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Help with camera settings: Mavic Pro, white roof

WildDoktor

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I'm using a Mavic Pro and need to document a small commercial roof (in sunny Northern California) that is white...like...blindingly white!

Any hints on what settings I can use to get decent photos and videos, and what time of day would be best?

I've already done before/during/after shoots of this roof, but I need to do one more shoot once the smoky air clears up, so I'm finally asking for help. :)

What I've tried so far:
3 different times of day: 9am, 8pm, noon
I tried all "auto" settings with no ND filter for the first two
I tried manual settings plus a 16 ND filter for the last one
- Manual settings: iso 100, shutter 1/60; WB sunny, Style +1 -2 -2, Color D-Cinelike. Jpg+raw.

Each shoot so far is like I'm filming a huge, powerful LED spotlight that's shining directly into the camera lens! I'm attaching both an unretouched dng and jpg from today's shoot as examples. (Edit: had to zip the dng as the site doesn't accept dng files.)

As for fixing them in post, I've tried auto and manual adjustments in PhotoDirector8, ACDSee's new beta called Gemstone 12, and in desperation I tried IrfanView64. The best I've gotten so far is by using irfan's auto adjust. For the first two shoots I got "decent" results...at least, the client likes them. Today's shoot (at noon, with manual settings), is worse, as it's the finished roof and it's *dazzlingly* white! And, today there's so much smoke in the air that the light is blindingly orange. So I haven't been able to get anything really "decent" yet.

The client and I agreed that if today's shoot didn't turn out well, we could try again once the smoke clears. (The bummer about that is that the roof won't be pristine by then, but if the photos turn out better, then he's ok with that.) I'm thinking the shoot didn't turn out well, so any hints you guys can give me for the next shoot would be welcomed!
 

RussOnTheRoad

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I think what you need help with is less about camera settings and more about understanding exposure. For still photos you can use whatever ISO, aperture and shutter speed that will give you the desired results as long as the combination creates proper exposure. By desired results I mean to include depth of field, blur or lack of it, digital noise etc.

Pure white, in RGB, digital terms, is when each of the three channels, red, green, and blue, measures 255 using the sensitometer tool (eyedropper) in a photo editing program such as PhotoShop. If the channels are unequal there is a color bias. If the difference between the channels is small, a few points, you probably won't see any bias and the whites will look neutral.

Something that is white with texture should have the values at 250 or perhaps a little lower using a software sensitometer if you want to preserve detail that can be printed.

I have a Mavic 2 Zoom and it has settings to show a Zebra pattern on the controller screen (that can be turned on or off) indicating overexposure. Assuming you have the same, and that it works properly, you should be able to adjust exposure for the roof using that. Personally, I'd shoot DNG and set the exposure a little lower than required to eliminate the zebra indications so as to preserve detail in the roof and adjust brighter in post if necessary. JPG processing can ruin a properly exposed photo because it changes the RGB values so stick with DNG.

If a white object is overexposed in-camera it would mean you cannot fix it later because the RGB values would have been clipped. You cannot retrieve detail that has been lost to overexposure, but you can brighten things that are somewhat underexposed without any real consequences.

Stick with DNG, expose so that the zebra pattern does not show anywhere (excluding specular highlights such as the sun reflecting in chrome bumpers and the like) and you should be OK. Adjust the whites in post so that all 3 channels are equal and you will have a pure white with no color bias. Keep the values at 250 or a little lower and adjust only one or two of the channels as needed. If you adjust all 3 channels you will be undoing previous adjustments. In order to understand why you need to understand color theory which is beyond the scope of this discussion.

Incidentally, if there is anything in your photos that is known to be a neutral black, then adjusting the RGB values so they are equal for that object at the same time adjusting for the whites should give you a perfectly color balanced photo across the board.
 
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mdurbanek

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The longer you wait, the dirtier the roof will get - especially with so much smoke in the air. Then, if the fog rolls in, you'll get condensation producing inevitable streaks from the dirt/smoke, and some low places where it will pool somewhat. And when it finally rains you'll be spending hours in what I call "Photoshop Hell".

Regarding shooting technique, it's impossible to record detail when there isn't any. But most of the rubberized roofing materials are sheets, so you do have some detail due to the seams. Shoot very early or very late in the day, using the sun's cross-lighting to beef up those seams and supply your detail.

Also, bracket liberally and experiment with HDR. You'll be surprised how effective that can be. Good luck!
 

WildDoktor

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As an update, the client was very understanding, and said that he was amazed at the quality of the pictures and video I got on that smokey day, and all of them are usable! So that's a relief.

You're correct, @mdurbanek, about the roof getting dirty; that's what the client said and why he sent me out even in the strange lighting conditions. Good idea about bracketing and HDR! I'll have to keep that in mind.

Thanks @RussOnTheRoad; that's a great summary and great advice! The "exposure" comment was right on. When I read that, and it hit me that I was very, very conscious during the flight of trying to keep the iso at 100 and shutter at 1/60 since I was shooting video in 4k/30fps. It's kind of obvious now, with your post and in retrospect, that I should have said "who cares" about iso and shutter; instead, do whatever it takes to get the correct exposure! Both my mavic pro and my xsp can do the zebra stripes, so I'll utilize that on future shoots.
 

PrudentialUAS

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A little late to this one, but wanted to share how I approach high-contrast conditions like this:

I've had to take images of marina's and boats - especially large "yachts" always stand out from the water. And of course I'm shooting on sunny days so it just blasts white.

Using my Mavic 2 Pro I use Auto Bracketing Mode (AEB) set at (3) images per shot. Afterwards, I process these three in Adobe Lightroom and I apply the "HDR Merge" function to the three photos (highlight all three, right click or go to "Photo" and it's at the bottom). This combines the three images...in a way I'm not 100% how but the outcome is really great. After this I do a little more post-processing to get the output the customer is looking for, but regardless, it really helps.

Here is a single shot (TOP) vs the HDR Merged (BOTTOM):


DJI_0067.jpg

DJI_0067-HDR.jpg
 

WildDoktor

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Thanks!

On the one hand, that would triple the amount of photos taken per roof shot, and add a significant amount of editing time.
On the other hand, for a small white roof, it might be worth it.

Well, food for thought, as I don't have any white roofs to shoot in my near future. :)

Hmm...however, I *do* hope to have a new construction site shoot where I'm pointing straight down at a bare field, brightly shining in the eerie orange glow of a completely smoke-filled sky (Northern CA); so I may try this technique. Again, super labor intensive, but worth a try.
 

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