Macro photography question

[shirin]

Hello,

I've got a quick question about macro photography as I'm a little confused:

From what I've read, it seems like it's best to use a small aperture of f/16 or f/22 for optimum sharpness. But what about achieving a shallow depth of field with a wide aperture to separate the point of focus from the background? Isn't that part of the beauty of macro photography?

Is there a way to achieve a shallow depth of field whilst still achieving sharpness of an entire insect/flower, etc?

Thanks

 

[photo1x1.com]

Hi there!
I´m afraid that´s all physics and you can either have shallow depth OR everything in focus (depending on the size of your object and how close you get to it). The only thing you can do is extensive photoshopping.
Maybe one of my videos helps you understand.
At 2:03min I show an example of a flower at different apertures:

Btw: there is an effect called diffraction. So "optimum sharpness" is a little relative. Usually, the best sharpness can be achieved around f8 to f11. Once the aperture gets smaller than that, diffraction kicks in and reduces the maximum sharpness while the depth of field still increases. Just give it a try and see for yourself. Take an image from a tripod (or something else that keeps your camera steady) once with f11 and once with the smallest aperture of your lens. Load both images into your computer and compare the part of the image that you focussed on at 100%.

 

[SCraig]

When shooting true macro photography a shallow depth of field is going to be the least of your problems. Even at f/16 or f/22 the total depth of field is going to be less than an inch. Look at macro photos of insects and take note that many times the head, and sometimes even just part of the head, will be the only thing in focus.

 

[fmw]

Don't confuse sharpness with depth of field. Sharpness is resolution. Depth of field is the amount of the subject back to front that is in acceptable focus. I do tabletop product photography every day. I shoot everything at f16 and I'm not doing macro photography. I just need to have the whole product in acceptable focus.

 

[benhasajeep]

Agree with what others have said. With macro where your as close as you can get to the subject. Your range of sharp focus is very small. Also you really don't want to use your lenses wide open or fully stopped down for the best results.

 

[Overread]

A few thoughts

1) As said above even with small apertures the depth of field in macro is tiny and as such the background blurring is still going to be present. If the background area is close (and macro can often get a bit cluttered in the field) then you might get some background aspects still showing, but even then it will be pretty blurry. If anything in macro its harder to get what you want in focus than what you want out of focus.

2) If you are using flash to provide the light for the shot then you can also get a near fully black background if your subject is up against an open area behind it as the light from the flash doesn't have the power to light the background; so the subject gets lit and the background goes fully black.

3) Aperture is linked to sharpness and depth of field, but only depth of field continually increases as aperture reduces. Sharpness is instead more of a curve. Typically it increases from wide open (smallest f number/widest aperture) and peeks around f8 or so (it varies lens to lens) and will then diminish thereafter. This diminishing of sharpness is the result of diffraction.
Now just like wide open isn't impossible to use, you can go smaller than f8 and still get sharp shots. Indeed down to around f13 (on Canon and f16 on Nikon*) you still get very useable sharpness. Thereafter the drop in sharpness becomes more obvious.

4) You can also use focus stacking as a method to get sharp shots and a really blurry background. Focus stacking is where you take a series of photos at different focusing points and blend them together so that the focused parts from each shot are added up to produce a single photo that holds far greater depth of field than otherwise possible. It's just like how you can stitch photos together to form a larger panorama.
You generally have to use software for this - Combine ZP is free and does this; Zerine Stacker, Helicon focus and Photoshop can all perform stacks. Stacks are complex and each one of those software options works a little differently and as such sometimes a stack might fail with one and work with another.
It's tricky and I'd advise learning to shoot normal macro shots before trying stacking but stacking done right can be very rewarding.


*This difference is not optical but interface based.
Essentially many (most) macro lenses on the market achieve closer focusing by reducing the aperture. As a result an f2.8 macro lens might be closer to f5.6 when focused at its closest distance. Canon lenses don't report this change in effective aperture to the user.
Nikon lenses do report this change, so can appear to not shoot as wide and be able to use smaller apertures and remain sharp. It's not really a performance difference, just a difference in how aperture is reported to the user

 

[preeber]

Hi there!
I´m afraid that´s all physics and you can either have shallow depth OR everything in focus (depending on the size of your object and how close you get to it). The only thing you can do is extensive photoshopping.
Maybe one of my videos helps you understand.
At 2:03min I show an example of a flower at different apertures:

Btw: there is an effect called diffraction. So "optimum sharpness" is a little relative. Usually, the best sharpness can be achieved around f8 to f11. Once the aperture gets smaller than that, diffraction kicks in and reduces the maximum sharpness while the depth of field still increases. Just give it a try and see for yourself. Take an image from a tripod (or something else that keeps your camera steady) once with f11 and once with the smallest aperture of your lens. Load both images into your computer and compare the part of the image that you focussed on at 100%.

Thanks for the video, I really learned a lot from it as beginner. I really was struggling with this photographing small things recently and this is going to help in the future.

 

[photo1x1.com]

Hi there!
I´m afraid that´s all physics and you can either have shallow depth OR everything in focus (depending on the size of your object and how close you get to it). The only thing you can do is extensive photoshopping.
Maybe one of my videos helps you understand.
At 2:03min I show an example of a flower at different apertures:

Btw: there is an effect called diffraction. So "optimum sharpness" is a little relative. Usually, the best sharpness can be achieved around f8 to f11. Once the aperture gets smaller than that, diffraction kicks in and reduces the maximum sharpness while the depth of field still increases. Just give it a try and see for yourself. Take an image from a tripod (or something else that keeps your camera steady) once with f11 and once with the smallest aperture of your lens. Load both images into your computer and compare the part of the image that you focussed on at 100%.

Thanks for the video, I really learned a lot from it as beginner. I really was struggling with this photographing small things recently and this is going to help in the future.

My pleasure. Thanks for the feedback. That was exactly what I had in mind. Creating lessons for the beginner that help unerstand photography as quickly as possible.

 

[petrochemist]

As others have said DOF with macro is normally too small so background separation is rarely a problem, just solved by choosing a viewpoint where the background is at least 6" from the subject.
There is a technique that can be used to increase DOF for static subjects that doesn't effect the focus of the background. Investigate focus stacking - it involves taking multiple photos from the same vantage point at slightly different (overlapping) focus, then using software to combine them. If the stacked shots don't include the BG it will be blurred
I find it essential if photographing anything 3 dimensional through my microscope where the DOF is sometimes many times less than a millimeter.