SPRING MOTOR AND FILMING FAQ

SCOPE

This FAQ covers all 8 mm spring motors from 1940's thru 1960'S.

GENERAL

The vast majority of all 8 mm film cameras sold from 1940 up through the 1960's have a flat spring wound motor to drive the film train. A spring made from tempered steel is wound into the shape of a coil. The spring coil is mounted on a shaft. One end of the shaft winds the motor's spring with a folding key.

When the camera's run button is depressed, a one way clutch holds the winding key in the same relative position while the now compressed (wound) spring tries to unwind itself. This unwinding causes the case of the spring motor to turn. The turning motion of the case outer ring gear powers the speed regulator which controls the rate at which the spring motor unwinds. Typical setting are: 8, 12, 16, 24 36 48 and 64 Frames Per Second.

Bolex 8mm cameras (all except the H8 series and Super 8) are infinitely variable with a dial to indicate the approximate frame rate per second (FPS). Other cameras such as Bell & Howell and Revere (and others), use a selector with a specific FPS setting. 

Following the winding procedure found in your camera's manual. The number of winding turns varies depending upon the make of the camera. Bolex cameras are fully wound at 21 1/2 turns or at about 11 full turns. There is a slight variance from motor to motor. Other camera such as Revere's, Keystone, and Bell &Howell's typically are fully wound at approximately 8-10 full turns.

Cameras other than Bolex wind until the spring is fully coiled. The maximum winding is mechanically limited in Bolex cameras. This allows the motor to be wound to a hard stop. Bolex's are advertised as "impossible to overwind" and uses a mechanism to prevent the camera from being overwound. For the most part, it works as advertised. However it is possible to overwind a Bolex. It takes a lot of forcing, but it can be done.

RUN TIME PER FULL WIND

The run time per full winding is shown below:

MODEL:                                                                    RUN TIME

      

       Bolex (All 8mm models except for H8)              20 seconds

       Revere 44                                                             10 seconds

       Revere K-45                                                         25 seconds

       Revere 99                                                             15 seconds

       Keystone K-38                                                     25 seconds

       Keystone K-36                                                     35 seconds

     NOTE:

     The above are average/typical run times measured from full 

     wound to full stop.Not all of the running time is usable, however. 

     Except for the Bolex, all 8mm cameras typically will run from fully

     wound to stop at a speed approximately that which is dialed in.

     I.e., 24 FPS will film 24 frame per second. However, at some 
     time after the initial start, the motor's speed WILL slow down

     and the FPS will become lower.

WHY?

The location (time) of the slow down will vary from camera to camera within the same model designation. It depends on the age and condition of the motor and at what wind point the camera was stored. Spring motors left fully wound can loose their elasticity (springiness) and will not last an average full wind. Spring motor cameras should be fully wound down when not in use.

SLOW DOWN

Slow down means that after developing, the finished footage will play normally (at the selected filmed frame rate) and the will "speed up" at some point in the clip. This "speed up" is due to the filming frame rate of the camera slowing down and the projection rate of the projector staying constant.

OTHER PROBLEMS

Cameras that have been left fully would can sometimes develop a permanent "kink". This "kink" is a weakness in the spring and can be felt while filming with the camera. It feels like a bump, thud or clunk. Sometimes it can be heard - sometimes only felt. The kink, depending upon the severity of the damage, may not be noticeable. The fix for this is usually to replace the motor.

REPLACEMENT MOTORS

There are no new motors available for any 8mm cameras. Nobody rebuilds them. Therefore a donor camera for parts is required. If you purchase a donor camera, be sure get the same model or a corresponding model with the same motor dimensions. Bolex cameras all used the same motor except for the H8 series and possibly the L8 model.

Ask the seller if the motor is usable. Given that these cameras are all over 50 years old, finding a donor camera may result in your having to purchase multiple cameras to get a good motor. Be advised that typical sellers do not know whether or not the motor is usable. The may state, "It winds and runs". They may not notice that the motor is unusable.

If you buy a camera with a bad motor and the seller has NOT agreed to take it back upon your inspection, you can always resell the camera.

USABLE RUN TIME

All camera manuals have information giving the usable run time for a full wind. This information is for a new camera. All 8mm cameras are now 50 plus years old. You will need to allow for this. All spring motors will have lost some of their usability after 50 years. You can wind and run the camera to the point at which you can clearly notice the motor running down.

