Depth Of Field Help Required

[johnharris]

I am a novice to photography (previously just used point and shoots), and I have just purchased my first ever RF (Bessa R with 50mm & 28mm), I therefore apologise in advance if my question has an obvious answer: I understand that one cannot determine correct depth of field by looking through the viewfinder, as everything is always shown in focus. If this is the case, how do I determine it?

[Finder]

There should be a depth of field scale on the lens barrel. Focus the camera and set the aperture. Use the DOF marks on the scale corresponding to the set aperture indicates the near and far points on the distance scale of the lens.

[oftheherd]

Take a look at the lens at this url: http://cgi.ebay.com/YASHICA-AUTO-YAS...QQcmdZViewItem

The top set of numbers is distance in feet and meters. The lower is the actual f/stop. Note that since f/1.7 isn't so much wider than f/2, the lens maker shows the widest opening; f/1.7, and a dot for f/2. The middle scale has a dot with matching numbers to either side. The dot is for f/2, again since f/1.7 and f/2 aren't so much different. Those numbers to either side show you where on the distance scale, things are presumed to be in acceptable focus. Hopefully your lenses have the same type of markings.

Note that it isn't entirely accurate, but is for most subjects. In actuality, the depth of field will usually be about 1/3 in front, and 2/3 behind the actual place you are focused on, called the plane of focus. The plane of focus is an imaginary line parallel to the film plane, right at the distance you are focused at. The film plane is where the flat portion of the film is at, in the back of the camera, that receives the light for the photo.

Hope that isn't too confusing. BTW, if your lenses don't have those or similar markings, look at the instructions that came with your lenses. It is probably there regardless. That should get you started, but you might want to go to your local library or used book store for some books that will tell you the same. Or, you could google "depth of field."

Good luck, and don't hesitate to ask questions. I am sure some others will chime in with better explanations, maybe even photos of the same lenses you have. Some may have even done so while I was typing this.

Edit: When you look in books, or google, be sure to look for hyperfocal distance. It will give you some breathing room. You will note the lens at the above url is focused at infinity so some of the numbers are to the right of the infinity mark. If you set the aperture at f/16, you could then move the infinity mark on the distance scale (on the lens shown) and everything between the two numbers 16 would be in acceptable focus.

[dexdog]

More than you ever need to know about depth of field at this link. Either that, or just look at the lens barrel.

http://www.vanwalree.com/optics/dof.html

[savuti]

I posted pretty much the same question some weeks ago (also a complete newbie);best use the numbers on the barrel (read the instructions, easy to use); try dofmasters.com, where you can download a DOF-calculator to your computer (or, much better, to your palm device). Good luck!

[markinlondon]

Another vote for using the lens scale. With a 28 you can just point and shoot when stopped down. Have a look at zone focusing as well as the much mentioned hyperfocal technique, do you always need focus to infinity?

[payasam]

There's a handy tool (a spreadsheet) for use on a computer. Admittedly no use in the field. I cannot attach it. Will send to anyone who PMs me an e-mail address. Source not recorded.