Question regarding shutter speeds at certain depths

[PuravidaUK]

Hello all,

I am a fairly experienced diver, but completely inexperienced underwater photographer. I've got a trip coming up in the Galapagos shortly and planning to buy a camera. At the moment i'm considering the Olympus TG-6. but am aware that there is a shortcoming in that it lacks a minimum shutter speed option. As such, I am trying to ascertain something that I appreciate is very difficult to answer, but am hoping that I may still be able to get some guidance.

I'll be doing some deepish dives, and am simply wondering if the shutter speed that I think I'll need to shoot moving large animals (1/160?) is possible without being underexposed, or whether I need to completely alter my expectations!?

Probable conditions

20-35 depth dives

10m visibility (though hopefully more)

Aperture fixed at f2.

ISO max 400

Ambient lighting only,

Assuming these conditions, would you think 1/160 would be possible? Or no way!?

Obviously I could wack up the ISO, but I understand that image degradation would be quite high over 400.

On land I have a fairly decent idea of what combinations of shutter speed/aperture/ISO I would need in different lighting conditions, but as I have no underwater photography experience I simply have no idea what I should expect.

If I'm not able to do the above (with the camera (TG-6) likely to force me to 1/30 or 1/60) then I think I may need to think again or readjust my expectations. Although relatively cheap, I'd still not rather spend £600-£700 on camera + housing if I won't be able to get the shots I want.

Any advice or comments would be very much appreciated.

 

[DavidFL]

The TG-6 has a minimum shutter speed that you can customize. But you also have to have "auto ISO" selected, which has a maximum setting you can customize. But both of those settings working together, as far as I understand it, only work when you are using flash. I have a TG-6, which I recently tested using the 'RC' flash setting (remote control of external flash) and two Ikelite strobes. This photo is from a TG-6, in aperture priority mode, with auto-ISO set to maximum 400 (and this photo is ISO 400) and minimum shutter speed set to 1/160. About 90' depth; visibility around 30 feet; drift dive near Jupiter, Florida

 

[PuravidaUK]

Thanks for the response, David.
It's really useful to see example photos.
Have you any idea what would have happened had you not been using the strobes?
I assume the camera would have pushed the shutter speed down - and hence produced a blurry shot?

Maybe the answer is allowing the ISO to go (much) higher, but i've read that results aren't great at high levels.

 

[tursiops]

Thanks for the response, David.
It's really useful to see example photos.
Have you any idea what would have happened had you not been using the strobes?
I assume the camera would have pushed the shutter speed down - and hence produced a blurry shot?

Maybe the answer is allowing the ISO to go (much) higher, but i've read that results aren't great at high levels.

I'm afraid with that camera at that depth for those kind of big-animal shots with no strobes you get to choose between, underexposed, blurry, or very grainy from very high ISO.

 

[PuravidaUK]

Hi Tursiops,

That is what I feared!
But very good to know as it will probably save me some money.

It may well just be better to go and enjoy the dives, rather than stressing over shots that I'm never likely to get - or get a cheap GoPro for 1/4 of the price and drastically reduce my photography expectations!

 

[mi000ke]

I shoot ambient light only. I use an old canon S110, but the exposure principles are the same. Here are some ambient light shots at somewhere around 80-100 ft. They were shot in RAW, which is pretty essential as you will need to adjust the exposure and white balance to recover the colors. I think you can get away with a shutter speed around 1/100 to keep the ISO lower. Also if you have noise reduction software you can reduce the graininess from a higher iso.

The first two are at 1/100 f5.6 ISO800
the third is 1/125 F5.6 ISO 500
the fourth is 1/80 F5.6 ISO 200

 

[DavidFL]

Maybe the answer is allowing the ISO to go (much) higher, but i've read that results aren't great at high levels.

This photo is from the same dive as the previous Turtle photo; also ISO 400 and 1/160. But the external strobes were neither turned on or aimed so they didn't fire. Happened less than ten seconds after dropping into the Jupiter Wreck Trek from drift-dive-boat. The little internal camera strobe fired the RC codes for the big strobes, but other than that it is ambient light. Also not as deep; probably less than 50'. 120 degree FOV wet wide angle lens, so I'm pretty close to the diver and shark. Original raw file seriously underexposed. Pulling as much as I could from the RAW file, and using the Lightroom de-noise to the point where the artifacts are obvious. So I agree, in general, any ISO higher than 400 with this camera is pretty much limited to snapshot-proof-of-something-you-claim-you-saw.

 

[DavidFL]

Have you any idea what would have happened had you not been using the strobes?

If you have flash turned on, even the small internal flash in the camera, then in low light conditions and/or large f stops the ISO (in Auto ISO) will go to the max you selected, the shutter speed will go to the min, and unless you are extremely close, the frame will be underexposed. This combination, as I understand it, was setup particularly for macro photographers to get dark backgrounds and use the flash for (macro) foregrounds.

If you don't have flash turned on, then as you suggest, the camera will try to find some "optimum" combination of slow shutter speed and high ISO to avoid being underexposed. The "maximum auto ISO setting" works with or without flash and you could have a specific fixed ISO selected, but my understanding is that the "minimum shutter speed" setting only works together with flash and auto-ISO.

I had pretty good results with the TG-5 predecessor using my handheld tech light and/or LED video lights. This photo is ISO 100, 1/250 sec at f2.8. 80 to 90 feet in 30-50' visibility.

 

[PuravidaUK]

Thank you all, this is a great help. It's very useful to be able to see the kind of images the camera is capable of.
Mi000ke - it's good to see that you can actual get shots without going crazily high on the ISO.
David - likewise, seeing how lights help is really useful and shows what's possible.