Back Up Camera Power Supply (Proof of Concept Model)
When recording long video sequences, animation or time lapse the last thing you need is the battery to suddenly shut down the camera as it becomes fully depleted. The use of an external power bank and step up converter to give 8.4v is a great solution provided that the power bank has enough capacity for the expected duration of the filming. I thought of a "hot-swap" power supply whereby the power bank would primarily be providing the main power to the step up convertor to give the 8.4volts but also would provide a floating charge to an inbuilt 1200mAH li-ion battery in the unit. Thus when the power bank becomes depleted the internal li-ion battery would then be providing a continuous 8.4volt to the camera. The depleted power bank could then be replaced during this period. One plugged in to the on-board step up converter the 9v provides 8.4v by means of a series connected silicon diode which typically drops around 0.6v. The 8.4volt the "tops" up the li-ion battery (the internal charge circuit will limit the current and than allow the battery to float) and continues to power the camera.
So far the solution has worked without any problems and I will be building it into a suitable project box to ruggedize it.
Below is the basic schematic and the proof of concept board.
A New Style Battery Box From Some Amazon Retailers
I am indebted to Ernie Smith of the USA who alerted me to a different type of dummy battery box that he had received. This new type appears
to accommodate both the bottom and side entry camera cable inputs.
Ernie machined out a hole in the side of the dummy battery box to establish what the pcb was like as it didn't appear to want to split as with the method (detailed lower on this page) I had described for the older style dummy battery box.
This is the hole machined out of the side wall of the new battery box with the new 10K resistor fitted.
To solder the resistor in place was quite as challenge:-
quote Ernie ; after I finally got the “T” pad tinned I measured the distance between the PCB connections, then I shortened the resistor leads, bent them 90 degrees and
here is the dimensions to cut out the hole in the side wall.
The positioning of the 10K resistor within the battery box/pcb
After milling out a slight rebate to the hole Ernie then infilled the hole with a piece of plastic card.
This is the interior of the new battery box which I managed to split by applying quite a bit of force to separate the two "wings" of the box. This fractured the ultrasonic welded seams.
This is the pad to which the 10K 1/8th watt resistor should soldered between it and the black lead pad.
Battery Eliminator for Olympus OMD Cameras using the BLN-1 Lithium Ion Battery
There doesn't appear to be a commercial dummy battery box for the BLN-1 battery used in Olympus cameras like the OMD-EM5 II so I made my own by de-constructing a third party (DTSE) battery and using a USB to DC-DC converter set to give an output of 7.6V
This is the completed battery box with the connecting cable installed onto the PCB of the battery. The lithium ion battery has been removed.
Carefully split the battery case using a sharp knife and then lift out the cells.
One at a time cut the three connections to the cells (don't cut the two + and - wires together as you will cause a dead short on the battery - it might not end well!)
This is the pcb where you will make the positive (red) and negative (black) connections to the indicated points on the PCB
Drill a small hole in the base of one of the battery shell halves to allow the cable to pass through. A suitable cable and female socket should be used.
Whilst it is not possible to close the battery door if you are using this on a tripod then an "Arca" plate will probably allow tripod mounting and the battery door open vertically.
With the USB dc-dc converter set at 7.6v the green battery full indicator shows on the LCD screen
As the voltage is reduced the red battery low warning icon appears at 6.93 volts
As only two wires are needed with no additional electronics this is an easy modification and any dc-dc boost converter capable of about 1A output will be sufficient
Adding Battery Level Indication to Panasonic Dummy Battery Boxes DCC8 and DCC12
For GH3/4/5 using the BLF19 battery andFZ200/300/330/1000/2000/2500 GX series and some G series cameras using the BLC12 battery.
Most of the generic dummy battery boxes are supplies with AC wall adaptors outputting 8.4v. This voltage is sufficient for the camera to operate however it does not give an on-screen indication of the voltage and moreover it limits the use of the battery box to power solutions like USB to 9v converters etc. If standard lithium ion batteries are connected at a full charge status of 8.4v then the camera will shutdown at about 7.2/7.3volts thus you are not getting the full charge potential of the cell. In this video I show you how to modify the DCC8 and the DCC12 battery boxes used in the FZ/GX and GH3/3/5 series of cameras.
