Over the past while I’ve had some readers contact me by email with various questions about buying lenses. Some have specifically asked why I chose particular lenses and not others. This article attempts to answer a few specific reader questions, as well as provide some general lens buying considerations.

To begin, I’d like to address four specific reader questions…

Why did you choose the M.Zuiko PRO 12-40 mm f/2.8 over the M.Zuiko PRO 12-100 mm f/4?

The biggest factor for me was gaining one stop of light. This allows me to shoot my video projects at an aperture of f/2.8 rather than f/4. I always prefer to capture my video clips at lower ISOs which would not require additional work in post. Using the PRO 12-100 f/4 would have resulted in a full stop higher ISO. Another factor was the potential focal length duplication between the PRO 12-100 mm f/4 and the PRO 40-150 mm f/2.8.

The fact that the PRO 12-100 mm f/4 has lens-based IS was a non-issue for me since I shoot with an Olympus OM-D E-M1X. This camera body has superb IBIS performance which was more than adequate to shoot video handheld with the PRO 7-14 mm f/2.8 or the PRO 12-40 mm f/2.8. Overall the PRO 12-40 mm f/2.8 was a much better fit for my needs. It was also smaller, lighter and less expensive than the PRO 12-100 f/4.

Would you consider the M.Zuiko 12-200 mm f/3.5-6.3 for travel?

While this lens would be an ideal travel lens for many photographers, it would not be of any interest to me personally. For most of my travel needs my Nikon 1 gear makes more sense given its size/weight/performance characteristics.

If for some reason I was going to use my Olympus gear for a travel photography tour, and I wanted to travel reasonably light, I would take an E-M1X body. Two zoom lenses (PRO 12-40 f/2.8, PRO 40-150 mm f/2.8) and the MC-20 teleconverter. I would not bring any tripods/monopods with me. Obviously these two lenses would be larger and weigh more than only taking a lens like the M.Zuiko 12-200 mm f/3.5-6.3.

Overall these two lenses would give me much more shooting flexibility with a combined focal length range of 12-150 mm at f/2.8. Bringing my MC-20 teleconverter would extend the reach of my PRO 40-150 mm f/2.8 to 300 mm at f/5.6. The combination of these two lenses and teleconverter would give me an equivalent field of view from 24 mm to 600 mm.

Even if I added my PRO 7-14 mm f/2.8 and 60 mm f/2.8 macro to a potential Olympus travel kit, it would still be reasonably small and light compared to a larger sensor format camera kit covering the same equivalent field-of-view and apertures. My E-M1X, three PRO M.Zuiko zooms, and macro lens would all fit in a single, mid-sized shoulder bag.

Will you be adding any prime lenses to your Olympus kit?

We have no plans to add any additional prime lenses. At the present time we have two M.Zuiko prime lenses in our kit. The 60 mm f/2.8 macro and the PRO 45 mm f/1.2. Since we prefer shooting with zoom lenses, we view primes as ‘specialty’ lenses for specific tasks like macro and low light portraiture. We chose the two M.Zuiko primes we own because of their fast apertures and weather sealing.

Did you consider any M4/3 lenses made by other manufacturers?

No, we did not. The selection of M.Zuiko lenses we purchased met our requirements very well. We also wanted to ensure compatibility with any new functionality that may become available in the future through Olympus E-M1X camera firmware updates. Previous experience with another M4/3 brand did not go as well as we would have liked. This was another reason that we did not consider other brands of M4/3 lenses.

Now, let’s move into some general lens buying considerations.

How long is a piece of string?

Asking someone else what lenses you should buy is akin to asking them how long a piece of string is. It depends on a lot of things. Ultimately there is no plausible answer until someone clearly defines the subject matter they will be photographing. The lighting conditions. Their shooting preferences and creative objectives. The focal length(s) needed. The camera body they will be using. And, their budget.

Which company makes the best lenses?

There is no answer to this question. You’ll get a different response depending on the ‘fanboy’ with whom you speak. The ‘best’ of anything is based on the specific needs of an individual and the points of reference one chooses for their lens evaluation.

Primes versus zoom lenses

Not that many years ago photographers would almost automatically choose prime lenses over zoom lenses because of image sharpness concerns. That thinking doesn’t necessarily make sense today. In preparation for this article I went on the Olympus website and looked at some MTF charts for comparison purposes. What I found was instructive.

Let’s look at two scenarios. If you wanted the best performing lens (based on published Olympus MTF charts) at 12 mm (efov 24 mm) and at approximately 40-45 mm (efov 80-90 mm) what lenses would you choose?

For the 12 mm focal length our choices are:

• M.Zuiko 12 mm f/2.0
• M.Zuiko PRO 12-40 mm f/2.8
• M.Zuiko PRO 7-14 mm f/2.8 (looking at the 14 mm MTF chart)
• M.Zuiko PRO 12-100 mm f/4

All three of the M.Zuiko PRO zooms beat the 12 mm f/2.0 prime in terms of MTF chart performance. It would be a close call between the PRO 12-40 and the PRO 12-100 for the best MTF performance at 12 mm.

One could argue that this isn’t a fair comparison since we have a much older, standard prime up against 3 different PRO zooms of newer vintage. Let’s compare the 40-45 mm focal length.

Our lens choices for the 40-45 mm focal length are:

• M.Zuiko 45 mm f/1.8
• M.Zuiko PRO 45 mm f/1.2
• M.Zuiko PRO 12-40 mm f/2.8
• M.Zuiko PRO 40-150 mm f/2.8

Which lens has the best MTF chart performance in the 40-45 mm focal length range? It may surprise you, but the MTF chart winner is the M.Zuiko PRO 40-150 mm f/2.8.

