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Red filters for GH4

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In my first trip with the GH4 I shot in a open cenote at -35m with the Pana 7-14mm. Some of the takes were shot with MWB done at around -17m (A), and some of them with the MWB done at shooting depth (-35m) (B). All of them at maximum aperture (f/4) and 1/25 (25fps).
I found B colors nicer compared with the greeny A shots but I noticed B shots were much noisier!!. Since my old HC9 was not able to WB under -15m, and I guess on land the electronic adjustments are not extreme enough to notice such a thing, I was very surprised and disappointed with this issue.
In my next trip I'm planning to shoot sharks in deep (-40m) channels in Maldives and I'm definitely going to try red filters in my lenses (Pana 7-14 and pana 12-35) as a work around for white balancing in this situations (red filter plus MWB or AWB. I'll try both).
Which filters would you recommend me. And, most important, how can I put a filter in front of the 7-14mm since it has no thread at all???!!!

Thanks

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Magic filter is good, I have used it a lot and it definitely help when getting deep, you do lose a stop of light. If the lens doesn't have thread, you still can use it, look at the instruction here:

 

http://www.magic-filters.com/magicfilters.html

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I've gone around in circles with red filter or not with my GH4. Due to most of my diving being sub 20m locally I don't bother, if you need to add any additional light - you are pretty much stuffed if you have a filter installed, unless you go down the route of Cyan filters etc - and sub 30m you are better off channel mixing later (I feel)

 

Alas the GH4 isn't the best for MWB

 

Peterkk on here uploaded some daylight PDFs of varying green casts to set your WB presets on your GH4 up for different depths.

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As Trickster says, if you start adding in filters the you're going to have real issues when using video lights. And a filter also works by blocking out light, so you're still potentially heading towards noise issues.

 

What did you have the ISO/gain set to, and what resolution and codec were you using?

 

Also, what's your aversion to using lights?

Edited by Stuart Keasley

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As Trickster says, if you start adding in filters the you're going to have real issues when using video lights. And a filter also works by blocking out light, so you're still potentially heading towards noise issues.

 

What did you have the ISO/gain set to, and what resolution and codec were you using?

 

Also, what's your aversion to using lights?

Well, I don't have aversion to lights at all. I'm talking here about specific situations. In both cases, the cenote and the Maldivian channel, I'm mainly shooting a landscape or subjects 4 meters away from my camera. No point to use any light.

 

I know any filters will make me lose incoming light but I need to test which way comes out with better results in terms of colors and noise.

 

 

I've gone around in circles with red filter or not with my GH4. Due to most of my diving being sub 20m locally I don't bother, if you need to add any additional light - you are pretty much stuffed if you have a filter installed, unless you go down the route of Cyan filters etc - and sub 30m you are better off channel mixing later (I feel)

 

Alas the GH4 isn't the best for MWB

 

Peterkk on here uploaded some daylight PDFs of varying green casts to set your WB presets on your GH4 up for different depths.

Please, can you find that post for me?. I can't find it.

 

Regarding GH4 WB capabilities, I had the chance to try a GH4 before buying mine and the MWB performance of the camera was one of the best PROS in my opinion. I found the colors pretty real and natural white balancing at -20 to -25m but, as I said, compared to my old HC9 everything is better for me.

 

Magic filter is good, I have used it a lot and it definitely help when getting deep, you do lose a stop of light. If the lens doesn't have thread, you still can use it, look at the instruction here:

 

http://www.magic-filters.com/magicfilters.html

Thanks a lot!!!

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Well, I don't have aversion to lights at all. I'm talking here about specific situations. In both cases, the cenote and the Maldivian channel, I'm mainly shooting a landscape or subjects 4 meters away from my camera. No point to use any light.

 

I know any filters will make me lose incoming light but I need to test which way comes out with better results in terms of colors and noise.

 

 

Please, can you find that post for me?. I can't find it.

 

Regarding GH4 WB capabilities, I had the chance to try a GH4 before buying mine and the MWB performance of the camera was one of the best PROS in my opinion. I found the colors pretty real and natural white balancing at -20 to -25m but, as I said, compared to my old HC9 everything is better for me.

