TG 6 in Cozumel

[jlyle]

We recently returned from a trip to Cozumel, MX. Most of the images in this report were taken with an Oly TG 6 in an Oly housing plus dual DS1 strobes.

Great little camera.

Too big to post here. Click on the link:

COZUMEL NOVEMBER 2020 YEAR OF THE COVID

 

[Rick Brant]

Great photos! Do you use auto focus or manual? I am using a TG-6 but find it tough to get exact focus. I may need more light so that I can get a little more DoF though.

 

[tursiops]

Great photos! Do you use auto focus or manual? I am using a TG-6 but find it tough to get exact focus. I may need more light so that I can get a little more DoF though.

More light doesn't help much with the TG series, because there are really only two apertures, which (when not zoomed) are f/2 and f/2.8. The so-called f/8 setting is achieved by a 3-stop neutral density filter, so drops the light like f/8 would but does not increase the DOF. Zooming can help though, because then the f/stop increases for real. This means if you have clear water, you can back off, zoom, get the same image size but more DOF. However, your light drops since the light is further away,AND your f/stop is smaller...so in this case more light is indeed useful.

 

[Jafo19D]

Great pics

 

[kmarks]

The so-called f/8 setting is achieved by a 3-stop neutral density filter, so drops the light like f/8 would but does not increase the DOF. Zooming can help though, because then the f/stop increases for real. This means if you have clear water, you can back off, zoom, get the same image size but more DOF. However, your light drops since the light is further away,AND your f/stop is smaller...so in this case more light is indeed useful.

Are you serious? This is how it works? I don't own TG-6, but this is why I hate compact point and shoot cameras (and I do own a Canon S-110). They are full of lies, lies, lies!

I'm not sure that the zoom workaround works, though. If you go from, let's say, an equivalent 50mm focal length to 100 mm, you will need to pretty much double the distance between you and the subject so that the subject takes up the same space in the frame (same FOV). It depends on how the camera allows you to change the f-stop along with the focal length, but I assume it is somewhat linearly related. If (you were using a full frame DSLR and) you go from 50 mm f/2, shooting something at a 2 m distance, your DOF is going to be about 12 cm. If you go out to 100 mm f/4 and back up to 4 m, you also double your DOF to 24 cm, but you lose a ton of light. You've closed down your aperture by 2 stops, so even in the best of conditions, you are down 75% of your light. Then, you are now twice as far away from your subject, which means that, without slowing your shutter, you need and additional 4 times as much natural light (law of inverse squares) or 16 times as much flash power - from the flash to the subject and back again means you are now 4 times farther away and the law of inverse squares applies the whole way.

Then again, if it is your only option, I guess you have to buy an R6 and housing work with what you have.

 

[tursiops]

Are you serious? This is how it works? I don't own TG-6, but this is why I hate compact point and shoot cameras (and I do own a Canon S-110). They are full of lies, lies, lies!

I'm not sure that the zoom workaround works, though. If you go from, let's say, an equivalent 50mm focal length to 100 mm, you will need to pretty much double the distance between you and the subject so that the subject takes up the same space in the frame (same FOV). It depends on how the camera allows you to change the f-stop along with the focal length, but I assume it is somewhat linearly related. If (you were using a full frame DSLR and) you go from 50 mm f/2, shooting something at a 2 m distance, your DOF is going to be about 12 cm. If you go out to 100 mm f/4 and back up to 4 m, you also double your DOF to 24 cm, but you lose a ton of light. You've closed down your aperture by 2 stops, so even in the best of conditions, you are down 75% of your light. Then, you are now twice as far away from your subject, which means that, without slowing your shutter, you need and additional 4 times as much natural light (law of inverse squares) or 16 times as much flash power - from the flash to the subject and back again means you are now 4 times farther away and the law of inverse squares applies the whole way.

Then again, if it is your only option, I guess you have to buy an R6 and housing work with what you have.

IF the lens is set on f/2 at its widest angle, then you zoom 4x (max zoom), the aperture reduces to f/4.9. If at f/2.8, at zoom it goes to f/6.3. Those are real f/stop changes with the associated increases in DOF. But (for wide angle) f/8 is achieved with a 3-stop ND filter.

In addition, you have a lot more DOF with aTG-6 than with larger-sensor cameras, because the lens is so short: 4.5mm for wide and 18 mm at max zoom. Think of an 18mm lens on your DSLR: lots of DOF! So it is not as bad as it may sound, at first blush.

Regarding the image size and your subject-camera distance and light needs, now that you have the actual lens info you don't have to guess and you appear perfectly able to work it out.

Note Compact cameras and apertures. Why only f8?. You get to f/4 by zooming but not to max. How to get max sharpness.

 

[jlyle]

Exposure compensation is a very useful tool. I've also found that physically smaller lenses like that of the TG 6 give greater DOF than one might expect.

 

[Rick Brant]

OK, so I am usually at least somewhat zoomed in as my typical subjects are nudibranchs or extreme coral close-ups. The DoF change described by tursiops makes sense as I did not really feel like the images looked like 2.8 much less 2.0.

Back where I started though -- focus is difficult. Using AF I usually take a bunch of shots and if I am lucky, one has great focus. Don't get me wrong, many of them are OK, it's just that very accurate focus is important to me. So I'm wondering if OP uses AF or manual.

 

[kmarks]

View attachment 628973
IF the lens is set on f/2 at its widest angle, then you zoom 4x (max zoom), the aperture reduces to f/4.9. If at f/2.8, at zoom it goes to f/6.3. Those are real f/stop changes with the associated increases in DOF. But (for wide angle) f/8 is achieved with a 3-stop ND filter.

In addition, you have a lot more DOF with aTG-6 than with larger-sensor cameras, because the lens is so short: 4.5mm for wide and 18 mm at max zoom. Think of an 18mm lens on your DSLR: lots of DOF! So it is not as bad as it may sound, at first blush.

Regarding the image size and your subject-camera distance and light needs, now that you have the actual lens info you don't have to guess and you appear perfectly able to work it out.

Note Compact cameras and apertures. Why only f8?. You get to f/4 by zooming but not to max. How to get max sharpness.

Ok, so that changes what DOF you would get just a little bit. You get 1.3 feet of DOF at 4.5 mm f/2 from 2 feet away and 2.9 feet if you zoom in to 18 mm f/4.9 and back up to 8 feet. But my point is the loss of light. From f/2 to f/4.9 is 2.5 stops (82% light loss) and you are 4 times farther away (4 more stops, 94%). You'll need to slow your shutter speed or raise your ISO or flash power to compensate. If you were shooting at 1/200s from up close at 4.5 f/2, you would need to slow down to about 1/3s to get the same exposure on your subject.

 

[tursiops]

Ok, so that changes what DOF you would get just a little bit. You get 1.3 feet of DOF at 4.5 mm f/2 from 2 feet away and 2.9 feet if you zoom in to 18 mm f/4.9 and back up to 8 feet. But my point is the loss of light. From f/2 to f/4.9 is 2.5 stops (82% light loss) and you are 4 times farther away (4 more stops, 94%). You'll need to slow your shutter speed or raise your ISO or flash power to compensate. If you were shooting at 1/200s from up close at 4.5 f/2, you would need to slow down to about 1/3s to get the same exposure on your subject.

I don't disagree, but it is not really relevant to the OP. The TG-6 does not have manual shutter speeds, and does not respond well to high ISO settings.
More light is the answer.