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From the moment I first saw a seagull TLR in a camera shop in Bethesda MD, I was in love. Having used a 35mm SLR all of my life, I was amazed by the features of this camera which felt so foreign in my hands. To begin with I was startled by the waist level view finder which relatively speaking is HUGE compared to the view finder on my Rebel 2000. Being one of the younger generation (I’m a high school Senior) I was also very confused when the salesman told me that the camera didn’t have a built in light meter. If I can remember correctly, my response was “So how do you take a picture?” Nevertheless, after returning to my home in Rochester, I could not get this camera off of my mind. By December of last year I broke down and bought one. Despite having no previous experience in medium format photography and having no idea what roll film was (roll film, thats just another name for 35mm film right? it comes in a roll doesn’t it?) I found learning how to use my Seagull was a snap, in fact not very different in operation from a manual 35mm slr. While I think this is a great camera, I had many unanswered questions even at the time I purchased this camera. There is not a lot of information on this camera out there, I hope that this article will answer any questions you have. If you find this article helpful, please rate it.
The Seagull 4B-1 has the following features:
—–Twin Lens Reflex design (TLR): this means for those who have never seen a TLR before, that the camera has two lenses, one through which the picture is taken, and the other through which the image is viewed. There are distinct advantages and disadvantages to this design. The advantages are that unlike a SLR, when the picture is taken the mirror which reflects the image into the view finder does not move. This means that you will be able to see the image in the view finder the entire time the picture is being taken, even when the shutter is open. This also means that there is no camera shake due to mirror movement, a common problem on SLR’s which don’t have a mirror lock up (like my rebel 2000).
The disadvantage to this design however is the small amount of parallax error that occurs from viewing the image through a lens that is perhaps an inch higher than the taking lens. On higher level Seagulls (the 4A-105,-107 and the new -109) this problem is solved by a mask that moves accordingly to the focus of the lens. The other disadvantage is that there is no depth of field preview on this camera due to the fact that the aperature is on the taking lens, not the viewing lens. While this may be a problem for some, there is a nice diagram on the focusing knob which will tell you what will be in focus at what aperatures. I actually prefer focusing this way rather than holding down a dof button on my Rebel 2000. A common feature on most older cameras, this feature is absent on both the lenses of my Rebel 2000.
—–Medium format film: This is a clear advantage of this camera. The seagull takes 120 format roll film. Here the Seagull 4B-1 has a clear advantage over other cameras in the seagull line, it can take both 6×4.5cm as well as 6x6cm pictures. Seagull provides a film mask so that you are capable of taking both rectangular as well as square pictures. A 6×4.5cm negative has roughly 3 times the area of a 35mm frame, so pictures are splendidly sharp.
—–Haiou SA-85, 75mm f3.5 lens: Interestingly enough, the lens that takes the picture is of the same quality of the lens that is used for the view finder. While this may make it seem like the lens is cheap (usually on other TLR’s like rolleiflex, the taking lens is of better quality than the viewing lens) do not be dismayed. After I enquired “Popular Photography” as to why they had yet to do a review of the Seagull, they published a comprehensive article which included lens tests of both the Seagull 4B-1 as well as the higher level 4A-107. As it is easy to assume, the 4A-107 did considerably better than the 4B-1, however the 4B-1 still had good results. If you plan on taking pictures on wide aperatures, the 4 element 4A-107 is for you. However if you are willing to leave your shutter at f16 or f22, you can achieve excellent results with the three element 4B-1 or 4A-105. At f16 and f22 the center resolution of the image was rated very good by “Popular Photography” with corner sharpness being rated excellent. While this lens is not considered to be relatively fast, a f3.5, this is much better than the f5.6 I get from the zoom lens on my Rebel 2000. Being the novice I once was, when ordering this camera I felt sure that It was coming with a telephoto lens of 75mm. Keep in mind that focal lengths in medium format are different from 35mm, and that the 75mm lens is roughly the same as taking a picture at 50mm in 35mm format.