What this exercise shows us is that we should not make assumptions about lens performance simply based on the old prime versus zoom lens assumption.

We also should not assume that an older generation, more expensive, faster aperture prime will have better optical performance than a new generation, less expensive, somewhat slower prime lens from the same manufacturer.

Modern lens technology has advanced significantly over the years. Regardless of the brands of lenses you own, and the format of camera you use, it can be insightful to compare MTF charts of newer versus older generation lenses within the same lens family.

If lens performance is a significant issue for you, it is important to go to the manufacturers’ web sites and look at the published MTF charts. Remember that higher performing lenses will have contrast and resolution lines that are higher up on the MTF chart. Typically top performing lenses will have contrast scores of 90% (0.9) or higher. Resolution scores are virtually always lower than contrast scores. The contrast and resolution lines of top performing lenses will also be at consistently high levels across the MTF chart. This indicates consistent performance from the centre to the edge of the frame. It is common to see some performance drop off on the edges in MTF charts for most lenses.

There are photography websites that do extensive, formal lens testing and provide graphs of their test results. These types of articles are worth investigating.

Choosing a fast prime lens can make sense if your photography involves a lot of shallow depth-of-field work. Or, if you need a fast lens to shoot in low light conditions. We also need to consider that aperture is not the sole determinant of shallow depth-of-field. Lens focal length, distance to subject, and subject distance to background can all impact depth-of-field and subject separation.

It should be noted that lens manufacturers use different MTF chart test methods. Some MTF charts are based on bench testing, while others use simulated data. There is no industry standard for MTF charts. Some manufacturers use 10 lines/mm for contrast and 30 lines/mm for resolution with their MTF charts. Panasonic uses 20 lines/mm and 40 lines/mm. Olympus uses 20 lines/mm and 60 lines/mm. Since these differences exist, MTF charts should only be used to compare lenses of the same manufacturer, not to compare lenses from different manufacturers. If you would like to read a comprehensive article on MTF charts, our friends at Photography Life have some very good information.

Do you need weatherproofing?

Not every photographer needs to have lenses that have weather proofing. In inclement weather you can use protection like rain sleeves if needed. The questions to ask yourself are how often will you be shooting in inclement weather, and what degree of weather proofing do you want with your camera and lenses? If the body you’re using isn’t weatherproof then obviously there’s no point in spending more money on weatherproof lenses… unless they offer some other important attribute. If one of your objectives with your camera kit is a maximum amount of flexibility and capability, buying gear with excellent weatherproofing can be worth the added investment.

Constant aperture or variable aperture zooms?

If you want the largest range of focal lengths at the lowest cost, variable aperture zoom lenses will provide the best bang for the buck. If you seldom, if ever, shoot in lower light conditions a variable aperture zoom lens can make a lot of sense. On the other hand, a constant aperture zoom lens will give you a lot more shooting flexibility in lower light conditions, and also from a creative standpoint when you may be concerned about depth-of-field.

Check the MTF charts when comparing constant aperture and variable aperture lenses. The differences between the lenses may not warrant spending extra money on the constant aperture version. From a pragmatic standpoint this may be especially true if you only use your images online, or only produce small sized prints.

Manual focusing rings

Not all lenses have manual focusing rings. This feature can be helpful when trying to focus under difficult lighting conditions. Over the past 6 months or so I have come to really value the focus clutches on my M.Zuiko lenses and the added functionality they provide.

Special lens coatings and glass elements

Less expensive lenses will not have the same degree of special lens coatings and glass elements to help minimize flare and other optical performance issues. The technical details on a manufacturer’s website will indicate what special coatings and glass elements have been used in a specific lens.

Size and Weight

At the end of the day the most important factors for you may be the size and weight of your overall camera kit and the lenses you use. Moving to a mirrorless camera system, a smaller sensor camera system, or using f/1.8 primes instead of faster and larger primes may make sense for you.  Choosing variable aperture zoom lenses over constant aperture zoom lenses will also reduce the size and weight of your kit.

IBIS and VR capability

The in-body image stabilization of your camera, or the built-in image stabilization/vibration reduction of the lens itself, can significantly extend the shooting potential of your kit. This can be a critical consideration if you are like me and hate using tripods.

Impact of post processing

Your skill level working with post processing can help improve the appearance of your photographs to a significant degree, especially when shooting in RAW. While post processing will not overcome all of the potential image quality issues associated with a particular lens, it can help produce an acceptable outcome that meets your needs.

Balance budget with overall lens system capability

Very few photographers have unlimited camera gear budgets. The vast majority of us have to balance our available budgets with our camera gear requirements. Some trade-offs are often required. Taking an overall system perspective with lens buying considerations is a wise approach. Determining your overall system needs, then prioritizing lens purchases, can help you build a robust, integrated system over time as your budget allows.

Old bodies sometimes don’t perform well with new lenses

We can sometimes run into difficulties when we try to match up an older camera body with new generation lenses. For example, auto-focusing performance can sometimes lag noticeably. This was the case for me a few years ago when I was using full frame gear.  I purchased a Tamron 150-600 mm zoom to use with my D800. I had no issues at all with auto-focus performance with that combination.  However the lens did suffer from some noticeable focus lag when used with a Nikon D7000. This issue was more pronounced with early copies of the Tamron 150-600 mm lens.

Deciding when, or if, a camera body should be replaced can be a difficult decision. If your old camera body is in very good shape with a relatively low shutter count, it may make sense to look for used lenses of about the same vintage as your camera body. At least you’ll know that the camera and lens were originally designed to work together. Buying good, used lenses will also help you add capability to your camera kit at a lower cost.

That concludes our summary of some lens buying considerations.

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