This photo was taken at aperture f1.8.

All matches are easily identified, and most may be regarded as being in reasonable, if not perfect, focus.

The closer the subject, the more critical is Depth Of Field.

* Strictly speaking, it's usually safer to NOT use the absolute minimum (smallest) aperture a given lens will allow, but use the next-to-smallest. The reason for this is an effect called diffraction. When one closes a lens to its smallest aperture, whilst the DoF is maximised, it's also possible for the image-forming light rays to be slightly distorted by the tiny hole, thereby possibly taking the edge off the sharpness of the image. Lenses on 35mm film cameras typically have minimum apertures of f16 or f22. If your lens has a minimum aperture of, say, f16, I suggest not using an aperture smaller than f11.

Many less-expensive digital cameras (and fixed-lens digital SLRs) have a minimum aperture of f8 or thereabouts; same rule applies. With digital of course you can conduct all the experiments you wish without cost, and I encourage you to do so.

Given the above, a logical question might be, "If my film camera lens has a minimum aperture of f16, but my digital camera only goes down to f8, doesn't this mean I can't achieve the same Depth of Field on my digital as on my film camera?". The answer is, "No, you can usually get good Depth of Field with your digital". I'll explain why shortly.