—–Leaf shutter: This is perhaps the most delicate part of the camera. The shutter speeds are marked off respectively at 1/300, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1, and Bulb. While the advantages of this shutter are that due to it’s size it creates nearly no camera vibration, it’s disadvantage is that it makes for slow shutter speeds. Even $2000 Rolleiflexes only have a maximum shutter speed of 1/500. While this is fine for me since I use this camera mostly for landscapes, if you need the faster 1/500 I would reccomend the new Seagull 4A-109 which has this faster shutter speed.
On a side note: The leaf shutter on this camera is very delicate, NEVER cock the shutter before adjusting the shutter speed, IT WILL JAM YOUR SHUTTER. Once you cock the shutter, you cannot change the shutter speed without harming your camera. I did it once accidentelly, the leaf shutter jammed overexposing my frame. It can be easily unjammed by recocking your shutter. If this happens once or twice, it is no big deal, as I have never tried this again, I have never had any problems with my shutter again. This is not meant to scare you in any way, its just that when the manual says not to readjust the shutter speed after cocking the shutter, they mean business.
—–Waist level viewfinder: Having used a 35mm all of my life, this feature was a big bonus for me. A feature common on professional medium format cameras, SLR and TLR alike, you will not find one 35mm camera on the market today with a waist level view finder, however Alpa once made one (Alpa’s were very expensive, as much or more than a Leica and have been off production for decades).
The advantages of having a waist level viewfinder are that you get a substantially larger viewfinder than on a prism viewfinder. The seagull’s viewfinder is no exception, measuring roughly 2×2 inches. Included in the viewfinder hood is a pop up low magnification lens which when popped up allows you to finely focus your camera. I think this this one of the neatest features on this camera, and use it almost every shot. I found the viewfinder on my seagull to be suffieciently bright, although the 4a-107 and -109 have faster f2.8 viewing lenses. My main complaint about the viewfinder is the fresnel lens which forms the groundglass. The fact that it is plastic does not bug me much, and when viewing the image normally without the pop up magnifier, the image is perfectly clear. It is only when the pop up magnifier is used that you can tell that the lens could be sharper, however you are perfectly able to focus the image. Keep in mind that it is the plastic groundglass that is not sharp, not your lens. If you have your lens focused properly you should be capable of taking some very sharp pictures.
The main disadvantage of having a waist level viewfinder is that the viewfinder acts like a mirror. Everything that should be on the left of your picture is on the right in your viewfider, and vise versa. The image is only reversed left to right, not up to down, so the image in your viewfinder should be right side up. So when you take a picture is everything reversed left to right on your print? No,the image is only reversed in the viewfinder, your print will be fine.
The other disadvantage of having a waist level viewfinder is that this makes vertical shots very difficult. Of course you will not run into this problem if you are shooting in the 6×6 format for the image is square and it does not matter what angle you hold the camera at. Still it is not impossible to shoot a vertical shot in the 6×4.5 format. I have done this successfully several times, you must simply turn your camera so that the left or right side is horizontal to the ground. I would reccomend a tripod when doing this though I have done it handheld.
Capturing moving action, like panning the camera for a passing car? The front panel of hood flips up to provide a direct viewfinder they call the “sports finder”. I recently used this feature for the first time last weekend on a photo shoot at Letchworth State park, this feature was very handy for taking shots at eye level that would normally have their view’s obscurred at waist level, ex: taking a photo from behind a fence. My only complaint about the so called “sports finder” is that in order to see the whole frame you must have your eye right up to the camera, which is hard to do with my glasses.
—–Film advance knob: This was perhaps the hardest thing to overcome (which says a lot for the camera, because it was pretty easy to get used to). The film advance knob is a seperate knob on the right side of the seagull. The tricky part about using the film advance knob is remembering that even though you have advanced the film, the knob does not cock the shutter for you. This makes it very easy to take double exposures, simply cock the shutter without advancing the film. Sometimes though it is very easy to forget if you have advanced the film or not, I still occasionaly make accidental double exposures because of this, some of which actually turned out pretty good.
