Choosing Manual Focus Lenses - Part 3: Zooms

A top-quality aftermarket Vivitar Series One zoom flanked by the OEM Olympus and Minolta 75-150 f/4s

​
    Zoom lenses really started to come into their own by the late-1970s and became standard equipment with most SLRs by the mid-'80s. Versatility was the name of the game, with such optics sometimes enabling a photographer to replace up to 3 primes with one lens. However, this was not a free lunch; there were always compromises involved. 

  Zooms - Convenience, Capability, and Compromise

​    One of the biggest strengths of a zoom is its capability to instantaneously bring your subject closer or push it away when you are physically unable to change your position (e.g. if you are on a walkway in a national park or another venue where you are not able to move freely, etc.). While perspective does not change with zooming, dialing-in the exact framing you want can be a major plus. Another benefit is the reduction of lens changes you need to make in relation to primes (single focal length lenses), which sometimes will enable you to get a shot you would otherwise miss while swapping lenses. Such versatility can be a strong incentive to use a zoom in appropriate situations. Also, a zoom will often weigh less than having the two or three prime lenses it can replace in your bag. Finally, many MF-era zooms can be had for insanely small prices nowadays, so they are definitely worth a look if their advantages will serve your purposes.

​    Some drawbacks, especially with zooms from the MF era, include: 1) image quality (IQ) very rarely will match that of a good quality dedicated prime lens of the same era at an equivalent focal length (but it is often close enough), 2) the zoom will not perform equally well at all focal lengths, 3) they have an f/2.8 max. aperture at best (and constant f/2.8 zooms are big and heavy), and that will be at the wider end of the zoom range, while at the far end it will almost always be f/3.5 or (usually) higher, 4) flare and ghosting are generally worse due to the greater number of lens elements in zooms versus primes of equivalent focal length. This is by no means an exhaustive list, but it does give an idea of some of the compromises inherent with zooms. So let's say your priorities lean towards the advantages a zoom provides. How can you maximize those advantages?

  What to Look for in MF Zooms

    Right off the bat, it is not realistic to expect current levels of zoom optical performance in lenses that are 25 - 50 years old. Even the cheapest, most plasticky kit zooms of today offer an amazing amount of image quality compared to their forebears. (Feel and build quality are another matter ;-)). However, there are some great vintage zooms that do an admirable job when their limitations are respected. Here are a few general guidelines when selecting and using zooms (in no particular order):

• Keep the zoom ratio under 3x if possible - Zoom ratio is an expression of the relationship between the shortest and longest focal lengths of a zoom lens. For example, a 70-210mm lens has a zoom ratio of 3 (70 x 3 = 210). Before the coming of affordable aspheric lens elements in the mid-to-late '80s, there was a limit to the correction of IQ-robbing abberations with standard spherical elements. This was especially apparent with zooms, and the wider the zoom range (and therefore the larger the zoom ratio), the more this problem was exacerbated. Some of the best zooms of the '70s & '80s had only 2x zoom ratios, and if they cover your focal length needs adequately, will usually maximize IQ. Also, 2x zooms almost always used fewer elements and could therefore be smaller and lighter than their higher ratio relatives. Having fewer elements (when combined with good multicoatings) also reduced the levels of flare and ghosting, in general. This doesn't mean that any lens with a zoom ratio higher than 3 is going to be a dog, but the chances of it being excellent are definitely lower.

• Look for a zoom that is strongest at the focal lengths you use most often - Even with the latest zooms, there is always some variability of performance as the focal length changes. This gap is far closer than it was three or four decades ago, so it is even more critical to analyze which focal lengths you favor when looking at vintage zooms. Most zooms from the MF era were strongest in the middle of the zoom range and weaker towards the ends (e.g. many 35-70mm lenses were strongest around 50mm). It was very rare to find a 70-210, for instance that was at its best at the long (210mm) end, and usually, that was the worst focal length for IQ.  For another thing, most 200ish mm zooms actually topped out in the 180-190mm range as far as true focal length went. This is not usually a big deal, but it is something to be aware of if you are looking get the maximum reach out of such a lens. If you are fortunate enough to find reviews for a lens you are interested in, watch carefully for comments or images that depict its performance at different focal lengths.

• A zoom should usually replace at least two primes in your bag - To maximize the advantages of a zoom, it needs to offer at least comparable performance or a major step forward in convenience versus equivalent primes. This also applies to weight and bulk. If you find yourself using one focal length predominantly, a prime will often save you weight and will offer, at the very least, equivalent, and most likely, better performance. If you shoot a lot in low light, you will either have to deal with at least a one-stop loss in aperture with most zooms or pay a big penalty in size, weight, and cost to maintain f/2.8 capability. If you need more aperture than f/2.8 in an MF-era lens, primes are the only option. 