EXAMPLE

If you fully wind your Keystone K-38 camera and it begins to run down at 17 seconds, you should stop filming and fully rewind the camera after 10-15 seconds. During filming, you can count (in your head) 1,000-one, 1,000-two, 1,000-three, etc. It was and still is good operating practice to fully wind the motor after each shot. Shoot for 3 seconds? Rewind - now. Shoot for 10 seconds? Rewind - now.

BOLEX IS THE EXCEPTION

Bolex cameras are the exception. A Bolex 8mm camera, in good operating order, can film for about 20 seconds. When the Bolex motor reaches the end of the wind it will stop abruptly while turning, and filming at the same FPS.

If a Bolex motor begins to slow down while filming, it is because the motor is weak. Depending on how weak the motor is, it may or may not be serviceable. Because of the limited run time, 8mm film cameras don't do well for interviews or documentaries.

FILMING TECHNIQUE

Good filming technique with any 8mm camera demands that the operator plan each shot prior to shooting. The means the you will need to keep track of the clip (shot) length (counting seconds in your head) and camera distance, focus and location. Failure to plan ahead will mean you will need to shoot more footage and your filmstock and developing costs will go up.

AVOID JUMP CUTS

Starting and stopping a camera can result in a "jump cut". Imagine on overhead view of the subject and the background. If the subject turns to either side slightly, and the camera is stopped and then filming starts in a slightly different location or angle, the subject can appear to "jump" from one place to another. Keystone Cops style. Moving the camera at least 15 degrees off axis between any two consecutive shots at the same distance to avoid a jump cut. Read more on Jump Cuts here:

https://en.wikipedia.org/wiki/Jump_cut

 

Try moving closer or farther away from subject to prevent a "jump cut".  After shooting, you can edit in/out similar angles or distances after filming to better tell the story.  Advance planning always helps. Not planning will waste film and result in a poorly made film. 

TELL A STORY

             1) Parents leaving on a plane for vacation,

             2) Kids graduating,

             3) Cat playing with dog, etc. 

Think of where you'll need to be to get the shots. Make the shots short. 3 to 8 seconds or so. Do not run the camera until wound down for a long shot. It will be boring and you have to edit out the bad parts, anyway. Given the cost of film and processing, this is an absolute necessity. Good footage is built up, shot by shot.

MORE INFORMATION ON FILMMAKING

Plenty of old "how-to-shoot film" books on the internet. Any books on filmmaking will help. If you are videographer, you will need to learn to limit your shots lengths. Books:

https://www.google.com/search?q=filmmaking+8mm+books&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb

 

Remember that film shot is gone forever. No mistakes allowed. No do - over's, etc. Plan ahead.

MY FILM HAS A SCRATCH IN IT. WHY?

The camera had an ExCLA. Working perflectly. Back from the developers, then telecined, the footage had 2 vertical lines. The film developer said:

"The camera is scratching the film".

Really, thats what he said. The camera is scratching the film. I don't think so. Here's why... 

WHO DUNNIT?

It's difficult to tell exactly where the problem is originating. Doe you have the original positive developed film? Can you see the scratches?  If there are NO scratches on the positive film, the the problem is NOT with the camera. The problem does look like scratches were on on the emulsion side of the film. They could be from any of the following situations :

            1) During the manufacture of the film.          

            2) During cutting down of the film from 35 or 16 millimeter to 8mm.

            3) During re-punching of the second set of sprocket holes to 

                convert the film to double run.

            4) During the actual running of the film in the camera to produce

                and image.

            5) During chemical processing of film.

            6) During the telecine process.

            7) During rewinding at any stage of any of the above process

                (except #4).

Basically, we need to know WHEN the scratches occurred.

How do we know which of the above 7 processes(s) are responsible for the scratches? Only process #4 involves the camera itself. The rest are either manufacturing,  developing or  telecine processes.

The ExCla covers disassembly, cleaning, lubrication and readjustment. No repair work on the gate or other parts of the camera. None was noted during the ExCla. There is only 1 part of the camera that actually touches the emulsion side of the film during filming - the gate.And the Gate ONLY touches at the outer edges where it does NOT matter.

The film is wound emulsion side in from the manufacture. It is 100% protected by the backing of the next portion of wound film on the reel. 8mm file is about .008" thick made of polyester. Tough stuff.

The film first passes over the tension roller. The roller touches the film on the backing side. To do any damage the roller would have to scratch the film ALL the way through the films thickness to reach the emulsion. Not possible.

The pressure plate presses the film between the plate and the gate. The pressure plate (flips away to reload film) touches the backing side of the film. Again the pressure plate is not able to scratch the film through to the emulsion.

