Cosina AF 100mm f/3.5 Macro Interchangeable Lens Review

One of the most desirable and useful lenses you can put on the front of your SLR is a dedicated macro lens. Gary Wolstenholme takes a look at a low cost option.

The main problem is that good quality macro optics like the Micro Nikkors or the Canon 100mm macro, are not cheap. Even the more reputable third party offerings come at a price, this can put macro photography beyond the means of some less affluent photographers. There is an alternative - the Cosina 100mm f/3.5 Macro lens retails for around £130. The question is whether a lens that is about a third of the price of the competition is a worthy substitute for photographers on a budget.

Cosina 100mm f/3.5 specifications

• Maximum Magnification Ratio - 1:2 (1:1 with included ‘Matched Macro Adapter’)
• Minimum Focusing Distance - 42.6 cm - 1.4 ft
• Aperture range - f/3.5 - f/22
• Angle of View – 24 degrees
• Weight - 307g
• Filter size - 49mm
• Retail Price - £130 (approx)
• Available to fit Canon, Nikon, Pentax, Minolta. The lens I have reviewed is Canon EOS fit.

When I first removed this lens from its box, I was not impressed. It really doesn’t feel like £130 of equipment. I’d be pleasantly surprised if it had fallen out of a luxury Christmas cracker, if it did though it would probably break when it hit the table!

The plastic it is made out of feels the same as the plastic used to make cheap slide projector magazines, this does make the lens very lightweight. On the positive side it does have a metal lens mount which clicks firmly into place when attached to the camera.

Autofocus is extremely slow and sounds like a cement mixer, when switched to manual focus the focus ring is very loose and fairly difficult to use when you get in close. These are all things I’d expect from a budget lens like this, what I didn’t expect was how well it performs optically.

This lens is good and sharp stopped down and still quite respectable wide open, on the coin shot above it has picked out every last detail in my grubby fingerprint. A problem I foresee with this lens is that many people also use their macro lenses for portraits. If your subject isn’t moving then this lens is fine, producing decent results at normal distances. If however you wish to capture a more informal shot, the autofocus is just too slow. As a rule of thumb, macro lenses are always slow to autofocus, just not this slow.

Included with the lens is a close-up dioptre lens, which screws into the filter thread so that you can achieve true macro life-size reproduction ratios. This is a very, very cheap way of allowing the lens to focus in closer.

When used with the adapter images are visibly softer as the optical quality of the adapter does not match that of the lens, in fact it becomes difficult to see just where the sharpest point of focus is. An extension tube would have been a better quality option, but then that would bump the price up.

Verdict
This lens provides fairly good optical performance at a very low price. If you really cannot afford the price of a more reputable lens, and you can cope with the Kinder Surprise build quality and slow autofocus, then this lens will do the job. However I would strongly recommend looking into getting some extension tubes to go with it as the performance of the ‘Matched Macro Adaptor’ will not fail to disappoint.

In summary the main positive points of the Cosina 100mm f/3.5 Macro are:

Very low price
Good optical performance when used without the ‘Matched Macro Adaptor’

Negative points are:

Poor Construction
Extremely slow autofocus
Matched Macro Adaptor’ is a poor solution for closer focussing