Red Filter Only Good to 70ft? Huh?

[JasonBoone 0]

So I need some advice here. Not really sure what to do. I am shooting video of a ship wreck next week (The Duane in Key Largo). Most of the shooting will take place at around 100ft. Here is my underwater video setup:

 

- Canon T2i

- Ikelite housing

- 8 inch dome

- Tokina 11-16mm 2.8

- Equinox Red Filter

 

Now for my question. If you take a look at the red filter that I am using, in the description on B&H it states that it will work in "up to 70ft of water." So what happens to your colors after you pass 70ft? I am not using a light, so I am wondering if I should just shoot the Duane without this red filter and without a light. I mean, what are my options? And what is the smartest way to go?

 

I've been shooting on the shallow reefs of Key Largo, and I must say the red filter (with no lights) does do the job well, giving me nice color. I just don't have any experience shooting in the depths below 70ft. And I really want to know why this filter says it's only good for 70ft...

 

Thanks for any help.

 

- Jason

Edited November 17, 2012 by JasonBoone

[johnjvv 11]

The red filter replaces lost red, the first colour to be lost in the colour spectrum. After 70 ft other colours are also lost and you would only be replacing red with your filter but not the other lost colours...

[JasonBoone 0]

So I am guessing the best bet would be for me to just keep the red filter on there?

 

And save money for some lights...

[MikeVeitch 0]

well.. the red filter also means you are losing a stop or two of light, at 100 feet you could use that extra light. Video lights are only good for stuff up to about 6 feet away, so they are good to light up close up shots of the wreck but they won't help if you are trying to get general "scenic" shots. I don't know the wreck so not sure if it has king posts and such that come shallow? Your filter would still be good for those, however, filter is really only effective until 50 feet, not 70 in my experience. Does the filter have a flip? or will it be fixed to the lens? If its a flip then you can try both and see what works better. Perhaps you can borrow or rent some lights for the closer shots?

[JasonBoone 0]

No it doesn't have a flip. What exactly IS a flip? Mine is just a thread mounted filter, fixed to the lens. Again, here is the one I am using.

 

Yeah I plan on just getting wide establishing shots, and I will most likely steer clear of any close ups. Stinks because I've heard that the Duane is covered in beautiful, colorful coral. But just curious, what will it look like if I get super close with just a red filter and no lights? I know that without the red filter and no lights that it will be cyan. So what is cyan plus a little red? hmm I don't know...

 

I guess I could look into light rentals, if they are in my price range.

Edited November 17, 2012 by JasonBoone

[ChrigelKarrer 52]

We used very successful a red filter on a professional Canon HD video camera between 25 and 35 meters on our "housewreck" in

the clear waters of Sardinia with the best results around noon when the sun is high and strong.

The video has clearly much more contrast and clarity and the colors are a bit more visible, but still not enough color to be "colorful".

Anyway even with the strongest video lights you will have problems to illuminate a big wreck and i personally like the blueish - and natural -hue of

ambient lights shots or recordings.

 

Check before the dive if the filter is vignetting!

 

Chris

[JasonBoone 0]

Ok cool.

 

Yeah I understand that you can't really light for a wide shot of a huge wreck, but I was just worried that having the red filter on there might make it worse. Looks like I am going to keep the red on there and shoot away. If I remember I will post some screen grabs or maybe even a clip.

 

Thanks again guys.

 

- Jason

[MikeVeitch 0]

a flip is a mount that the red filter fits into and sits between the lens and the port. You can flip it down in front of the lens when you want to use it and flip it up out of the way when you don't.. its very handy.. not sure if Ikelite has that option but you may want to ask them

[JasonBoone 0]

Oh ok I know exactly what you're talking about. Wow that would be convenient. I will look into that.

 

By the way, love your work! That shot of the four whalesharks in Cendrawasih Bay was amazing! Looks like that dive was a crazy fun time.

[Timmoranuk 10]

'Deep' video will require some creative lighting, both on-camera and off-camera. Presently, I'm working on a project which will mount 21,000 lumens on-camera / on-me, not to mention the lighting off-camera/me. Of course, having that degree of lighting is not license to use it...

[Glasseye Snapper 67]

Hi Jason,

 

There is nothing magical about the 70ft. For every 2-3m of water your reds loose a stop or so more than the blue/greens and the white balance needs to boost reds to compensate. This works until the boosted red becomes too noise. You can also boost the reds by increasing the exposure and you can do so without blowing out the blue/green by a red filter that selectively filters out blue/green. Depending on how strong the filter is you gain one or two stops of red, which means you can go something like 3-6m deeper than if you had not used the filter. If you go very deep the filter still helps but it would need to be much stronger to properly re-balance the red with blue/green. You can stack filters but loosing to much green/blue makes proper exposure and focusing more difficult.

One thing to remember is that the red channel of the sensor represents a broad wavelength range. The longest wavelength reds will disappear fastest and filters don't really help much with those, whereas the shorter wavelength reds will fare better and may still be present on your deeper dives.

