First I should warn you that my impression was that the Tachyon was not ready for prime time, that it was burdened with way too many difficiencies, and had very limited utility for divers. My S500 crapped out in Nome, Alaska so I needed a new camera. Since I don’t take many “land” pictures I decided to try the Tachyon, despite it’s perceived limitations. I am SO glad I did.

Cons: The internal switches are tiny (well the camera is tiny – duh) and are best manipulated with a semi-sharp point rather than fat fingers. You can’t turn it on and off while diving at more than 20’. You can’t switch from pictures to video while diving.

Pros: You can’t turn it on and off while diving at more than 20’. You can’t switch from pictures to video while diving.

You may wonder about the Pros and Cons being the same. Perceived versus reality. When using the S500 I was constantly diddling with the camera. It was hard to find an acceptable way to attach it (seriously bouyant), was hard to aim (missed ton's of stuff), was continuously switching from video to still (task loading), and (due to battery saving settings) could never be sure if it was on or off. In short it occupied a bunch of time and attention.

The thing I liked most about the Tachyon (and I couldn't say enough about this) was that I hit the record button and forgot it for the rest of the dive. That's one less task to be concerned with when under the water. You just take a relaxing dive and the camera gets everything you see. I didn't miss not being able to switch from video to photo mode during the dive at all. It’s something I can easily decide before the dive. The freedom of “set it and forget it” is more than wonderful.

On the dive the visibility sucked but when I was close enough (to weeds/fish/objects) for the vis to be relatively clear (through my mask) the picture was HD sharp. It was amazing when the viz was real poor how small the particles were that it would show.

I found that the video was smoother than when I hand hold because my head movements are more smooth. Also, what I was looking at was centered. When in Bonaire I missed several mobs of Blue Tang in a feeding frenzy because I was shooting just behind them as they went. Had I been using the Tachyon I would have got the action. I also missed (3 times) a huge school of Houndfish or Flat Needlefish because the camera was turned off when I thought it was running.

Be sure to take a close look at the online documentation. It points you to a really good, free player that handles the .MOV format (as well an all others) really well. That way you don't have to convert the video to watch it.

The only problem I see is figuring out a mounting that will put the lens in front of the mask and keep the lens parallel to the mask lens. My mask is an old style rectangular frame type so I had no trouble. It could be that the ultra low volume masks are close enough to your face that the mask will not show in the video.

Anyway, I think you will be very happy with the Tachyon. The price is low and it performs well.