Ye olde 144 degree shutter angle and lightmeter rant

[Dom Jaeger]

It can be a bit confusing with some models overlapping feature upgrades, but this other page from the Bolex Collector site discussing serial numbers confirms what I wrote:

http://www.bolexcollector.com/articles/07_05_11.html

My information came from Bolex service manuals.

 

The 190 degree shutter went with the older cam-driven pulldown claw design, once the newer trailing claw design (with a second claw for rewinding) came in they had to go with a smaller shutter angle. So if your Bolex claw looks like this, it should have the 190 degree shutter:

 

https://m.youtube.com/watch?v=IHMfzwf0Q9E

[David T. Nethery]

Thanks for the additional info, Dom . That is helpful.

 

So , yes, I wonder if the camera I have , with serial no. 98890 , is in the transitional period from the 190-degree shutter to the 144- degree shutter ... I looked at the video you linked to ... mine looks almost, but not quite the same as the camera interior shown in the video.

 

I'm also going to email Bolex Intl. SA to see if they can tell me for sure.

 

I'd be happy to know it's got a 190-degree shutter, because then I can use one of my standard light meters (Gossen Scout 2 or Sekonic L-158) with the Cine Scale , because those are based on a 180-degree shutter and the difference between a read-out based on 180 (1/48 sec.) or 190-degrees (1/45 sec.) is going to be minimal .

[Simon Wyss]

If you don’t see two claws, one of which (the upper) serves reverse transport, you have the single-claw cam movement and 190 degrees shutter opening angle. The claw cover is rather triangular. According to [(360/190) × frame rate]^‒1 exposure time is ¹/_45.5 second at 24 fps. Serial number 98890 is from 1954 but before the introduction of the trailing double claw which was in March of that year with number 100401. The cameras weren’t numbered in strict sequence but after batches that were begun XX001 or XX501.

 

Only the H-16 M has a 144 degrees shutter. Opener would be a better term. B)

[David T. Nethery]

If you don’t see two claws, one of which (the upper) serves reverse transport, you have the single-claw cam movement and 190 degrees shutter opening angle. The claw cover is rather triangular. According to [(360/190) × frame rate]^‒1 exposure time is ¹/_45.5 second at 24 fps. Serial number 98890 is from 1954 but before the introduction of the trailing double claw which was in March of that year with number 100401. The cameras weren’t numbered in strict sequence but after batches that were begun XX001 or XX501.

 

Only the H-16 M has a 144 degrees shutter.

 

Ok, yes, the older H16 I have (with serial number 98890) does have the single claw (with the slightly triangular cover) , so it has the 190-degree shutter. I had previously assumed my H8 (serial 112886) was also a 190-degree shutter , but as I reexamine the H8 more closely I see that the H8 has the double claw.

 

So, I'm confused about your mention that the H16 M is the only Bolex with a 144 degree shutter , because the Bolex H16/H8 user manual I have (found here: Bolex H16_Bolex H8 _user_manual) gives this information about exposure times when using a light meter:

 

"When using an exposure meter, remember that at 16 frames per second , exposure time is 1/40 sec. ; at 24 frames per second it is 1/60 sec."

(see screen shot from manual here)

 

Which would be exposure times consistent with a 144 degree shutter angle . My Bolex H8 has a serial number 112886 (which would be a manufacture date of 1955 , according to this list of Bolex serial numbers: http://bolexcollector.com/articles/07_05_11.html ); my H8 has the two claws , it is non-reflex (so it is not one of the later 130 degree shutter H8 RX cameras) , but according to what this manual says about exposure times it would have the 144 degree shutter , not 190 ...

 

However, to add further confusion for those of us in these latter days who cannot casually "consult your Paillard dealer" as the user manuals advise , another combined H16/H8 manual I found here: https://16mmadventures.files.wordpress.com/2011/07/bolex-camera-h8-h16-user-manual.pdf says this of the exposure time:

 

"The normal time of exposure is 1/30 second at 16 frames per second, which is the normal speed for shooting. When the film is run at 64 frames per second, the exposure is reduced to a quarter of the normal i.e. to 1/120 second."

