ARTICLE 9-LENSES-A COMPARISON OF EACH-(THE ZOOM LENS)

ARTICLE 9
Zoom Lenses

If there has ever been a lens to revolutionize photography, it unquestionably has been the invention of the zoom lens. Here you will find a lens with tremendous versatility and control, featuring outstanding optics and ease of operation. Years ago when zoom lenses were developed, photographers had a tendency to disregard them due to their in-ability to produce images as sharply as fixed length telephotos. Now, with the introduction of computer design and excellent glass refinement methods, the marketplace is favouring the zoom lens. I believe it would suffice to say that they are now as equally sharp as their telephoto counterparts, producing imagery containing remarkable levels of contrast as well. The greatest advantage of this lens, is it’s ability for photographers to produce a series of portraits or landscapes with a variety of picture content, from one standing or seated position. Last year during a nature photography field trip I was hosting, I was producing a series of transparencies of a sunrise over a remarkably calm lake. Mist flooded the area before me transforming the entire lake into an ethereal scene almost biblical in description and appearance, if one has the capacity to draw this conclusion. After photographing for approximately 15 minutes from shoreline, the mist began to dissipate revealing, unbeknown to me at the time, a small island emerging and jutting out from the main coastline. With the zoom lens I was using at the time, (an 80-200mm), I had it set in the wider area of view-(the 80mm end), concentrating on the overall scene so to speak. However, when the island came into view, I then had the opportunity of zooming into the lands point, focusing on one isolated tree bathed in golden mist. The only other way a photographer could produce a photograph like this standing where I was situated at the waters edge, would be to use a stronger zoom/telephoto lens, higher than 200mm. This is where another factor comes into play–the cost. Zoom lenses price range have dropped considerably over the years as telephotos have, but think how many telephoto lenses you would have to purchase and carry with you in your camera bag compared to the numerous focal lengths contained within one zoom lens.

Although I’m relatively certain I do not have to mention the following, I feel the additional comment worthy of a brief discussion. Zoom lenses contain several pieces of glass in their lens barrels. This is how they are able to achieve the many variable focal lengths within one unit. What this means to you, is extra care must be given to this series of lenses regarding handling. I recall one of my students walking along a rocky watered coastline one day, then slipping on wet rocks and falling to the ground. Great concern was his immediate expression when he realized the front lens element of his zoom lens struck a rock and cracked the glass. This, unfortunately, was not all that happened. Upon further inspection by a qualified service technician, he then had to re-align each piece of glass in his lens because all pieces shifted internally upon impact. A tremendous repair bill awaited him. Although lower than the cost of a new lens at the time, it was a hard lesson learned. Hopefully the reader will benefit from this article meaning……keep your lens capped at all times if you are casually strolling while searching for material to photograph.

Always use the recommended lens hood from the lens manufacturer as well. This is important because you may encounter vignetting problems if an incorrect hood is attached-(especially when using the smaller apertures on your lens—F16, F22, F32 etc). Always use a “high quality” UV,(ultra violet) or skylight filter attached to the front of your lens for protection. Many people I have encountered over the years have not given much thought to this filter. It only stands to reason that if you’re going to invest hundreds if not thousands of dollars in finely produced optical equipment, placing a $15-$30- filter on the front of your lens is senseless. Your lenses are phenomenally accurate well designed products, that have taken years to develop and produce. With certainty, a photographer would never intentionally wish to degrade the inherent optical sharpness and contrast of high end lenses with inexpensive filters. Do “not let price” dictate the selection process. I currently use either brand name filters, (what ever your camera company is), or the very high end B & W filters made in Germany.-(more about filters in an up-coming article).

Another characteristic of the zoom lens is that as you zoom from for instance, from an 80mm position to a 200mm one, the maximum aperture of the lens changes. To be very specific: we could use any focal length of a zoom lens for comparison sake, so let’s refer to our current example of the 80-200mm lens. As you look at the markings on your lens, it typically indicates something similar to this—80-200mm F4/F5.6. What this means is, when you operate your lens around the 80mm end of the scale, your lens will be able to collect enough light through the lens barrel and all glass elements, producing a maximum “working aperture” of F4. Alternately, when you see something off in the distance that you want to zoom closer to, the light intensity often changes inside your lens while zooming, usually decreasing in light intensity, hence the now adjusted maximum working aperture of F5.6. Let’s assume that you have changed your lens from the 80mm position to the 200mm setting. Your light meter may be giving you at this time, a warning of underexposure if changes in exposure settings are not made. By pulling objects in closer to you, a zoom lens may have difficulty collecting all the light required for a correct exposure in comparison to when it was set in the 80mm position, since it’s field of view in the 80mm area is much wider than that compared to the 200mm setting. Should this underexposure warning occur, simply make an exposure adjustment which will compensate for the light loss due to the zooming in function. You could correct the exposure problem by either changing your shutter speed to a slower setting, or opening up your lens aperture from say F16 to F11-(which allows one more full stop of light to pass through your lens had you not made any changes), or by adjusting your exposure compensation scale.

