Digital Photography With Flashbulbs

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Flashbulbs and Digital Photography

by Bill Storagephotos by Bill Storage & Laura Maish

updated July 20, 2006

Why Flashbulbs?

Even tiny miniature-base flashbulbs emit far more lightthan most electronic flashes. This makes them attractivefor a few special artificial lighting situations. Cavephotographers like their high output and their long burntime, which adds an appealing blur to moving water.They are also useful for places where studio strobes aren'tpractical, such as certain outdoor situations, and wherestrobes would be destroyed, such as in destructive testing.There is also some degree of nostalgia centered aroundHollywood glam shots of the '40s that has resulted in thestrange belief that bulb lighting produces a certain look

that cannot be achieved with strobes, e.g. Bill Cress'claim that because bulbs ignite and burn from the centerof the bulb, they produce more intense light in the centerof the image plane (which he curiously dubs a "halo").This is utter baloney. Everyone is entitled to their ownopinion, but not their own physics. The lookof light is afunction of its size (softness), duration, direction andcolor. The '40s glam look resulted from reflectorcharacteristics and a very low depth of field; and the mythof its resulting from the magic of bulbs stems in part fromthe marketing materials of flashbulb dealers.

Photo 1 - Lechuguilla Cave Passage lit by three M3B flashbulbsmanually triggered; no tripod.

The flashbulb mystique has resulted in the hoarding of some very old screw base bulbs. I bought small quantities of them over

the past 20 years from estate sales; and purchased a few boxes recently on EBay. Over the past year, we (Laura and I) attemptedabout eight photo shoots using large bulbs, and detected what seemed to be a large variation in the light output of batches of thesame type of bulbs. We also found we had a lot of duds that wouldn't fire in a 4.5 volt Graflex gun, in Honeywell 9 volt guns,or in Ron Simmons' custom-built waterproof 22 volt guns (see Photo 6).

Digicams with Flashbulbs - the Dilemma of High/Low Tech

Flashbulbs take a surprisingly long time to ignite and reach maximum brightness. In the old days, cameras had several settingsfor delaying the time between hitting the shutter button - which started the ignition process - and opening the shutter. As bulbtechnology progressed, cameras accommodated the delay for bulb ignition by adding "M" and "FP" synchronization settings,corresponding to delays of roughly 10 and 20 milliseconds. FP (Focal Plane) bulbs were designed to allow high shutter speeds,(above the camera's "sync speed") the faster shutter speed during which the window onto the film plane is completely open (asopposed to a slit between two curtains traveling across the film plane - see Figure 1, FP Sync at 1/250).

FP bulbs effectively waste bulb output; much of the bulb's light is

striking the curtain blocking the film plane. Consequently, someFP bulbs have huge total light output, making them attractive forsituations that need a lot of light, such as big rooms in caves.

Since flashbulbs have not been in general circulation for severaldecades (one manufacturer, Meggaflash, still exists), modern filmand digital cameras tend not to have M and FP synchronizationsettings. This means that a digital camera must use a shutter speedequal to the sum of the times needed to catch the full burn of theflashbulb plus the ignition delay for that bulb (Figure 1 - Digital1/20). In mixed-lighting scenarios, this increases the likelihood ofblur, either from subject motion or camera motion.

Most digital cameras are designed to emit, either through a small

on-camera flash or through an attached flash unit, a so-called "pre-flash". This small burst of light that the camera uses to set focallength, aperture, white balance and/or main flash output occursbefore the camera's shutter starts to open. Unless the pre-flash canbe switched off, as it can on many newer digicams, it prevents the

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09/02/2010http://www.bstorage.com/speleo/bulbs/


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Photo 2 - Black Chasm lit by three flashbulbs - a No.40B on astand near the camera, an M3B above the man on rope, and anM3B in a Simmons flash held 6 inches under water. Three WeinUltra slaves fired the bulbs simultaneously, initiated by an on-camera electronic flash with black electrical tape over its head.ISO 200, f/11, 1/30 sec.

use of optical slave triggers unless the slave has a correspondingdelay. Several such "digital slaves" have emerged as aconsequence. With many digicams, you can also attach a low-techmanual electronic strobe to trip slave sensors, but beware thatdigicams are reported to tolerate only low hot-shoe voltages, somany flashes cannot be safely used in this manner (see hot shoevoltage links and discussion below).