 

Thanks a lot!!!

Try taking a flood beam video lamp on a night dive, then tell me it's only good for subjects that are closer than 4 metres away ;-) For sure, it loses punch and power, and you're still going to be losing reds, but it will still bring up light levels which is what you need.

 

Back to the other question, what ISO/Gain were you set to, and what codec and res are you recording in?

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Sorry, I forgot to answer those questions.
I was shooting mov files 4K(100Mbps), 25fps (3840x2160). Iso 1600. (as I said much more noisier with my second MWB than with the first)
Regarding shooting subjects 4m away.... At night I can get by with my two Sola 2000 lights in some situations. But in daytime, I always try to avoid using lights for subjects further than 1 meter because of the issues of mixing lights of different color temperatures. My very first term can be lighted with my Solas and a do the MWB for them. But at 3 meters my lights loose a lot of their influence and getting the right light filtering with nice results is really hard.

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Sorry, I forgot to answer those questions.

I was shooting mov files 4K(100Mbps), 25fps (3840x2160). Iso 1600. (as I said much more noisier with my second MWB than with the first)

Regarding shooting subjects 4m away.... At night I can get by with my two Sola 2000 lights in some situations. But in daytime, I always try to avoid using lights for subjects further than 1 meter because of the issues of mixing lights of different color temperatures. My very first term can be lighted with my Solas and a do the MWB for them. But at 3 meters my lights loose a lot of their influence and getting the right light filtering with nice results is really hard.

 

Personally, I wouldn't be overly concerned about different colour temperature light sources, your SOLA's are at circa 6000 Kelvin, so tending towards natural light, and will probably be fairly close once you've had the light and colour fall off from a bit of distance. But more importantly, throwing light in raises over all exposure levels and so gives you something to work with. Trying to grade a noisy and low exposure image is always going to be a nightmare...

 

Again, personally I wouldn't go above 3db of gain (on the GH4), I would try and stick to 0db as much as possible... so that puts you on ISO 800, with circa 1200 as an outside

 

Also, unless you really need 4K, then I'd be inclined to shoot Full HD at 100Mbps instead. Whilst it's possible to supersample 4K to Full HD to improve quality, you're still reliant on decent source footage at the 4K end. Shifting to Full HD @ 100 Mbps, you're effectively reducing compression by a factor of four... the more compression you have, the more you'll see noise and issues in the low lights, so this is going to help.

 

Just ideas and suggestions....

Edited by Stuart Keasley

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Sorry, I forgot to answer those questions.

I was shooting mov files 4K(100Mbps), 25fps (3840x2160). Iso 1600. (as I said much more noisier with my second MWB than with the first)

Regarding shooting subjects 4m away.... At night I can get by with my two Sola 2000 lights in some situations. But in daytime, I always try to avoid using lights for subjects further than 1 meter because of the issues of mixing lights of different color temperatures. My very first term can be lighted with my Solas and a do the MWB for them. But at 3 meters my lights loose a lot of their influence and getting the right light filtering with nice results is really hard.

 

ISO1600 is too high. I shoot at ISO1600 at night without problem because the background is black anyway, but during day time, you need to keep it ISO400 or lower, if the visibility is great, you can get away with ISO800.

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Magic filter is good, I have used it a lot and it definitely help when getting deep, you do lose a stop of light. If the lens doesn't have thread, you still can use it, look at the instruction here:

 

http://www.magic-filters.com/magicfilters.html

I wrote to Alex and he replied that he is not sure none of his rear lens filters would fit in the Pana 7-14mm. Let's see if someone comes up with a solution...

 

 

Also, unless you really need 4K, then I'd be inclined to shoot Full HD at 100Mbps instead. Whilst it's possible to supersample 4K to Full HD to improve quality, you're still reliant on decent source footage at the 4K end. Shifting to Full HD @ 100 Mbps, you're effectively reducing compression by a factor of four... the more compression you have, the more you'll see noise and issues in the low lights, so this is going to help.

 

Just ideas and suggestions....