Another area of concern when using a zoom lens are inherent flare problems, however I would like to indicate that by once again, using the correct lens hood you should be able to minimize this problem; but not always eliminate it. If when looking through your viewfinder you visibly detect lens flare occurring, try using your hand as an additional sun blocking device-(we call them go-bo’s in professional photography standing for go between’s). If flare still persists, consider my solution, and carry in your camera bag a thick piece of “black MATT cardboard”. Hold this slightly over sized card-(mine measures at least 8 x 10″) adjacent to your lens to prevent any extraneous rays of light from striking it. The majority of your flare problems are usually reduced significantly at this point. If you find that the positioning of this card requires additional distance from yourself to your camera to thoroughly block the rays of light from striking it here is another suggestion. I have found in numerous situations that I have had to stand approximately 10 feet away from my camera to block all unwanted light from striking my lens. But by doing this one can hardly be expected to operate the camera’s controls at such a distance during the time of exposure unless you have sophisticated infra red firing control circuitry or excessively long cable releases. A simple solution to this problem is as follows. Set your camera on self timer for roughly 10 seconds, then hurry to the spot which will effectively block the extraneous rays of light prior to your making the exposure.

When purchasing zoom lenses, my recommendations are as follows: select lenses that have staggered focal lengths which will compliment each others performance levels. For example: purchasing a 28-85mm and a 70-300mm or a 80-200mm will work quite well for the majority of your photographic needs. Unless you are specializing in very specific areas of image creation, lenses over 300mm or under 28mm are often unnecessary. I would also like to recommend that if you have a friend who has acquired lenses that you are interested in purchasing which are different focal lengths than what you own, to give their lens a try before you make the commitment of purchase. If people are reluctant to lend you their lenses or any other piece of photographic equipment, consider your local camera stores used dept. or second hand outlets as well, and inquire if they will rent you gear for a modest fee.
The topic of purchasing brand name equipment verses “generic” equipment has been an issue with photographers for a number of years, and I would prefer not to aim you in any particular direction, but would like to say this. Years ago when I worked in a photography store, we had at our disposal all the equipment in the store to sample at our leisure. I performed a number of extensive tests with both brand name and generic cameras and lenses and found that lenses from the actual camera companies produced sharper photographs with better contrast and resolution, especially when making enlargements of significant size. What you decide to purchase is inevitably your decision but again, give a great deal of thought to this topic of lenses. If you are going to want excellent high quality imagery when producing photographs, it might be a wise investment to purchase better quality gear, especially if you have a tendency to keep it for a considerably long period of time.

I will be discussing the characteristics of electronic flash in an up-coming article, however I would like to mention that many novice photographers have had difficulty in the past obtaining correct exposures when using flash “with zoom lenses”. Specifically, most of the images they have brought me for evaluation are suffering from extreme underexposure. Where they are making errors so to speak, is in the fact that they are not judging the amount of distance “they are” from their subject in relation to their electronic flashes output distance. For example: if you are at a social event and using a zoom lens of an 80-200mm length, and are making pictures of people ranging from approximately 6-12 ft. away from you, your imagery will be exposed properly given the fact that you have set your electronic flash settings correctly. Now let’s change the scenario slightly. Perhaps you are interested in photographing individuals across the room from you, and in many instances they are farther away from you than 15-20ft. This means that if you zoom your lens in close to your subject, perhaps to the 200mm position, (making the people on the opposite side of the room fill your viewfinder), what now takes place is that even though they appear to look acceptable when looking into your camera, their distance from you hasn’t being properly calculated or compensated for pertaining to your selected aperture(s). Here is where many photographers create exposure errors. What is needed here is that you must re-adjust your flash & camera settings to accommodate the increased distance between you and your subject matter. By referring to the distance markings on the lens itself easily indicates the distance you are from your subject. It is now a matter of setting your flash accordingly. Setting your flash/camera properly will involve you opening up the lens aperture,(f-stop) to a wider opening other than what you have your camera lens and flash currently set at. For instance: if you have your camera lens aperture set at F16, and your flash set at the same f-stop, making a change to a wider f-stop such as F11 or F8 means that you are opening up the lens aperture thereby allowing more light to enter the exposure chamber resulting in correct exposures. Don’t forget that you “must” change both your camera lens aperture “and” the flash settings aperture as well. They must be synonymous.

Another item to consider when purchasing second hand zoom lenses is not only the external appearance of the lens, which incidentally will give you a fairly good idea as to how it was handled by the previous photographer, but also zoom “slipping”. This refers to a deficiency of the zoom barrel itself when you are pulling it towards you or extending it in the opposite direction. Slipping is a sign of wear in the lens and you will find this most annoying when you are photographing objects on the ground when your lens is aimed downwards. Taking into account one example for instance; I have found while photographing the forest in autumn, I will notice interesting patterns of coloured leaves on the forest floor and will set up my camera/tripod and make a composition. Just prior to tripping the shutter on the camera, I noticed while looking through the viewfinder that the picture was gradually going out of focus. What occurs at this point is, the lenses zoom position could not remain locked into the particular setting I had initially positioned it at, because gravity and lens slippage was forcing it in a downwards direction towards the ground. Focusing became such a problem at this point I had to revert to my 105mm macro telephoto lens to eliminate this problem. If you encounter a situation like this at the used camera counter, you should consult a technician first to obtain total repair costs regarding making the necessary tightening and adjustments before purchasing the lens you had in mind. What might at first seem like a excellent offer might actually end up costing you more than one initially expected.

With Good Wishes,

Jeff Ryan Photography/Ryan Studio Ottawa, Ontario. 2017
Email—jeffryan@storm.ca
613.599.5363
www.jeffryan-photography.com

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