light to enter the camera - it's one long experiment at the moment.

The most consistent results I had were with the fixed turret lenses because they lost no light. I am determined to master the zoom lens though. The slight variation in light & shade is caused by hand developing.

https://youtu.be/fzdd8qcjLZk

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craig_shearman1 · March 16, 2016

The shutter opening, coupled with the number of fps, determines your shutter speed. The shutter is basically a circle with a pie-shaped wedge cut out. On most cameras it's a 180-degree wedge, or half the circle. On your camera at 144 degree it's a little more than a third of the circle. So your shutter speed is a little higher than on other 16mm cameras. But the bottom line is your shutter speed at 16 fps is 1/40. Set your meter at ISO 100 and the shutter speed on the meter at 1/40 and take a reading. That will give you your f-stop, but without accounting for how much the lens viewfinder and camera viewfinder soak up. Unless you've got some Bolex literature that tells you, you need to do some tests to determine that. Cant' do much about that until you get your backwound roll of film out of the camera. To give you a ballpark idea, 100 speed film in bright sunlight at 1/40 gives you an aperture of about f/22. Your lens probably doesn't go down that far but with the light loss to the viewing system you would probably be pretty close. If you got good results with the fixed lenses, then everything should be the same except for compensating for how much light is getting lost to that dogleg. I think that might be your biggest problem -- that lens is intended for a non-reflex camera. Hand developing can be fun, but that's just one more of the many variables you have going on here. To get consistent results, you need to eliminate variables and work on one problem at a time.

Charles_Webster · March 16, 2016

Bolex didn't use a rotating shutter. The shutter opened up and down in sync with the pull down claw. that's how they could make the camera body as narrow as it is.

That said, the equivalent shutter angle is still 144deg. And at 16 fps your shutter speed is just less than 1/50.

Are you making allowance for the viewfinder beam-splitter loss in both the camera and the lens?

ric1 · March 16, 2016

Thanks. Ages after taking delivery of the lens someone pointed out the 2,66T formula on the aperture ring which apparently gives the loss of light for this lens as about 4/5 of a stop? If even more light is being lost due to the reflex mechanism we are talking big in f-stops :-o My problem is to work out exactly what is being lost so I can calibrate my light meters for accurate exposure. Yes, I take your point about DIY developing. After the present film (a project) I may shoot 100 feet of pure test footage. Back in the day I did this for all my cameras but there have been many changes in my life over the past 3-4 years or so, more or less coinciding with acquiring the Pan-Cinor. I need to do a series of tests, just like I did with the fixed lens. Well, at least summer is on the way, so I will have some decent light to test out with.

So no, I am probably seriously underestimating the light loss associated with this camera plus the zoom lens. This explains why I have been troubled with underexposure all the time I used this set up. I also got underexposure using a Krasnogorsk-3 several years ago, and that also has a whopping zoom on it, but you can film TTL no worry. Hardly use that though, it is so very difficult to load and so very unforgiving if you get it wrong. Never had a misload with the H-16.

craig_shearman1 · March 16, 2016

Just got to look at your sample video of lens tests. You have a huge amount of weave there. Either the camera or the projector is having serious problems. Have you done transfers of other film and do you get this problem? Sometime you can see weave in the scrolling titles at the end of a movie but you shouldn't see it to a noticeable point with regular action footage. Also the images are way too soft, to the point it looks like they are out of focus. Again this could be in the transfer. But keeep in mind that on the Bolex Reflex models, the fixed lenses were supposed to be special "Rx" lenses or you could get soft footage.

AJG · March 16, 2016

If you have T-stops, then you know how much light you're losing through the lens and can set an accurate f/stop for exposure. The Bolex beam splitter takes another third of a stop, and with Craig's plausible calculation of your shutter speed, you should be about there. Good luck!

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