I show how a standard 2S lithium ion battery can then be used to provide full capacity to the camera. Additionally if you use a SB power bank and a DC-DC converter solution you can drop its output to 6.5volts. This means that the power input to boost the 5v to 6.5v is far less than if the converter had to boost it to 8.4v. The converter is more efficient, runs cooler and you will get more run time from the power bank.
The DCC12 battery box used to replace the BLF19 battery
The case can easily be opened by inserting a sharp knife blade at each of the four corners and gently prising the seams apart
The modification consists of soldering a 10K resistor (brown, black, black, red colour code) between the -ve terminal and the "T" terminal. Use a small 1/8 watt device.
Once soldered the case can be re-assembled with a dab of super glue to secure it again.
For the DCC8 box the soldering is a little more delicate but achievable with care and a small tipped soldering iron.
The generic DCC8 dummy box used with many mains converter solutions
Again the case can be opened with a sharp knife blade inserted at each corner and gently prising the seams apart
The pcb used is probably from a battery manufacturer and merely provides connection to the + and - terminals.
Remove the PCB by lifting off the hot melt glue.
The connection to the "T" terminal is at the third pad from the bottom left hand side.
Apply some solder to tin this connection before attaching the 10K resistor between this pad and the Black lead on the -ve terminal
Here the 10k resistor is soldered between the pad and the -ve terminal.
Re-assemble and glue the case again using super glue.
USB POWER BANK POWERED CAMERAS AND THEIR FAILURES
I've been spending a lot of time investigating and building my own USB power bank dc-dc converter to power Panasonic cameras.
I have found that most of the commercial units are good for 1Amp intermittent operation and are thus suited to video recording or continuous shooting with the electronic shutter selected. If you select the manual shutter and burst mode the power bank & converter cannot keep up with the demands made upon them and the camera often resets or freezes - the only way out is to remove the USB power lead at this point.
This then begs the question whether there is such a solution to this current demand. The FZ1000 seems to be OK but the FZ2000/2500 suffers this problem.
If you are running your Panasonic camera (or any other DSLR/Mirror-less camera) which was designed for using the 7.2volt lithium ion battery and using a dummy battery box with a 9v power supply then you may be overstressing the camera and may cause premature failure of the camera power supply.
Some 9v power supplies have a tolerance in the specification of 1 volt so you could in fact have a power supply which is nearer 10volts than 9volts thus stressing the camera even more so. There is likely to be a slight voltage drop to the camera by the very nature of the connecting cable and connectors and this may be in the order or 0.5 volts depending upon the load taken by the camera. When the camera is idle the current drawn is only about 300mA so the volt drop on the cable is low so the higher voltage will appear at the camera dummy battery terminals.
A safer way is to use the forward voltage drop of a silicon diode to drop the voltage by about 0.6volts without any current compromise.
Here's how to construct a suitable connection socket and plug to achieve this. The diode a GP150 (general purpose 1.5A diode or use a 1N54 series diode) connected in series between the input and output. The cathode (ringed end of the diode) goes to the output
Here's the completed unit with a couple of plug shells over the connectors to add mechanical strength.
A better idea if you cannot solder this small component pack is to build the diode and a 104pF capacitor and a 100uF 10v capacitor into a box. The output of the diode is connected to the 104pF and the 100uF capacitor to a common ground.
This capacitor network helps to smooth out some of the switch mode power supply "noise" making the input to the camera both safer and cleaner.
Such a project is shown below.
Here the unit uses the same 5.5mm x 2.1mm input and output but it could be fitted with the 4mm x 1.7mm plug and cable for Panasonic DCC coupler units.
This is the pcb from the Qutaway product. The case is easily removed by inserting a sharp blade at each corner and prising the two halve apart.
on the left is the input from the USB plug and on the right the output cable.
We are going to add a series diode in the red output lead to drop the 9v to 8.4v as shown below.
Note that the adaptor featured here will support video recording or burst mode with electronic shutter and single mode shooting with the mechanical shutter operative otherwise the camera demands too much current and resets when used with the FZ2000/2500, on the FZ1000 it is OK.
Here you can see the addition of the GP150 silicon diode (or a 1n54 series diode) connected in series with the red lead.
De-solder the red lead from the pcb, insert the diode with the anode (plain end marking) to the pcb and then connect the red cable to the cathode (ringed end) of the diode.
