Deep photography - natural light

[DuncanS 0]

We have been playing around recently in Sharm as it has been fairly slow on the tourist front. What we are trying to do is get some half decent shots of some popular (and not so well dived) technical dive sites. We have been playing around with tri pods and long exposures to try and squeeze out some detail using natural light. The image below is looking down Thomas Canyon at Tiran. The tripod was set up at 48m, the top of the arch is around 38m, the blue area below the arch is around 50m and the bottom of the shadows is at 68m. We took a series of shots and bracketed the at +2 and -2 on AEB as the tripod was not steady enough (modification in progress) The shots were iso200 and f11. Ideally we want to close down the f-stop once the tripod is more stable. We then tried an HDR conversion. This is all quite rough as I have never tried HDR on land let alone underwater. The plan is to try and get round to The Lara at the back of Jackson and try a similar thing.

 

 

Does anyone have any experience / input that could help us out?

 

Couple of questions;

 

Magic filter - I understand they are designed to work down to 25ish m. Is there any (however small) benefit of using one at this depth.

 

Can you stack the filter(ie 2 layers) to double the strength?

 

Any other advice,comments gratefully received.....

 

Duncan

[james 0]

Wow - that's an awesome concept Duncan! I would recommend shooting at ISO400 and a lower f-number next time. What shutter speed were you getting for your shots?

 

If you can get a nice steady tripod you'll be able to shoot some longer exposures and stack them up into a nice HDR.

 

If you use a strong filter you MAY be able to bring back some color, however there just isn't going to be much at 50m to begin with. You'll want a strong filter something with over 30 color units of strength in a mix of red(strong), amber(medium), and yellow(weakest).

 

Cheers

James

[Timmoranuk 10]

Hi Duncan,

 

Your project is something akin to that which I have planned for August. I'm hoping a Gorillapod 'Focus' and a Manfrotto ball head (which together weigh in at about 1.25 kg), plus an Ike housed Canon will provide sufficient stability. I can always dangle an addtional kilo if required. I find using the self timer is useful if shooting AEB (HDR) shots which means I have enough time to bear down on the tripod for additional stability. I have a couple of weeks booked in the deep south and plan to shoot the yacht and tug at Abu Galawa in HDR and maybe HDR panos too (!) and I may try to get another sneaky week in at Sharks Bay in order to hit Tiran and, maybe, Ras.

 

Hey, looking forward to seeing your Lara...

 

Thanks for sharing, Tim

[DuncanS 0]

Wow - that's an awesome concept Duncan! I would recommend shooting at ISO400 and a lower f-number next time. What shutter speed were you getting for your shots?

 

Thanks James,

 

Settings were as follows. iso 200, f11, 0.8s, 1/5s, 3.2s

 

The tripod itself was rock solid, it was the connection to the housing that was not the best. There is a nice sandy slope with a big rock which was perfect to rest the tripod on. Then off came the ankle weights and they were hung on the back legs. I also had 2x ds125 strobes to keep the housing a bit negative. To connect the housing we cable tied a 10bar slot stay tray off a compact to the tripod head and then at depth cable tied the housing to the slot stay. This was a bit wobbly!!!!! Cable ties are tricky buggers with a tinge of narcosis (tri mix too expensive for a lowly instructor!!!) The plan is to drill a hole through the tray on the housing and attach the tripod mount with a suitable bolt!! Tripod is nothing fancy and had it clipped to a stage for transport. The guests on the boat thought we were nutters!!!

 

Once we get it a bit more solid I was hoping to be able to fire off more than 3 shots for a better conversion.

[DuncanS 0]

Hi Duncan,

 

Your project is something akin to that which I have planned for August. I'm hoping a Gorillapod 'Focus' and a Manfrotto ball head (which together weigh in at about 1.25 kg), plus an Ike housed Canon will provide sufficient stability. I can always dangle an addtional kilo if required. I find using the self timer is useful if shooting AEB (HDR) shots which means I have enough time to bear down on the tripod for additional stability. I have a couple of weeks booked in the deep south and plan to shoot the yacht and tug at Abu Galawa in HDR and maybe HDR panos too (!) and I may try to get another sneaky week in at Sharks Bay in order to hit Tiran and, maybe, Ras.

 

Hey, looking forward to seeing your Lara...

 

Thanks for sharing, Tim

 

Tim,

 

Good luck with your trip. Maybe your son could take some pics of your setup in action. I would ask my mate to but he is already loaded up with my stages!!!

 

What software do you use to convert your HDR, Photoshop? Do you know of any good articles on HDR as I am new to this style of shooting.

 

Good news on the Lara, the boss has said we can have some free mix, another guy has offered us some scooters so we can get round there regardless of the swell and the tech boss has decided it would be a benefit for him for me to be a ccr trimix diver so has just done my mod 1 for free!! Happy days!!! Gonna build up some hours on the unit before I start plying with the camera though!!

