Red Filters

[craig chamberlain]

Hi i am thinking about buying a digital camera and housing. I heard that to take a good picture you need a red filter. Is this true? if so do cameras come complete with them? Any other tips would be appreciated.

Thanks
Craig Chamberlain

 

[DevonDiver]

Hi Craig,

It's untrue.

The red filter has limited uses. It serves to reduce non-red light reaching the lens of the camera, this 'balancing' the color of the photograph. However, as you descend and the total amount of ambient light decreases, the red filter will prevent sufficient light reaching the lens for any good photograph to be taken.

In reality, this means that it only useful above 10m...and in clear, brightly lit water.

Red lenses work best in the tropics (blue water). For the UK (green water) you would need a mauve/purple coloured lens.

In reality, filters are a 'throw-back' to the days of wet film cameras, when no other processing options were available. Now that we are in the digital age, you would get far better results using some simple digital editing techniques with common photo processing software (i.e. Adobe Photoshop).

If you use Photoshop... there are several good threads on the forum already that illustrate the techniques for effective colour balancing, backscatter removal etc... (or just drop me a PM).

 

[bvanant]

As Andy has said, you don't need a red filter. If you are going to shoot video in relatively shallow, blue water without lights, then a red filter is a good idea. Most video cameras have built in red filters. Most still cameras are designed to be used with a strobe and so a red filter is a waste. On the other hand, there is something called a magic filter from Alex Mustard. In the right conditions, (shallow, well lit, clear water) the results can be stunning but that is really an advanced option. Get a strobe for your camera and don't worry about the filter.
Bill

 

[Charlie99]

Manual white balance is what you should be looking for as a required feature on any camera you intend to use underwater.

For example, when you take a photo using available light at 50' depth, the illumination source is not your normal white light. The water and gunk in it has filtered out most of the red, leaving a very bluish illumination source.

A red filter attenuates (and throws away) much of the blue and green light hitting your camera. It causes you to increase shutter speed, increase aperature, and/or increase ISO and the resultant increase in noise.

A better solution is to have the camera use all of the available light, and for it to recalibrate the red, green, blue sensors for the skewed lighting source. That function is called manual white balance. You point the camera at something white (or grey) and tell the camera that "this is what white really looks like".

Even if you don't get the white balance exactly right, you will be in the right general ballpark and a very minor tweak after the fact will clean up your colors.

What it cannot correct for is that the light from objects far away has traveled through more water than lights from nearby objects. So far away objects will be slightly more blue (or near objects slightly more red).

Charlie

p.s. You should play around with any camera you intend to buy and find out how awkward it is to do a manual white balance. Some cameras, such as my Canon point and shoot let you assign a button (which is normally a print button) to other functions, with manual white balance being one option. So my manual white balance is nothing more than pointing at the my SPG (mostly white) and pushing the button.

 

[diver 85]

Look @ some of mine in my sig below--no strobe & NO red filters--on these.....

 

[DevonDiver]

Here's an indication of what you can achieve with Photoshop:

Pic #1. Lionfish photographed in Anilao, Philippines.
Unprocessed photo. The shot was taken with a Sony Cybershot P&S camera, on Auto U/W mode. No flash. Depth was approx 16m. Viz was about 12m.

Pic #2. Lionfish photographed in Anilao, Philippines.
2 minute process on Adobe Photoshop. I used Channel Mixer, followed by Levels and then Hue/Saturation, to restore the reds and achieve a 'dry land' effect.

If you look at my Scubaboard Gallery, you can see other examples of photos that have had simular processing..

http://www.scubaboard.com/gallery/showgallery.php/ppuser/82070/cat/500

 

[MauiScubaSteve]

Manual white balance is what you should be looking for as a required feature on any camera you intend to use underwater.

Charlie has earned my respect with regards to 99.9% of his diving advise posts, but this one falls in the other .1%.

RAW files and manual capabilities are what I feel everyone should be looking for. A camera with those features will have manual WB, but some fairly accomplished underwater photographers NEVER use manual WB.

I used Channel Mixer, followed by Levels and then Hue/Saturation, to restore the reds and achieve a 'dry land' effect.

Why in the underwater world would you want to achieve a 'dry land' effect?

 

[diver 85]

Here's an indication of what you can achieve with Photoshop:

Pic #1. Lionfish photographed in Anilao, Philippines.
Unprocessed photo. The shot was taken with a Sony Cybershot P&S camera, on Auto U/W mode. No flash. Depth was approx 16m. Viz was about 12m.

Pic #2. Lionfish photographed in Anilao, Philippines.
2 minute process on Adobe Photoshop. I used Channel Mixer, followed by Levels and then Hue/Saturation, to restore the reds and achieve a 'dry land' effect.

If you look at my Scubaboard Gallery, you can see other examples of photos that have had simular processing..

ScubaBoard Gallery - DevonDiver Gallery

PS is a diver's best friend------if you're shooting UW pics.....

 

[Charlie99]

Charlie has earned my respect with regards to 99.9% of his diving advise posts, but this one falls in the other .1%

RAW files and manual capabilities are what I feel everyone should be looking for. A camera with those features will have manual WB, but some fairly accomplished underwater photographers NEVER use manual WB.

RAW is another good alternative, that is more likely to be found in full DSLR sort of cameras. The RAW format saves unprocessed data from the 3 color channels of the camera sensor and you can adjust white balance after the fact.

I claim to avoid the 0.1% penalty on the technicality that, as you note, any camera with RAW format option most likely has manual white balance.

In actuality, I was thinking point and shoot cameras when posting and ignored the very powerful tool of RAW. A few point and shoots do have RAW format, which is a very powerful tool. OTOH, I have the CHDK hack that enables RAW format on my Canon SD1100 point and shoot and I don't bother using it anymore, because it doesn't significantly improve my results compared to manual white balance, particularly since the RAW format is not available for the videos I take with the point and shoot camera.

The next time around, the other feature I will be looking at closely is the low light level performance .... the combination of wide aperture and low noise at high ISO.

 

[MauiScubaSteve]

In actuality, I was thinking point and shoot cameras when posting and ignored the very powerful tool of RAW. A few point and shoots do have RAW format, which is a very powerful tool.

...

The next time around, the other feature I will be looking at closely is the low light level performance .... the combination of wide aperture and low noise at high ISO.

I have waited nearly a decade to make a significant new P&S purchase because up until now there has been no valid contender to the camera in my sig line.

RAW files and manual capabilities are what I feel everyone should be looking for.

Back in '06, I picked up a cheap/used Canon S70 due to compact housed size and RAW capabilities, but the small sensor, less than full manual control and cheap glass pretty much negated the RAW advantage. I was only mildly peeved when it floated away one day.

For someone to make an informed purchase, should we not give a full range of recommendations?

The Canon S90 is the most reasonably priced full featured P&S on the market today, IMHO. Beginner underwater photographers are getting very nice results with that camera and they can grow a long ways without changing cameras. I am ponying up for the S95 w/ most of the top end bells and whistles.