Ups!. Well. That is the theory. And that was the main reason I never considered buying anything to shoot in 4K at all at first, but after reading a lots o reviews articles it seemed that 4k postpo and grading and downscaling from to HD actually gives better results than shooting and post-producing directly in HD.

The argument basically is based on the fact that the 4k compression algorithm is much more effective than the HD one.... but I don't remember well the details, I ended up dizzy from so much research.

If I tell you the truth I haven't had the chance to test it myself... but I will!

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The argument basically is based on the fact that the 4k compression algorithm is much more effective than the HD one.... but I don't remember well the details, I ended up dizzy from so much research.

If I tell you the truth I haven't had the chance to test it myself... but I will!

That's not true the H264 codec as well as any intra codecs are not optimised for 4K and perform worse than what they do for 1080p

The downscaling theory is based on the resolution available and the theory that downscaling a 4:2:0 color space becomes 4:4:4

The first is true only for cameras without full sensor readout and the second is just not true

Edited by Interceptor121

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I wrote to Alex and he replied that he is not sure none of his rear lens filters would fit in the Pana 7-14mm. Let's see if someone comes up with a solution...

 

Ups!. Well. That is the theory. And that was the main reason I never considered buying anything to shoot in 4K at all at first, but after reading a lots o reviews articles it seemed that 4k postpo and grading and downscaling from to HD actually gives better results than shooting and post-producing directly in HD.

The argument basically is based on the fact that the 4k compression algorithm is much more effective than the HD one.... but I don't remember well the details, I ended up dizzy from so much research.

If I tell you the truth I haven't had the chance to test it myself... but I will!

 

 

 

 

That's not true the H264 codec as well as any intra codecs are not optimised for 4K and perform worse than what they do for 1080p

The downscaling theory is based on the resolution available and the theory that downscaling a 4:2:0 color space becomes 4:4:4

The first is true only for cameras without full sensor readout and the second is just not true

 

I don't really care so much about the technical reasons of how and why, just want to know if my goal is to have the best possible edited footage in HD, is it better to record in camera 4k or HD ? Not sure if it matters, but I am talking about a Sony A7s ii, which excels in low light and low noise.

Edited by ronscuba

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The A7IIs has the same video modes of the RX100 IV. Unless you want to use crop for 4K the XAVC 50 mbps HD will also have full sensor read out and effectively allow for more dynamic range of the 4K 100 mbps when you record internally. Do some tests yourself and come to your own conclusions

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I don't really care so much about the technical reasons of how and why, just want to know if my goal is to have the best possible edited footage in HD, is it better to record in camera 4k or HD ? Not sure if it matters, but I am talking about a Sony A7s ii, which excels in low light and low noise.

As per my suggestion to Etc, I'd personally say record in HD. Everything you may gain from super sampling down from 4K will be more than lost by the relatively higher compression (compared to HD) that onboard on the A7s uses.

 

If however you were pushing out uncompressed to an external recorder, 4K to HD wins by a mile

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I don't really care so much about the technical reasons of how and why, just want to know if my goal is to have the best possible edited footage in HD, is it better to record in camera 4k or HD ? Not sure if it matters, but I am talking about a Sony A7s ii, which excels in low light and low noise.

As per my suggestion to Etc, I'd personally say record in HD. Everything you may gain from super sampling down from 4K will be more than lost by the relatively higher compression (compared to HD) that onboard on the A7s uses.

 

If however you were pushing out uncompressed to an external recorder, 4K to HD wins by a mile

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I wrote to Alex and he replied that he is not sure none of his rear lens filters would fit in the Pana 7-14mm. Let's see if someone comes up with a solution...

 

 

 

There are two solutions. Nauticam USA have suggested using tape to stick a magic filter to the rear of the 7-14mm. I believe Chris Parsons used this method.

 

The alternative is: the rear filter holder,Part number VXQ1911 Frame, from the panasonic 8mm will fit the 7-14mm with some minor modifications. You need to remove part of a plastic raised ring on the lens side of the holder.

