A1-FX1 Screen grab

No Cinegamma or any other 'colour' feature on. Blackstretch=on. Steadyshot=off. Full Scan=on. WB=Manual Assign. Converter=WA. Auto Exposure. Auto Focus. CCFilter on. Depth around 15m. Lighting conditions overcast, but 'ample' light. Lot's of red around - sponges, corals, etc. Frogfish was very black with occasional small bright white spots.

Nick,

It looks like there is plenty of light for the rest of the shot. Perhaps the black-stretch is the problem. Also, can the camera white balance without the color correcting filter? It cuts out a lot of light.

--Mark

I'll be testing the A1 WB without a CCFilter in Malaysia in a couple of weekends Mark. I'll be using a 'warm' slate to bring out the reds better, but of course with no CC filter below 10m there ain't too much red to bring out. Will be an interesting experiment.

Also analysing my Bali footage more, it's evident that when there is enough light in the center of a shot, then the black or underexposed areas to the sides are fine - no noise at all (see A1Cave1 clip for an example). The worst noise comes from having the whole shot underexposed (see A1Cave2). So I'll also be experimenting in Malaysia with daylight lights with the forground exposed correctly, and the background dark - I think this will be fine.

Learning learning learning

BTW I've noticed that some of the pros and cons remarks re the A1 vs FX1, TRV950 etc have taken on a religious fervour. This was not my intention at all! Just trying to learn how to optimise footage with this little chap. All cameras have their idiosyncracies - gotta make the best out of what one has at the time

Don't worry Nick.

Thats the thing about forums, we are all learning as new stuff comes out and playing with it to find what works and what doesn't. Its great that we can all share our thoughts and experiences.

Of course there will always be differing opinions and what not, i think its great! Pushing the envelope so to speak.

The religious fervour you will find all over different forums all over the net. It comes with the trade...

Besides, a little controversy in life is fun!

That's tru Mike, actually this forum is quite genteel compared to some - I haven't seen anyone totally flamed yet!

The hard-core u/w video community is quite small it seems, and we're all doing new stuff with new toys and techniques. Of course we all have opinions, but that's why I'm online. I need to understand what the other biggots are up to as well

I think the problem is that when someone criticizes the A1/HC1, it demeans the camera's worth and possibly the owner's decision, whatever it may be. So a few persons may take it personally that you're raggin on their camera.

I think the problem is that when someone criticizes the A1/HC1, it demeans the camera's worth and possibly the owner's decision, whatever it may be. So a few persons may take it personally that you're raggin on their camera.  

<{POST_SNAPBACK}>

Well yes this is the problem...

But you and i are here to diffuse these things and make everybody feel better....

Now everybody kiss and make up!!!!

I love you guys...and what a multi-continent group hug...i think we have most major land masses represented:) Buying equipment is like choosing a wife for fanatics like us. We want everything to be fairtale perfect...and when people point out its not...it bums us out. I have the FX1 and can point to a number of issues. Add a housing and it just gets harder. Then add my shooting "technique" and all hope is lost:(

Anyway, i have never been on a forum as honest, helpful and supportive as this one...that is why I keep pushing to have this video forum moved to the front pages of wetpixel. Then again our little secret society is kinda nice too:) Anyway, i want to thank everyone for having helped me with many answers, tips and fixes.

-shawn

Nick,

"but of course with no CC filter below 10m there ain't too much red to bring out."

That is the thing about color correcting filters – they don’t *add* any red at all. They only *remove* blue and green so that the amount of blue and green is back in balance with the available red. So, with a filter, you are removing a lot of blue and green light from which the camera can get luminescence information. Of course, whether or not the camera can use this information would depend on the kind of signal processing the camera does.

To get an idea on how well the white balance works, put the filter on the camera and white balance on land. If it can cut out all of the red from the filter, it should be able to white balance under water without the filter.

Were the two cave pictures from the same depth? (same brightness in the open parts?) My guess is that the camera’s auto exposure is adding gain to try to bring out something in the blacks that are simply below the threshold of the camera. The black-stretch is then just amplifying the video noise. If you shot it on manual exposure, and did not expose into the region where the camera starts to add gain, I would think that the pictures would look a lot better.

Of course, this is all pure speculation. I’m just trying to decide if I want to buy this camera or stick with my 7 year old JVC mini-DV (with very good low-light capabilities).

--Mark

You make a very interesting point Mark. The A1 certainly will WB right through the CC Filter on dry land - so that begs the question why have a filter at all?

I thought the filter did actually add some red, but if it acts as you say then there is demonstrably no reason to have a filter with this camera. In theory! I'll try all this out shortly. BTW my earlier DV cam (TRV950) absolutely could not WB through the filter at the surface - but these new HDV cams seem to WB through anything. I've noticed that with the FX1 too.

So - interesting - the end of CC filters as we know it? Be excellent news if the results are the same or better - the CC Filter certainly reduces light.

The caves were shot at different depths and very different ambient light levels. I think your analysis makes a lot of sense, although actually there was NO black stretch on the two cave shots, but I agree the auto exposure was adding a lot of gain and therefore grain on the low light shot.

I don't have access to manual exposure with this housing yet unfortunately. An omission I may rectify with yet another mod in due course.

You make a very interesting point Mark. The A1 certainly will WB right through the CC Filter on dry land - so that begs the question why have a filter at all?

BTW my earlier DV cam (TRV950) absolutely could not WB through the filter at the surface - but these new HDV cams seem to WB through anything. I've noticed that with the FX1 too.

So - interesting - the end of CC filters as we know it? Be excellent news if the results are the same or better - the CC Filter certainly reduces light.

<{POST_SNAPBACK}>

Well the filter does wonders after 15 m, which is the limit of in camera WB can correct for. At least that's for the PD170. I used a filter at 50m a few times in crystal viz, plus MWB the reds were back for anything about 3-5m away. That's 55m of adjustment. You lose 1.5 stops of light.

Ah your WB thru filter was electronique ou mechanical...because we all know electronique WB can be flakey

For a lot of camcorders, a color-correcting filter is required. However, I’ve heard (no first hand knowledge) that the manual white balance is so good on the A1 that you can do without the filter. This is one of the main reasons to go for the A1 over the HC1. This makes sense because the algorithm to add back missing red and (to a lesser degree) green information is relatively simple. Nick’s experiment on land seems to lend a little credibility to this statement. The important thing is, of course, that you need to white-balance at every depth as the amount of light attenuated by water is a function of both depth and frequency (red goes first, then green, finally blue).

--Mark

I've WB'd on land with the red filter on against a white wall and bingo - white wall. This is really amazing compared to other cams I've owned.

I'm pretty convinced that balancing the A1 against a warm card with no CC filter will be OK in the top 10-13 metres or so, but I'll have to do some field tests to see what happens below that depth. Not having a filter with the A1 would be a huge bonus based on the realtively poor low light experiences I've had.

Anyhow more field tests in two weekends in Tioman and Palau Aur. I'll report back.

well I can corroborate that notion. My tests has shown up to 12m isn't a problem in 10 m viz.

Hey Encik Jackson, it's Pulau... Palau is in micronesia LAH.

Oops - that was my wishful thinking, not done Palau. Thanks for keeping me on track Sensei