The answer is a definitive YES, YES, YES. Now, perhaps, you could ask another question, Why? Why? Why?
Last summer on our Complete Nature Photo Course we had a few students who owned cameras that lacked this feature. Incredibly, and much to these students credit, most of the students did quite well, but they recognized the enormous limitations and experienced the very real frustrations of not having this essential camera feature.
So, why should you have it?
The depth of field button allows you to see an approximation of what your film will actually record. I say an approximation because the viewfinder gets dark when you close down the lens at a minimum aperture and it can be difficult to really ascertain exactly what is, and what is not, in focus. If your eyes can adjust to this darkness, and truly assess the image seen, it would be possible to determine the true range of sharpness, but in actual fact this is rarely possible. But you can see what looks like it is in focus, and more.
In addition to what is in focus, the depth of field preview button will show zones of apparent sharpness, or degrees of sharpness, that may make or break a photo. Wide open, there is no depth of field and anything beyond the actual point of focus will be soft, increasingly so the further and further these objects are beyond the point of focus. Closed down, objects out of focus will take on a certain degree of sharpness, even though they are not technically sharp or perhaps even remotely so. However, these background objects could be discernible, and being so, could be distracting and lead the viewer's eye away from the subject.
For more on this issue, make sure you check out our Tip of the Month for October/November and some of the topics from our past Q of the M.
Do YOU have a Question you'd like addressed? If so, please forward your question to our email address, below, and title the subject of your email (in the Subject field) 'Proposed Question of the Month. Can't promise you we'll address your particular question but we'll do the best we can do.