Hello there! Just came back from the Maldives! I was disappointed with my videoshots... I use (for the second time) a L&M bluefin with a Sony CX 550 camera and a Fathom 90 ° lens. The visability on depth (30 m) was not great. So when a was filming upclose ( 1 m) a leopardshark on the sandybottom and it swam away with a nice slowly whipping tail, it was in and out, in and out focus, .... Because this is focusproblem us difficult to notice on the small screen and I'm a real amateur, I only discovered this afterwards. The same problem with a school barracuda's while changing directions always went out of focus.
What can I do to avoid this? I'm scared to push on manual focus while the subject is swimming away from me.
On 9 september I go on the Galapagos Sky and want to approve my skills....
Thanks for some help.....
Moved to Video Forum per OP's request.
Stop using auto focus. Pre focus to 1m and let the depth of field take care of the rest.
Stop using auto focus. Pre focus to 1m and let the depth of field take care of the rest.
i am also just getting into the hobby and have had the same problems. what do you mean by pre focus to 1m metre? could you please explain how to set up my focus properly. thanks
A quick technique is to auto focus on your fin, zoom in about 1/3rd switch to manual focus and then pull back to wide. everything from a few centimeters in front of the dome to basically infinity (weel as far as you can see underwater)will be in focus. If you zoom it won't be accurate, and if you switch back to auto it will need to be reset, macro work will need to be in auto or manual.
J
A quick technique is to auto focus on your fin, zoom in about 1/3rd switch to manual focus and then pull back to wide. everything from a few centimeters in front of the dome to basically infinity (weel as far as you can see underwater)will be in focus. If you zoom it won't be accurate, and if you switch back to auto it will need to be reset, macro work will need to be in auto or manual.
J
I'd like to understand the part where you zoom before you focus lock. I am sure you realize that the Fathom 90 is not a dome port, it is a dry-mount wide-angle lens? Is the rule identical for both? In photography, it is usually recommended to adjust aperture to have everything in focus up to infinity, which is something not all camcorders allow doing...
So far, focus-locking at full wide on my fins (or something more stable (!) at about 3 ft seems to have worked for me (using the Fathom WA 90 and CX550). I usually unlock the focus when I zoom on a subject and leave it on auto in close-ups. as described above.
When you zoom in it makes sure that the fin is in focus. It's just like if you were shooting an interview, to start you zoom in on the face, focus and then pull back to get the frame you want, this way you can be sure you have critical focus.
Rule is the same for Flat port, dome port and super wide.
Remember you are focusing on a virtual image underwater, setting focus to infinity is not a way of confirming correct focus.
It's pretty simple:
1. Put camera in manual focus.
2. Focus on an object 0.5-1m (1.5-3.3ft) away while underwater.
3. If you cannot switch focus modes, pre focus in manual before you close the housing.
4. Learn about depth of field and how it affects focus.
5. DO NOT USE AF underwater for anything but maybe macro.
Hello there! Just came back from the Maldives! I was disappointed with my videoshots... I use (for the second time) a L&M bluefin with a Sony CX 550 camera and a Fathom 90 ° lens. The visability on depth (30 m) was not great. So when a was filming upclose ( 1 m) a leopardshark on the sandybottom and it swam away with a nice slowly whipping tail, it was in and out, in and out focus, .... Because this is focusproblem us difficult to notice on the small screen and I'm a real amateur, I only discovered this afterwards. The same problem with a school barracuda's while changing directions always went out of focus.
