controlling DOF in Macro

[davros]

I'm starting to stretch the legs my 105mm Micro, but I'm not getting the DOF I want. For instance, the shot below I had to push in on the tiny shell to fill the frame and get rid of a bright distracting background. In doing this I was right at the minimal focal distance. I've tried closing down the aperature to f9 and all the way down to f32 but I cannot see the difference. Part of the shell will be in focus while the rest of it is blurry. Is this due to the fact that I'm at the edge of the focus range or am I missing something else?

This was shot handheld and manual focus. Normally I would have used a tripod, but I didn't have one on this trip. 74575

[arthurking83]

You should see a massive difference between f/9 and f/32 in terms of DOF, there's probably something you did 'wrong'.


I dare say that you've focused behind the optimal point of focus in this image.

LOL! I just posted a remark that I thought that the image looked to captured handheld for some reason(without reading the entire post), and then I finished reading the post! :p

OK, so it seems that in handholding, you've almost certainly swayed to and fro (and in this shot closer towards the subject) in the fraction of a second between focus and exposure.

It's a very difficult task to get an absolutely spot on macro image when hand held(in one snap).
What I tend to do if I don't have a tripod with me(unlikely!), or is impossible to set up for the shot(more likely) is to rattle off many frames in the hop that one will turn out OK.

With respect to DOF and what's the best aperture to use, this is highly dependent on the subject matter you've chosen. I think up to about f/22 should produce OK results, at distances between 1:3 and 1:1, and you could easily get away with less if you shoot further back than 1:3 and then crop to fill the frame.

What you are looking for in this shot, as a tell tale for what you've done.(I dare say this is the f/9 shot).
I don't know which part of the shell you wanted to focus on, but the focus is on the fine blue lines, to the left of the main central spine of the shell, which also correspond with the point of the tip on the RHS.
That's your plane of focus.
From that point and back by a few millimeters you can see some parts of the shell to be in focus.
You can see the DOF zone along the rock faces, where blur turns into sharp detail and then back into blur again.

if you were expecting to simply see a sharper image because you stopped down(or opened) the aperture, then you would have been mistaken in this line of thought.

I think you fully understand the concept of DOF and how it works, and how to achieve it, but if you handhold the camera, then the results could be misleading due to other variables(such as camera shake, or different framing.. etc).

[soulman]

I've tried closing down the aperature to f9 and all the way down to f32 but I cannot see the difference.There will be a significant difference between these two. Maybe it wasn't visible on the camera screen, but it's there.

I think the issue is simply that at such close focusing distances, there really isn't a lot of DoF. You have to keep this in mind when you're setting up your shots, try to avoid the need for a larger DoF and stop down your lens as much as possible.

[ytf]

This is an interesting bit of software: http://www.heliconsoft.com/
I've demo'd it with mixed results. Like anything, it takes some practice. I found it a bit pricey, but if I were a true macro-holic, I'd probably make the investment.

[arthurking83]

There are limitations to using focus stacking.

I guess attempting to do it handheld may not always work well, with slight camera movement making it hard to align all the images correctly.

There are free programs that one can use available too.
I've only done very basic preliminary tests, but I've found that CombineZP worked well enough in the one single test I've tried(well actually two tests, but using the one set of images).
The reason I tried CombineZP, was 'under instruction' from another bit of software(that I've also not had much time to play with recently :p) which is a camera controlling software from the PC.
It all tied in smoothly to make focus stacked macros an automated and seemless activity. All I really needed to do (properly)was to make a decent cuppa and watch it all happen(automagically) :D

[ytf]

There are limitations to using focus stacking.

I guess attempting to do it handheld may not always work well, with slight camera movement making it hard to align all the images correctly.

:D


Totally agree. I wouldn't bother trying to accomplish the stacking process with a macro handheld. In order to capture the full depth of field for a shot like the posters would (from my experience with the demo) require as many as 40 shots. I know from experience shooting hand-held HDR and stereo that the closer one is to the subject, the more difficult it is to maintain enough steadiness for the auto-alignment software to be successful. Since the essence of macro is closeness, and as already mentioned, just a slight movement closer or farther for,m the subject will screw up your focus, a locked off camera would be essential.

