What do you think of this macro I took last Summer

[soufiej]

Hi Soufiej,

The aperture of the camera is can be adjusted to increase or decrease the diameter of the clear opening through which the lens can collect light.

Rather than reporting the diameter of the aperture (which turns out not to be of any immediate use to us), the camera provides us with a "focal ratio". But we usually say "f-stop" or write the value in a notion such as f/3.5. The "f/" in "f/3.5" is short-hand for "focal ratio" meaning the ratio of focal length (in this case it's a 100mm lens) compared to the diameter of clear aperture is 3.5. That means the diameter of clear aperture would have been roughly 28.5mm (because 100 ÷ 3.5 = 28.5 (and I'm rounding that value. That's ok because the camera makers also round their values.) But the "ratio" actually does have a meaningful purpose. It turns out whenever the "ratio" of the focal length divided by clear aperture for any two different lenses works out to the same "ratio" then the amount of light collected inside the camera (given identical lighting circumstances) will be the same. This is why a light meter can tell you that on a sunny mid-day outdoor light situation that you can use ISO 100, 1/100th sec exposure and an f-stop of f/16 (the focal ratio) even without knowing specifically WHICH lens or focal length you intend to use. Knowing the ratio is more useful than knowing both the focal length and aperture diameter (and of course knowing any two values means you can derive the third.)

So that's the "focal ratio", but here's how it relates to the depth-of-field (DoF):

You can change depth of field using a few factors that contribute to it. These are primarily:

1) Focal length of the lens (Short focal lengths broaden depth of field. Long focal lengths narrow depth of field.)
2) Focus distance to subject (Far focus distance broadens depth of field. Close focus distance narrows depth of field.)
3) Focal ratio (High focal ratio broadens depth of field. Low focal ratio reduces depth of field.)

Consider the OP's shooting circumstances... and where they have some wiggle room to alter the DOF:

1) The OP was using a 100mm focal length. Canon makes two different 100mm focal length macro lenses, so I'm guessing this is one of them. Changing the focal length of the lens likely isn't an option here.

2) The distance to the bee and the angle of view to depict the flower and bee in this size also can't be increased without making everything smaller (which defeats the point of a macro lens). Changing focus distance likely isn't a viable option either.

This leaves:

3) The OP indicated that they took this at f/3.5

But that means the OP had plenty of room to stop down to a higher focal ratio (f-stop). I did a few measurements and backed into some estimates that the OP was likely about 2' away (that's from bee to focal plane ... not to end of the camera lens which would have been closer) then at that same distance but using f/22 the DOF could have been increased to .7" which would have rendered the full honey bee in sharp focus (BTW, we know the OP cropped this because it's square and the sensor isn't square... so the 2' assumption isn't necessarily safe.)

Option #3 turns out to be the winner in the OP's specific case because this is where they have lots of wiggle room to increase the depth of field... by increasing the focal ratio.

A focus stacking technique would render even more in focus... but the active bee would have moved on before that was possible.[/QUOTE]



Great answer! Way more than I was expecting but perfect to understand the term. I wasn't at all expecting the back engineering of the distance from the bee!

Would you think the slightly out of focus subject would have been caused by movement of the flower/bee caused by a breeze? Or, simply a less experienced photographer's understanding of how to achieve DOF? Quite honestly, I probably wouldn't have shot that at f22 either.

 

[TCampbell]

Would you think the slightly out of focus subject would have been caused by movement of the flower/bee caused by a breeze? Or, simply a less experienced photographer's understanding of how to achieve DOF? Quite honestly, I probably wouldn't have shot that at f22 either.

The OP says this was shot at 1/500th, which is enough to freeze most typical motion (fast motion... for example if the bee were in flight and you wanted to freeze the wings... would require much higher speeds. But this bee is working the surface of the flower and not flapping her wings.)

Also if you inspect the bee's legs and the center area of the flower, you can see nice focus -- and no appearance of motion blur. Also, at f/3.5 at this focal length and distance, we expect the depth of field to be extremely shallow.

