Fly Field

[WestLothian]

What are the tips for getting enough light in for macro depth of field?

This was with ISO 800, f/16, bright sunlight and flash.

Any longer exposure would need a tripod this was 1/160 second.

[matt_xyz]

It's not easy using f16, but you don't always need such a small aperture, particularly for a side-on shot such as this where DOF isn't as critical. I'd use something closer to f10 and drop your ISO to 400.

this shot only used f8 for instance;

[Fourwings]

I agree with Matt, you will find that f16 is a bit high for effective macro work, your image is excellent but could have been achieved with an f-stop of around f.9.

Side-on shots of small insects only require a shallow depth of field, using these should give you much higher shutter speeds and therefore enable you to use a lower ISO.

Most images that I take of Dragonflies are taken using ISO 400 with f-stops between f.8 and f13, even these large insects do not usually require using stops as high as f16, as an example the image below was taken using f.9 at an ISO of 400 which generated a shutter speed in excess of 1/400th sec.



However, I always use a tripod for macro work and have even been known to use the camera's built in speedlight as a fill-in flash should it be required.

[WestLothian]

I referred to the lens chart and selected a DoF of 3mm to get from the centre of the back hairs to the fly's knees roughly when 1:1 (so this gave f/16 at minimum 12 inch focus distance).

Thanks for the tips. I looked up f/9 and that still gives a useful 2mm DoF when at the 1 foot minimum.

[richardkm]

Originally Posted by WestLothian

I referred to the lens chart and selected a DoF of 3mm to get from the centre of the back hairs to the fly's knees roughly when 1:1 (so this gave f/16 at minimum 12 inch focus distance).

Thanks for the tips. I looked up f/9 and that still gives a useful 2mm DoF when at the 1 foot minimum.

One point to note about depth of field is that in macro work the dof is centered on the point of focus and distributed equally, unlike landscapes where it is a third in front and two thirds behind.

[WestLothian]

Thanks Richard,

I am thinking about making my own table using an Excel spreadsheet.

The more I look in to the "greatest circle of confusion" Depth of Field charts, I see it is mainly based on conventional focus for 35mm and film print.

It would be more useful surely to have it based on the digital sensor size and pixel density and the target resolution at the final image size. So it is more a "greatest circle of acceptable image blur" chart for reference.

[richardkm]

Originally Posted by WestLothian

Thanks Richard,

I am thinking about making my own table using an Excel spreadsheet.

The more I look in to the "greatest circle of confusion" Depth of Field charts, I see it is mainly based on conventional focus for 35mm and film print.

It would be more useful surely to have it based on the digital sensor size and pixel density and the target resolution at the final image size. So it is more a "greatest circle of acceptable image blur" chart for reference.

Forget about focal length and sensor size, depth of field is directly related to magnification. I did a course on photography at Manchester University some years ago and we were given tables on depth of field, I'll see if I can find them and pass them on.

p.s. Zeiss use a much smaller circle of confusion in the calculations for their lenses than other manufacturers. Just thought you might like to know!

[WestLothian]

Your course should have explained about the circle of confusion which leads to identifying the size of point spread that is still considered "in focus" within the depth of field. Once this circle is determined, the DoF is then related to the lens as you describe.

I was using several of the excellent online interactive tables for doing the calculations where the Circle of confusion is stated as 0.019 mm .

Online Depth of Field Calculator

Thanks again.

[richardkm]

The course went a lot further than that, and as a qualified Dispensing Optician (though no longer practicing) I have studied optics quite thoroughly. Focal length is not important when calculating dof, only magnification.

[WestLothian]

Indeed, magnification and the Circle of Confusion