While camera makers do not publish the pre-flash to main flash(pre-flash to open-shutter) interval, experimentation withflashbulbs and our Canon cameras suggests that it iscoincidentally about the same as the FP-synch delay in older filmcameras. Therefore, you can leave the pre-flash on, and reduce theshutter speed by about 20 mSec, and still catch more than 90% ofsome FP bulbs' output.

Unfortunately, our testing showed a wide range in delay values for different FP bulbs. Initially we thought that different models(e.g., No.3 vs. No.31) had greatly different sync delays. Further testing revealed huge variations within different batches from aspecific type and manufacture (here "batches" means groups obtained from different sources with apparent similarity within agroup, not manufacturing batches or lots). Sync delays of most batches of old bulbs that we tested were far greater than thatspecified by their manufacturers - some exceeding one second. Apparently, loss of contained oxygen through the bulb base overthe years leads to slower ignition. More on this below.




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Scenarios for Flashbulb Use

Figure 1 - Sample burn curves for electronic flash (strobe) and several types of flashbulbs, including open-shuttertiming and duration for several sync settings. Black/white rectangles indicate closed and open shutter at 5 mSecintervals. Note partially open shutter when shutter speed exceeds sync speed (e.g. 1/250 FP). Based onmanufacturers' info, our testing, and Popular Photography's Photo Information Almanac '84.

Caves are no doubt the most common subject of flashbulb photography. Since caves lack common visual clues of space, suchas converging parallel lines and landmarks of known size, backlighting is commonly used to enhance the perception of depth.Backlighting also avoids the fog effect caused by light from a flash reflecting off mist between the camera and subject. Cavers,for whom equipment size and weight is critical, are remarkably adept at shooting backlit shots with multiple bulbs, noelectrical/electronic synchronization and no tripod. Impossible, an outsider might think. But in a dark chamber, bulb-firingcavers have learned to fire their bulbs with amazingly small time intervals after seeing a first flash go off. The photographeropens his shutter (on the B setting), calls "fire", sees a flash, and releases the shutter. The shutter may be open for half a second,but the opportunity for a blurred image exists only in the interval between the first and last flash, provided stray light fromheadlamps is eliminated. The shot of Lechuguilla Cave (photo 1) used this technique with three flashbulbs. The interval wasperhaps 1/10 second. Any camera movement during this time was masked by the fact the intersection of the exposures fromeach of the flashes is relatively small and is in a dark or uninteresting part of the photo.

Despite the relative weakness of portable electronic flashes compared toflashbulbs, modern film and digital cameras are sensitive enough to allow

use of electronic flashes for many cave shots. But output isn't a bulb's onlyadvantage however. Cavers benefit from the fact that bulbs emit light inall directions. They can use partial reflectors, vary the distance from thebulb to a reflector, or use no reflector at all to control where the light goes,and to control the transition from light to dark areas of a picture. A few"bare bulb" electronic flashes can do this, but their domes tend to be ratherfragile.

Finally, one aspect of bulbs usually seen as a weakness, burn time, oftenturns out to be an advantage for cave photos. When raging torrents areexposed for a few thousands of a second (the duration of an electronicflash), their motion is unnaturally frozen. The 1/30 second burn durationof an M3B bulb gives the appearance of motion, as seen in photo 3, a shotof me on rope in Cueva de Agua Carlota, Mexico, by Jim Smith.

Big screw base bulbs are attractive for shots of very large cave chambers.Their output-to-volume ratio is lower than that of small bulbs, but it isoften impractical to fire a large number of small bulbs. For impressivebig-room shots and discussion of technique, see the sites referenced at the




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Testing Flashbulb Output and Reliability

Photo 3. Moving water effect of long exposure(James H Smith photo).

end of this article.