The desire to avoid high f-stops... such as f/22, is sometimes based on the trade-off in shutter speed, but usually it's based on the notion of diffraction problems. As light is squeezed through a smaller opening, the wave-nature of light causes the "Airy disk" (the "point" where the light will come to focus isn't technically a single point, but rather a round disk. It is named for it's discoverer... an astronomer named George Airy.) will increase in diameter. As long as the Airy disk is smaller than a single "pixel" on the sensor, this effect is not noticed. But once it overflows the size of a single pixel and onto adjacent pixels, it causes an overall slight softening of the focus. For most cameras this does not happen until the f-stop exceeds f/11 (but very high megapixel cameras like the Nikon D800 will start to have this at around f/8).

While this sounds like a problem... you have to keep in mind that even if it's technically measurable on the sensor surface, we tend to not use all the pixels our cameras can capture when we display our image on an output medium. You'd normally need a very large print and close inspection to detect the diffraction issue. ALSO... as long as the softness of focus is moderate, sharpening software can tighten that up.

This means avoiding shooting at f/16 or f/22 may mean worrying about something you're unlikely to notice.

What's FAR MORE noticeable... is an out-of-focus subject due to inadequate depth of field. We can stand several feet away from the image and notice that problem right away! So when faced with that decision... I'll take the minute amount of diffraction over the inadequate depth of field any day.

 

[Bluegrasser]

Love the complementary colors working here. Congrats on capturing that little guy

 

[dennybeall]

I must admit to being a little spoiled by some of the current macro shots done with max DOF and focus stacking to get close-ups that show entire small objects in focus.
This picture has nice colors.

 

[TCampbell]

Love the complementary colors working here. Congrats on capturing that little guy

Not guy... gal! "Worker Bees" are always gals!

BTW, I should say... these shots of active working insects are HARD. Every time that yours truly tries to get one of these, I watch the flowers and the bees ... looking for my next subject. I try to get my camera into position... and the insect is GONE! These camera shy girls do not stick around for long. So yes... congrats are in order for getting this as well as you did.

 

[Bluegrasser]

Uggg..... Yes workers are females, good catch.

 

[soufiej]

Would you think the slightly out of focus subject would have been caused by movement of the flower/bee caused by a breeze? Or, simply a less experienced photographer's understanding of how to achieve DOF? Quite honestly, I probably wouldn't have shot that at f22 either.

The OP says this was shot at 1/500th, which is enough to freeze most typical motion (fast motion... for example if the bee were in flight and you wanted to freeze the wings... would require much higher speeds. But this bee is working the surface of the flower and not flapping her wings.)

Also if you inspect the bee's legs and the center area of the flower, you can see nice focus -- and no appearance of motion blur. Also, at f/3.5 at this focal length and distance, we expect the depth of field to be extremely shallow.

The desire to avoid high f-stops... such as f/22, is sometimes based on the trade-off in shutter speed, but usually it's based on the notion of diffraction problems. As light is squeezed through a smaller opening, the wave-nature of light causes the "Airy disk" (the "point" where the light will come to focus isn't technically a single point, but rather a round disk. It is named for it's discoverer... an astronomer named George Airy.) will increase in diameter. As long as the Airy disk is smaller than a single "pixel" on the sensor, this effect is not noticed. But once it overflows the size of a single pixel and onto adjacent pixels, it causes an overall slight softening of the focus. For most cameras this does not happen until the f-stop exceeds f/11 (but very high megapixel cameras like the Nikon D800 will start to have this at around f/8).

While this sounds like a problem... you have to keep in mind that even if it's technically measurable on the sensor surface, we tend to not use all the pixels our cameras can capture when we display our image on an output medium. You'd normally need a very large print and close inspection to detect the diffraction issue. ALSO... as long as the softness of focus is moderate, sharpening software can tighten that up.

This means avoiding shooting at f/16 or f/22 may mean worrying about something you're unlikely to notice.

What's FAR MORE noticeable... is an out-of-focus subject due to inadequate depth of field. We can stand several feet away from the image and notice that problem right away! So when faced with that decision... I'll take the minute amount of diffraction over the inadequate depth of field any day.

"Airy disk"! Another term I was not familiar with. I knew of the effect but had yet to know the guy whose name is on it. Thanks.

Any chance you could come to Dallas for a few months to walk me through some photography mentoring? Just kidding, I'm sure I couldn't afford you. I am, however, very impressed by your ability to look into an image. Further, your explanations are great. Technical enough for the slightly geeky but done with average shooter language. That's a difficult skill set to put together. I try to do the same on high end audio forums and I know you can easily talk over someone's head and lose them totally. "Dude! all I want is tight bass."

I very much appreciate your input. Many thanks.