I have a TG-5, but I think the focus works the same way.
For microscope mode, I use manual, especially when there’s no high contrast edges in the subject area (the AF really depends on high contrast to work properly). And so many critters are experts at blending into their backgrounds, or hiding behind natural screens like foilage etc.
To engage manual focus in a difficult situation, you first focus lock on something within the range you’re after (while in AF), say by using a hand or finger, tapping the shutter half down to set the focus to this range, and while holding that half-shutter, you hit the ‘OK’ center button. That brings up a little green rectangle in your focus centre with the word ‘FOCUS’ under it, meaning the focus is now locked to that distance (even between shots), so you can now release the half shutter and move in for your shots. The focus will remain locked until you hit the ‘OK’ button again (or menu twice).
If you made a mistake in the focus distance, you can manually adjust the focus distance while the focus is locked using the up and down switches on the main dial. Or the top control dial that’s beside the shutter button. But I find in practice, the up and down switches work best and are most convenient in cramped, quickly changing situations.
The nice thing with the manual focus is that the Peak indicator (usually a red highlight) turns on, as well as a zoom-in, to really help you set the focus to a specific point. That kind of specific visual focal feedback you just don’t get with Auto Focus.
In a dark space (like when you’re head is inside a hollow tree, for example), I keep the LED illuminator on just so I can see where I am. It usually doesn’t spook the subject and helps when you’re focussing.
Mind you, I also tend to shoot most of my in-woods shot at 10000 ISO. Noisy, yes – but it nearly all magically vanishes when I run the RAW file through DxO’s PureRaw batch correction software.
IMHO, if you own an Olympus TG-6 (or 5) the money spent on PureRaw is worth it as it extends your ISO options so dramatically – like gaining extra f-stops, in that sense. And if you’re lucky, if you have other cameras, they will be supported on the list of compatible cameras that PureRaw supports. To tell you the truth, if the TG hadn’t been supported by PureRaw, I’m pretty sure I would have not purchased it. I use it on my Sony Alpha too were I can push the ISO even higher.
Almost every macro tutorial or site I’ve read online mentions the importance of getting a flash and a diffuser in there as an absolute necessity for good shots. And yes, I don’t disagree that this can help tremendously for sharpness, colour, detail. But, OTOH, it ain’t always possible to fit a diffuser or an external flash into a field shooting situation. And with the TGs, the whole pocketability thing makes the idea of lugging extra gear along seem to defeat a lot of its best feature — pocketability! Which is why I prefer to stick to available light/high ISO and when needed, the LED illuminator. If the shot is in bright sunlight (it rarely is), different game – I adjust the ISO down to get better exposure control.
The ring flash accessory does look like it would be a great to have for bug shooting but for me, I can’t (at least not yet) get myself past paying almost as much for the accessory as I did for the camera (bought it used for $150 CDN). And I’m not exactly happy with the stuff I’ve seen taken using the ring.
I mean, it looks great for flat stamps and coins, but it tends to look, at least in comparison to high ISO available light shooting, pretty flat with bugs. (Or maybe I’m just trying to rationalize my cheapness?)
The only big issue I have with the TG? The light purple hazy blob that will pop up under certain zoom/light and contrast situations. They say it’s an artifact reflection of the sensor? In any case, it’s been there in the TG-4, TG-5, and even the TG-6, so I figure it’s not an easy thing to squeeze out of the camera’s optical architecture.
Overall though, I still love the little TG cameras! I also like the 4K video for faster and flightier creatures. Often the best hope is a solid frame grab. (Though shooting video in manual focus is usually much tougher than a still.)
I’d also echo using stack focusing when you’re pretty sure of enough stillness. I find that after 3 attempts at a stack focus shot, the TG-5 I have at least, locks up and I have to shut right down and pop the battery out and in again to get it working!
A lot of how you use any camera depends on what you are trying to get to. The thing I like about iNat observations is that the principle goal is identification. Aesthetic composition, background/foreground contrast, perfect focus, interesting angles… all great things if you’re a macro photographer hoping to make a splash with your nature shots. But there’s nothing wrong with thinking about ‘getting’ a difficult observation shot and not worrying about all those other things. For me, at least, it’s all about minimizing the ol’ “ones that got away” list. (aargggh!!)
The TG cameras go a long way to helping you get there.