Mixed light photos can also require high output flashes. The model in photo 4 is primarily lit by diffuse daylight. That meantthat we had to use a small aperture, in order to properly expose the model with an exposure time slow enough to catch the burnof two large screw base bulbs. A small aperture was also needed for depth of field; the far wall, seen above the model's head, isabout 100 feet into the cave. At f/11, we needed very bright bulbs.

A No.31B bulb with a Graflex 7 inch reflector is 30 feet directly infront of the model, 2 feet above the water. 80 feet directly in frontof the model is a bare No.31B bulb a foot above the water. Bothbulbs are aimed directly at the camera, but are obscured by themodel. Small flashlights attached to the light stands allowalignment of both bulbs and the model. Front light is diffusesunlight and an electronic flash to illuminate the model's legs fromthe knees down, which was in shadow (note uncorrected slightbluish cast on calves, and sharp shadow beside right leg). Theelectronic flash also triggered the Wein slaves attached to the bulbguns. Our favorite slave is the Wein Ultra. Smaller Wein slaves areless sensitive. We bought two Firefly slaves, also very sensitive,but found their reliability and durability to be poor.

The slaves worked a bit too well, occasionally firing when ripplesresulting from our walking in the water beamed sun rays into thecave causing misfires. The big bulbs were another story. About tenconsecutive No.22 bulbs failed to fire (details below). This shootinvolved difficult logistics (travel, hotels, assistants). While caversmight think shooting nudes underground would be the best of alljobs, unrelenting equipment problems can be quite stressful,especially when the model is paying for the shoot, and has toarrange travel to the site.

Flashbulbs can also be attractive when studio strobes just aren'tfeasible. We shot a series of pictures of San Francisco's vintagestreet cars and cable cars for Market Street Railway, the non-profit

preservation partner of the San Francisco Muni System. Fordramatic effect, many of the shots were at night. We used bulbs tolight all or shadowed parts of some of the cars. Without thebacklighting on the side of this street car, the shot really lackeddepth and interest. Many other rail car shots are also on ourwebsite (links below).

Photo 4 - Lighting test for an underground model session.ISO 100, 1/15 sec, f/11.

Photo 5 - Rail car backlit by No.50 flashbulb (just out of view at right rear) ISO 200, 10 sec, f/5.6.




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Since modern flash meters cannot measure the output of bulbs accurately, we chose to measure only their output relative toeach other (or a baseline bulb) by comparing brightness of images recorded by digital cameras. To do this we wrote a computerprogram that calculates the average brightness of an image, allowing the user to define upper and lower brightness thresholds tobe included in the calculation. We set the lower threshold to a high enough value that with low ambient light, dark portions ofthe image would not be counted in brightness measurement. This covered the possibility that the image was larger than the arealit by the flashbulb. The program also warned us if part of the image was overexposed, having a brightness equal to themaximum value possible in a digital image, thereby resulting in an invalid comparison. We varied the threshold values for avariety of flash tests, confirming that the evaluation was not sensitive to changes in the threshold setting between 0 and 10percent of the maximum brightness value.

In photo shoots, we used about fifty Number 50/50B bulbs with only a few duds and non-fires. We opened a second, muchfresher-looking box of No.50s for the below tests. Eight of the eleven bulbs we tried from this box did not fire at all. Theprevious owner reported that he had stored them in a dry basement since the mid 1950s. They showed no rust or mildew.

We shot thirty No.11 and No.40 bulbs with a no-fire rate of about 10%. We used twenty-three No.2As consisting of 10 shots oftwo bulbs each with two misfires and one bulb that broke lose from its base, before sensing that their output was way underwhat it should be. At this point we began the controlled testing, experiencing a somewhat higher rate of non-fires, as shown inthe data below. We also shot twenty-four GE No.31 (Class FP) bulbs with good results, but retained none for testing. FP bulbsare discussed below.

Photo 6 - Motion of a vintage trolley is partially frozen by a single No.2A flashbulb. ISO 100,f/11, 1/2 second.