 

Bart

[RWBrooks 26]

I'd say do some dives with filter for the wide and accept that you will get noise past a certain depth, then do another with the lights for closer shots to mix things up and get some colour of those corals coming through, povs even interiors if that's your cup of tea.

That's the big problem when you don't have a flip, can't swap mid dive when you have the opportunity, unless you can re- white balance the cam with the filter and lights to compensate for the filter.

Dive safe

 

Richard

[JasonBoone 0]

Wow thanks for all of the great info guys. Looks like I will go with the filter and start saving for some lights!

 

I am diving the Duane (100ft) this Monday, so I will for sure post some screen grabs from the video so you can take a look. I am also diving the Benwood, which is a WWII wreck sitting in about 25ft - 45ft of water, and I am sure the red filter will rock and roll on that dive. I am really excited!

 

Thanks again.

 

- Jason

[MikeVeitch 0]

Oh ok I know exactly what you're talking about. Wow that would be convenient. I will look into that.

 

By the way, love your work! That shot of the four whalesharks in Cendrawasih Bay was amazing! Looks like that dive was a crazy fun time.

 

Thanks.. the Whalesharks are incredible for sure

[peterbkk 110]

The red filter replaces lost red, the first colour to be lost in the colour spectrum. After 70 ft other colours are also lost and you would only be replacing red with your filter but not the other lost colours...

 

Don't want to be picky but one of the common misconceptions about the red filter is that it "replaces lost red". It can not. Red light that has been absorbed by the water is gone. Can not be replaced by a filter (only a artificial light can do that - and only over very short distances). The red filter looks red because it does not allow blue and green to pass through it.

 

Why is this important?

 

Because, if you don't understand what is really happening with the light and colours, you'll make wrong choices.

 

The red filter is reducing blue and green.

 

If there is enough red left in the ambient light, it will reduce blue and green, shifting the balance between the three primary RGB colours, creating the appearance of more red. If there is none or little red left, it wont help at all.

 

But, by reducing blue and green, it is reducing the total amount of light that the sensor is receiving. So, if the sensor is struggling to get enough light to get a decent image, you are just making it worse. Different cameras react differently. Some try to boost the light by amplifying it (gain). This can cause ugly fuzzies.

 

So a red filter (should really be called a "blue and green reduction filter") is only useful if there is a lot of ambient light and some red left in the mix of ambient light.

 

The depth range in which it is actually useful varies a lot from dive to dive and even during the dive as the sun disappears behind clouds. As a rule of thumb, you'll get some improvement between 5 to 15 meters with a red filter. If it very sunny, don't swing it in until 8 meters deep, otherwise some things will look too red. If it is cloudy start using it from 5 meters deep. Definitely have it swung out by 15 to 18 meters deep as you are just losing light to the sensor. There is no R left to "balance" with the GB.

 

If you turn on video lights, flip out the red filter. if you do a silhouette by pointing the camera towards the sun, flip out the red filter.

 

Better than a red filter, if you have a camera that can do white balance in low light, I suggest that you forget about the red filter all together and just set a suitable white balance for the depth that you are at. But that's a whole new story...

 

Regards

Peter

 

PS. If you like whale sharks, watch this: http://www.peterwalker.com/cenderawasih.html

Edited November 20, 2012 by peterbkk

[Oceanshutter 121]

I personally wouldn't use the red filter. The dslrs are good in low light, and as long as you get a good white balance, you should have good footage. I personally don't like a red filter, below 40. So I typically end up never putting it on. You may need to up your ISo a bit. In your particular instance, I would think light is going to be more importannt than color. If you do a red filter, you are going to lose 2 stops of light. Thus pushing your ISo too high and being too noisy.

 

Just do a good manual white balance and you should be good.

 

Dustin

 

[Lwang 0]

white balance is the sure way to go. If you don't want to do it once you reach the wreck, find some picture of a wide shot of a 100 ft deep wreck on the web that hasn't been color corrected and do a white balance on a section of the picture that should be white but is very bluish. If the camera has multiple white balance memory, do some WB for variation of bluish water like deep blue, shallow blue, etc. Then depending on your depth, just recall the one that looks apropriate.

[peterbkk 110]

Found this in a blog on the Canon T2i:

 

Take a picture of a white object – fill the entire frame with white

Menu: 4th tab says ‘custom WB’

Choose the white picture

Click on Set

Go to movie mode

Click the quick menu button and cursor over to WB and change it to the custom setting

 

http://www.learningdslrvideo.com/custom-white-balance/

 

If you take this approach, don't use the red filter.

 

Instead of a white object, you might use something that has some red in it so that the camera does not to push the white balance beyond a reasonable balance. Rust, brown coral, human skin, pink fins all enough red in them to help get a better UW WB.

 

regards

Peter

Edited November 21, 2012 by peterbkk

[johnjvv 11]

Don't want to be picky but one of the common misconceptions.......

 

Thanks for the clarification....I thought I had it all figured out!