Ensure the diode is clear of the pcb when installed.
Re-fix the covers and add suitable marking to the unit to designate it now to be 8.4 volt output.
The completed unit.
Amazon link for module
Amazon UK http://amzn.to/2w34ZW5
Amazon USA http://amzn.to/2u1w52s
The FZ2000/2500 being powered by a modified 5v USB to 9v dc converter unit (amazon UK http://amzn.to/2w6Oibi amazon USA http://amzn.to/2eTt11G amazon Canada http://amzn.to/2v4iFCw)
Note that the adaptor featured here will support video recording or burst mode with electronic shutter and single mode shooting with the mechanical shutter operative otherwise the camera demands too much current and resets when used on the FZ2000/2500 camera. It appears to be OK on the FZ200/300/330 and FZ1000.
These units provide a well regulated 9v output however with the addition of a series 1N series diode like the IN4007/1N4001 the voltage will be reduced by up to 1v bringing it within the safety voltage limits of the camera
By opening the plastic shell using a thin knife blade inserted at each corner of the unit and then de-soldering the red output lead and inserting and soldering in the diode with the cathode (ringed end) facing the red wire the unit will perform reliably from a power bank with a genuine 2A output port,
Generally these are fitted to the higher capacity units.
If the power bank cannot provide a continuous current of 2A then the camera may not power up, shut down on zoom or recording video)
With the diode in place the unit can deliver the 8.4 volts needed by the camera (7.9 volt lower limit).
It has a conversion efficiency of around 75% in my full load tests.
Depending upon the camera model the 8000mAH power banks should last for about 10-12 hours for the FZ200/300/330 and 6-8 hours on the FZ1000/2000/2500
To connect to the DM -DCC8 dummy battery you will need to adapt the 2.5mm male plug by use of the 4.0mmx1.7mm Male to 5.5mmx2.5mm Female Jack DC Power Connector shown opposite
USB Power bank 8.4v convertor for Panasonic Cameras.
After a lot of testing different dc-dc boost converters that are commercially available I have now chose the board that will be used in this project.
These boost modules typically can change the input voltage by a factor of up to 10 times. In theory that sounds fantastic, in practice however, the story is a little less so and here's why!
These units work by the same principal that the ignition coil in your car works. If you "break" an inductive circuit you get a very high voltage appearing across it. This is harnessed in these converters by using a high efficiency diode to charge a small capacitor. As this switching occurs at a frequency of about 400KHz the output appears almost as thought it was DC voltage as the diode/capacitor smooth this out.
The "efficiency" of these units in converting the low voltage to a higher one varies considerably from make to make depending upon the components used in the design. Some are more efficient when providing lower voltage step ups such as 3.2v to 5 volts as used in lithium ion battery power banks than at higher voltages.
Typically the Panasonic cameras have a quiescent current of about 250-350mA just powering the OIS and the LCD screen and when the camera is set to a zoom operation it can rise to 850 mA. Typical power on surge when the camera is first turned on can be in the order of 1.25A.
So my little converter has to be able to cope with these power demands and have a high enough efficiency in converting the power bank USB output of 5v to 8.4v.
The first converter that I thought was going to be ideal (based upon the spec sheets for it) turned out to be very inefficient at these low voltages. Typical modules ( I tested a batch of 5 of each type) gave a conversion rate of 1.3A drawn from the USB to provide 500mA at 8.4V.
So that is 6.5Watts input for 4.1Watts output which is just 63% efficient. The module ran quite warm.
I did test a unit which ran at 93% efficient however it was five times the price so in a cost/benefit calculation I decided against this unit.
The one I chose for the final design gave 4.9Watts input for the same 4.1Watt load which is 84% efficient and the module was a lot cooler when tested over a 24hour soak test.
In reality either module could have been used however the higher efficiency one would give longer run times from the USB power bank.
I have built the unit into a small battery case and added some extra over voltage protection to the output. The actual "chip" on this particular unit provides a soft start to prevent overshoot of output voltage, over current and thermal protection I added the "belt and braces" over voltage to prevent the unit delivering too high a voltage to the camera that it is attached to.