The most reliable and highest-outputbulbs we found came from a batch of

Westinghouse Number 22s. Of tenbulbs in a second batch of Number22s, this time from GE, none wouldfire with 9 volts. Screw base bulbsexpected to put out more light than aNumber 22, including No.3, No.3S,No. 2A, No. 50 and No.3B, all showedhuge variations in their output. A fewseemed to burn for the better part of asecond, burning much longer anddimmer than expected. None of the bigbulb types had a higher output than ourgood batch of Number 22s. Thesuperiority of this batch of No.22sundoubtedly owes much more to the

storage conditions of that particularbox of bulbs than to any inherentsuperiority of the Number 22 type or toWestinghouse manufacturing.

The results of these tests were far worse than we anticipated. In addition to the high failure (non-fire) rate, we found most of thebulbs to be weaker than expected in comparison to the good batch of No.22s and to all brands of miniature base M3/M3Bbulbs. Note that while we did not attempt to measure absolute output of any bulbs, the relative outputs of No.11 and No.22 andthe much younger M3 and M3Bs is exactly as expected based on the manufacturers' data. This finding tends to validate ourtesting methodology. Our No.22s average output was 1.5 stops greater than an M3. No.11s were 1/2 stop greater than M3s andblue M3Bs are 1/2 stop dimmer than M3s. Our testing also shows that M3 bulbs are vastly superior to all screw base bulbs interms of light output per size (volume) or weight. Their reliability is also much higher; we have fired hundreds - maybe

thousands - of M3s in caves with only a handful of failures.

We also evaluated relative light output, within a bulb type, at different exposure times. Manufacturers' data states that class Mbulbs (M3, No. 11, No.40, and No.22) reach 50% power at 12 milliseconds (ms) and have a duration above 50% power lasting15 milliseconds. Using a baseline of 1/15th second, we found the M3s to be down 1/4 stop at 1/30th and down 2/3 stop at1/40th. Thus, M3s can easily be used at speeds up to 1/40 second. No.11s, however, based on a small sample, seem to be down1/2 stop already at 1/20th. Significant differences exist between burn curves of M type bulbs.




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Photo 7 - Bulb flash equipment:A Graflex 3 D-cell flashgun with 7 inch reflector with household connector socketB Honeywell Tiltamite flash with 5 inch folding reflector (bayonet, miniature) fitted with RCA connectorC Waterproof Simmons flashgun with 4 inch polished reflector (miniature only) with RCA connector

D Bayonet-screw base adpater, allows Tiltamite to fire screw base bulbsE Firefly 2 slave unitF Wein XL8 slaveG Wein Ultra WP-SSL slaveH Household to RCA converter/extension

S-type bulbs (No.50, No.2A, No.3) are reported to reach mid power at about 19 milliseconds, and have a duration above 50%power of about 30 milliseconds. While we would need to test more class S bulbs to be conclusive, it appears they were downwell over 1/2 stop at 1/30th second.

We found a wide discrepancy between manufacturers' data and claims made by enthusiasts about the burn curves of class FPbulbs. A contributor to an online discussion forum reported that some FPs have a half peak duration of 27 milliseconds, while

the GE No.31 has a duration above 50% power of about 53 ms. In photo shoots, we found that we could use No.31 bulbs withthe Canon electronic flash in pre-flash (labeled ETTL sync in the below test data), thereby allowing us to shoot the large No.31bulbs at a relatively fast shutter speed of 1/25th. Unfortunately, we retained no No.31 bulbs for lab testing. We did test the pre-flash (ETTL-sync) arrangement with Class S bulbs, and found their output to be unacceptably low, due to the open shutterbeing out of sync with most of the bulb burn.




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Test Data

After having fairly good results with one batch of No.3B-S bulbs, we tested six bulbs from another batch of 100. These werethe newest looking bulbs and boxes we had seen. We mounted one in the test gun, a Graflex 3 D-cell unit, connected the slaveand opened the shutter. When it didn't flash I went to remove the bulb from the gun and it went off as I touched it. "Badconnection", I thought and set up another. When the shutter opened, the second bulb didn't fire either. I took a step toward theflash unit, but didn't touch it, and it went off - well over one second after the shutter. The next four bulbs behaved the same.With a 2-second exposure, I finally caught the output of the 5th test on "film", and found it to be a bit over one stop below itsrated output. The 6th bulb fired with 120 volts, but I didn't meter it.

