Wow! First thing out of the box, trying several random TTL snapshots around the house, just Wow! Really excellent easy results. First impression was really good. I like it.
What's not to like? It's a relabeled Meike flash, for only $54 USD, the Neewer VK750 II speedlight is decent power and fully featured. Not quite fully powered, about 0.6 stop less power than the SB-800, or about equal to a SB-700, but the SB-700 price will buy six of these!
It works very well in TTL and Manual modes, performance is nice. Results seemed to just always be about right, amazing minimal need for TTL compensation (that's Big Talk, TTL simply cannot work like that, but it really does seem nice). It has convenient menus, and all the necessary features to use it: Zooms 18 to 180 mm (18 mm really means for DX only). iTTL of course, bounce head tilts to 90 degrees, head rotates 180 degrees left and 90 degrees right, with pullout bounce card and pull out wide angle diffuser. It has 1/3 stop compensation for TTL mode (and the camera can of course control it too). Manual mode does third stops to 1/128 power. Has a PC sync connector (threaded) for Manual flash. It has optical slave modes S1 and S2, each with their own normal menus (handy and obvious to use).
It recycles full power level in about 2.5 seconds (Eneloop NiMH, batteries Not included). FV Lock and Rear Curtain Sync work of course (those are camera functions). This flash has both the wheel clamp and pin shoe lock, so you have to rotate the wheel all the way up, which retracts the pin, then you can remove the flash. Foot has a steel hot shoe plate. It comes with a fabric draw string case and a plastic flat slave stand (aluminum threads in bottom). Sync voltage is a very safe five volts. Says it accepts a Nikon SD-8A type external battery pack. There are more descriptions about flash features at Beginners Guide to Select a Hot Shoe Flash.
TTL Bounce flash, standing under a ten foot ceiling, works at ISO 400 f/5.6 (but f/4 is always routinely safer to allow some margin, for scene variables and compensation and faster recycle, etc).
HSS FP flash mode and a Remote mode for Nikon Commander seem the only features Not in this model. If your camera does not have a Commander, those would be of no use anyway. It seems a really fine flash for general use, certainly including bounce flash. The VK750 II would be an really excellent choice for a beginner just getting into flash, before spending hundreds of dollars.
However yes, there are a few little things.
Based on the few I have seen, the following appears to be true of all third party flashes:
But the VK750 Plus Factors are:
The Neewer VK750 II, the Yongnuo YN565EX, and the Aperlite YH-700 flash heads are larger than some, and if you might want a clear snap-on diffuser dome for bounce flash, those for a SB-900 Nikon will fit all three of them. I am not a fan of the domes, I prefer the pull out bounce card, but I bought one to check size. The one I tried for $4.50 was Neewer Flash Bounce Light Diffuser Dome for Nikon SB900 Flash Speedlight and it fits all three flashes well (Not included with the flashes).
The Nikon iTTL system defaults to actually be TTL BL mode (Balanced Fill Flash, same as the SB-700 mode). And like the Nikon flashes too, indoor TTL BL bounce flash often is better exposed with up to about +1 EV flash compensation, but that's the camera metering system, not the flash. Camera Spot metering mode switches the flash metering out of TTL BL mode, to be actual TLL mode, but Spot metering itself is only about the ambient light, and the flash system does not use Spot metering (more below). The camera controls TTL flash and TTL metering.
The VK750 II does do the job very well, it is a very usable flash, ample power, versatile, and seems dependable. I am well satisfied with the flash and its features and power and performance, and the price for this much flash seems amazing. If a few hundred dollars of price has put off acquiring a flash, consider this one, a good usable flash. The price is a great feature, which simply buys more in this model.
It is $50 currently, and shipped by Amazon, but Amazon vendors rotate. Amazon has alternative vendors if the prices vary.