This unit will connect to the DMW-DCC8 for the FGZ200/300/330/1000/2000/2500/G series and all other cameras which use the BLC12e lithium ion battery. With other dummy battery boxes it can power other cameras such as the DMW-DCC7 for the GH3 or Canon/Olympus cameras with the right dummy battery. You can of course also use a wall outlet USB charger providing it has a rating of 2A so you don't need to take the larger, heavier mains power supply with you an a trip.
These dummy batteries are readily available with AC power adaptors from Amazon for as little as £12 in the UK
or $18 on Amazon USA
no need to buy the Panasonic DMW-ACC8 box at three times the price!
(this adaptor #3892A300 I have disassembled three units now to verify compliance to good design principals such as track separation between input and output, component choice, protection devices and general soldering technique and then carried out a 24 hour full 2A load reliability test).
So with the mains power unit you have the benefit of continuous power in the home/studio and can then use the DMW-ACC8 battery box along with my USB to 8.4 v adaptor and a power bank, outdoors.
The components for a USB powered Panasonic camera using the DCC8 dummy battery box from the ACC8 power supply.
The range of a Wi-Fi connected camera to a smart phone/tablet appears to be about 10 metres (30 feet). Whilst this may be adequate for most users sometimes you want to control the camera over greater distances. I had the idea to use and old router as a Wi-Fi-extender to allow these greater distances. The router I chose was an old D-Link which was mains powered through a 9v dc power adaptor. To allow this to be used away from the house I used a USB to 9v adaptor (from Amazon - it also supports 12volts at 2A) and a 8000mAh power bank.
You begin by connecting the camera to the router via the camera Wi-Fi menu selection By Network option.
When the list of Wi-Fi devices is shown, chose your router and enter the router password from the camera screen.
You can now open the Panasonic app on the smartphone/tablet and connect to the router to establish the connection to the camera.
The router will give an additional distance (100 feet) 30 metres so if the router is placed within the 10 metres of the camera the smartphone/tablet can be up to the 30 metres point giving 40 metres in total.
USB adaptor - Amazon UK http://amzn.to/2uoldv0
USB adaptor - Amazon USA http://amzn.to/2sVxfaV
Schematic for the working version of the AGC Defeat Unit
The final circuit turned out to be more simplistic than I had originally thought.
I assumed that the input would need to be a sine wave to prevent harmonic distortion if a square or triangular wave was used for the input to the camera. In testing I found that the camera would still perform well with a square wave input so I decide to try both an astable multi-vibrator pair of transistors running at 20 KHz and a NE555 timer IC.
In the end I decide to use the more stable 555 IC as the frequency remained solid even during the battery run down.
Here is the schematic for the project.
The timing is done by R2-C2 giving 20KHz. The output from pin 3 is attenuated by R1-R3 to 7-8millivolts at the camera input after being coupled with the mic input and allowing for its impedance.
the right hand mic input goes straight to the camera input whilst the left hand input has the 20KHz signal injected into it.
If you wanted to get finer control of the AGC defeat voltage input R3 could be substituted with a 27K resistor and a 100K potentiometer in parallel with it. The output would be taken to C3 form the wiper of the pot. This would allow the output to be set for 0V to about 10millivolts.
The unit is powered by a PP3 9v battery.
Here is the built unit. I used a stereo splitter cable from £/$ store to get the wired 3.5mm inline socket. The 2.5mm plug I wired but again it could be obtained from a 2.5mm to 3.5mm audio cable if you didn't want to have to solder one up.
The version 2 of this unit now features a trim pot (22K) in place of R3 ( the wiper connects to C3) so that you can adjust the level of the bias signal sent to the FZ200. Adjust to about 1/3 or the rotation as a starting point. Do a test recording with the unit on and adjust the trim pot until the background noise doesn't increase when you stop talking.
AGC Control for Panasonic Lumix FZ200
This is work in progress to produce a small device which will defeat the automatic gain control (AGC) of the FZ200 camera when using external microphones.
The AGC is responsible for keeping the audio recording levels at a point which is audible but not clipping causing distortion.
In most situations where the audio is constant this circuit performs well. However, in other situations like interviews, music recording and dictation there may be brief periods where there is no audio input. During this period the camera AGC will attempt to raise the background noise from the mic or its own pre-amp circuits to the normal level. You can here this as random hiss noise on the recorded audio track. As soon as the audio breaks this silence the camera AGC has to then quickly turn down the gain to get the audio back under control. The first second of this might be distorted as the AGC has a hysteresis lag.
