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dreifish

Member Since 25 Oct 2013
Offline Last Active Jun 18 2018 07:56 AM
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#396515 Panasonic GH5: what do you use to get the correct exposure?

Posted by dreifish on 17 June 2018 - 02:31 AM

I shoot in manual unless I know I need to follow fast action where the subject might be below me one second and above me the next (exposure can vary quite a bit when shooting down vs up in the water column). Like others, I usually lock down my aperture and shutter speed and then adjust exposure using ISO only, or go into AutoISO where necessary.

 

I like knowing what my ISO is at though, which is why I shoot in manual. It lets me know the conditions in which my lights are going to perform well and when they're going to be too weak to bring back colors. And with the excellent layout of controls on the Nauticam GH5 housing, it's quite easy to adjust the ISO on the fly manually. 

 

In terms of monitoring, I primarily rely on zebras to tell me what's blowing out and the camera meter -- I find that -2/3 to -2 stops underexposed for ambient light (according to the internal light meter) usually produces the most pleasing "blue" water column color for me. So that's what I aim for.

 

For those of you who do use the waveform, what IRE do you aim to expose the background water column at, generally? I'm quite curious what IRE level of blue people find most pleasing as a backdrop.

 

And by the same token, what do you set your exposure by? Topside, I usually expose to get the skintones of people in the right IRE range, and let the rest of the image fall where it may. Since underwater people shots are a lot less common, I'm curious what everyone sets their exposure by? 18% grey? The water column? Expose to the right just shy of blowing the highlights and fix it later in post? 




#396098 Panasonic LUMIX GH5 for underwater video

Posted by dreifish on 06 June 2018 - 07:20 AM

There are plenty of subjects that you need f/16 if you want to focus more than the eyes like pygmies, bobtail squid, shaun the sheep nudis and you can’t really work out with f/11 likewise you want more depth of field on a larger subject if you want to focus the whole fish I have plenty of examples where the same shot on the same subject looks better on a full frame but less so on ambient light wide angle


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But if you need f/16 on m4/3 to get the entire subject in focus, then you'd need f/32 on full frame, not f16 to get the same depth of field. And the loss of resolution to diffraction would be the same (assuming the same pixel size). The shot may look better on full frame because of dynamic range, for example, but assuming the same level of magnification and the same depth of field, they should look basically identical if I understand the physics correctly.




#396097 Panasonic GH5 and mini flash DMW-FL70

Posted by dreifish on 06 June 2018 - 07:15 AM

Yeah, I've been using it for a few months now. Works great! I've only tested it in manual mode, but I see no reason why it shouldn't work with TTL also. Since it draws its power directly from the camera, you don't need to worry about recharging or changing its battery like with the nauticam led trigger. Plus, it's more compact, cheaper, and does TTL. Overall it's great. I think it's the best option for the GH5.

 

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#396016 Panasonic LUMIX GH5 for underwater video

Posted by dreifish on 04 June 2018 - 05:50 AM

Dreifish is spot on you have at least two stops benefit with full frame however where you shoot f/4 in a mft fisheye with ff you are qt f/8 negating the benefit for ambient light wide angle.
The resolution however is much better with full frame and this is something that doesn’t go away if you print. On a screen unless is 4K you don’t see the benefits and in video definitely you don’t see them.
As a paradox I have seen full frame having much better performance in macro because mft have quite a bit of diffraction from f/11 onwards and at f/16 most lenses are weak and become garbled at f/22. Full frame you keep sharpness until the smallest aperture and the resolution is amazing


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But why would you shoot macro at F16 or F22 on m4/3? At F11 on m4/3, you get the same depth of field and diffraction characteristics as you would at F22 full-frame. Some full-frame sensors have more megapixels to crop into, but in actuality you get greater magnification in m4/3. 1:1 macro for m4/3 works out to filling the frame with a subject that would require 1:2 reproduction ratio on full frame to fill the frame. So in terms of detail, you should be able to extract more detail from small subjects with m4/3 than full frame simply because the pixel density is greater. Diffraction scales with depth of field, so it's ultimately equivalent for the same depth of field across different formats. 

 

The main advantage I see for macro with full-frame cameras is actually faster focusing with less hunting at macro distances. And I think that's primarily an advantage with newer generation Nikon (and perhaps Canon -- I have no personal experience) bodies. The 90mm macro on Sony A7x bodies is also quite slow to focus, like the 45mm and 60mm macro lenses on m4/3.




#395993 Panasonic LUMIX GH5 for underwater video

Posted by dreifish on 03 June 2018 - 10:31 PM

First, I don't think crop sensors are a disadvantage in terms of noise performance underwater, because if shooting THE SAME DEPTH OF FIELD on a Full Frame sensor or a m4/3 one, your noise performance will be the same. Yes, a full frame sensor will have about a 2 stop advantage in terms of ISO performance over m4/3, but that's entirely negated by the fact that you need to shoot at a narroer aperture on full frame in order to keep your corners sharp. Basically, when using a full frame camera, I almost never shoot at anything below F8 for wide-angle. Usually at F11. With the GH5, I'm usually at F4 or F5.6. Which means my ISO is 200 or so on m4/3, and 800 or so on full frame. Guess what? That gives you basically identical noise performance.

