Manual focus fine-tuning and misleading previews: Am I asking for the impossible?

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Hi! :bowing_woman:

I’m still discovering and experimenting with my Canon EOS R6m2, which I bought with a “RF 24-240mm F4-6.3 IS USM” lens. I turned on the neat camera feature that allows to manually fine-tune the focus via the lens ring after autofocus did its job, while holding the trigger half-pressed, and then finally pressing it fully to take the picture.

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In French this option is called “One-Shot→activé (agrandir)”. That’s the version that also zooms in on the target while you fine-tune the focus – the enlargement-less version seems kinda useless to me as you can barely see what you’re doing. It’s in a menu about focusing with the lens ring.

I tend to (figuratively) shoot myself in the foot by:

  • Zooming as much as I can (for pseudo-macro stuff).
  • Lowering the f-number as much as the zoom level allows me (6.3, if I’m not mistaken).
  • Getting as close as I can to the subject (green vs. red autofocus indicator).

When I’m in this configuration, things get horribly frustrating. I hold my breath and try to steady the camera as much as I can, I carefully fine-tune the focus with the ring, the preview on the screen or visor (tried both) looks perfect, I sloooowly press the trigger in full, and… about 50% of the times, the result has its focus shifted by 1–5 millimeters, one way or another (but perhaps more often behind the subject), which can completely ruin pictures of insects and the like.

  • Using full autofocus (even in one-shot mode) with no manual fine-tuning somehow seems to work better (as long as I’m very still), but I’d still like to be able to choose between the two options…
  • Being farther from the subject (still max zoom, but standing farther, I mean, instead of looking for the green-vs.-red autofocus-indicator limit) seems to drastically increase my chances of success as well.

I initially thought about shutter shock, but my shutter settings (the default values) seem to be in line with the general recommendations (one mechanical, one electronic). Furthermore, shutter speed does not seem to help much; it is generally significantly above the so-called “safety” values.

My paranoid side made me wonder if this is some sort of malfunction, but that would be strange, especially on a brand new camera and lens. I did a quick test by shooting a ruler (focusing specific numbers written on it) by putting the camera down on a hard surface to make sure it did not move, and the results were OK.

So I guess I’m just moving too much when I hold the camera? But that doesn’t change the fact that the pre-shooting preview looks generally OK to me, even with the enlargement provided by the aforementioned semi-manual focus feature. I know that the simple fact of pressing the last half of the trigger can induce movement, but I’m trying to do that very carefully (and tried with a two-second timer as well, to be able to steady again after the press).

Sure, I could change the f-number to increase the depth of field (I think I read somewhere that using the lowest available value was rarely a good idea, but I’m not sure), etc., but if my focus is off anyway, that would not change the fact that the picture may be suboptimal (possibly without me even noticing it until I inspect it very carefully), and that would therefore still bother me a lot.

  • Am I asking for something virtually impossible without full autofocus or a tripod? Should I just bite the bullet and step back a bit more, systematically, instead of aiming at being as at-close-range as possible when zooming to the maximum?
  • Are my camera and lens behaving “normally”? :sweat_smile: (The misleading previews worry me.)
  • Am I just terrible at standing still? I thought I was OK at this, with my previous camera.

I haven’t experimented that much with fully manual focus but I think it was more or less the same.

Transitioning from a compact camera to this is not as straightforward as I thought. I’m spending lots of time shooting the same thing multiple times, and then deleting the missed pictures by zooming on each (on the camera screen, the issue is generally not noticeable without zooming in), which kills a large part of the fun.

Thanks in advance to anyone that’ll manage to bring back part of that fun.

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You can easily move a mm or so while you think you are perfectly still. There is usually a small delay between pushing the button and taking the picture. I’d say 50% success under the conditions you describe isn’t bad at all.
And if you move in as close as possible, the slightest movement forward will give an unsharp image, even on autofocus (can’t focus closer than the minimal distance…)

As for the aperture, wide open usually isn’t optimal: even with perfect focus, you’ll only get a thin slice of the insect sharp, and most lenses give a better result if you close down one or two stops. For me, F8-F11 would be the more standard aperture for close-up work (F16 when there’s enough light, ISO 800-1600 isn’t really a problem). But, I also try and keep my shutter at 1/500 or shorter…, “sometimes” something has to give.

And of course, a malfunction or poor adjustment can show up on a brand new camera/lens. Best way to exclude that is testing on a tripod (use remote control or delayed shutter).