Are you the kind of person who would easily forget to do something like this? Try any other of the seagull TLR’s, they all come equipped with a crank instead of a knob and both cock the shutter as well as advance the film in the same movement. Keep in mind that only the 4B-1 shoots different formats of film. On the back of the seagull there is a slide with two red tinted transparent circles, as you wind your film, the paper on the back of your film (which prevents your film from being exposed when you open the slide) has numbers which indicate what frame you are on and when to stop cranking. The holes are respectively labeled 12 and 16 for the amount of exposures you will get depending upon which format you shoot (12 is for the 6×6 and 16 is for the 6×4.5). There are no locks to keep you from cranking through the whole roll of film, so don’t needlessly crank on this knob. Such a film advance was popular on low end rolleiflexes in the 50’s, and many of the older gereration like my dad know how to operate this.
—–No internal Light metering: Thats right, this camera does not come with a light meter! For the first several months, I used metering off of my Rebel 2000 to properly expose shots. Two months ago I purchased an old (but never before used ) argus flash shoe mounted light meter with disasterous results. I went on a two week cruise to NYC on a local tall ship cruising down the Erie Canal and Hudson River. The old meter was very inaccurate when I came back and tested it in comparison to my rebel 2000, and the color shots I took were ruined, while some of the black and whites were salvageable. I am back to metering off of my rebel for the time being until I get $60 to buy a new meter.
Metering off of another camera is fairly easy to do, I simply set the zoom lens on my rebel to 50mm, compose, properly expose and then set the shutter speed and aperature displayed on my rebel onto the seagull, a tedious process but I get much sharper enlargements from the seagull. I know if you are using Kodak film, you can also guess at the exposure settings off of the chart displayed in the box your film came in. While I have never tried this, I don’t think I’d reccomend this unless you dont’ own another camera or lightmeter or are already a highly skilled photographer.
—–flash shoe: Standard flash shoe, nothing special here.
—–PC Sync: Standard socket. When using type “X” flash all speeds can be used synchronously, when using type “M” flash, use a shutter speed of 1/30 or slower. I am not familiar with the operation of a flash unit on this camera as I do not own an external flash.
—–Self timer: works nicely, I use it for landscapes and long exposures because I dont’ have a remote shutter release.
—–Shutter release button: takes standard remote shutter release, not an expensive electronic one like the one made for my Rebel 2000.
Click Here to see Seagull’s Pamphlet on Loading your Seagull
—–Film Loading: The film loading procedure is perhaps a little slow compared to my rebel 2000, but still fairly simple. Put the spool of fresh film onto the bottom of the seagull, and then feed the threading paper into the spool at the top and wind until a set of arrows lines up with the bottom of the film frame. Before you load your film, you should decide wether or not you want to take 6×4.5 or 6×6 pictures, if taking 6×4.5 you should set the film mask in the frame. The latch that closes the camera is very common on TLR design, and you will find this on many rolleiflexes. Unfortunately as the price decreases from a $2000 rolleiflex, to a $125 seagull, the quality of manufacturing also decreases. This simply means that you have to put gentle pressure on the latch at the bottom of the camera to line the latch up with the hole as you turn the round knob at the bottom of the camera to lock the back, no problem for me. When the lock is set, flip the metal slide on the back of the camera to view the two red circles. Crank the film advance knob until the first frame appears in the appropriate circle (for the 6×4.5 format use circle 16, for the 6×6 format use the circle 12). You are now ready to take your first photograph!