 

A full frame camera will still have better dynamic range and higher resolution, but whether that matters largely depends on what you intend to do with the photos. Unless you're making really large prints, I think the GH5 is perfectly adequate for stills. About half the photos in my portfolio are taken with a GH4 and the other half with a Nikon D800 and Sony A7RII. I'd be surprised if many people would be able to guess which is which. 




#395516 HDR Underwater

Posted by dreifish on 17 May 2018 - 06:32 PM

 

 

You are right as it appears that the GH5 uses V gamut that is like or wider than Bt.2020

 

I guess the same reason why VLOG looks washed out makes also HLG look weird on a rec709 screen

 

Going back to the ops question you don't need to be shooting HDR effectively either VLOG or HLG are HDR capable or HDR ready I guess the issue is that with both neither the camera LCD nor the recorder screen if you use atomos are HDR so you don't really see what you are shooting

 

The GH5 has a built-in display LUT for VLOG-L that restores some of the contrast. It's good enough (in conjunction with zebras and the waveform) to expose the footage correctly and get a rough idea of what the contrast range will look like.

 

In terms of where it could produce better results underwater (in terms of dynamic range), I think the backlit scenario is the most common. (I mean, how often are you shooting inside caves with the opening in frame?). This is a scenario I generally try to avoid shooting in 8 bit because the results never look good. Maybe with a log file you would be able to pull decent details in the foreground subjects, but my thinking is you'd need more than the 11-12 stops of dynamic range of the GH5. Maybe with a 14-15 stop cinema camera.

 

For sunburts, it theoretically isn't going to make much of a difference, since the sun is going to be blown out regardless. If you're exposing for the sunburst, the rest of the shot is going to be so many stops underexposed that ever 14 stops of dynamic range isn't going to save it.  Usually with photos, you need quite powerful strobes to get nicely balanced sunburst photos. 




#395365 HDR Underwater

Posted by dreifish on 13 May 2018 - 05:01 PM

Is anyone producing HDR underwater content?

 

What sort of shots/scenarios do you think would actually benefit from HDR? Usually, we don't have a lot of specular highlights or deep shadows underwater, at least not when shooting balanced light scenes where you blend the ambient light with illumination you bring down.

 

Maybe the reflections off silvery fish?

 

But I'm curious if there is potential from the technology underwater, and if anyone is doing cool things with it.




#394976 Nauticam using images without consent

Posted by dreifish on 02 May 2018 - 01:07 AM

From a purely legal perspective, I think it's an interesting case. I wouldn't rush to conclude that what occurred is copyright infringement. I think it's an un-litigated issue, so it's unlikely that there's law directly on point. There's good arguments, however, that no infringement occurred so long as the image was hosted by Instagram and only integrated on the Nauticam website through their third-party APIs. You should probably check the license you grant Instagram when you post an image on their platform -- if it doesn't cover this exact use case, then Instagram's lawyers are really doing a bad job. The OP might have a case for unjust enrichment, if he could actually show Nauticam commercially benefited as a result of the image's use. Good luck with that though :)

 

From a business ethics perspective, well, that's a different matter entirely. I can certainly understand why the photographers who ended up having images featured on the Nauticam page without any prior contact would be upset. There's a number of reasons I can think of for using a hash-tag that have nothing to do with the desire to endorse the manufacturer. Maybe the OP would just rather not answer the inevitable question of what equipment he or she used. 

 

(And for the record, I'm a copyright lawyer, but this isn't legal advice). 




#394921 Winter musings

Posted by dreifish on 01 May 2018 - 01:31 AM

For best ergonomics and overall zoom flexibility without having to fiddle with wet lenses, the camcorder route is hard to beat. Your white balance will suck without a filter, but 1) the GATES housing has a flip filter option and 2) IMO, most scenes below 5 meters benefit much more from good lights then they do from great white balance capabilities. 90% of my shots with the GH5 are with the WB set to 5200K and video lights. I only really shoot ambient light 5 meters and shallower.

 

That said, the GH5 is definitely the better option when it comes to image quality and faster frame rates. It's just not the most ergonomic or streamlined solution in the water once you add all the extra flotation and wet lenses you need. 

 

Macro is a wash -- whether or not you need a tripod largely depends on the magnification you're shooting at. At equivalent levels of magnification, you're going to get equivalent levels of shakiness and moving in and out of focus based on your movement in the water, basically. This has nothing to do with depth of field or sensor size really -- larger sensors can get the same depth of field as smaller sensors by shooting at a smaller aperture. And actually, the 1" sensor in the AX700 and the m4/3 sensor in the GH5 are not that different in surface area at the end of the day. 2x crop on the GH5 vs 2.7x crop on the AX700 vs full frame. That's only a one stop difference in aperture to achieve the same depth of field.