[Interceptor121 842]

Interesting thread but filters can actually be useful

If we are talking stills in post processing you can do what you like in video you need to be the footage to be nearly there already

Cameras when setting custom white balance usually range between a max value of 8000-9900 and allow limited changed to tint

In some days color temperature underwater is above 10,000 plus stretching the camera white balance to boundaries creates noise in those circumstances the warmth of the filter helps taking down temperature a few 1,000K that helps let alone the tint adjustment

It is trued that in low light conditions filter as they take 1-1.5 stops end up with the camera increasing gain and creating noise to a point that can be unbearable but is not true that a filter absorbs more as you go deeper, the light goes missing by itself that is what looses exposure

So as you go down the combination of less light and the added 1.5 stops of the filter make your camera behave so badly that is not worth having a filter

What depth is workable depends on camera performance at high gain, general brightness and light conditions, visibility etc the manufacturer specs are a broad recommendation

[AllisonFinch 7]

Not to hijack, but really nice video, Peter!

[JasonBoone 0]

OK!

 

So......epic fail for me last month. Haha. I even had two dives on the Duane, and I blew it!

 

I used the red filter that is recommended to only 70ft, and white balanced on a large white card at 100ft, which is where most of the shooting took place. The only problem was...my focus was off the entire time! Oops. My eyes are so bad that I didn't even notice on my tiny LCD screen. Take a look at some screen shots from both dives:

 

 

 

 

 

 

 

Nevertheless, I still have some questions. I notice on almost all of my video that I occasionally get red fringing around the edges. Usually on the top edges of the screen. It is like red vignetting. The second photo that I posted above is REALLY bad in the upper left hand corner. Any way to avoid this aside from totally ditching the red filter? I get this even in shallower waters, such as the 30-40ft range.

 

I am also not very happy with the lack of blues in the water. I want my blues to POP!

 

So to conclude, do my colors even look accurate? Am I at least in the ballpark and (if the footage was in focus) would I be able to salvage this footage with some color correction? I think that the colors are accurate, I just need to figure out the issue with the red fringing and the lack of blues.

 

Any and all suggestions/advice are welcome. I am heading back to the Duane next week, and I am going to get some nice footage, come hell or high Key Largo water. Should I use the same red filter setup with a white balance at 100ft? But only this time get the focus correct....haha

 

Thanks for any help guys and gals.

[Nick Hope 151]

... red fringing around the edges.... Any way to avoid this aside from totally ditching the red filter? I get this even in shallower waters, such as the 30-40ft range.

 

Can be avoided to some extent during capture by white balancing on something pinkish. For a long time I zoomed in on a fin covered with white gaffer tape with red marker pen scrawled on it. Now I zoom in and white balance on the palm of my hand (old Z1 HDV camera with urpro filter). Look at this old thread.

 

I am also not very happy with the lack of blues in the water. I want my blues to POP!

 

Can be improved with primary colour correction to shift the balance away from red and towards blue, then you could increase the saturation of the blue. Watch this. But there's only so much you can do if the water wasn't really blue to start with. Relocate to Fiji.

 

So to conclude, do my colors even look accurate? Am I at least in the ballpark and (if the footage was in focus) would I be able to salvage this footage with some color correction? I think that the colors are accurate, I just need to figure out the issue with the red fringing and the lack of blues.

 

Yes, you're in the ballpark. That red caste is very common in underwater footage, especially in the highlights. It's very easily fixed with a 3-way colour corrector, or curves, or colour balance control in your NLE.

 

Should I use the same red filter setup with a white balance at 100ft?

 

I would say you're not far off. What you have is a good basis for fixing the colours. The whole spectrum is there in abundance. Make sure to repeat your manual white balance if the depth or condtions change.

Edited December 24, 2012 by Nick Hope

[JasonBoone 0]

Wow thanks for all of the info Nick. It is REALLY helpful. That Underwater Realm color grade was extremely cool. I especially loved how they made the light rays pop in the background. Way cool.

 

And its good to hear that I am in the ballpark with my colors. I assumed that if this footage was properly in focus that I could've salvaged it with a color grade.

 

Anyways, I've concluded that I just need more time underwater with my new camera setup to get experience and practice. On the next dive I am going to try some experimentation with white balancing on the sun. It looked to provide good results from your tests. I am a little curious if this will be possible at 100ft with low visibility.

 

Thanks again Nick. And by the way, I love Bubble Vision! Big fan.

[Nick Hope 151]

You're welcome, and thanks.

 

On the next dive I am going to try some experimentation with white balancing on the sun. It looked to provide good results from your tests. I am a little curious if this will be possible at 100ft with low visibility.

 

I have never found white balancing on the sun to give as nice a result as using my hand or fin. I don't know if your setup will allow you to white balance one-handed to do that though. On my DV and HDV cameras the sun was useful for times when I descended too far without white balancing. Those cameras don't like to make big leaps in white balance, and pointing at the sun was often the only way I could get a new white balance fix, before white balancing on my hand or fin again. But your camera might not have a problem with those big leaps.