Hotshoe flash. They’re all the same right? Well not really. There are so many weird quirks with each brand, and sometimes it’s not obvious that your brand doesn’t work the same way as another brand. Physical differences are easy enough to spot if you know to look, but technical anomalies – they’re the fun part.
In the late 80s, Minolta invented this ‘enhanced’ hotshoe with a button-operated latch to prevent flashes from wiggling lose, which was a problem with the ISO standard hotshoe.
Meanwhile, Pentax and Canon added a tightening wheel, and Nikon added a locking pin which brought the same benefits to the standard hotshoe.
The result? Universal flash and flash accessory sharing between all current DSLR brands, except Sony. For Sony users, finicky adapters, and 2nd class status for flash products.
Products you may one day buy that are affected:
- popup flash diffusers (or diy)
- wireless flash triggers
- optical flash triggers
- cheap manual flashes
- flash stands
- speedlight umbrella adapters
- speedlight softbox adapters
- microphone attachments (for video)
- LED video lights
- flash L-brackets
- some DSLR rain covers
Someone new to DSLRs wouldn’t know what most of these are, so it would be hard to decide if incompatibilities will be troublesome. When you do find the need for these things, you can buy these 3rd party adapters for $10-20 to turn the Minolta shoe into a standard shoe. Minolta used to make them for the first 2 years, then stopped. Users were not happy!
If you own Minolta gear, then you may consider going Sony to keep your lenses. However if you are new to DSLRs then this would be another real reason not to go with Sony.
The Nikon solution to the loose hotshoe is shown above. A flip of a switch and a locking pin drops down into the hotshoe and locks the flash in place. The flash can only be locked or unlocked, there is no halfway.
Pentax also has a locking pin, but the ring also clamps down on the hotshoe. Still a single action, but a less smooth action and the shoe cannot be tightened or removed with one hand.
While either is good when using the flash on camera, the problem is when using third party cold shoes or things like flash triggers. Some of them won’t have the hole for the locking pin, and there will be no way for Nikon flashes to be locked down securely, which is a liability. In this respect the Pentax design is better. Canon also has a similar sort of clamp.
Regarding just the flagship models, Nikon and Pentax flashes can be used as optical slaves for any flash. Canon flashes can only act as optical slaves for Canon flashes when using the Canon wireless system. Cheaper flashes generally don’t have this feature.
This means Canon users can possibly borrow others’ flashes in a multi-flash setup but nobody can use theirs. However when using radio triggers even Canon users will not be able to use their slave function. Thus Canon is a closed system.
When would you want to use optical slaves? If you are triggering a bunch of flashes, only one of them needs to have a radio trigger. The others can be triggered using optical slave mode, saving you from buying radio triggers for every unit.
FEV and EV
For Pentax and Nikon, changing EV affects flash value as well, because flash metering is integrated with exposure metering. For Canon the two things are completely separate and don’t talk to each other, so FEV is the only way to change flash power.
This generally means by using manual mode you can get an effective ±5EV control on flash power by combining EV and FEV on Pentax and Nikon. And that’s before adding the FEV on the flash unit! Realistically situations needing this would be rare – you’d either be doing something absolutely amazing, or completely wrong.
Because the EV button is more easily accessed, Pentax and Nikon users will often use ±EV to control flash in manual mode. If you aren’t using manual, then on Pentax and Nikon EV can control both the background and foreground brightness in one setting. This makes working with TTL flash much easier.
Rear curtain sync
Nikon can fire wireless flashes in rear curtain sync mode, both using the camera’s wireless flash system, and 3rd party radio triggers.
Pentax and Canon’s wireless flash systems do not support rear curtain sync mode, neither using the camera’s wireless flash systems, nor using 3rd party radio triggers. In other words, Pentax and Canon can only fire in rear curtain sync mode when using TTL flashes attached to camera.
There are certain cool things that you can only do using wireless rear curtain sync. As such, there are complex workarounds people have invented.
One workaround involves having another TTL flash on the hotshoe. An optical trigger such as thie one is taped to the flash head, which is blacked out so that it will not affect the exposure. The optical slave is attached to the radio transmitter, which will transmit the signal to the remote flash.
Sounds messy? Looks even messier!
In addition, Canon has another limitation where rear curtain sync with on-camera flash only works at shutter speeds slower than 1/60s or 1/25s depending on model.
High speed sync/Focal plane sync
Canon flashes can only perform wireless HSS in TTL mode. If you have multiple identical flashes in HSS, you will find they may vary in power by up to 3 stops due to wear and age. Canon’s popup flash commanders (only available from 7D onwards) cannot command HSS.
Nikon and Pentax flashes do not have the above limitations on HSS. However Nikon flashes have been tested to have 1 stop less power than Canon in HSS. This is presumably due to an electronic limit on the capacitor to ensure different flashes will output the same power.
To workaround these limitations you can use more expensive TTL radio triggers. The optical workaround for rear curtain sync will not work.
HSS is useful in bright sunlight, so maybe Canon does not expect its users to use off-camera flash in such situations.
High speed sync and Image stabilisation
When using HSS in Pentax and Sony, the in-camera image stabilisation is turned off. This is expected if you think about it. The camera is trying to balance pulses of flash across the sensor, it cannot afford to shift the sensor around for image stabilisation at the same time otherwise the pulses will not be even!
At HSS speeds you probably won’t need image stabilisation anyway.
Well, those are the issues I’ve been able to find out about, I’m sure there are many more which I don’t know of yet. If you find any others feel free to send them in so I can add them!