I have been working on a small unit which will be battery powered and will allow you to plug an external stereo mic into it and then this unit plugs into the 2.5mm mic input socket of the camera.
In operation this unit generates an inaudible 20KHz signal of about 6-8 millivolts and is combined with the left hand channel of the audio. As this waveform is what the camera would expect to see for average recording at the right level no change in the AGC is made if the input volume decreases. It will still control the passages which exceed this recording waveform. As it is over the normal threshold for hearing the audio track does not contain this and cannot be heard.
The initial proof of concept uses a commercial waveform generator IC however my final design will be a much smaller unit using smaller and discrete electronic components. Here is the proof of concept at the moment
Here is the test of the unit in the proof of concept stage.
I now have a prototype of the simplified version and her is the video test
Studio Flash Equipment for Amateurs
whilst not everybody needs to invest in studio grade flash equipment I thought that I would share my experience in trying to put together a simple, cost effective system that I could use for general photography in my small studio space. For most purposes I can use speedlites with a guide number of 50 metres or more at ISO 100 and trigger then either optically, or increasingly these days using wireless triggers. Larger, more powerful flash heads give more creative possibilities but I didn't want to have to spend lots of money on something that doesn't get a lot of use.
I settled for the Godox systems using the AD200 (200 watt second) and the AD600 (600 watt second units).
The AD200 is quite a remarkable, dual flash head, system. It has a conventional xenon fresnel lens speedlite head with a guide number of 52 and it also has a bare bulb flash head with a guide number of 62. The bare bulb head can be modified with any number of reflectors and, if mounted in the Bowens type adaptor plate (as seen in the top illustration) can be used with an even more extensive range of flash modifiers.
The AD200, at a push, can be hand help and triggered by an on-camera Godox "X" series transmitter (Canon,Nikon or Sony) however it is quite a heavy (0.5Kg)unit despite being only the size of a regular speedlite. It is lithium-ion powered and recycles in just 2 seconds from a full power discharge
The AD600 is just a bare bulb unit with LED modelling light. again lithium-ion powered and recycles in just 2.5 seconds from a full power flash discharge. It is too heavy to hand hold and is supplied with a handle which can be fitted to a conventional lighting stand.
Both units have a 3.5mm sync port so they can be used with any remote cable triggering device and support the S1 and S2 optical trigger modes for instantaneous and pre-flash suppression modes.
Wireless Flash Trigger Systems
wireless trigger systems have evolved to quite an advanced level now.
It is possible to get systems which will transmit the TTL data from the camera to the flash enabling full TTL control without the need for extension cables from the hot shoe to the flash
unit. The Godox "X" system is such an example of this implementation. It is currently only available for Canon, Nikon and Sony flash systems to enable full TTL control. It can however be used to
trigger manual flash guns and also act as a remote shutter release as well.
Wireless triggers have a superior performance over optical (line of sight) devices. They have a range of up to 80 metres or so outdoors and can pass through solid walls and floors making them ideal for situations where the camera and flash are in different locations or out of line of sight.
With the Godox "X" system normally a dedicated transmitter and receiver pair are used to link the host camera and the flash unit. It can, however be used to provide centre pin firing on nearly all flash units which have the capability of being able to be set up in a manual power mode. In the example above the Canon system transmitter pair are firing the Nikon flash unit. The camera can be any camera capable of triggering via the centre electrode.
Audio Equipment For Videographers
Getting good audio quality for your video productions is almost, if not equal to, getting the right lighting and exposure!
Viewers may be tolerant of out of focus or badly lit shots but poor audio quality is likely to be a big turn off.
It needn't cost a fortune to improve the audio quality of your productions and in this section I will introduce you to a few ideas that might help you do this.
The biggest improvement that you can make is to use an external microphone. The internal mics are omnidirectional and pick up sound sources all around the camera. Handling noises, the image stabiliser whirring in the lens barrel and generally they are too far away from the subject in an interview type situation. They are good for providing a perfectly synched audio track from another external recording source such as a portable audio recorder.
The external mic ideally should be "off-camera" and close to the sound source however even a directional "on-camera" mic can make a vast difference to your sound production.
