Fishrock Dives SRP filter on GoPro Dive housing

[Marty Cerven]

Interceptor I take it you haven't used a GoPro before, they are fully auto. No WB, No ISO, all you can select is frame rate, resolution, FOV, Spot or center metering and all the rest is you battling the auto settings lol.

They are a great little underwater camera for people starting out thanks to the simplicity but if you want to push it further then its sometimes a bit of a battle. They are also great because of the size and price making it much easier for people to get started in UW video, your not going to get Nat Geo quality but much better video then all the point and shoot cams. So even though they have some pretty big limitations for the cost including a good filter they are still a great deal and with a bit of practice can take some decent video.

The best control you have atm is via different filters, the AWB struggles underwater without one and from what I have noticed having a filter like the URPro range does give a great boost when enough light is there. As can be seen in my cave video where I havent needed to touch the wb in post it did quite well at those depths, the deeper stuff has had some issues with all the cameras I used but the URPro filters have done best of the bunch in the conditions I had here.

I do use a slate to base my wb adjustments on in post and this also shows the difference between filters and no filters, with no filter there is very little data in the red channel and so there is very little you can do to try and bring back any colours. This also shows in the filters with some working better then others at deeper depths, overall at 25m or less the URPro's did a great job but the Magic filters best is at 10m and its starts to look like no filter much beyond 15m in most cases.

Here is the last of my basic videos, its a compilation of all the best shots including some new ones from the GoPro worn on my friends head. I hadnt even noticed that he shat himself at the cave exit when a grey nurse did a quick turn right in front of him lol. Shame the camera was pointing down a little too much so the shark isn't quite framed properly as it was above eye level and he was likely already ducking for cover but you can see he got a good fright lol.

All the tray shots were set to 1080p30 wide mode and the helmet cam on my friend had a Blurfix and screw in URPro cyan filter, not ideal for in the cave with just a basic crappy dive torch but I added that shot to show him going over the bull ray before he kicked it lol. His camera was set to 1080p30 wide in the cave video and all other shots had it at 960p30 to help frame a little in post things like the shark in the cave video that was just out of frame using the regular 16:9 1080p mode.

There are some shots with both turtles from the headcam and the others should be pretty obvious.

[video=youtube;xuG1IVobYNk]http://www.youtube.com/watch?v=xuG1IVobYNk[/video]

 

[Interceptor121]

Interceptor I take it you haven't used a GoPro before, they are fully auto. No WB, No ISO, all you can select is frame rate, resolution, FOV, Spot or center metering and all the rest is you battling the auto settings

Marty the situation for a gopro is nothing different from a user of a compact camera shooting a video
The only setting that a compact camera user has in addition is custom white balance
The rest is the same both the gopro and any digital compact will shoot at fixed aperture fixed focus and to React to the lack of light they will increase the ISO
There is no difference whatsoever between the gopro and any other compact in the auto mode behaviour
I know you can't balance on a slate but you can shoot footage of a white slate and use it later to white balance the clip
You are right that the filter adds some red I have URPRO filters and they work well
However when there is little light depending on the editing program you use you can apply the filter afterwards using not only white balance but also the RGB gain sliders
If you send me a piece of footage in Dropbox raw where you captured the slate during a dive or even one where you didnt have a slate at depth of 30 meters I will send you back an example

 

[Marty Cerven]

I can send you a couple of clips but they will be trimmed off the original as all the raw files were all one continuous shot here, this means that all the deep footage is at the beginning of a 3.7GB video file.

I pretty much use the method you suggest with the slate and magic bullet colorista 2 plugin in adobe premiere pro, if there is enough light its pretty simple and you can just click the eye dropper on the slate and it does its magic literally. I didn't get the slate in enough shots this time around as I just forgot I had it most of the time on my first dive with currents, surge and a rookie gearing up error I battled all dive, then the next dive I got my dive buddy to wear it assuming it would be easier to just shoot his hand every so often. Problem was he put it on his right hand and seemed to prefer sticking close to the rock on his right so I couldn't see it most of the time lol.

In the deeper sections you need to be a bit more creative with the RGB gain controls, the gopro is meant to have a firmware update that will give it a fixed wb as an option and flat image profile which should make it easier to work with using this method. This will help a fair bit as atm once the light gets low it tends to get pretty much all green with the cameras awb just about giving up at times it seems, using filters does help avoid the green out most of the time but as you said reduces light so causes more noise.

I can send you a clip at 30m with no filter and see if there is anything you can do beyond redrawing the scene by hand.

 

[Interceptor121]

I am good at drawing send away!!

 

[toozler]

Marty, I have a feeling from seeing this and other videos with red filters is that they give the image a murky, creamy, foggy look. Is it the filter or the water was just like that?

Would a contrast bump on editing fix that?

