What do the Aperture settings on the TG6 actually do?
Earlier this year while preparing to run the first of my online underwater photography courses specifically for TG users and after reading a range of conflicting reports in reviews I decided to do some testing of the Aperture settings on the TG6.
On conventional cameras when you take a picture the Aperture setting is one of the ways you control the amount of light reaching the camera sensor. In simple terms a larger f number equates to a smaller aperture in the lens so less light comes in.
As you change aperture size you also have the side effect of changing depth of field. A smaller aperture, larger f number will give more depth of field at the same focusing distance and the same focal length. On the TG6 when you use Aperture priority (A Mode) that isn’t entirely true, as the following pictures illustrate.
The first picture is taken with aperture set to the ‘widest’ setting available for the focal length the lens was set to. In this case f4.9 with the lens zoomed to its longest focal length. Normally the widest aperture setting will give the shallowest depth of field.
This second picture was taken at the next of the three Aperture settings the TG6 offered. This time the f number was 6.3 with the lens still at the longest focal length. As would be expected with a conventional camera the smaller aperture gave slightly more depth of field so a bit more of the tape measure appears in focus.
But when I upped the f number again to what should be the smallest aperture setting of f18 the depth of field hasn’t increased. If anything it looks to be worse.
Why then did we not get any more depth of field at that supposedly smaller aperture setting? That’s because the high f number setting in Aperture priority mode isn’t actually a change of the aperture size. Instead the camera is applying a built-in Neutral Density (ND) filter that reduces the amount of light reaching the sensor. That gives the same effect as the aperture being smaller when it comes to exposure and using that setting where I was taking the test pictures resulted in a slow shutter speed of 4 seconds. But because there isn’t an actual change in aperture you won’t gain depth of field.
What does this mean when using the TG6? If you want maximum depth of field to give you the most of your subject in focus from front to back I’d recommend you use the second of the three Aperture settings available, rather than going to the highest f number as I’ve seen some pundits recommend.
There are uses for the other two settings, when you want a bit faster shutter speed and are less concerned with depth of field the smallest f number will give a slight advantage. While for land photography that high f number setting with the ND filter in effect gives the TG6 the ability to shoot slow shutter images that potentially will give you the misty smoothing effects you see in some pictures of sea or waterfalls. But you’ll need a tripod to keep the camera steady and overcast conditions to get the slow speeds. Be aware you only get those slow speeds when the camera flash is turned off. With the flash on the camera limits the shutter speed to much faster.
The high f number settings that use the ND filter still have the effect of reducing the amount of light in your pictures. This makes them useful for achieving dark backgrounds in your pictures, like in this picture of a coral in the Red Sea taken at a setting of f18.
Hopefully this little blog has been helpful to you and it wasn’t too geeky.
If you’d like to learn more about underwater photography we offer courses online including a specific one for TG users and workshops in the UK and overseas. We are also an equipment dealer for a wide range of brands including several housing manufacturers. Email info@alphamarinephoto.com with any enquiries or use our contact form to get in touch and sign up to our newsletter at the same time.
We also run a Q and A group on Facebook which anyone is welcome to join if they obey the rules.
If you found this blog useful and would like to support us you can ‘buy me a coffee’.