Conclusion

While the quality and available quantities of small flashbulbs (e.g., M2, M3) will support years of bulb photography, the futureof big-flashbulb photography appears fairly dim. While some enthusiasts report good luck with bulbs and only an occasionaldud, we found screw base bulbs to be generally not reliable enough for critical shooting. We carried an entire box to a fairlyremote location only to find that almost none of them would fire. We also found that the largest bulbs seem to have lost muchof their output and to ignite and burn more slowly than they did when they were new, more than fifty years ago in some cases.In addition to the cost associated with big bulbs that fail, the risk of a failed photo shoot (travel, hotel, etc.) seems just too high.The outlook for small bulbs seems much brighter. Finding M3 bulbs only 1.5 stops dimmer than large screw base bulbs, thepossibility of building bulb guns that can fire several miniature base bulbs simultaneously is very attractive. The M3 bulbs arealso suitable for more types of photography, being usable at shutter speeds (X sync) up to 1/40 second.

Update July, 2006

Diana Gietl and I have recently had some good results using inexpensive radio transmitters and receivers to trigger flashbulbguns. These work well in some situations where optical slaves fail, such as back-lighting setups where the subject intentionallyshields a foreground gun from a strong flash aimed toward the camera. While their range is good (~100 feet) in open terrain,they do not work well in sinuous passages, which apparently absorb or deflect the radio waves dramatically. We found that acombination of optical and radio receivers was useful

Bare vertical bulb (1/20 sec) comparison of M3 and screw base bulbs to establish relative brightness of M3 and screw basebulbs

f/16Bulb type Sample number

Stops different from baseline

M3 Sylvania 1 0 - baselineM3 Sylvania 2 -0.15M3 Sylvania 3 -0.04

No.22 GE 1 -0.19No.22 Westinghouse 2 1.52No.22 Westinghouse 3 1.44

No.11 GE 1 0.55

No.40 GE 1 0.37No.40 GE 2 0.75

ConclusionsAverage good No.22 is 1.48 stops brighter than M3(1)

Average good No.22 is 1.42 stops brighter than average M3

No.11 is .49 stops brighter than average M3Average No.40 is .60 stops brighter than average M3

Notes4 No.11s would not fire with 9v2 No.22 GEs would not fire with 9v

Graflex 3D w 7 inch reflector comparison of screw base bulbs to establish relative brightness of screw base bulbs f/22

Bulb type Sample number Ex time Stops different from baseline

No.22 Westinghouse 1/15 0 - baselineNo.22 Westinghouse 1/25 -0.10




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Links

No.22 Westinghouse 1/30 -0.408/8 No.22 GEs failed to fire.65 Westinghouse No.22s remain in batch.

No.3B Sylvania 1 1/20 -0.34No.3B Sylvania 2 1/20 -0.28

No.3 Sylvania 1/10 0.33No.3 Sylvania 1/20 0.20

No.3 Sylvania 1/30 -0.51No.3 Sylvania 1/30 ETTL sync -2.86

No.2A Sylvania 1/10 -0.16No.2A Sylvania 1 1/20 -1.04No.2A Sylvania 2 1/20 -0.60No.2A Sylvania 3 1/20 0.16One other No.2A from this batch did not fire with 4.5v. No.2A(1) glowed yellow for at least a second after firing.

No.3S Sylvania 1/20 0.16No.3S Sylvania 1/30 ETTL sync -1.90No.3S - batch 2 5 bulbs with > 1 sec rise time couldn't measureNo.3S - batch 2 6 2 seconds -1.20

No.11GE 1/10 -0.97No.11GE 1/15 -0.96

No.11GE 1/20 -1.43No.11GE 1/25 -2.874 of 8 No.11s failed to fire with 4.5v.

