DOF issue/quesiton

[Ernicus]

I was reading/watching a course on DOF. That compiled with reading here I thought I had a pretty good understanding of DOF. I took some shots today and was having trouble. Few different questions.

Does it matter...(obciously it does)...but how do I adjust when doing close up shots? I have seen the online dof calculators and what not, but when out in the field, I don't have access to them. However, I would have thought when talking about a half inch or inch, I'd be able to get it right.

I took these shots posted below. I also put on single point focus instead of auto area focus. I shot at f/5.6, f/7.1, and f/9. I put focal point on area behind center mass, on center mass, and in front of center mass. Center mass being the center of the flower. In each shot, the area of focus was small and all of the flower parts were not in focus. It got better as I moved up, but it started raining on me and I could not finish stopping down.

I would not have thought I'd have to shoot smaller than f/9 to get it all in focus. I also wanted to shoot at 5.6 to get the nice blur in background.

am I missing something? Is it just not possible to get the entire flower in focus that close? With this lens do I have to back up more and just crop to get proper dof and focus of desired parts?

Ignore the comp and colors etc. These are unedited files and not the point of the question.




Shutter speeds vary between 250 down to 100, dependant on aperture for exposure. ISO at 200. The flower is about the same cir***ference as a baseball...maybe a bit bigger..well..actually more like a grapefruit. I was at focal length of 55mm and I physically was as close as I could get for the auto focus to lock in, I would guess 4 inches maybe...5.

f/5.6










f/7.1










f/9

 

[groan]

The greatest DOF will be had at a much smaller aperture, like 21 or 32.
What lens are you using?

At close range you will rarely get your subject, especially one this large, in focus. At the f-stops you are using you definitely won't. I don't know what camera you have but some have a DOF preview button.

I'd suggest you try the shots again at a higher F-stop (smaller aperture) and see what your results are.

 

[cgipson1]

Did you notice that each shot has more DOF, in a progressive fashion (although it looks like you missed focus on the F7.1 shot)? I shoot most macro at F16 to F22...

 

[Ernicus]

I was going to use smaller stops, but it rained me out.

Problem I have in my head with that, I drop down to f/22 and then I will have to use too slow of a shutter speed to hand hold.

I have nikon d3100 with kit lens 18-55mm

 

[Ernicus]

Well, yeah, I just misunderstood some things. I just went and used the dof calculator and at settings I was shooting, I had given myself a depth of 0.01 to 0.03 range the smaller being larger aperture obviously. Well, numbers never lie, so I guess I'm lucky to have gotten as much in focus as I did. lol.

 

[cgipson1]

I was going to use smaller stops, but it rained me out.

Problem I have in my head with that, I drop down to f/22 and then I will have to use too slow of a shutter speed to hand hold.

I have nikon d3100 with kit lens 18-55mm

Hint... either crank your ISO.. or use flash!

 

[Josh66]

Yeah - the closer you get, the smaller the DoF gets (for a given aperture).

DoF can be a real pain in the ass with macro...

 

[Ernicus]

Did you notice that each shot has more DOF, in a progressive fashion (although it looks like you missed focus on the F7.1 shot)? I shoot most macro at F16 to F22...

Yup. So logic was telling me I had to step down a lot more...but like I said, rained out so I figured I'd ask you folks. I had no idea macro shots were done stepped down that far.

 

[Espike]

Would diffraction not be an issue at f/22?

 

[Ernicus]

I was going to use smaller stops, but it rained me out.

Problem I have in my head with that, I drop down to f/22 and then I will have to use too slow of a shutter speed to hand hold.

I have nikon d3100 with kit lens 18-55mm

Hint... either crank your ISO.. or use flash!

Yup again. Time I start using my flash. I hate cranking up iso. I have been testing with that lately, but i hate grainy pictures.

 

[Josh66]

Would diffraction not be an issue at f/22?

Would you rather have less than optimal sharpness due to diffraction, or not enough DoF?

It is an issue, but sometimes it's better than the alternative.

 

[cgipson1]

Would diffraction not be an issue at f/22?

I have taken shots in the mid to high 30's... that were sharp! Was there diffraction? YES... was the picture better for the increased DOF? YES!



shot at F32

 

[o hey tyler]

Diffraction is a lot more noticeable on kit lenses than dedicated macro lenses as well.

 

[yerlem]

Total noob question, but shouldn't you compensate exposition if you are trying to compare DOF?

 

[Josh66]

Total noob question, but shouldn't you compensate exposition if you are trying to compare DOF?

I am going to assume that English is not your native language, but I still don't know what that means...