Long exposure photography is tricky, especially in the studio when you're trying to combine multiple light sources within a single frame that have very different brightnesses and colour temperatures etc.
So although I believe this article will be very useful to many of you, there will most certainly be others that perhaps have little to no experience with long exposure photography and as such this article might seem to brush over certain long exposure lighting ideas. That is because as lot of you know, I now have an extremely comprehensive Long Exposure Portraits video that goes over everything there is to know about shooting long exposure shots and this article is designed to help those that may have very sensible equipment questions after watching it.
In the video tutorial I only use tungsten modelling bulbs, but what if you don't have tungsten modelling bulbs? What if you only have LED ones? This article aims to answer the question 'Can you use your LED modelling lamps for long exposure photography?'
First off, let's just double check we're all talking about the same thing here when we're referring to LED modelling lamps. In the context of this article I am actually specifically referring to the modelling light that comes with the studio strobes you likely already own. These newer strobes are often used for location work and are often battery operated with no direct power supply via a plug into the wall.
The LED modelling bulbs on these lights are ideal because they consume very little power which is perfect for those more popular battery operated flash heads.
Characteristics of LED lights versus more traditional tungsten modelling bulbs
This should come as no shock to you all but size most certainly does matter. LEDs by their very nature are tiny and that has significant disadvantages when we're referring photographic lighting. For example one of the core reasons I encourage people to upgrade from speedlights to strobes is their size. Speedlights have a tiny light source point which creates a fiercely harsh and contrasty light that is very difficult to modify in a flattering way. LEDs have exactly the same problem and in fact they are even smaller than speedlights with many strobes LED modelling bulbs being no bigger than your fingernail.
Contrast the tiny LEDs to the considerably larger tungsten modelling bulbs. These bulbs are not only far larger but they also protrude into the lighting modifiers thereby allowing their light to be spread far more evenly and create a much softer light. Remember that lighting modifiers are designed to work specifically with flash tubes and flash tubes are physically large and spread light all around themselves when they are fired. Tungsten bulbs do exactly the same thing so the look of the light produced by them looks very similar to the actual flash light itself.
Bulb Colour Temperature
LEDs can be made to produce practically any colour light we could imagine but most of the LED modelling bulbs in our strobes produce a clean white colour. This colour is designed to be very similar in colour temperature to our flash bulbs. This makes our lives a lot easier if we are trying to mix both LED light and flash light in a single shot which is something you'll need to do a lot if you're shooting long exposure shots.
Tungsten modelling bulbs produce an entirely different colour of light to flash and is far warmer in comparison. If you're familiar with white balance and the Kelvin scale, tungsten produces a colour around 2500-3000 Kelvin whereas flash and daylight produce a far colder 4500-5000 Kelvin colour. This drastic difference in colour temperature becomes a major issue when you're trying to combine both tungsten and flash in a single shot and this mismatch in colour often requires you to use additional colour correction gels to match the two colours together.
We just spoke about colour temperature but here I'm referring to the physical heat emitted from these two light sources. LEDs require very little power to operate as they are incredibly efficient at converting power to light and this efficiency results in very little heat being produced as a result. This means that they can be left on at full power surrounded by lighting modifiers and gels with little fear of melting anything.
Tungsten on the other hand is incredibly inefficient at converting power to light. If you didn't already know, tungsten light is produced by passing an electric current around a tightly wound coil of tungsten metal. The warn coloured glow you receive from that light is simply super heated metal. The tungsten metal is only used as it's one of the strongest metals around meaning it can withstand this incredible heat for thousands of hours without breaking or melting. This is great if you want to warm a small room but not ideal if you want to encase that tungsten bulb in a lighting modifier alongside colour correction gels. A constants vigilance is required to ensure you don't your gels and equipment.
As I previously mentioned, LEDs are often very small in size and even larger LEDs are ultimately only made up of multiple smaller LEDs. This lack of size unfortunately does mean that there are often not that bright when compared to other photographic lighting. Also the LED modelling bulbs that come with your strobes are fixed and unchangeable by the end user. This means that you're stuck with the brightness of the modelling bulb the manufactured gave you and this can vary significantly from brand to brand.
The older strobes that come with tungsten modelling bulbs had to come with the ability to be replaced by the consumer. After all, tungsten bulbs die and will need to be changed out for new ones. This ability to replace them also means that we have the ability to adjust the power of the modelling bulbs we put in them. If you're old enough like me, you may remember a time before all the energy saving bulbs where we had the ability to purchase fairly powerful and extremely bright bulbs. Those old tungsten bulbs ranged from 30 watts all the way up to 240 watts which is what I currently use in my strobes today and is a very bright light indeed.
So now that we've discussed some of the key differences between LED and tungsten modelling bulbs, let's quickly recap the positives and negatives of each.
- Small light source that results in a very different looking light when used in consecution with certain modifiers.
