Hollyland Mars 300 PRO HDMI Wireless Video System Review A look at a modern Wireless HDMI system

We recently received two wireless HDMI units from Hollyland which represent part of their new line of affordable app supported devices. The Mars 300 Pro that we shall be looking at today is an update to the original Mars 300 wireless video system that was announced over a year ago and was one of the first fully-featured affordable sub $500 wireless units on the market.

As we have mentioned in our original post covering the Mars 300 Pro announcement, since the original version came out, the company released several other systems with important innovations including USB-C power as well as full wireless app support for both iOS and Android.

The Mars 300 PRO in action

The Mars 300 Pro

Let’s take a closer look at the Mars 300 Pro. In the box, we got the transmitter (TX) unit and the Receiver (RX) unit which is almost identical externally aside from the TX/RX markings on the side and the input/output HDMI on the TX unit vs. the two outputs on the RX unit. You also get a simple mounting cold shot and a single mounting attachment with a female 1/4″ 20 with small thumbscrews (this one is great and we wish Hollyland included two of these – one for each unit). Do note that you will need to provide your own HDMI cables and USB cables if you want to power the unit via USB-C.

The app support is one of the biggest additions to the Mars 300 Pro over the previous generation. Initially, we had some issues connecting our devices to the Mars 300 Pro over WIFI. We believe that these originate from the devices that we used especially our aging Google Pixel 2 XL. Our phone seems not to see the WIFI signal from the Mars 300 Pro even at close range. What was helpful was turning the Mars 300 Pro on, waiting a minute or two, and only then start looking for the WIFI signal on the Smartphone. One drawback which we would really love to see Hollyland fix is the fact that when you connect your phone or tablet to the Mars 300 Pro you lose your internet connection which of course is not ideal if you are going to use the device for a long time.

Connection Update:

After lots and lots of testings, we found out that us using channel 1 on the TX unit allowed our devices to see the transmitter on our mobile devices. Regardless though, our Pixel 2 continued having all sorts of issues (which we didn’t have on our Lenovo tablet) so we are pretty sure that these are device-specific.

The HollyView app (which exists in an Android and iOS versions) is possibly the best remote camera app currently on the market. It has almost all of the advanced options of a professional monitor including waveform, histogram, focus peaking, zebras, frame zone, magnify (it would be nice if this one would have the option to also magnify the entire frame and not just one area), false colors, mono color and LUTs including some common built-in options for Canon and Sony and you can load your own.

You can also take a snapshot (super useful for those YouTube thumbnails) or even capture a video that can be useful as a reference. We didn’t find a vectorscope option but we guess that  Hollyland might add one later on. We also asked Hollyland if in the future this type of app will be able to also control the camera but this will obviously require hardware changes so we might have to wait for a new model for that.

Use cases

There are many possible use cases for a unit like the Mars 300 Pro. In our studio, one of the most common ones is viewing the image captured by the camera when shooting top-down products and food videos and photos.

In a recent project we shot of a Vegan dinner we used our Sony A7R IV mounted using a 9.Solutions double joint arm from a Kupo wheeled stand over a table and instead of running a long HDMI cable all over the floor, we hooked the camera to the Mars 300 Pro TX unit which was powered by a USB power bank and transmitted the signal to our 27″ 4K Benq monitor on another wheeled stand with the Mars 300 Pro RX unit on the back powered by a NUC computer (which itself was mounted on the back of the screen).

This setup worked flawlessly for several hours and the only thing we wish we could add was a simple way of controlling the camera when it was not physically accessible (the Sony Imaging Edge app might be able to do this but it is clumsy and annoying to use and pretty limited).

Although we really have no need for very long-range wireless HDMI in our studio, we did run a test at the two ends of our studio which is close to 20 meters (or around 65 ft) and had no real issues when working with the TX/RX units (testing the app at this distance given our already problematic devices didn’t really make sense).


There is very little not to like about the Mars 300 Pro kit. It is lightweight and compact, pretty well built with a useful screen but most importantly it works out of the box, no need to change anything, a true plug and play, especially in the unit to unit mode.

Affordable, professional wireless HDMI

the mars 300 pro TX and RX units

The addition of the USB-C power option is a very welcome addition in our view and although some users actually prefer the 6-16V DC power input of the previous generation, we are huge fans of USB-C power, being much more affordable and universal and the way it is implemented on the Mars 300 Pro is such that it can use even very basic, compact USB power banks (with a USB-C to USB-A cables).

The Mars 300 Pro has some lag but it is relatively low from our experience when using the transmitter and receiver units from a normal working distance in our studio.  The app had significantly more lag in our testing (although this might have to do with the devices we used and the WIFI connection) and we would use it for monitoring and composition and certainly not for time-sensitive work like pulling focus.

Although we did experience some issues connecting the Mars 300 Pro to our mobile devices we are more inclined to see this as a problem with our aging units and not with the Hollyland products. Regardless, when connected the app itself is very well made and Hollyland should really get a big credit for that.


Selling for just under $450 for the “standard” unit which we tested (or $470 for the enhanced version with two external antennas for better reception in high interference environments) the Hollyland Mars 300 Pro is certainly not inexpensive, but present a very good value for money in our opinion.

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Iddo Genuth
Iddo Genuth is the founder and chief editor of LensVid.com. He has been a technology reporter working for international publications since the late 1990's and covering photography since 2009. Iddo is also a co-founder of a production company specializing in commercial food and product visual content.

1 comment

  1. Hi,

    I own the 300 Pro but having problems with audio/video out of sync. Audio comes half a second later than video when you use the app on iPad/iPhone. Hollyland says I’m the only one with this problem and they can’t reproduce it so they don’t help me. Can you please check this out with your device and see if you’re having the same problems? Thanks!

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