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adamhanlon

Member Since 09 Feb 2007
Offline Last Active Jan 21 2019 01:24 PM
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Posts I've Made

In Topic: Canon Underwater Haze

16 January 2019 - 01:26 PM

One of the issues you are having here is that you are simply too far away from your subjects. Lights is absorbed by water and the further away you are, the greater the distance that the light has to travel. Judging by the focal lengths you are shooting at, you are considerable further away than you need to be to get sharp images. I guess these are all with the 18-55mm. I'm not sure about this lenses' performance underwater, but would only be using focal lenths like this at the 18mm end. If I need more zoom...get closer!

 

To be blunt, strobes would have little effect if you are too far away either. Their light drops off pretty rapidly

 

Another issue is that of white balance. Whe shooting using ambient light, it helps to manually white balance at the subject's depth. 

 

Underwater color correction filters can help with this too.

 

Lastly, any RAW file will need editing in order to get the best from it. This is especially true when dealing with the way water absorbs light.

 

The screen grab from your friends GoPro footage is actually a case in point. GoPro footage is typically automatically corrected to some extent. 

 

Adam


In Topic: White balance options for video lights (Wide Angle)

11 January 2019 - 05:19 AM

I agree that WB options vary from camera model to model! This means that it is impossible to provide generic advice.

 

I tend to keep the camera pretty still whie shooting and shoot short sequences and find that this helps to minimizes WB shifts. There are exceptions, like when there is bright sunlight filtering through the water, but arguably, fixed WB will produce funky color cast in this situation too.

 

The blue keldan light filters correct the light's output to reflect the actual color temperature of the ambient light at depth. This produces a natural looking scene.

 

Adam


In Topic: White balance options for video lights (Wide Angle)

10 January 2019 - 02:34 PM

Keldan color correction (light) filters: http://keldanlights....nt-filters.html

 

They are blue and are not excitation filters!

 

I think I perhaps misspoke in my reply above. I would use auto WB when using lights (assuming the camera will WB). With a camera that will not WB well underwater, I guess I will force it to WB, but would normally try and use a slate and WB off that.

 

With stills we can control the color of the background by using shutter speed. This is not really an option with video.

 

Practically, I find that video footage in which I can see the effect of the light looks unnatural. I prefer the lighting's effect to be more subtle.


In Topic: Tokina 10-17 with a dome and 1.4x question

08 January 2019 - 12:26 PM

You are correct about changing the nodal point in relation to the dome's curvature. It is highly likely that you do need an extension.

 

Most housings seem to need around 18mm of extension with the 10-17mm and another 15mm of extension with the Kenko 1.4 TC. Of course, the amount does vary, so the only way to be sure is to try it out in the water.

 

There are a few manufacturers that offer specific extensions sized precisely for this lens.

 

In terms of domes, bigger is (nearly) always better in terms of IQ.

 

Adam


In Topic: White balance options for video lights (Wide Angle)

07 January 2019 - 03:04 PM

There is a significant difference between the way we light video and stills.

 

With stills, when shooting wide angle, we light the foreground subject with a strobe and then balance this with a "correctly exposed" background. Hence we would tend to expose for the color temperature of the strobe's output.

 

With video, the light is used to lift shadows and, if used correctly, is not really visible in the footage. Hence, WB should be based on that of the ambient light, not the light's.

 

As mentioned above, Keldan actually offer color correction filters for their lights that correct their output to match the ambient's color temperature.

 

Adam