—–Picture taking: You are now ready to take picture, I will assume that most of you by now know how to operate a manual camera, and have some sense of what shutter speed and aperature mean. Compose your shot using either the waist level viewfinder or the “sports finder,” keeping in mind that there will be some parallax error with the “sports finder” and that it only provides a 6×6 frame. The two horizontal lines on the top an bottom of the waist level finder mark the edges of 6×4.5 format, if shooting this format, compose your picture within these lines.
After composing your shot, focus the image in the waist level viewfinder with the help of the pop up magnifier, or simply use the depth of field scale on the focusing knob to focus your picture without using the waist level view finder. Now you need to meter your shot, so either using a hand held light meter, or another camera (using this method is explained under the features section) meter the light and adjust your aperature and shutter speed dials on the front of your seagull.
Cock the shutter on the front of your camera and then snap the picture. The next thing to do is to advance to the next frame, I do this immediately after I take any picture with this camera, I would rather have the knob accidentelly bumped in the future and waste a frame of film rather than have an accidental double exposure.
—–After finishing the roll of film, take the film out of the camera and seal the roll with the the paper sticker. (the paper sticker for those who have not shot medium fomat before is like a postage stamp, lick the underside to make the glue sticky and then wrap the paper around the roll to seal)
Pros and Cons
As with any camera, there are both pros and cons associated with this camera:
—–inexpensive: I got mine for $125 new from a merchant on ebay
—–medium format: Larger negative size, much better resolution that a 35mm camera
—–multiple fomats: shoot either rectangular or square images in 6×4.5 or 6×6 format
—–twin lens reflex design: no camera shake from a spring action mirror like on SLR’s
—–fixed focal length lens: the Haiou SA 85 75mm f3.5 has greater resolution and is faster than many zoom lenses
—–all metal body construction: the only plastic parts on the camera are the focus knob, film advance knob and the back locking knob, the rest is solid metal.
—–no batteries: your camera will never run out of juice, only film
—–seperate shutter cocking and film advancing levers: it can sometimes be easy to forget to advance the film before taking an exposure, resulting in double exposure
—–no built in light meter: for some this adds an extra piece of equiptment, a handheld light meter, to their camera outfit
—–leaf shutter: relatively slow shutter speeds, plus you cannot adjust the shutter speed once you have cocked the shutter
—–parallax error: although this is more uncommon unless you take very close up shots with your waist level viewfinder, or shots closer than 10ft with the “sports finder” this is a realistic concern
—–only takes 120 format film, not 220: 220 film gets twice as many pictures as 120, but the roll is roughly the same size mainly because of an absence of paper backing on the film. The most picures you can get from a roll of 120 film is 16 exposures.
—–medium format film processing: if you are the person who will only take your film to the pharmacy to be developed (you know who you are, I was once one of you) you will not like developing this film. Only specialty photolabs will develop medium format (even living in the image capitol of the world it took me a little time to find a lab that would develop my film) for those living in rural areas often times mailers are the best ideas. Processing medium format black and white film in the home darkroom is no harder than processing 35mm film, and may enlargers are medium format capable. You may need a different negative carrier or enlarger lens to do so.
—–quality control in manufacturing: for the price this camera is an excellent investment as a first step into medium format photography, however because the cost of the camera is relatively very low to other medium format cameras keep in mind that the quality control is not on the same levels as brands like mamiya, canon or nikon. If you search the web I’m sure you can find horror stories of consumers who purchased a defective seagull, but you can find such stories for any camera, a friend of mine had a brand new rebel 2000 die in his arms. In the same way, keep in mind that you are purchasing a camera from a foreign company, and that returning a defective seagull for repair will certainly not be as easy as going to canon to get your camera repaired.
I hope this article has been helpful as well as infomation for those of you interested in purchasing a new seagull. I feel very strongly that this is a great entry level medium format camera. This article answered many of the questions that I had before purchasing my seagull, but if you still are unsure if the seagull is for you, I would suggest going to your local camera shop and looking at a rolleiflex or similiar twin lens reflex camera (I would seriously doubt if they would have a seagull in stock). Having a camera in your hands for real can be a lot more convincing than reading my article. In saying that I hope you have enjoyed reading my article and hope you will take time to rate my article.