Finally, the film that passes through the gate and the emulsion does touch the gate, but only at the extreme edges away from the gate open area.  At the point where the film does passes over the gate, it passes only over the extreme edge of the gate. There is nothing to scratch the gate anywhere. I've attached 2 images. One is the gate dimensions. The other is a picture of the Bolex 8mm gate.

The width of the gate opening (horzontally) is .177". The estimated scratch lines, are about .020" to .040" wide, relative to the gate widths. I got this by viewing a still of the footage on my HP 24" monitor and measuring the width of the scratch with a vernier caliper. The .020" to .040" estimate is about 10x to 20x the width of a human hair.

           

If it's anything related to problem 4 above, I will fix it at no charge. Keep in mind, this is not covered under the performed ExCLA. I do have the actual roll of expired film that I used to test your camera. I have inspected it with a 3x lens under strong light and I see no indications of the film's emulsion being scratch when I inspected it.

WHAT I CAN DO TO HELP

The are a couple of things I can do to help:

1) Send the camera to me and I will run another, different roll of test film through and look for scratches.   It there are scratches added to the film's emulsion layer, after passing through the camera, I will locate and repair/replace the problem at no cost to you. If there are no scratches after running the test film, I will return the camera with you paying the return postage.

as an alternative:

 2) I will send you a 1/2 roll of unexposed film and you can run it though yourself. If it comes out scratched similar to the finished film; send me the camera and the film for repair. I will pay the return shipping.

If it turns out to be a problem other than the camera adding the scratches, the problem must be with manufacturing, developing, processing or telecine.

MY CONCLUSION:

Given the size of the scratches, relative constant position, and  the relationship to the gate size, I believe the scratches were caused by 1) Developing, 2) Processing or 3) Telecine processes. As much as I hate to blame anybody, it is most likely the problem due to 1 of those 3.

JUST SHOT FILM - ITS ALL BLACK - WHATS WRONG?

Customer writes to BolexRepair saying they just shot a roll of film and had it developed. Its all black. Why? And can we fix the problem? Yes, we can fix the problem (if there is one) and do we work on a B8L cameras. Here's our reply:

We do work on Bolex 8mm cameras such as your B8L. All Bolex cameras should be checked every year or two. Bolex recommends that the camera be cleaned, lubricated and adjusted on a yearly basis. 

This is called a "CLA". Most likely the camera has not be checked for 40 - 50 years. A lot of these cameras were sold and after a few years, retired to the closet or were replaced by camcorders. In any event, cameras can and do stop running for no apparent reason if not in serviceable condition. For more information, click on link:

          http://www.bolexrepair.com/camrep.html

It can be one of several things:

1) Old film. Was the film fresh? If not fresh, the most obvious answer is that the film was the problem. When I see film that's marked: "Best used by Feb 1987" or whatever, I know it's "out of date". No good. Customers sometime ask, "Is it any good?" My reply:

     "No. Even if it was stored in a refrigerator for 27 years, it will still be degraded. Some people like to argue film is film and its good forever. No, not really..."

2) The iris was not set properly. The B8L uses a it's onboard light meter to calculate the iris opening. Keep in mind that the iris opening suggested by the camera's meter is for ASA 25 or ASA 40 film. Both are no longer available.

ASA 100 is available. If you use ASA 100 film, the meter will STILL assume its 25-40 and all film will be overexposed by about 1.5 to 2 stops. The fix is to select proper calculated ASA and then close iris by 1 to 2 stops. The exact amount will depend on light available. 

A better option is to use a light meter made specifically for cinema (motion picture) cameras, such as the Sekonic L-398. The film's ASA, metered light, shutter angle and FPS are pre-calculated by the meter to give the iris opening as an lens F-stop. Just dial-in the calculated number on the lens.

Given the cost of film and developing, this is the safest option. Used L-398 meters can be found on eBay for $75 and up. Click this link to download the manual:

           http://www.sekonic.com/downloads/l-398a_english.pdf

3) The film was processed incorrectly. Not very likely, but it does happen. Because 8mm processing uses chemicals, exposed film is typically saved until there is enough film footage to process economically. Maybe a week or two (or more). Then the chemicals are mixed fresh and ALL the processing is completed.

The chemicals once used don't stay fresh for very long and must be discarded. Not sure? Ask the people processing the film:

     A) What is their policy regarding processing chemicals, 
     B) Are the chemicals fresh?, 
     C) Do they send the processing out to an outside vendor? 
     D) Do they process in-house?

I recommend buying fresh film and if possible, have the seller do the processing. Not everybody sells AND also does processing. See the link below for film sources and processing:

            http://www.bolexrepair.com/links.html

4) If the film failed to go through the camera, it will not be exposed. When developed, the film will develop as black.