It is very simple to operate. It has a rotary switch to turn it on. Holding that center Select button while turning it on is a Reset, not necessary, but it initializes everything, and fixes little problems. The Mode button cycles through five menus for TTL, Manual, a repeating flash mode called Stroboflash mode, and S1 and S2 slave modes. It doesn't have any lower setup menu to vary the small parameters. The LCD light times out in about six seconds, but tapping the center select button turns it back on. On-camera, it enters a standby mode after one minute, display says SL then. Tapping shutter half press wakes it up. Or the Pilot test button is the only flash button that wakes it then. Off-camera in Slave modes, it appears not to have a standby mode (which is the normal right way for slaves).
Definitions: The term TTL has multiple meanings, and it can be different actual modes.
For the Nikon system, its TTL menu is actually TTL BL mode (same TTL BL default as the SB-700, SB-400, camera internal flash, and Commander - Nikon is a TTL BL system). TTL BL is automatic balanced fill flash in bright ambient (i.e., reduced flash when mixed with ambient level, probably not the full metered exposure flash level then). Camera Spot metering switches it to be actual TLL mode (but the flash system does not do Spot metering, more below). A few flashes (the Nikon SB-600, SB-800, SB-900) have a menu with overt TTL vs TTL BL override choices on it, but the rest (without said menu) default to the TTL BL system. The TTL LCD distance scale shows maximum direct TTL range for the camera settings. The four arrow buttons are compensation control for TTL mode (vertical is full stops, horizontal is third stops), and of course the camera flash compensation works too (preferable to me).
The last few flashes I've seen have the following Exif ExternalFlashFirmware identification, which I think is Nikon CLS compatibility:
Manual mode power (to 1/128 power level) is changed one stop at each half power step (1/2, 1/4, 1/8, etc.) with the vertical buttons, and does 1/3 stop clicks with the horizontal buttons. For off-camera use, it has a PC sync connector, and slave modes. If on-camera (to know ISO and f/stop), the Manual LCD advises the distance on its scale (in meters) indicating Guide Number exposure for the current camera settings (zoom, ISO, aperture). No way to set ISO and f/stop off-camera. It remembers the last on-camera values until power is off, but these values have no use off-camera (Manual flash mode does not use them, Manual mode just flashes at the power level we set).
Stroboflash mode - is a repeating flash, for stroboscopic effects, like to follow the path of a bouncing ball. The chart in manual (at right) shows the possibilities it allows (due to heating concerns). The maximum power allowed is 1/8 power in any case, to prevent overheating. You specify the number of times you want it to flash, and the frequency it flashes (10 Hz is 10 times per second). The shutter has to be open long enough for the count (or the Test button has to held down). If you want 25 flashes at 10 Hz, chart says the power has to be 1/64. And your shutter speed obviously will need to be 2.5 seconds. Low power means the flash has to be close to the subject. The SB-800 has a similar function, and a chart with these same numbers in it. This strobing flash is certainly a specialty feature.
Zoom - the flash zooms automatically to match the lens zoom, 18 to 180 mm. The motor is a little noisy. 18 mm assumes DX, it won't fully cover a FX frame there (24 mm and up is OK). You can press the Zoom button, and the zoom value starts blinking, then you can zoom it manually with the arrow keys. But then it will not zoom automatically with the lens, which is expected. I'm too dumb to figure out how to make manual zoom reenter auto zoom mode, so I just use the reset (hold center Select button down while turning power on), and it initializes everything OK.
The AF Assist light pattern (at right, seen in a second camera), seemingly not very bright, fairly hard to see in a bright room (but of course, it is infrared, and it is bright, and not needed in a lighted room anyway). It works very well. I tried focusing at 40 feet down a very dark long hall, and it worked, camera focused easily. If not working, see Troubleshooting section of Nikon camera manual (AF assist requires AF-S mode, and selecting focus sensors near center). There is parallax up close, and it is slightly off center in the viewfinder, but doesn't seem to matter, there are dots everywhere. There is a little slack in the hot shoe, and the flash can be nudged back towards center. Unlike others, it does not flash once a second continuously in the slave modes (seems a plus). The AF Assist failed to light up one time, but the flash reset (hold the center Select button as you turn it on), and it initializes and started working again.