No.50 GE 1/30 -1.84No.50 GE 1/20 -0.07No.50 GE 1/20 ETTL Sync -1.448 of 11 No.50s failed to fire with 4.5v.41 bulbs remain in batch.

Observations & Conclusions

No.3 is 1/2 stop brigher than average No.3B at 1/20 (note color difference)

Average No.2A is .18 stops darker than No.3B at 1/20 (note color difference)

No.11 is 1.0 stops darker than No.22 (as it should be according to manufacturer info)

Westinghouse No.22 has same brightness at 1/20 as No.50 GE

No.3 (all varieties) requires 1/20 second exposure, except batch 2 of No.3S, which required over one second

All screw base batches except No.3Bs, No.22 (Westinghouse) and No.11s show significant variance between samples

Westinghouse No.22 can be shot at 1/30. All others require 1/10 to 1/20

No.11s seemed to have retained their strength but require a longer exposure (maybe they alweays did - i.e., maybe they are as new)

M3 shutter speed and brand comparisonBulb type Sample number Ex time Stops different from baselineM3 Sylvania 1 1/15 0 (baseline)M3 Sylvania 2 1/15 -0.12M3 Sylvania 3 1/15 -0.06

M3 Sylvania 1/25 -0.03M3 Sylvania 1/30 -0.20M3 Sylvania 1/40 -0.67M3 Sylvania 1/50 -1.06

M3 GE 1 1/15 -0.14M3 GE 2 1/15 -0.05M3 GE 1 1/25 -0.13M3 GE 2 1/25 -0.20M3 GE 1/30 -0.28

M3B 1/25 -0.47M3B 1/30 -0.69M3B 1/40 -1.23




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Flashbulb suppliersCress Photo http://www.flashbulbs.com/index.shtml - also has a lot of bulb output infoCole's Cameras http://www.colescameras.com/flashbulbs.htmEBay - Search on both flashbulbs and "flash bulbs"

Flashbulb manufacturers - one still exists:Meggaflash http://www.meggaflash.com/ - your only option if you want big bulbs that haven't weakened over the years

Flashbulb usage and general info

Christopher Anderson'sDarklight Imagery http://www.darklightimagery.net/flashbulbs.html - great cave photos tooBob Biddix's Innermost Gallery http://www.innermostimagery.com/camps/campsarticle.htmDavid Brittain's Flashbulb info http://dlbrittain.com/FlashCollect.htmGraflex Site http://www.graflex.org/ - Graflex enthusiast site with good info on flashes, including links to Graflex instructionmanualsUnderground Photographer Flashbulb Resource http://www.dhios.co.uk/archives/flashbulbs/Popular Photography 1954 article on the new M2 flashbulb http://www.popphoto.com/assets/download/1162004154246.pdfDiscussion of bulb output and cave usage http://medfmt.8k.com/mf/flashbulbs.html

Hot shoe voltageWhile using these links, note that David Gibson, a reliable source on flash technology, stresses that the high voltage present on aconventional flash circuit is usually at a very high impedance. Unless you measure this with a meter that has an even higherimpedance, the reading you get could be very wrong. See more from Gibson at http://www.caves.org.uk/flash/docs.html

Strobe trigger voltages http://www.botzilla.com/photo/strobeVolts.htmlVoltage-protected sync cords http://www.paramountcords.com/vp.htmWein Safe Syncs http://www.weinproducts.com/safesyncs.htmNon-dedicated flash with Digital Rebel http://www.covingtoninnovations.com/dslr/EosFlash.html

Night/street car photos of San Franciscohttp://www.bstorage.com/photo/US/CA/SF/Night/http://www.bstorage.com/photo/US/CA/SF/Night2/

Cave photography tutorialDave Bunnell's Virtual Cave http://www.goodearthgraphics.com/virtcave/cave_photography.pdf

John Ganter assisted with testing and provided information used in this article. Bill Prewitt provided technical advice and producedseveral delay circuits used to test pre-flash intervals.

Text and graphics copyright 2005 by William Storage. All rights reserved. Caching in search engines is explicitly permitted. Please link to this page rather than reproducing copies of it. This

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