• How important are the corners in your images? - Especially at wide apertures and the extreme ends of the focal length range, vintage zoom lenses can be pretty nasty in the corners of the image (see note above about the lack of aspheric elements until the late-'80s). They often need stopping-down to f/8 or f/11 to make the corners acceptable to good, and some never do get to that point. So, again, your personal priorities are going decide if a zoom will do in this case. If you are expecting modern levels of corner performance in a vintage zoom, you will be disappointed. But, if you are realistic, you may find something you can live with.

• Construction - This is an area where many people are drawn to older zooms; they just feel better than many modern lenses. You will find more metal (and thus weight :-)) in vintage MF zooms, although plastics started to make major inroads by the early-'80s. Don't let plastic put you off of a lens if the focus and operation is otherwise smooth and positive. The big reason most MF zooms feel smoother and better than AF zooms is the fact that they used traditional helicoids that had closer tolerances and were damped with heavier grease. With the rise of AF, and especially the motor-in-body designs used by Minolta, Nikon, and Pentax, something had to give. To keep the AF motors compact, there was a finite level of torque to work with, which required that the lenses have shorter focus throws and be far easier to turn than their MF counterparts. This is what led the sloppier manual focus feel of AF lenses. One-touch (focus and zooming combined in one ring) zoom designs were very popular in the MF era. A possible drawback for some users is the fact that many such lenses develop what is called "creep" after many years. Creep is when the zoom/focus ring slides of its own accord depending on the orientation of the camera, usually as a result of things loosening up inside with extended use. Most two-touch (separate focus and zoom rings) zooms do not have such problems, but that is not to say that it doesn't pop up on some cheaper designs.

• OEM versus the aftermarket - There are literally millions of MF zooms sitting out there, and many people wonder if they should just stick with the OEMs or if the aftermarket is worth a look. It is a similar situation to primes: there is a pile of cheap junk, but there are some good aftermarket lenses. It is worthy of note though, that it is harder to build a decent zoom than a prime, due to the greater complexity of the designs and the number of components involved. So sticking with the better aftermarket manufacturers cannot be emphasized too strongly. One area that the OEMs often were able to keep a bit of distance between themselves and the aftermarket was in the quality of their multi coatings, but this was not a hard and fast rule. Here is a brief review of some of the better aftermarket manufacturers:
• Tokina - Tokina probably had the best build quality of the third-party lens makers, being as good as the OEMs, particularly with their AT-X (professional), RMC, and even the consumer-level SZ-X lenses. Optically, they were right up there as well, one example being a Consumer Reports comparison of 80-200ish f/4ish zooms (including OEMs) in the mid-80's. The winner was the Tokina RMC 80-200/4, a lens that can often be found for less than $25 USD nowadays, or thrown in with an old SLR kit. One area Tokina did tend to trail the OEMs a bit (and still does even today) was in chromatic abberation (color fringing) correction, but that was about it.

• Tamron - Tamron was one of the most innovative of the third-party companies, especially when it came to zooms. Their SP line of lenses was very strong, and their Adaptall II mount meant that you only had to buy an adapter to use their lenses on different lens mounts instead of buying a whole new lens. Build quality was very good and Tamron also did (and continues to) sub-contract work for the OEMs. A great resource for Tamron lens information can be found at adaptall-2.com.

• Kiron - A long-time supplier to brands such as Vivitar, Soligor, Panagor, and Elicar, in 1980 Kino Precision Industries named their U.S. subsidiary Kiron Corporation and began to sell their own designs under the Kiron brand. Kiron was probably the hottest name in aftermarket lenses in the early-'80s. Their build-quality was definitely up to the OEMs and their optical quality met or exceeded OEM levels. The biggest issue with their lenses today is that many suffer from oily apertures, due to the breakdown of the helicoid grease. The advent of auto focus spelled the end for Kiron as a force in the 35mm lens arena.

• Vivitar - One of the most well-known third-party brands, Vivitar was the name applied to lenses and other photographic accessories made by a variety of suppliers, including Kino, Komine, Tokina, and many others. With the introduction of their Series 1 optics, Vivitar was taking direct aim at the optical and build quality of the finest OEM zooms. Vivitar would design a lens and then sub-contract its production to one of its suppliers. They were on the cutting edge of zoom design from the mid-'70s into the early-'80s. Their standard range of lenses was your basic aftermarket fare, but the Series 1 line is definitely worth a look. Have a look at cameraquest.com for information on how to identify Vivitar lenses produced from the 1970s to 1990 by means of serial #s.

• Soligor - Similar to Vivitar, Soligor was a brand name applied lenses produced by various third-party suppliers. Known mostly for decent, cheap glass, Soligor took the same approach as the Vivitar Series 1 lenses with its C/D line of premium lenses. The manufacturer of a lens can be decoded from the serial # as with the Vivitars. Check out the apotelyt.com website for more information.

  Coming Up

    Next time, in Part 4, we will look at specialty lenses such as macros and tilt-shifts and the place they can have in your kit along with lens sets in general.