Slave Modes - Slave modes have their own menu, no mystery finding them. The slave modes then wait to be triggered (off-camera use). S1 is a normal optical slave (triggered by another manual flash). S2 is manual flash too, but can be triggered by TTL (S2 ignores TTL preflash), for example, from compact cameras without manual flash. No standby timeout, as is normal for slaves (no way to wake them up remotely). S1 slave mode is a simple optical slave (manual flash mode), just set it out there and it will flash in sync with the other manual flashes. It is very sensitive. It was triggered by a D300 internal flash at only 1/128 manual power at least at 90 feet (Measured direct line of sight - I did not have space to go farther. The 1/128 on this little internal flash would compare to about 1/512 power in other speedlights). It is more than plenty sensitive indoors with normal working power flashes, anywhere in a reasonable room, even if hidden behind subject (is sensitive to wall reflections). The internal slaves are powered by the batteries, and is much better range than most external optical slaves (which must be powered by sync voltage).
Guide Number Check - The VK750 manual has this guide number chart in the manual. The chart has a 14 mm value, but the flash only zooms to 18 mm. The 14 mm must mean with the diffuser screen down, and the flash LCD does report 14 mm then. The following guide number check uses a DX D300 camera, ISO 200. All of those pictures are shown here with normal Flash white balance, 5500K - but the correction ought to be about 6000K -14 tint. Flashes are rarely precise color, we always need to give white balance attention, and this one is no different than any flash.
Aperture is determined by the guide numbers in the GN chart at ISO 100. Values multiplying by 1.414 to convert to ISO 200 are shown and used below. GN charts are not precise (situations differ, judgments differ too), but normally a reasonable first approximation. The distance below is measured to be 10 feet. The f/stop is set to GN/10 feet.
Exposure results using guide number chart (converted to ISO 200). Manual flash at Full power, to check the guide numbers. My first thought was that this chart is same as any fully powered chart, but the VK750 is really about 1/2 stop down from fully powered,. But yet, it did hold up fairly well. I do suspect this one is just a chart they copied from somewhere else, not really a measured correct chart for this flash. But I am well pleased with the flash, and certainly its price.
See more at A comparison of power capability of a Yongnuo YN-565EX, a Neewer VK750 II, and a Nikon SB-800.
Bare wall at 4 feet. Small WhiBal card taped to wall for focus point. FX 14-24 mm lens, f/8, TTL.
D800 FX view is 10.3 feet wide at 14 mm, 6 feet wide at 24 mm.
D300 DX view is 6.8 feet wide at 14 mm, 4 feet wide at 24 mm.
VK750 18 mm is OK on DX 18 mm, but really not OK on FX 18 mm. It is a 24 mm zoom (but it is slightly wider than the SB-800).
The flashes have pullout diffusers to make them wide angle. The Nikon says it makes the flash cover 14 mm.
The VK750 manual says 18 mm, but the flash reports 14 mm with it down. Maybe it is not 14 mm, but the diffuser is a little wider. However it costs about 2 stops of power. VK750 on first row, SB-800 on second row.
In this lower power situation, the VK750 and Nikon SB-800 reasonably agree on temperature degrees K (± 100K not significant), but many flash situations are Not particularly close to standard Flash WB 5500K. We always have to pay attention to white balance, it makes a big difference (actually true of about anything except bright direct sun).
Here's a few quickie point&shoot snapshots with the VK750 and a D300 camera (DX). Camera mode M and 1/125 second shutter. No adjustments were made other than selecting camera ISO and f/stop (for automatic TTL flash power). No compensation attempts, and just standard Flash white balance (at least it was Flash WB instead of Auto WB, but the idea was to be just point&shoot). NOT suggesting that is the best procedure, it hurts me that I didn't tweak them a bit, but they do seem reasonable, and it's trying to show what the flash system does. We can always fix the white balance.
Bounce sometimes needs a bit of +EV flash compensation (just do what you see you need to do), but bounce normally improves things. Better WB for bounce is generally true of speedlights, due to the higher power level... also the better diffused softer lighting from natural angles, and bounce lightens the background more. And bounce is so easy indoors... just set ISO 400 f/4, and aim the flash head up.