 

[Interceptor121]

Filters absorb light the camera compensates increasing the ISO
This in turn increases noise that gives it a grainy look
That's why at depth where there is little light you should not use a filter
However the noise should not normally be present at the working depth of the filter unless the filter itself is poor quality

Marty, I have a feeling from seeing this and other videos with red filters is that they give the image a murky, creamy, foggy look. Is it the filter or the water was just like that?

Would a contrast bump on editing fix that?

 

[Marty Cerven]

Marty, I have a feeling from seeing this and other videos with red filters is that they give the image a murky, creamy, foggy look. Is it the filter or the water was just like that?

Would a contrast bump on editing fix that?

I dont think its the filters its just the visibility conditions here. Most of my videos are shot in low vis under 10m at home and conditions here werent much better. Comparing no filter to filter doesnt make it much murkier but possibly some of my colour corrections may have made some shots a little murkier if anything.

Here are a few side by side pics from a couple dives, I wont say which filter is which maybe let you guys guess and see which you think gives the best result. The small middle one is the headcam with a blurfix adapter worn by my friend the others are in the same order for each shot. They are all GoPro dive housings with a either no filter, SRP clipon URPro, magic by BS and the oculus filter.

I still haven't got around to adding the depth data to my comparisons so I will give rough estimates but could be out by a few meters.

These are aproaching the turtle cave, first image is at the top and the others about 3-5m deeper at around 18-20m I think lol



These 3 are coming out the exit of the cave which is at 14m and dropping down last image likely around 20m



These 3 are a bit deeper at 25 to 28m and in this light they all struggled a bit but id go with a filter over the clear in most cases here still.



@ intercpetor I will get around to getting you a sample to play with soon. Most should be able to pick which is the clear lens quite easily here. In all the shots the filters haven't had a very negative effect even beyond their most effective depths given the conditions.

 

[Interceptor121]

This may be useful URPRO Patented Underwater Correction Filters

It refers to the times we had film but explains light loss with filter. Here is where you see that subjects to distance should not exceed 80 feet or 24 meters. This includes your depth+subject distance. This rule comes from the fact that ISO films were available to a value of around 800 with some other peaking at 3200. New digital cameras reach ISO values that are higher such as 16000 or even 32000 or higher. I don't know what the GoPro can do but probably some really high values in the region of 12800

This means the GoPro can push the depth limit to more than the recommended 24 meters and still come up with something. However this something will be more grainy like a clip at night. So it would be interesting to compare side by side two small clips with and without filter around 30 meters and a close subject to compare the noise and color adjustments

 

[rdog]

Marty,

I am looking to purchase either the SRP clipon URPro, magic by BS or the oculus filter. Can you spill the beans on which filter is which in the comparison photos you posted? I feel the best one is the upper left hand corner.

Thank you,

Rich

 

[Marty Cerven]

Ok the top left is the srp clipon, top right is no filter, bottom left is the backscatter and bottom right is the oculus. The headcam has a blurfix and screw in filter.

I will try and get a comparison video up by Sunday just wont be home much the next few days. Surprisingly the oculus isnt that far away from the urpro but it does get more red/orange shallow and then deeper it tends to lose more detail compared to the urpro, also the colours are just that little bit off in comparison. The backscatter does produce nice colours at the shallow sections probably the best at under 10m but loses effectiveness not much beyond that and levels out with no filter at around 15m. The urpro and oculus were best to about 25m here and with better light and vis i think would have been ok to 30m.

No filter with no lights tends to lose all colour between 4-10m but usualy before about 6m in most cases. The urpro clipon for both options gives pretty much the same results as does the original screw in for the blurfix. This one I dont have a direct side by side comparison of as it was always on the headcam, and so its always at a slightly different angle along with more movement but is fairly consistant with the other filters by urpro.

In actual use of the filters uw the flip is a good simple method and the clips are no issue handling and it should come with a handy way of storing it safely both in and out of the water. The oculus string attachment method is a little crude and quite fiddly to do on land, I didnt attempt this uw this trip as i didnt have enough acces to it and going by how fiddly it is on land i didnt want to have to deal with it uw lol.

The backstatter flip has one very annoying side effect, you cant really get access to the gopro back door latch when its installed. You can just about get a finger in there but its a major pita, even with the srp clip you have limited acces to the latch. The difference however is you can take the clip off in a second but you need a small allen key to remove or attach the bs flip assembly. I found I needed to use a tool such as a screw driver to get in under the latch to help open it so this is something i dont like much in their design.

Storage wise srp have come up with a neat solution that i think will be included with the filters, the other 2 have no lens caps or way of storing them so you will need to find something. As you need a tool for the bs to install or remove you most likely will want to keep it on the housing so will need to find something to cover and protect it in that setup.