 

So according to those times (1/30 at 16fps , or 1/120 at 64fps) the camera would have a 190 degree shutter . :wacko:

 

It's a bit maddening that none of the Paillard documentation I can find posted on the internet (or the few original manuals I possess) have a DATE printed on the document.

 

 

.

Edited January 5, 2019 by David T. Nethery

[Dom Jaeger]

As that first manual indicates, I believe all Bolexes from around 1954 to 1961 had the 144 degree shutter, including the first reflex H16s as well as the non-reflex 8 and 16mm models. A H8 with serial no 112xxx should have a 144 degree shutter.

 

The other manual you linked to would have been from before 1954, when the cameras had 190 (or 192) degree shutters. Note that it does not include reflex models, which were introduced in 1954.

 

I don't know where Simon's information about only the H16-M having 144 degree shutters comes from, I used to have access to all the Bolex service literature when I compiled the list I wrote in post #22 but I don't work for that company anymore to double check.

[Simon Wyss]

It is confusing, yes. The combined Instructions for use are younger than 1956 when the H-16 Reflex came out. It is not clear there which models are meant by the Care! note on exposure times.

 

From what I have measured on various models from all periods the H cameras from 1935 to 1954, serial numbers 7501 through 100400, have a 192 degrees shutter. 190 degrees can be taken as effective. Then the H-16 and the H-8 got the flung-on claws and a 170 degrees shutter (about 169-168 degrees effective). The H-16 Reflex, introduced in 1956, has the same mechanism as the regular or standard H-16. The H-16 M(onoptic) was introduced in 1958 with serial number 153001, having a rotationally angled 145 degrees shutter for filming off TV screens in countries with 60 Hertz mains at 24 fps. Paillard aimed specifically at the US market knowing that the Arriflex 16, the new rival, couldn’t be used in that application. The H-16 RX V(ariable) S(hutter) model came to the market in 1959 from serial number 162306 on having a rotationally angled 145 degrees opening, of which 144 degrees must be reckoned with due to its standing away somewhat from the film. The shutter edges aren’t depicted sharply on the aperture, therefore a little light loss. The moving shutter wing is smaller than the fixed wing and hides completely behind it in the fully open position.

 

The little light loss, by the way, is the case with every film motion-picture camera. From a French 8mm camera I have read that its shutter would operate as close as to a tenth millimeter from the film, the Armor 8. Honestly, I don’t believe that until I’ve disassembled one, something that lies still before me. With mirrored shutter reflex cameras the angled shutter position leads to a similar unsharpness of its edges shadows either across the image width (ARRIFLEX, CINEFLEX, Arriflex 16 St, reflexed Mitchell) or the height (Eclair, Arriflex BL, Panaflex, and others). The error is small, though, and not visible from the processed film. Just as a technical fact and explanatory background

 

The Revere 101-103 cameras have rotationally angled shutter edges, too. https://de.wikipedia.org/wiki/Umlaufverschluss#/media/File:Revere-Verschluss.JPG

[David T. Nethery]

It is confusing, yes. The combined Instructions for use are younger than 1956 when the H-16 Reflex came out. It is not clear there which models are meant by the Care! note on exposure times.

 

 

I actually have a physical copy of the same set of instructions that came with the H-8 camera (serial number 112886, c. 1955) . Of course, I purchased this camera used , so there is no way of knowing for sure if the previous owner(s) had acquired those instructions with the H-8 camera originally or had picked up that instruction booklet somewhere along the way and added it to the kit. But if those instructions were part of the original camera kit from Paillard , then that note about exposure times : "16 frames per second , exposure time is 1/40 sec. ; at 24 frames per second it is 1/60 sec." means that this H-8 camera has a 144-degree shutter.

 

But then there is this:

 

 

Then the H-16 and the H-8 got the flung-on claws and a 170 degrees shutter (about 169-168 degrees effective).

 

Ok, now there is one more piece to add to the puzzle ... I had thought the shutter angle options were: 190-degrees (earlier non-reflex H16 and H8, before serial number 100401) , 144-degrees (later non-reflex H16 and H8, earlier H16 Reflex) , and 133-degrees (reflex H16 and H8 ) . 170-degrees is a new number to deal with.