 

Will post a report of the Lara project once it is complete, then maybe the arch at the Blue Hole. Ever inverted a tripod........could be interesting!!!

 

Rgds

 

Duncan

[Lennart 0]

What software do you use to convert your HDR, Photoshop? Do you know of any good articles on HDR as I am new to this style of shooting.

 

Hi Duncan,

 

It sounds like a really interesting project and I´m very curious for your final results. I´ve found the following link very useful when I started to play around with HDR (on land, I haven't tried it with UW-photography): http://www.cambridgeincolour.com/tutorials...namic-range.htm

 

Regards,

 

Lennart

[DuncanS 0]

Hi Duncan,

 

It sounds like a really interesting project and I´m very curious for your final results. I´ve found the following link very useful when I started to play around with HDR (on land, I haven't tried it with UW-photography): http://www.cambridgeincolour.com/tutorials...namic-range.htm

 

Regards,

 

Lennart

 

 

Thanks for that Lennart...

[myesque 0]

Wow - that's an awesome concept Duncan! I would recommend shooting at ISO400 and a lower f-number next time. What shutter speed were you getting for your shots?

 

If you can get a nice steady tripod you'll be able to shoot some longer exposures and stack them up into a nice HDR.

 

If you use a strong filter you MAY be able to bring back some color, however there just isn't going to be much at 50m to begin with. You'll want a strong filter something with over 30 color units of strength in a mix of red(strong), amber(medium), and yellow(weakest).

 

Cheers

James

 

I have done quite a bit of long exposer shooting top side. I have found that using the camera's native ISO setting is always best in time exposures. Use the shutter speed to get the fstop you desire. The HDR shots will thank you for this. The native ISO will get you the "clean" Low noise shots you are looking for.

[tdpriest 115]

I've talked to a few people about this, and their consensus is to use a really big, heavy tripod and weights.

 

I've never had the patience, and as a Photoshop addict shoot high ISO and post-process through NoiseNinja (examples on Flickr, 2004-6 folder, shot at 55m in Bikini). With the most modern cameras I suspect that there's almost as much noise from a slow exposure as from a high ISO setting?

 

I doubt if you can pull back any colour with a filter much beyond 40m, even in ideal conditions: probably slow exposure to capture what little red remains is better than the additional loss of light.

 

Tim

 

[myesque 0]

Quoting from http://www.digitalphotopro.com/tech/...-speeds_2.html

 

"Image sensors have an innate “native” sensitivity, generally in the ISO 100 to 200 range. When you set a higher ISO speed, amplifiers in the image sensor’s circuitry increase the gain before sending the image data to the A/D converter to be digitized. The sensor’s sensitivity doesn’t actually increase; the camera is just amplifying the data it produces. In the process, image noise is also increased, making the image “grainier”—sort of like what happens when you “push” film speed. But generally, digital SLRs produce better image quality at higher ISOs than film, especially pushed films.

 

If you set a lower ISO speed than the sensor’s native sensitivity, the camera’s image processor adjusts the image data after the A/D converter converts it to digital form. In the process, the dynamic range is reduced. So it’s best to shoot at the sensor’s native ISO whenever possible."

[loftus 42]

Just a point on HDR. I do a fair amount, and have shown some UW HDR on this forum. I use Photomatrix. Having said that, I'm not sure I see any benefit for you using multiple image HDR on this project. In my mind the main advantage of multiple image HDR is when having to deal with extremely high dynamic range subjects, such as sunballs with deep shadow under water that exceed the capability of your sensor. On your histogram this would show as a highlight spike on the right with shadow information all the way to the left - highly unlikely at depth. At this depth, dealing with high dynamic range subjects should not be the issue. If the dynamic range of your subject does not exceed the range of your sensor as shown on your histogram, there is no real advantage to capturing multiple images for HDR. Using HDR with multiple exposures at slow shutter speeds also increases your chances of motion artifact which degrades the image topside, and even more noticeably underwater. Even with a rock solid tripod, any water movement that moves light rays, fish movement etc, will degrade the image. HDR processing in general will also tend to increase noise problems if they exist, in the image rather than decrease them.

Long exposure noise problems are not characteristic of the shutter speeds you are using with most modern cameras. In my opinion your best results will be with the highest ISO your camera can utilize without significant noise degradation, obviously camera dependent. (Possibly 400 on a D200 type camera or say 800-1600 on my D700) Then use a larger aperture than f11 that you describe and shorter shutter speed, I would prefer a wider lens aperture as sharp corners are again not likely to be a major concern for the type of subject matter you show. Use your histogram and expose as far to the right as possible.

Then you can worry about dealing with any noise in post processing, and if you want an HDR effect do single image HDR technique in post processing.

I think this approach will get you the best possible image quality at capture, which you can then manipulate to best advantage in post.

Edited June 2, 2009 by loftus