And to keep the fun in, I most often try to take several shots of a subject, but I only do the sorting/deleting once I’m back home and have downloaded the images (as you said, the camera screen isn’t optimal for judging sharpness), I hardly ever delete “in camera”: too time-consuming and finicky, and cards are more than large enough not to need it (it also minimises writing to the card, supposedly prolonging card life).

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Maybe. I find the ‘zoom in to check focus’ feature almost impossible to use when taking macro shots hand-held. In my case, even if I don’t move out of focus, my composition often shifts by the time I take the shot. It is useful when I’m on a tripod.

For hand-held shots, I don’t use that feature, I focus manually, with final corrections via moving the camera physically closer/further from the subject. Precise focus with the focus ring is hard at macro distances.

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I guess that could be a significant part of the explanation. :laughing: Not sure that’s the whole thing, but I don’t see what else it could be, so…

I shot random stuff in my bedroom before you posted and arrived at a similar conclusion. While having only the head of an insect sharp can be stylish in its own way, it’s probably not something I should deliberately aim for.

Not sure how far that can go, though. I saw stuff mentioning diffraction issues or whatever with exageratedly large f-numbers, but I have yet to actually dive into that topic. I guess there’s a limit to how much you can compensate the focal length and distance with aperture.

I probably have stupid habits because of my old camera, with which F8 was the largest number and ISO 400 was already a bit noisy (and ISO 800 warranted quite a bit of filtering during post-processing, with the risk of losing details). When I see the numbers that the R6m2 spits, I’m like “Did I get teleported to another dimension?”. Well, the downside is that I can’t hit low f-numbers now; I fear someday I’ll get frustrated over that when shooting God knows what.

Yeah I didn’t either with the old one and tried to see if it worked out better now, but meh. To delete multiple images in one go, I seem to have to get out of preview mode and look for a dedicated “Delete images” thingy in the settings menus. I initially thought that sorting stuff on-camera after a walk outside could let me relax and reflect on what I saw, but it’s kinda counter-productive indeed.

I tend to do some kind of mix of those, with the physical moving serving as a (lame) tool to find the minimal focusing distance.

Well, so, basically, as I thought, flirting with all the limits of the lens at once is a bad idea, and I should hold my horses and shoot more realistically, so to speak. Even if it means cropping a bit afterwards or whatever. And therefore limit my use of literally three-millimeter depths of field.

I saw a simplified depth of field formula on Wikipedia earlier and I was like “OK, the distance to the subject and the focal length are squared, in there, so I guess I’m just asking for trouble”.

By the way, I’m been trying to use the electronic viewfinder while investigating that stuff, assuming it provided a firmer contact between my body and the camera, limiting motion blur, but maybe this is just superstition. And it’s not that convenient when you wear glasses. :roll_eyes: My old compact’s EVF was so bad (I think it was dubbed “a mere afterthought” in a review) I never actually used it, so that’s something quite new to me.

Thanks for those clarifications. I suck at quickly summarizing my woes so I appreciate that you took the time to go over this.

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Here is my advice for macro work.

1: DON"T USE AUTOFOCUS. Just switch the camera to manual focus and if needed move the camera towards or way from the subject to get perfect focus if hand holding, but tripod is obviously recommended when practical.

2: Depth of field is always very shallow when doing macro so this makes focusing critical and magnifies small errors. There are two ways to reduce this problem. The first is to close the aperture down (possibly a long way down) and the second is to back away from the subject and not try to fill the frame with the final composition. Crop into the picture post shooting. Both of these steps greatly improve focus issues.

3: Shutter speed needs to prevent camera shake. No editing program can truly fix a blurred imaged from shake or bad focus. Tripod is preferred but otherwise work out how steady your hands are and how good the IS system is, but err towards a faster shutter speed.

4: Crank up the ISO probably much higher than you are comfortable with. Low ISO is the enemy of good macros as blur from slow shutter speed or poor focus is a cardinal sin while noise is only a minor sin. Programs like darktable can really do miracles with noise. You also have a modern full-frame camera and its real strength is the low noise issue at very high ISO settings. Don’t be afraid of ISO 4000 or higher. I would much rather tackle the minor noise of that than the blur from a f6.3 aperture when shooting macro.

Good luck.

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Does the viewfinder of your camera have a diopter adjustment? That might allow you to shoot without your glasses on.

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Only thing I might add to what’s been said already is that you could try focus stacking, if you have a stationary subject.
I don’t know much about the actual process of that though. :slight_smile:

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Thanks again for the valuable input, everyone.

I guess the first-auto-then-manual-fine-tuning-before-trigger is OK-ish, though? It seems to me that this saves a bit of time while offering as much flexibility.

