G12 Focusing and Metering Modes

[DaveCT]

Hi,

I have just upgraded to a G12/Fix Housing/Dual Inon strobes from an Oly SP-350/single Nikonos SB-105 TTL setup that served me very well over the last several years. You can see some photos I took with that rig here: Diving. My main driving factors for the upgrade were the long shutter lags, long RAW write times, and less than satisfactory autofocusing performance in difficult scenes. Also, I have used several generations of land-based Powershots in the past, so I always had a relearning curve when switching to the Oly for u/w.

So, I am now a couple of weeks away from my first trip with the G12 and am still struggling to understand the choices of AF modes and which will serve me best, both for reef shots and macro. I have been through the manual at least 5 times and been experimenting, but I am looking for advice based on experience. I plan to start shooting in P mode, then move to AV/TV mode as I gain familiarity. With the Fix G12, I will do my exposure adjustment through the separate dial.

The FlexiZone AF mode seems straightforward and akin to the only choice I had with the Oly. Manually adjust the AF frame position (awkward) or simply reframe the scene after locking focus with the shutter half-pressed. On the Oly, I always kept Continuous AF off, because otherwise I would eat batteries and I never saw much reduced delay to focus lock while keeping it on. Can I assume the same for the G12?

Servo AF in FlexiZone mode seems like it would be most useful in macro mode, where the subject is in the center of the frame and slight movements of it or myself could throw things out of focus easily. Does anyone use Servo AF or have a recommendation on it?

What about FlexiZone or Tracking AF, has anyone had success with these modes? FlexiZone seems like it could be useful for general reef shots where the main point of interest is not necessarily in the center. I guess I will have to experiment to see how well the algorithm picks the focus points vs. me doing it manually. Tracking AF seems like it might be useful for rapid fish action, but my topside experiments so far cast doubt on how fast the system tracks and adapts. Again, any experience or advice is welcome.

Finally regarding metering modes, on the Oly SP350 I always got better exposure and flash results when using spot metering mode, vs. evaluative or center-weighted. This was true for macro and for med-distance fish and reef shots. Maybe this was a product of the particular camera/strobe setup and TTL metering. I guess I will have to experiment with the different modes on the G12 to see what works best, but would welcome any suggestions.

Sorry for the long post, but have already done quite a bit of searching through the archives and did not find exactly what I was looking for.

Thanks,

DaveZ

[Reefwalker]

Hi Dave
I recommend using the Flexi Zone AF mode, only because in other modes(AiAF/Face Detect) the camera doesn't always focus where you would like it too, particularly in close-up photography.
Your method of setting the focus point to "Centre" and then focus on the desired part of the subject in the centre of the LCD, half depress the shutter (locks the focus) & then recompose the desired scene without moving the camera closer or further from the subject works best.
Turn OFF the Servo focus & Tracking AF, underwater these features are just too slow to track subject movement. Plus they will also wear-out your lens focusing mechanism faster than you may think.
As for metering, different scenes require different metering modes. Wide angle works well with Centre weighted average, while in close-up photography nothing beats Manual (M) exposure for consistent results.
Most important with all G Series camera's (underwater) is too have the "Macro" turned ON for all subjects less than 1.5 metres (5 feet) from the camera. This will speed-up focus and allow you to focus much closer to the camera. Most people think it is only used for very close macro (15cms/6"), but this is incorrect. You'll get much more consistent focusing using the "Macro" setting on most u/w shots - even 2-3 metres from the camera.

[DaveCT]

Jeff, thanks for your thoughtful feedback. As I did on my Oly, I am planning to have two custom presets, one for wide angle, the other for closeup/macro. For wideangle, I am gunshy of FlexiZone mode probably due to my Oly experience. It seems to have a hard time achieving focus unless there is a clear hi-contrast edge in the zone. I would often end up pointing the camera at all different points in the scene trying to get focus lock, wasting valuable time. This is why I was leaning toward AiAFI for this scenario- it would be faster to let the camera find a couple of places to focus lock than me pointing wildly. I admit that the G12 is several generations beyond the SP350 and on land so far, I have been very pleased with its ability to focus in difficult situations that defeat the SP350. I will consider your point and try both on my initial dives with the new setup. I also agree with you that servo and tracking modes make no sense for wideangle reef shots.

For closeup/macro, I agree that FlexiZone makes the most sense. The subject is usually front and center and there is not much repositioning you need to do anyway. Thanks for confirming my suspicion that tracking mode is not really fast enough to track rapid action and will just burn batteries. But I would think that servo focus might be useful for macro, where slight movement of you or the subject can immediately throw the locked focus to be wrong.

Re: metering, I was just re-reading Martin Edge's bible in light of my new system. It is amazing that all the DSLR info, which I ignored before, is now eminently applicable to the G12! He also makes the CW metering recommendation for wide angle, so I will definitely give that a try. I am testing on land whether spot still makes the most sense for closeup/macro.

Cheers,

Dave

[rgrollins]

Reefwalker-
Thanks for your helpful posts.
I'm using a G12 with DC34 case and just finished a week of diving/snorkeling in Maui with exciting but mixed results. I'm reviewing my pictures to get a better handle on the modes/setting/conditions under which I get the best pictures. I noticed your recommendation to use Macro mode for pictures closer than 1.5 meters, yet on land my G12 indicates that it cannot correctly focus in Macro mode closer than about 0.6 meters. Does the air/water refraction extend the distance at which Macro can correctly focus?
- Bob R.

[cardog]

Reefwalker-
Thanks for your helpful posts.
I'm using a G12 with DC34 case and just finished a week of diving/snorkeling in Maui with exciting but mixed results. I'm reviewing my pictures to get a better handle on the modes/setting/conditions under which I get the best pictures. I noticed your recommendation to use Macro mode for pictures closer than 1.5 meters, yet on land my G12 indicates that it cannot correctly focus in Macro mode closer than about 0.6 meters. Does the air/water refraction extend the distance at which Macro can correctly focus?
- Bob R.

The camera should focus down to 1cm for macro.

[rgrollins]

My error. I meant to say that, in Macro mode, the camera would not focus at distances GREATER than about 0.6 meters.

- Bob

[cardog]

My error. I meant to say that, in Macro mode, the camera would not focus at distances GREATER than about 0.6 meters.

- Bob

Correct. It's about .5" to 18" in macro. You should be shooting macro pics at under 12" on most occasions.

[diver 85]

I leave my S95 on macro about 90% of the time------or try to anyway, lol.....
see pics from 2 weeks ago:
UW PS CB 2011 pics pictures by GEAUXtiger - Photobucket

[charlesml3]

Dave,

I don't think you're going to get very good results in "P" mode. Your aperture is going to be shifting around and that's the one thing you really want to control.

Shoot in Av mode. I found that the G12 really likes f/6.3 or so. I tried shooting a much shallower DOF at f/4.5 or so and wasn't really wild about them. The DOF is really shallow on a close object at f/4.5 Here's my last set from Cozumel with the G12:

Cozumel 2011 - a set on Flickr

[cardog]

Nice pics!