Let's begin by looking at the cheapest option and one, which surprisingly, gives really good audio quality for interviews, voice overs and commentaries etc.
A simple £3 ($) electret condenser lavaliere (tie clip) mic can be plugged directly into the mic port of the FZ300/330/1000/2000 or with a 3.5 to 2.5mm adaptor into the FZ200.
They usually come with just a couple of metres (6 feet) or so of cable so it might be necessary to add a 3.5mm extension cable to allow you to rig the mic without danger of pulling over the camera!
I have used over 6 metres (20 feet) of cable without any noise/hum pick up.
When positioned about 20cms ( 8 inch) from the mouth and clipped to a shirt/blouse/coat etc will give surprisingly good audio. because of the close proximity to the sound source the mic level can be turned down in the camera and this will help to reduce other ambient noises.
The mics are omni-directional so will pick up sound from all directions. You can mount the mic with the front port facing down and this will help prevent "popping" noises on some syllables.
A step up in quality is the use of a self powered electret condenser mic such as the one shown opposite - the Audio Technica ATR3350
(or the Boya mic http://amzn.to/2mHAdPZ) £16 ($).
This mic has its own inbuilt silver oxide battery which lasts for ages and has abot 6 metres (20 feet) of cable terminating in a 3.5mm (1/8 inch) plug.
It will work directly with cameras with the 3.5mm mic port or via a 3.5mm to 2.5mm adaptor on the FZ200.
Sound quality is excellent with very little electrical noise. Again the mic level can be reduced to help with ambient noise reduction.
If you are worried about the possibility of walking away from the camera whilst still attached via the lavaliere mic (yes it does happen)
then the next alternative would be a "wireless system" like the one opposite. Its a UHF system so wireless interference is very much reduced. The range is over 80 metres (200 feet) outdoors.
Again audio quality is excellent and it gives you a lot more freedom during your presentations etc.
For isolating unwanted sound a "rifle" mic is often recommended such as the one shown opposite the Boya BY PVM1000
This is a self powered (single AA alkaline battery) electret condenser microphone with XLR (and phantom 48v power) connection.
Although this isn't the ideal location for this type of microphone it is better than the internal mics.
The ideal placement for such a mic is directly overhead the subject with the mic pointing down.
The front lobe pickup from the mic then picks up the voice whilst the super cardioid pickup pattern (where the side of the mic are largely insensitive to external sound) help to reduce any other ambient sounds
For videos or podcasts where the mic being in view doesn't really matter then the studio condenser mic is a good choice. The BM-800 is only about £23 ($) and comes with its own shock mount system. Some suppliers also offer table stands or full mic stands to support the mic.
It can be powered from the camera by the slight bias voltage which appears at the mic input port but best operation is attained by using a phantom powered pre-amp system.
Again because of the close proximity to the speakers mouth the sound is rich an d golden and again ambient noise is reduced by being able to reduce the mic input gain level.
Above is one of my recording setups for use with the FZ2000 but it could be used on any camera system.
A BM-800 studio mic, the ATR 3350 lavaliere mic, the Saramonic smart rig+ for the phantom power and mic pre-amp and a pair of headphones for audio monitoring.
An alternative system utilising the Boya BY-PVM1000 rifle mic and the Saramonic SR-AX100 power supply/pre-amp unit.
LED Light Panels - Looking at what they exactly offer the stills or videographer.
I think we can all agree that natural daylight is probably the best light source we can use to create our images and video clips. Even in harsh sunlight we can employ techniques to tame it into the quality that we might need for a particular photoshoot. The use of reflectors and diffusers are some of the techniques that I have previously covered to show how to do this - particularly when photographing flowers as too much contrast kills the delicate tonal shades and destroys the very fine detail that we can see in petals etc.
But what about indoors when sunlight is not available such as after darkness fall?
Traditionally this was the place that tungsten lighting was employed. Photoflood bulbs and reflector lamps were the key components and I can still remember many a burned finger trying to adjust the position of these lights!
but today with advancement in LED lighting more and more studios are converting to LED light panels if they do not shoot with studio flash equipment. Running costs are more lower, the heat generated is far less and some can be self powered meaning there is less likelihood of trip hazards from trailing power cables.
This is a typical 10 x 12 inch LED light panel from Yongnuo.