Regarding full autofocus, is it that bad? I generally use a tiny area and manually place it where I want it, and when the subject is not too weirdly shaped, it seems to do an acceptable job. Maybe there are subtleties that I fail to see, though. I also have yet to try the non-one-shot modes (AI thingy and servo blahblah), but I think that’s more for moving subjects.

That’s interesting to see all of you mentioning physically moving back and forth to fix focus: I didn’t think it was actually advised. Now I’ll do that without feeling stupid.

Not sure how much is “a long way”, but anyway I suppose that when shooting small things, by definition, you don’t need something too extreme to get the entire subject in focus. I think the stuff I read about diffraction was for landscapes.

OK, thanks. I use the “Flexible value mode” and I admit that so far I almost always left the ISO in auto, while only selecting specific values for aperture and / or speed. While the camera does what looks to me like a good job at adjusting stuff accordingly, it probably doesn’t try to guess whether I’m shooting something tricky or just lazing around.

Yes there’s something like that; I have yet to experiment with it though. I was trying to keep my glasses on and it just bumped on the soft thingy around the EVF. :sweat_smile: Taking my glasses off for every shot sounds like a hassle, though. :neutral_face: I should read stuff about that – obviously I’m not the first person in that case.

That sounds interesting, but not sure how well RawTherapee (and myself :laughing:) would handle that. On a similar topic, I think my camera can do focus bracketing, which might help to make sure at least one of the shots used the right focus distance. I’d have to try that someday. Dunno if you people have any feedback on this feature.

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Edit on focus bracketing:

Focus at the nearer end of your preferred focal range, then press the shutter button completely. […] The camera shoots continuously, shifting the focal position toward infinity.
— Canon’s manual

:unamused: I wanted something more like “focus the average wanted distance and then it shifts both ways”.

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It works well with macro work, because you’re making such small adjustments. It’s a bit different with a landscape, for example. :wink:

Diffraction is definitely a thing, but lenses can respond differently when focusing really close, plus it may be worth the tradeoff - a little less overall absolute sharpness in return for having a larger range of focus. Depends on the lens, really. Well worth experimenting with.

Not directly related perhaps, but I find that macro becomes an awful lot easier with really good lighting. Bright daylight is pretty good, sunlight or reflected sunlight even better. Means you can use a small aperture and fastish shutter speed without needing to push the ISO too high. Modern cameras are a lot better at high ISOs though.

You could also consider using flash? I have a couple of cheap very basic Neewer speedlights (i.e. the sort of flash that stick on top of the camera) and a matching set of wireless remotes that let you use the flashes off the camera. The whole setup was under $200 AUD if I remember right and gives a lot of flexibility. Mine are basic, no auto flash setting, no comms with the camera, nothing except manual power setting and a trigger from the camera, but it’s all you need if you’re happy setting it up manually.
I’ve never mastered flash though, so take my ‘advice’ with a grain of salt. :slight_smile:

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Mm. I suppose it’s designed for focus stacking in post.

BTW, as far as I know, that’s not something any of the open source raw processors can do, but there is good software around - you’d need to export all the images from RT with identical processing, then load them into the stacking software.
There was some discussion about this somewhere on the forum…

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I was under the impression that moving around was more brutal than turning the lens ring, but maybe I was wrong. Those two techniques feel so different!

Is that how diffraction issues manifest themselves? OK.

I received a 60 cm ø 5-in-1 reflector and a 8×8 LED thingy a few days ago. Not quite the level of quality you describe, but I’ll first try to make-do with that – I have yet to use them (work + weather + intimidation when faced with so much new stuff at once). I’ll have to experiment one step at a time. The LED panel is tiny enough to be taken around during walks and fits on the old small gorillapod I had for the previous camera, too.

Yep, that’s pretty much how they present it.

I suspected as much. Simple bracketing with no intention of stacking may still come in handy, though, even if it means deliberately screwing up the first pic’s focus by setting it a bit too close.

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Well, the focussing ring usually has only part of a turn to cover the whole range from infinity to say 0.7m. That’s quite a lot of distance to cover, or in other words, adjusting the focus distance by a few mm gets delicate… For close-ups, you move over a few mm to fine-tune the focus.

Also, avoid using the screen to compose the image and focus: you have to hold the camera away from your body, which means the weight of the camera+lens is harder to keep immobile (as soon as your elbows don’t touch your body anymore). I find I’m much more stable using the viewfinder, unless I have to get into a weird position to get the composition I want. Of course, the best is to use a tripod (or even a monopod, depending on how and what you’re hunting).

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There are two modes for its sensibility, one referring to degree and the other to rotation speed or something. Frankly, I don’t really see the difference. :sweat_smile: Perhaps because my adjustments are generally small.