[Bennymiata]

The DOF is always dependant on the distance you are away from the subject.
The further away you are, the bigger the DOF, the closer you are, the smaller the DOF is.

Unfortunately you just can't get much DOF if you are going 1:1 with a macro lens, irrespective of the lens opening.
In fact, once you get passed about F18, the lens itself won't perform well and will introduce its own diffractions etc.

That is one of the reasons macro photography is so interesting, because you always have to juggle your distance from the object, trying to get the object to fill the frame and the DOF.

Sometimes you're better off stepping back a little and then cropping the photo afterwards to get a decent DOF.

Taking macros at 1:1 handheld is a very big ask too, unless you have lots of light, but generally, at 1:1, it's very hard to hand hold the camera well enough not to get some OOF bits as even the most minute movement will mean an OOF shot.

[soulman]

Regarding the diffraction that Bennymiata mentions above, the diffraction limited aperture (DLA) actually varies a lot depending on the sensor size & pixel count and can be as low as f5.6 or less for some combinations, particularly compacts. The Canon 7D (crop sensor, 18MP) for example, is diffraction limited above f6.8, whilst the original 5D (full frame, 12MP) will go to f13.2 before it starts to tail off. It's worth noting though, that one still might be better off going past the DLA and ending up with less sharpness overall but more evenness across the frame.

As everyone says though, the main thing is really to use a tripod, stop down as much as is practical and be aware of the compromises you need to make regarding distance to subject.

[davros]

Thanks everyone for the replies. Obviously shooting macro without a tripod isn't the greatest idea. Unfortunately I didn't bring mine with me on this particular hike and I'm not one to pass an opportunity took take a picture - despite it's potential poor quality.

I had another look/play and I can see a big difference between different apertures as you would expect. The issue I'm seeing is merely the limited focal plane at such close distances.

[Mary Anne]

And that why my Monopod goes everywhere with me I never use a Tripod and all my work is Macro :D

[Bennymiata]

Macro is great fun, but there is a serious learning epxerience involved, which is fun in itself.

Keep trying and try different tecniques until you find one that works for you.

[jgknight]

Hand-held macro is very difficult and you need to have a lot of experience with it. With a shot like this one, the DOF looks like it is only 2 - 3mm if that. Shooting macros at apertures above f11 or f16 is really a no-no, as tiny apertures create distortion and other associated problem with the image. In landscape photography it is not noticed but macros, definitely. In most of my tiny macros, I usually work with a DOF of 0.02mm and therefore the only way to accomplish this is to focus-stack. If I have a subject which has a depth of 2.0mm, then I will need to take 100 shots each at just under 0.02mm (to allow for overlap) to cover the 2.0mm depth.

Of course, if you are photographing a rose, you can easily cover it in 2 or 3 shots.

[davros]

Hand-held macro is very difficult and you need to have a lot of experience with it. With a shot like this one, the DOF looks like it is only 2 - 3mm if that. Shooting macros at apertures above f11 or f16 is really a no-no, as tiny apertures create distortion and other associated problem with the image. In landscape photography it is not noticed but macros, definitely. In most of my tiny macros, I usually work with a DOF of 0.02mm and therefore the only way to accomplish this is to focus-stack. If I have a subject which has a depth of 2.0mm, then I will need to take 100 shots each at just under 0.02mm (to allow for overlap) to cover the 2.0mm depth.

Of course, if you are photographing a rose, you can easily cover it in 2 or 3 shots.

I'm not quite ready to rush into stacking, but I have a question on the principle. When you say that most of things you shoot have a DOF of .02m how do you know that? I can understand how you would be able to see that when looking at the picture on your computer, but the view finder and LCD screen on the camera wouldn't show you that kind of detail. In that train of thought, are you just guessing how many pictures you will need to take for the stack?