It has 600 LED's and can be adjusted fro 0 to 100% brightness in fine incremental steps.
At first you would imagine that the light output from these large panels would be adequate for both stills and videography as they do look very bright when turned on and set to maximum intensity.
In reality the light output is actually quite low and two or three lights may be needed, especially for video work where we need to use shutter speeds of around 1/60 second. For commercial work where the subjects are static then long exposure times can be used. However for portraiture type work large apertures may be required, or higher ISO settings, in order to make these work in this situation.
Apart from light intensity there are two other factors which must be considered when choosing and using these lights; colour temperature and colour rendering index (CRI).
Having just acquired a new app for my smartphone it makes it very easy to measure colour temperature now rather than having to shoot an image and look at it photoshop or lightroom
It was these two later parameters that I wanted to investigate more so I did a series of tests on the LED lights that I most frequently use and which are still generally available for sale on Amazon or Ebay.
To do the tests I used the Canon 5D mark 3 as Canon digital colour science, in my opinion, is extremely good.
I shot a series of test images using a 18% grey white balance card and a colour checker patch in daylight and with each of the LED's. I kept the LED's at exactly 1 metre from the subject to that I could get a comparative Light Level reading in LUX and translate this into exposure times at f5.6 and ISO 100.
This is a typical image from the test series:
Using the camera in AWB (auto white balance) enabled me to also see the range of automatic adjustment made by the camera in each colour temperature situation.
The meter shows the measure light level in Lux (x10) and I have indicated the camera exposure to give the correct exposure for the gray card. The colour patches show any variation in light output in terms of RGB as traditionally low CRI LED's may have green spikes or low red outputs.
here is the full gallery of the test images.
This is the Aputure AL-528W by Amaran:
It measured 5200K, so pretty close to daylight and produced 3000 lux at 1 metre with the diffuser fitted. Without it there is a slight noticeable fall off in this image set but the light increased to 4460 lux giving 1/3 stop extra light.
When the 3200K CTO filter that is supplied was fitted the light level dropped dramatically to just under 1000 lux and just over 1 f-stop needed to correct the exposure. Note how this shift was not accurately corrected by the Canon 5D mk3 - quite a surprise! it took a further adjustment in adobe photoshop to render the gray card correctly as seen in the last image.
This is the MCOPLUS LE-520B, soon to be replaced by two more powerful units.
I note I have made a mistake in labelling the lux output - it should be 780 and700 Lux, not 7800 and 7000 in images 1 and 3!
This is a two bank LED system, one bank made from 3200K LED's and the other one 5500K. This obviously drops the power output as only half the lights are on (unless you switch both banks on)
the measured colour temperature was slightly warm at 5130K with the 55K bank on but pretty close at 3140k with the 3200K bank on.
Again the %D was not able to correct the white balance and post processing was needed to bring the white balance back to neutral.
Exposure times were down to 1/13 sec to produce the correct exposure at 1 metre distance.
This is the Yongnuo 300 LED panel which is just one colour temperature. Again it measured slightly warm at 5060K in the supposed 5400K daylight mode. Quite a good output from this light although it is more compact and casts stronger shadows as it is more of a pin point light source compared to the larger panels. With the diffuser removed it gave 1/3 f-stop increase in light.
The two remaining lights were the typical small 32 and 64 LED lights sold as hot shoe mounted video lights.
With outputs down at 1/3 second these are really totally unsuited to video work unless the camera is within a few inches of your subject. They hardly produce enough light for fill in if used on camera in bright conditions out doors and at 67K are too cold to try and mix with tungsten light if filming indoors. They can me used as small accent lights in some scenes but not by any means key lighting.
So in summary what have I learned from this testing?
Well it confirmed that the newer light panels are now pretty close to their advertised colour temperatures and don't need colour gelling to get the right temperature. Colour rendering across all the lights now looks perfectly adequate for most amateur lighting use and when a manual white balance in camera is performed should give some very accurate colour reproduction.
What was a total surprise was the fact that the Canon 5D mk3 was unable to apply enough correction in the AWB mode to correct for scenes shot with the CTO orange filter fitted on the fixed temperature lights or with the 3200k LED lights.
The final composite is a sample of the LED lights showing the relative outputs, colour temperature and colour rendering