LIMITATIONS
In a nutshell all the functions of the SN600SN appear to be working quite well, even when used with the YongNuo YN-622N radio transceivers (see the notes on that further below though).
Though I did find the Nikon Optic wireless range when used as a slave flash appears to be around 60% of the genuine Nikon flash units.
Otherwise the SN600SN, like most Shanny flash models, are nice solid feeling flash units with very good power and recycle times, and a nice large clear LCD display. The SN600SN even fit a lot more snugly into the camera hotshoe than the Nikon flashes.
The one main feature the SN600SN currently lack is a USB port for firmware updates. Again you can read more detail on the physical design and features of the Shanny flashes in the SN600SC review here.
ITTL EXPOSURES
UPDATE – I originally reported seeing some difference in ITTL exposures between the SN600SN and a Nikon SB-700 flash.
Though this appears to be due to my own inexperience with the Nikon system, and changing the camera to spot metering mode removed the discrepancies, and the SN600SN is providing very similar exposures to the genuine Nikon flash.
FEC (Flash Exposure Compensation) also appears to be working correctly.
OPTIC WIRELESS RANGE
The Nikon optic wireless flash system is renowned for its exceptional range, even outdoors in bright light. With both the basic S-U4 optic slave mode, and the full AWL / CLS optic wireless ITTL system.
In SU-4 mode, with straight line of sight to the flashes slave sensor, and in open shade, I found the SN600SN was also very good, and actually reach around 90% of the distance of the SB-700.
In the same conditions when using the Advance Wireless Lighting / CLS mode, the SN600SN only reached around 50% to 60% of the distance of the SB-700, even if only using remote manual power settings (no ITTL).
So it appears the SN600SN perform more in the 20 meter range of the Canon flashes they were originally designed after. Which is not particularly bad, its just that the Nikon flashes are very good with this.
Used as a master unit there was no difference in range between the Shanny and Nikon flashes (as the pre-flash pulses they both output would likely be of similar intensity).
USB PORT / FIRMWARE UPDATES
Unfortunately there is no USB port currently available in the SN600SN speedlite. Which is a pity, and a little bit of a strange decision, as a number of other Shanny flash models already have USB ports included now.
The SN600SN are a variation of the SN600SC for Canon though, which were one of Shanny’s earlier flash models.
And both of these flash models were originally intended to, and may possibly have, an SN-E3-MD radio receiver module available in the future, which would plug into the side of the flash, and include their own USB port. That port can then be used to update both the receiver and the flash units firmware as needed.
Shanny have postponed the release of the SN-E3-MD receiver a number of times though. And they have also changed their product plans numerous times. So I don’t think anything can be guaranteed at this point.
At this stage though, the SN600SN do not have any method of firmware updates available. So if any early bugs are found or confirmed, then the flash units would currently need to be exchanged to resolve those.