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That is much more elegant than cutting tiny pieces of magic filter and sticking on the 7-14mm

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There are two solutions. Nauticam USA have suggested using tape to stick a magic filter to the rear of the 7-14mm. I believe Chris Parsons used this method.

 

The alternative is: the rear filter holder,Part number VXQ1911 Frame, from the panasonic 8mm will fit the 7-14mm with some minor modifications. You need to remove part of a plastic raised ring on the lens side of the holder.

More detail on how to fit a rear filter holder that give full zoom range.

http://www.dpreview.com/forums/post/51390321

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Ah, missed the limit on the wide angle on the adapter

 

Again, personal choice, but I wouldn't be too bothered by trying to retro fit a back filter if it means using tape etc... Too much potential for gunk near the sensor and owns workings for my liking.

 

Another option would be to fit a filter step up ring to the outside of the lens hood, then fit a filter to that. Provided that the adapter ring ding sit proud of the lens hood, you wouldn't get any vignette etc, although you would need to ensure the step up ring fitted inside the done port aperture.

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Ah, missed the limit on the wide angle on the adapter

 

Again, personal choice, but I wouldn't be too bothered by trying to retro fit a back filter if it means using tape etc... Too much potential for gunk near the sensor and owns workings for my liking.

 

Another option would be to fit a filter step up ring to the outside of the lens hood, then fit a filter to that. Provided that the adapter ring ding sit proud of the lens hood, you wouldn't get any vignette etc, although you would need to ensure the step up ring fitted inside the done port aperture.

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I have retro-fitted the VXQ1911 part in the back of my Panasonic 7-14mm. It cost me a blummin' fortune from www.partsimple.com... USD 79.24 including shipping to Thailand. It was the cheapest option I could find. I used a craft knife rather than a Dremmel to shave off the material that wasn't needed.

 

Using tape does work OK. Use the thinnest 3M Scotch Magic tape which leaves less residue than others.

 

As for filters, in my experience the Original Magic Filter does not give good results underwater with the GH4. I don't know how their Auto-Magic filter performs. In the back of my Panasonic 8mm fisheye I have recently been using a piece of Rosco Dark Salmon (#008) e-color+ gel which perfectly matches the UR-Pro blue-water filters that are used in Gates, L&M etc. housings. With a manual white balance on the palm of my hand, results seem good. You can contact Rosco or their distributors and ask them to send you a set of Rosco swatch books for free then you can test different colours. The swatches themselves are big enough to cut a couple of filters out of. Be careful not to scratch them as you flip through the swatch book. These gels are intended for lights, not lenses, and purists will tell you that you should be using a proper optical gel filter such as Kodak Wratten, but the Rosco material looks pretty clear to me! I don't know which of the Rosco gels is theoretically the most optically clear. Once I know that I will probably order a bigger sheet. I have also used Rosco lighting gels as ND filters on the back of my Panasonic 7-14mm.

 

Rosco-gels.jpg

Edited by Nick Hope

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Thanks guys. Since I'll use the filter just in specific situations I think all the options seem to be a little bit messy, so I guess the right way to go is first use the filter in the 12-35mm. If it works fine, I'll return to this topic.

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I know the 'scene' is poor and so to the vis, but I hope the colours show at least what I'm trying to convey

 

Taken at the same time (at 15m'ish) on the same dive.

 

No Filter - Manual White Balance

post-43742-0-43632200-1461780191_thumb.jpg

 

UR Pro 'Red' Filter - Manual White Balance

post-43742-0-26715200-1461780195_thumb.jpg

 

Adding +30 Sat in Post to the No Filter File:

post-43742-0-23931800-1461780792_thumb.jpg

 

Using a White Balance Slate and Sceney Profile.

 

This made me realise the GH4 does a pretty good job without one.

Edited by thetrickster

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Generally I find panasonic custom white balance to work pretty well. The filter gives just extra saturation so the footage is ready to go. In shallow water the filter also helps avoiding the camera to use small aperture. In general sony needs filters panasonic doesnt is my appraisal. The LX100 tends even to oversaturate colours and definitely doesn't require a filter in any scenario

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