3 Big, Wide, Lenses

 

Images are not to scale. Sources can be seen af the bottom of each lens.

My Sony A7 has given me a chance to play with the manual lenses I saved from my film days. The shallow body form factor of the mirrorless Sony allows plenty of space for a variety of adapters to introduce these optical gems to the bliss of the digital workflow. Up until now, my efforts had been confined to older film-era prime lenses, but these soon expanded to several samples of the new and inexpensive Chinese optics. My collection also includes several non-Leitz Leica-mount lenses, purchased for their compact design. They almost disproportionately small when mounted on the bulky A7 body, but together they make a compact photo-making machine.

Sigma 15-30mm Lens: I started accumulating full-framed, super wide zoom lens started long ago. At the time, I was using APS-sensored Nikon DSLRs, and due to the 1.5X crop factor, any superwide lens would have had a much narrower field of view. However, I knew that someday I would upgrade to a full framed body, so I kept my eyes out for full framed lenses. The first one that I purchased was a used Sigma 15-30 F 3.5-4.5 zoom. I read the specifications before I purchased the lens, and was satisfied that it would be a good starter lens. The price was right, and it turned out to be a satisfactory lens for my purposes. At its 15mm minimum focal length it had a reasonable F 3.5 shooting aperture. Its bulbous front element makes it impossible to mount a filter. All in all, this lens a good value.

The Fallacy Of Unlimited Depth Of Field: Like many photographers, I had long believed that wide angle lenses (short focal length lenses, actually) had very generous depths of field. This is true at greater distances. For example, if I examine the zone focusing (depth of field) scale on the lens barrel, I might find that if I set my aperture to F 11.0 and align the infinity mark with F 11 on the far side, the lens "should" provide sharp focus from infinity to as close as 1.5 feet. This is an interesting notion, but in this case, I was focusing at a subject-to-film plane distance of about 14 inches. The nearest  "horn" of this cleat (camera left) was about 10" from the front of the lens, and based on a close examination of this image, outside of the "in focus" range of this particular aperture. For the record, I was concentrating on the pattern of the ropes, and hadn't considered if the aperture would be small enough for a subject so "deep" (front to back). Now this softness could also be the result of the lens being incapable of high degrees of sharpness towards the edges of the frame. Either way, this image would not pass muster if printed to 11"x17", framed, and mounted on a wall.  Whatever the cause, the lens may well prove acceptable if the subject is centered in the frame and the edges were expected to be "blurry".

When working with subjects where the center sharpness was more important than edge sharpness, the lens performed well. This red bit of plumbing, centered in the frame, is properly rendered, while the edges show a definite softness. Again, I can't say whether this was due to inadequate depth of field or poor edge resolution. I could certainly test this by photographing a brick wall, or something suitably flat and full of fine detail. That, I will leave to another day, or maybe another enthusiast.