depth of field no scale or button

[seany65]

Does anyone know if there is a way of estimating 'depth of field' when the the lens doesn't have a 'depth of field' scale and when the camera doesn't have a 'depth of field' button?

The lens is a Tamron 35-70 f3.5 (17a) on a nikon f301.

Also, does anyone know why so many lenses have 'infra red' focus index markers but no 'depth of filed' scale?

Any help would be much appreciated.

 

[unixrevolution]

Some zoom lenses dispense with DoF scales because estimating DoF for the zoom range is difficult, as opposed to a prime with a single scale. The Infrared marks are much easier to mark and include.

If you have a smart device you could bookmark a DoF calculator on the web, or find a DoF app.

If you are not so inclined, you could inscribe or sticker the DoF on the lens for various focal lengths.

EDIT: Thanks, google! Here's instructions on how to make one yourself:

http://www.karlrainerbirk.com/AnalogDofComputer.html

And an image of a 35-70 DoF scale on a zoom lens:

 

[CMur12]

As you can see in Erik's illustration, back in the manual focus days, one-touch zooms often had DOF scales. However, auto-focus required zooms to be of the two-touch variety, which eliminated the possibility of such.

We don't see DOF scales even on most modern auto-focus prime lenses because the focusing arc has become too short for a detailed scale, so they usually only show one or two of the smaller apertures.

- Murray

 

[Dogman]

There's an app for that!

More than one actually. I use the free "Simple DOF" app for iPhone. With a zoom it can be a little involved due to the infinitely variable focal lengths but it's still a useful reference.

 

[seany65]

Thanks for the replies. The main lens is a manual focus tamron 35-70 f3.5, but I was hoping for some quick 'trick' to use with my ricoh 500gx with it's 40mm lens.

I've not got any 'smart' things like iphones etc.

Thanks for the link unixrevolution, I'll have a proper look later.