DOF Question from a noob

[4hero]

Hello,

I'm new to dslr's (5 months) and still can't get my head round depth of field. All my macro shots seem to have DOF regardless of how far/close I am from the shot, or aperature setting.

Here's an example (shot with 350D and 100mm f2.8 and mounted flash).

http://farm2.static.flickr.com/1063/532034177_c1cfaf74bc_o.jpg

Exposure: 0.005 sec (1/200) Aperture: f/3.5 Focal Length: 100 mm ISO Speed: 100 Exposure Bias: 0/2 EV Flash: Flash fired
I have tried changing the focal point, but still seem to get DOF :confused:

Can anyone help me please? Sorry if it's a silly question, but I'm having real problems getting my head round this.

Thanks in advance!

[bieber]

First of all, all shots have a depth of field, it's just a matter of what type of DOF you're getting. In the case of macro, you're getting an extremely shallow depth of field due to the fact that you're using a relatively long focal length extremely close to your subject. To get more in focus, you're going to have to stop down your lens a whole lot; think around f/22 if you can do it, maybe further. Some experienced macro shooters will come in here in a minute and give you all the details, no doubt...

[tdodd]

Have a look at this DOF calculator - http://www.dofmaster.com/dofjs.html.

DOF varies depending upon focal length, distance from subject, aperture and sensor size. Plug in the numbers for your shot - 350D, 100mm, F3.5 (pick 3.4 or 3.6) and your distance to the subject and see just how narrow the DOF is - less than 1mm probably. I reckon you'd need F22 or higher for this shot to get the whole insect in focus. The problem with going over around F16 on a crop body is that you get diffraction effects that start to soften the whole image. You may need to try a few shots at different F-stops, say F16, F22, F32, F45, to see what works best.

[Radtech1]

As it turns out, you are interested in a process called "Focus Stacking", despite the fact that you do not yet know what that means.

It is a method of shooting several shots, as a slightly different focus depth, and using a specialized software to "stack" the photos so that the object is in focus, top to bottom.

Do a google search, or search the forums for "focus stacking" (with the quotes) and you will be buried in a wealth of information.

Rad

[Wildewinds]

Use a smaller aperture (like f8 or something). Kick up the ISO if you have to.

[hatmandue]

You may also try looking in the Macro forum for more information on this subject. I recommend looking at the threads started by a user named Lord V, he is easy to find in the macro section, and his expertise is invaluable. He covers the focus stacking technique which was mentioned earlier by Radtech1, and he has some tutorials on focusing techniques.

[4hero]

First of all, all shots have a depth of field, it's just a matter of what type of DOF you're getting. In the case of macro, you're getting an extremely shallow depth of field due to the fact that you're using a relatively long focal length extremely close to your subject. To get more in focus, you're going to have to stop down your lens a whole lot; think around f/22 if you can do it, maybe further. Some experienced macro shooters will come in here in a minute and give you all the details, no doubt...

Thanks for your comments Beiber, much appreciated.

Have a look at this DOF calculator - http://www.dofmaster.com/dofjs.html.

DOF varies depending upon focal length, distance from subject, aperture and sensor size. Plug in the numbers for your shot - 350D, 100mm, F3.5 (pick 3.4 or 3.6) and your distance to the subject and see just how narrow the DOF is - less than 1mm probably. I reckon you'd need F22 or higher for this shot to get the whole insect in focus. The problem with going over around F16 on a crop body is that you get diffraction effects that start to soften the whole image. You may need to try a few shots at different F-stops, say F16, F22, F32, F45, to see what works best.

tdodd, I had a look at this site the other day, but still had trouble getting to grips with dof. I tried a F16-22 but obviously this darkens the image using iso100. After reading the best setting to shoot macro (ISO 100, Flash, 1/200sec, Manual mode) the higher F's didn't work.

As it turns out, you are interested in a process called "Focus Stacking", despite the fact that you do not yet know what that means.

It is a method of shooting several shots, as a slightly different focus depth, and using a specialized software to "stack" the photos so that the object is in focus, top to bottom.

Do a google search, or search the forums for "focus stacking" (with the quotes) and you will be buried in a wealth of information.

Rad

I think you may have answered my question Radtech, much appreicated, I will look into stacking.

Use a smaller aperture (like f8 or something). Kick up the ISO if you have to.

Thanks, but higher ISO seemed to lower the quality of my shots.

[In2Photos]

Thanks for your comments Beiber, much appreciated.



tdodd, I had a look at this site the other day, but still had trouble getting to grips with dof. I tried a F16-22 but obviously this darkens the image using iso100. After reading the best setting to shoot macro (ISO 100, Flash, 1/200sec, Manual mode) the higher F's didn't work.



I think you may have answered my question Radtech, much appreicated, I will look into stacking.



Thanks, but higher ISO seemed to lower the quality of my shots.
This should work. Are you using ETTL on the flash or M mode on it as well? I would probably use ISO200 but otherwise these settings should work just fine.

[Wildewinds]

Thanks, but higher ISO seemed to lower the quality of my shots.

True, but not as badly as the whole fly being out of focus. It's a compromise.