OK, that’s what I suspected, but hearing it from someone else gives it more substance.

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I forced myself to go outside during lunch break despite the looming clouds.

  • While using the viewfinder while keeping glasses on is OK-ish in landscape orientation, things get really weird in portrait orientation. :sweat_smile:
  • Many of my pics were ruined by the fact that… I left my white cardboard props-storage box lying behind the subject and did not notice it until I got back inside. :woman_facepalming: I suppose stuff like that happens to everyone one day or another…
  • The LEDs are kinda OK as a fill light, but I generally have to crank them close to the maximum, and I’m not always sure about the orientation. I think I often ended up nullifying contrasts and I fear some of the pics may be a bit dull as a result. It also seemed to worsen the clipping caused by the sun when there was a sudden hole in the blanket of clouds. :sun_behind_small_cloud:
  • When I physically move to fine-tune the focus, I get the impression that the stabilization mechanisms (I have them ON in the body and lens, I think) try to fight against that. But perhaps it’s just me moving in a way that’s too erratic instead of linear (not sure how to put that into words). Regardless, as a result, the effects are less predictable than I’d like. Still useful, though.
  • Nothing desperately out of focus, but, well, always ≥F8. Does not mean the placement was optimal, but at least mistakes are less noticeable.
  • Speed fixed at 1/500 but I suspect I could have asked for something shorter. I’m still not sure what is overkill or not in each situation with this camera. This requires practice.
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The specs of this lens (https://www.canon.ca/en/product?name=RF_24-240mm_F4-6.3_IS_USM#specifications) say:
Minimum Focusing Distance
Wide: 1.64 ft./0.50 m
Telephoto: 2.56 ft./0.78 m

I’d say, make sure you are at least that far from the subject, and in fact a little farther so you are not right on the edge of the lens’s ability to focus.

There are many mobile apps available that will calculate depth of field for you, based on camera, focal length, aperture and distance to subject. Having one is pretty useful, and will help you to understand what to expect.

When you manually fine-tune the focus via the lens ring, do you return your hand to a position supporting the lens or leave it by the ring? Either way could cause movement and waste your effort of adjusting the ring. If you move your hand, it’s very likely that your body will move too and throw off your focus (we’re talking millimeters here). If you leave your hand by the ring, you may not be supporting the camera/lens sufficiently and might get blur as a result. FIne-tuning the focus by controlled movement of a well-supported camera is almost certain to get better results more easily.

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I assumed that the “green or red indicator” took basically care of that. But indeed that’s more or less the order of magnitude that I observed (and now that we chatted, I agree that I need to take an extra little step back for safety).

I should take a look at that, yeah, even if I often don’t have my mobile when I’m out. I just hope that there are some open source ones that do not ask for random permissions like contacts access and so on. :laughing: (Yeah, generally not a huge fan of apps.)

I leave it on the ring (while still trying to support the camera somewhat with it, because gosh that lens sure is heavy), while slowly pressing the trigger.

That’s possible. My grip on the ring tends to be a bit less firm than when I’m free to put my fingers where I please. So I guess it’s a three-step process, from coarse to fine-grained, starting with auto, then ring, then firm grip and move a bit.

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In that case, make sure your autofocus mode is such that once the camera focused, it doesn’t change until you release the shutter. (you probably know that, but it has bitten me…)

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I think that’s OK with the default “One-shot” mode?

One-Shot AF for Still Subjects
[…] When you press the shutter button halfway, the camera will focus only once.
[…] The focus remains locked while you hold down the shutter button halfway […].

The AI thingy sounds like a mix of one-shot and servo (at least now I know):

The AF mode is automatically switched from [One-Shot AF] to [Servo AF] based on subject status while you are pressing the shutter button halfway or shooting continuously.

However, I’m not sure that my manual fine-tuning is retained after a shot. I do it over and over again for each picture, even when I haven’t moved, but, well, it allows me to benefit from the enlargement and double-check that the focus is still OK.

By the way, I think that when the view is thus enlarged to help with manual fine-tuning, the depth of field is artificially made shallow as hell to clearly show what is getting focused. At first I panicked, thinking that even with humongous f-numbers I was getting a ridiculous depth. :sweat_smile:

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It isn’t, and that’s what you want!

Also, the diaphragm always stays wide open until just before the image is taken, to get as much light in the viewfinder as possible. It also helps the autofocus to have a shallow depth of field. I don’t think the camera artificially reduced DoF, though, the apparently shallower DoF is an effect of the zooming.

Some cameras do have a button to temporarily close the diaphragm to judge the DoF.