[Simon Wyss]

David, look, as I said, the instructions are from not before 1956 because the RX is treated in them. I think the booklet dates from 1960. There’s that code on the last page, something-06. Maybe, I don’t know Paillard’s secrets. Now, with the Reflex H-16 we have to include a light loss of between 20 and 25 percent at the prism block according to a lens’ design and that is compensated for by a shorter exposure time with the calculation. From ¹/₄₀ s to ¹/₆₀ s you have 33 percent decrease. Starting at a ¹/₄₅ s the shorter time compensates for 25 percent. ¹/₄₀ s is inaccurate.

 

Many instructions and manuals carry imprecise values and false things. Just of late have I studied the instructions to the Pentacon Pentaflex 8 camera. The exposure times in there are so crudely rounded that four different shutter angles derive from the values and none of them is even close to the truth, namely 172.8, 177.2, 184.3, and 192 degrees. The three openings are of a 50 degrees angle, so the true value is 150 degrees per cycle.

 

[David T. Nethery]

It is indeed a mysterious brew of imprecise values . I had never come across the "170-degree" shutter value you mention, except with reference to the later Bolex EL and EBM . Previously my reading from various internet sources (including this forum and BolexCollector.com ) was that we had earlier non-reflex H16 and H8 with the 190 (192) degree shutter, then after serial number 100401 the 144-degree shutter , then finally with REX-2 - through- REX-5 the 130-degree shutter .

 

I contacted Jesse Chambless (recommended by Bolex Intl.) about my Bolex H8 and he said based on the serial number and the double-claw , it would be a 144-degree shutter.

Edited January 10, 2019 by David T. Nethery

[Gregg MacPherson]

The three openings are of a 50 degrees angle, so the true value is 150 degrees per cycle.

 

 

Is that shutter spinning at 1 rev per frame..? Do those three 50 deg increments really sum..? If so the pull down happens in 70 deg. Is this right...?

[Simon Wyss]

The Pentacon-8 shutter makes one third revolution per cycle, the pull-down takes a little more than 180 degrees of it. I’d like to come up with an English version of the article I’ve written on the cam. If I may ask for a little patience for a translation, had never thought that there is any interest in a GDR product.

[Simon Wyss]

Here’s a link to the other thread. http://www.cinematography.com/index.php?showtopic=78796&do=findComment&comment=506168

[Simon Wyss]

Back to Paillard-Bolex, I am so embarrassed.

 

From wishful thinking I said that H cameras from 1954 on had 170 degrees shutters because it makes no sense to go to 145 (144 useful) degrees with the trailing claws. In the fifties 80 percent of Paillard-Bolex exports went to the USA and filming off TV screens with 144 degrees had a point at that time. The first videorecorders became available in 1956, not at bearable prices. The H-16 models EBM and EL do have a 170 degrees shutter. I always thought there were European (170) and American variants (144) of standard H cameras but that is not true.

 

Right now I have a younger H-8 here that the owner wants to be converted with a 172.8 degrees shutter. That angle goes with 24 fps and artificial light in 50 Hertz mains [(360/172.8) × 24]^‒1. To adjust the timing is a little bit trickier but feasible. It helps to know that the film comes to halt somewhat before the end of the perforation pitch distance and that the hole edge yields a little elastically during the last few hundreds of a millimeter. There are about 16 degrees of the claw drive rotation that go away at the end of the stroke, still the 172.8 can be had between periods of the film completely stationary.

 

[Carl Looper]

The difference between 144 deg and 135 deg is a difference of only 0.09 stops. Slightly less than 1/10th of a stop. In other words: insignificant.

The more significant difference is  between 135 deg and that which a light meter assumes (180 deg). This is a difference of 0.4 stops.

Prism loss is another 0.3 stops. Together they come to 0.7 stops (or 0.6 stops difference if you want to belive a 144 deg shutter). Rounded to the nearest 1/3rd of a stop (which is common practice) both 135 deg and 144 deg arrive at the same compensation: 2/3rds of a stop compensation.

As Tuohy pointed out, the simplest solution is to rate the film as 2/3rds stops slower. So rate 100 ISO film as 64 ISO. And then use light meter as is (as if camera had a 180 deg shutter without a prism)

500 > 320

250 > 160

100 > 64

50 > 32

 

 

 

Edited February 11 by Carl Looper
grammer