- Produces a very similar colour temperature to flash meaning that colour correction gels are not required when using both LED and flash in the same shot.
- Produces very little heat meaning you are able to use them for extended periods with any modifier and gel without fear of melting anything.
- Fixed modelling bulb power means you are stuck with a low powered LED light that cannot be changed or increased by the end user.
- Large physical size that replicates the look and appearance of the flash tube enabling you to use them with any lighting modifier.
- Produces a very warm colour temperature compared to flash meaning that colour correction gels are required if you plan on using both tungsten and flash in the same image.
- Very hot when operating at full power. This requires constant supervision to ensure you are not melting both lighting modifiers or gels.
- Bulbs can be switched in and out as often as required meaning the end user can increase the power of their modelling bulbs as required.
Ultimately the choice is yours but more often than not, this situation will be dictated to you by the strobes you already have. If you have some modern battery powered strobes then they will often come with LED modelling bulbs as standard. If this is the case then you will need to bear a couple of things in mind should you want to use them for long exposure photography; namely the way that the LED distributes light around your chosen modifier and the power of the LED.
If you're using hard-light modifiers where the LED will not be diffused in any way before it reaches its destination, I strongly recommend you try and soften the light a little during the process. For example, if you're shining an LED through a straight reflector dish, add a diffusion gel to the front to soften the light a little. This will distribute the light more evenly onto the target resulting in a far more even exposure rather than the light coming straight out and not using the modifier in any way.
The power problem is far harder to fix I'm afraid and is ultimately why I personally prefer to use tungsten modelling bulbs in my long exposure work over the LED ones.
The power difference may not seem significant and most of the time it's only about 2 stops of light difference between LED modelling bulbs and tungsten modelling bulbs. For example you could just compensate for an LED lamp being 2 stops darker by increasing the ISO on your camera from 100 ISO to 400 ISO (2 stops) and get exactly the same shot using the same shutter speed and aperture.
The problem comes when you try and combine LED light with flash. Most strobes actually produce a fairly powerful flash even on their lowest powers, so when you combine powerful flash with weak LEDs in the same shot, the flash just washes out the LED effect.
For example, your flash is on its lowest power and your LED is on its highest power but the difference is still 2 stops of light. You can't increase the power of the LED's and the only way to decrease the power of your flash any further without changing the camera settings is to add neutral density (ND) gels to your flash. It's possible but it becomes a real pain.
DIY Tungsten Modelling Light
It's worth pointing out here that when I use flash and ambient light simultaneously in my long exposure images, I only use a strobe head to flash and separate strobe heads to light for the ambient. Think of these ambient heads simply as modifiable lamps, not flashes.
The model image displayed here is a great example. It uses 4 strobes but only 2 of those strobes are firing flash, the other 2 are only shining their tungsten modelling lamps.
So what if your strobes all have LED modelling bulbs but you'd like to incorporate brighter tungsten long exposure effects? Here's a very cheap and quick DIY alternative that is super easy to setup.
All you'll need is:
- Clip-on lamp
- Tungsten bulbs (of varying powers if needed)
- A bayonet to screw fit bulb converter if needed
- S-fit (your strobe Bowens/Godox/Elinchrom etc.) to speedlight L-Bracket
- Cinefoil optional
Then all that's left to do is set it up. Get your Speedlight L-bracket on a stand, attach your clip-on lamp to it and then add your required tungsten bulb power. Finally all that's left to do is add your desired modifier like you normally would to your flash head.
The best part about all of this is that you can use your strobe modifiers on this tungsten lamp. I've used a regular reflector dish here but you could just as easily use a beauty dish or soft box.
Just incase you were curious as to how the strobes modelling bulb compared to the clip-on modelling bulb, they're displayed below. Plus I've also included how the LED modelling bulb stacks up against the two tungsten lights too (once the ISO on the camera had been increased by two stops to compensate for the darker LED lamp).
So there you have it, if you have some old strobes tucked away, dig them out as they will likely have the tungsten bulb for a modelling lamp and this can make your life a little easier when shooting long exposure work. If you only have LED lamps in your strobe then that's also fine, you have a couple of options. You can either shoot with an increased ISO value and simply ND or strobe lights, or you can very easily and cheaply make your own tungsten modelling lamps that can be modified with your current strobe modifiers.
If any of this long exposure work sounds a little complicated, I assure you it isn't, it just requires you to think in a slightly different way....oh and to work in complete darkness ;)
If you'd like to learn more about Long Exposure Portraits then I have a brand new 6+ hour video tutorial that RGG EDU is practically giving away. More details can be found here Long Exposure Portraits
PLUS: If you'd like to learn more about Long Exposure & Light Painting in person then I have a lighting workshop available on September 22nd that is specifically all about learning how to create beautiful images like these. For more details including exactly what we'll be covering on the day follow the link Long Exposure & Light Painting Workshop