The light you're interested in has a max beam angle of 37 degrees. I would never recommend any light for video with an angle below 60 degrees, and the higher the better. I have dual sola 1200s, i find their 60 degree beams to be too narrow, even when used together. I have yet to see a light at any price I would use for stills. I've used an 18,000 lumen light, and it was inadequate for sharp stills. If my 7D didn't take sharp photos with that, you aren't going to get much with 900 lumens. There should be many threads about why video lights don't work well for still photography.
I am curious as to why you want an adjustable beam light. Wide beams do fine in tropical waters, granted they can scare the critters off, but switching to wide to shoot video will do that anyway. Narrow beams are great for turbid water, as they allow other people to see your location more easily, and wide beams tend to produce a "high-beams in fog" effect, effectively blinding you. Adjustable beams would not be my priority for tropical diving, though it may be anise feature in general, if the difference is great enough. My aforementioned Solas have a narrow beam of about 10, which is not super narrow, and a wide beam of about 60.
I can't help you with your price point, hopefully someone else on here has good experiences with lights in that range. UK and iTorch both make some less expensive lights that would likely work for you, but I've never dived them.
Alex