EVALUATION

If you are not sure which service is necessary or if the camera even needs to be serviced, we will evaluate your camera for a flat fee of $45.00 (includes return shipping and insurance, USA, only) and notify you of the camera's condition and any cost for repairs.  

The $45.00 fee also applies to any work to be done. In the event that no work is done beyond the initial evaluation, we will return the camera postpaid and insured along with a written estimate of the camera's condition and a recommendation of any work necessary to return the camera to operating condition.

BOLEX L8 LENSES AND ADAPTERS

A customer writes: "I need the correct adapter to use with my antique Bolex L8 8mm camera. Can you help?" I have to answer, sorry - no. The adapters are quite rare. However, they do show up for sale on eBay, occasionally. You may however, have to buy a complete camera to get the adapter :(  

Fortunately, the cameras are NOT a popular seller, so the price may be affordable. Be sure you verify with the seller that camera comes with adapter.

I just looked on eBay (old and new sales). Of the 2 cameras I saw for sale, neither had the LUGOM adapter, although BOTH had D-mount lenses! So both were not usable for filming. Also, you can occasionally surf the net searching for the word: 

             LUGOM

A lot of L8 cameras were sold in the UK, so you may find a camera dealer/ebayer selling a LUGOM adapter.

L-8 RING ADAPTOR FAQ

(from: http://www.bolexcollector.com/accessories/filter50.html)

"This was a D-mount lens mount adaptor for use with L8 cameras. The L8 cameras used a non-standard lens mount. Although the thread diameter was similar to a D-mount (5/8" or 15.8mm), the setting was different (0.3075" or 7.8mm). The L8 Ring Adaptor (LUGOM) allowed normal d-mount lenses to be used by increasing the setting to 0.484" (12.29mm).

 It was simply attached to the lens mount; the desired d-mount lens was then screwed into the adapter. Although they're not rare, they seem to be difficult to find. It can be identified by the word "L8" stamped on the side of the ring."

COLLECTABLE

The L8 is collectable if only given the fact that it is a Bolex. The camera is very complicated internally. So much so, Bolexrepair.com services them by quote, only. Other, later 8mm Bolexs are typically the same internally and are much easier to service. The L8 is the "oddball". The need for a lens adapter didn't help, either.

Bolex 8mm cameras typically use a prime mount which takes a "D-mount" lens. Most D-Mount lenses will fit and work. Bolex sold 2 brands of their own: Yvar and Switar. Switars are the premium lenses. Both are difficult to clean and reassemble and, as necessary, collimate (align) the lens. Collimating a lens will most likely NOT be possible, so sometimes the only fix for a dirty Bolex lens is to replace it :(

OTHER USABLE LENSES

Elgeet brand 8mm D-mount lenses are very nice. USA made with stainless steel bodies, these lenses fully disassemble to allow complete cleaning.

Japanese Yashica D-mount lenses are the same thread and focal size. However the body diameter is slightly larger and they can interfere with each other in multiple lens configuration. The L8 has only one lens mount, so the Yashica lenses will most likely work. 

The cost for lenses in very low compared to the high quality.  Typically a 3 lenses Yashica 8mm camera is about $25 to $50.00+ on ebay.

LENSES LIMITING FACTOR

The limiting resolution factor of any 8mm lens is the film grain. All film has "grain" from the silver halide crystals used in the manufacture of film. The crystals are the same size, but are more noticeable as the film size goes down. 8mm film stock is cut from 16mm film stock which is cut from 35mm film stock. The sprocket holes are re-punched as necessary. 

Because of the grain of 8mm film, lens manufacture becomes less critical and/or noticeable. The grain could "cover up" lens deficiencies. Small imperfections in the form of microscopic air bubbles in both camera and projection lenses is common and not visually noticeable when projecting onto a screen. This is very different as compared to 16mm and 35mm lenses image quality (IQ) is "King". Cost is a factor, also. Better lenses cost more money. The Top-of-The-Line Switar f/0.9 lens sells for $300-$500, today!

  

FIXED FOCUS LENS

A large number of Elgeet lenses are designed to be "fixed focus". Regardless of where the iris is set in these lenses, the image will always be sharp.Easy to set and use. Just meter the scene and dial in the required f /stop.

OBSERVATION

8mm lenses choice seems to be based on: 1) the finished film look and/or 2) the ability to clean the lens elements. I prefer Elgeet lenses (fixed focus or with focus ring). Some people prefer Bolex original lenses (Switars and Yvars). Some like a particular lens just because it "looks cool".