 

Given your budget, I think both the GH5 and AX700 are options, and I'd make the decision based on what's more important to you -- ergonomics and ease of use vs ultimate image quality, basically.

 

One other thing to mention -- since you only shoot fish portraits and nothing larger than sharks, you don't really need the wide field of view the GH5+WWL-1 combo would give you. That's more for reef scenes. Indeed, I find that with the WWL-1 on, I usually have a tough time approaching fish/sharks close enough to get a good portrait, even zoomed in all the way to 42mm. For that use, you might be better off with something like the Panasonic Leica 12-60mm lens inside a 180mm dome port or even the olympus 12-50mm inside it's specialized flat port, which gives you the whole range from macro to 35mm equivalent. Note that if you go the 12-60 +180mm dome port route, you're looking at $2500 on top of the $1500 for the GH5 body and $2650 you're spending on a housing, so it might be above your budget.




#394863 Raja Ampat aboard the Blue Manta (GH5/Inspire 2)

Posted by dreifish on 29 April 2018 - 08:03 PM

Lovely. I especially like the grading on the drone shots, lovely cinematic look!

 

I used the Sedona LUT for the topside and aerial shots. You can download it for free here: https://luts.iwltbap...r-grade-sedona/. It's a quite nice teal & orange look.




#394830 Show me your GH5, How you trim your buoyancy?

Posted by dreifish on 29 April 2018 - 03:36 AM

That’s the key, being neutral - does matter if it looks weird. That’s the only issue with these ‘slim’ housings compared to gates and the like. They are neutral to begin with - we have to slap on all sorts of float arms.

Do you find the float arms give you enough separation to avoid backscatter?

Love the computer mount. That’s nice and easy to see.

How have you got the rear configured? Looks like it comes out flat (towards you) ?




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 Yes, there's enough separation to avoid backscatter with subjects within a meter of the lens. The lights aren't really strong enough to make a difference with objects further away. If the object is closer than about 30 cm, I need to turn the lights inwards to light it properly. But it's worth noting that the GATES GT14s have a 90 degree angle, whereas the V6Ks have a wider angle around 120 degrees so they need to be further out.

 

I've got three arms with stix floats rigged up at the back (connected to the tripod-mount ball arms) to provide a place to store my wet diopeter and Weefine ring light combination. The 9 stix jumbo floats basically render that setup neutral, so the whole rig is neutral with the ring light or without it (if I'm doing a wide-angle only dive). I also find that having the rig extend at the back like this helps to add a bit of mass and roll stability.

 

(As a side note, I have 4 V6Ks in my possession currently. Two of them together are not quite as powerful as a single GT14 (maybe about 75% as powerful). I don't know if this is because the wider beam angle distributes the illumination over a wider area or because the 12000 lumen rating is overstated or a combination of the two, but I guess you still get what you pay for at the end of the day. I haven't compared the V6Ks to the Keldan lights directly though, so maybe that's a more even battle.

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#394826 Show me your GH5, How you trim your buoyancy?

Posted by dreifish on 28 April 2018 - 09:08 PM

This is probably not the most elegant setup, but the rig is neutral in the water and massive enough to give pretty stable footage.

 

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#394825 Raja Ampat aboard the Blue Manta (GH5/Inspire 2)

Posted by dreifish on 28 April 2018 - 06:37 PM

Raja Ampat season is coming to an end, so here is a short film celebrating some of the things that make it such an amazing place. The visibility may at times be challenging, but the scenery and wildlife is truly spectacular both above and below the waves. 

 

Altogether, I spent 7 trips in Raja Ampat aboard the Blue Manta liveaboard in 2017/2018. It's incredibly hard to try to condense that into 3 minutes, so my initial version was 6 minutes long. But most people's attention spans being what they are, here is a shorter edit. Hope you enjoy it!

 

https://youtu.be/hUBSZQ-SphI

 

Edit: Here is the 6 minute version as well: 

 




#394320 Who is excited about Blackmagic Pocket Cinema 4K?

Posted by dreifish on 11 April 2018 - 06:51 AM

It really is a bit of an odd form factor, isn't it?

 

I can't see this as being all that useful hand-held since the monitor doesn't swivel out or even tilt -- and without an evf, can't really use it like a DSLR. Given how wide it is, it's not going to work great on any of the one-handed gimbals. Seems like this is meant to live on a tripod..

 

Whoa!!

 

Its gonna be a big housing! (But obviously you potentially don't need an external monitor...)

 

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#394110 GH5S Better colour

Posted by dreifish on 05 April 2018 - 08:32 AM

Yeah, the vectorscope comparison is pretty interesting. Having less of a green tint could definitely benefit underwater footage, but the differences aren't astronomical -- I imagine you could tweak the GH5 to be pretty similar to the GH5s just using the G-M and A-B WB adjustments..