Understanding camera lenses can help add more creative control to digital photography. Choosing the right lens for the task can become a complex trade-off between cost, size, weight, lens speed and image quality. This tutorial aims to improve understanding by providing an introductory overview of concepts relating to image quality, focal length, perspective, prime vs. zoom lenses and aperture or f-number.
All but the simplest cameras contain lenses which are actually comprised of several “lens elements.” Each of these elements directs the path of light rays to recreate the image as accurately as possible on the digital sensor. The goal is to minimize aberrations, while still utilizing the fewest and least expensive elements.
Optical aberrations occur when points in the image do not translate back onto single points after passing through the lens — causing image blurring, reduced contrast or misalignment of colors (chromatic aberration). Lenses may also suffer from uneven, radially decreasing image brightness (vignetting) or distortion. Move your mouse over each of the options below to see how these can impact image quality in extreme cases:
|Original Image||Loss of Contrast||Blurring|
Any of the above problems is present to some degree with any lens. In the rest of this tutorial,when a lens is referred to as having lower optical quality than another lens, this is manifested as some combination of the above artifacts. Some of these lens artifacts may not be as objectionable as others, depending on the subject matter.
Note: For a more quantitative and technical discussion of the above topic, please see the
tutorial on camera lens quality: MTF, resolution & contrast.
INFLUENCE OF LENS FOCAL LENGTH
The focal length of a lens determines its angle of view, and thus also how much the subject will be magnified for a given photographic position. Wide angle lenses have short focal lengths, while telephoto lenses have longer corresponding focal lengths.
Note: The location where light rays cross is not necessarily equal to the focal length,
as shown above, but is instead roughly proportional to this distance.
Required Focal Length Calculator
Note: Calculator assumes that camera is oriented such that the maximum
subject dimension given by “subject size” is in the camera’s longest dimension.
Calculator not intended for use in extreme macro photography.
Many will say that focal length also determines the perspective of an image, but strictly speaking, perspective only changes with one’s location relative to their subject. If one tries to fill the frame with the same subjects using both a wide angle and telephoto lens, then perspective does indeed change, because one is forced to move closer or further from their subject. For these scenarios only, the wide angle lens exaggerates or stretches perspective, whereas the telephoto lens compresses or flattens perspective.
Perspective control can be a powerful compositional tool in photography, and often determines one’s choice in focal length (when one can photograph from any position). Move your mouse over the above image to view an exaggerated perspective due to a wider angle lens. Note how the subjects within the frame remain nearly identical — therefore requiring a closer position for the wider angle lens. The relative sizes of objects change such that the distant doorway becomes smaller relative to the nearby lamps.
The following table provides an overview of what focal lengths are required to be considered a wide angle or telephoto lens, in addition to their typical uses. Please note that focal lengths listed are just rough ranges, and actual uses may vary considerably; many use telephoto lenses in distant landscapes to compress perspective, for example.
|Lens Focal Length*||Terminology||Typical Photography|
|Less than 21 mm||Extreme Wide Angle||Architecture|
|21-35 mm||Wide Angle||Landscape|
|35-70 mm||Normal||Street & Documentary|
|70-135 mm||Medium Telephoto||Portraiture|
|135-300+ mm||Telephoto||Sports, Bird & Wildlife|
*Note: Lens focal lengths are for 35 mm equivalent cameras. If you have a compact or digital SLR camera, then you likely have a different sensor size. To adjust the above numbers for your camera, please use the focal length converter in the tutorial on digital camera sensor sizes.
Other factors may also be influenced by lens focal length. Telephoto lenses are more susceptible to camera shake since small hand movements become magnified, similar to the shakiness experience while trying to look through binoculars. Wide angle lenses are generally more resistant to flare, in part because the designers assume that the sun is more likely to be within the frame. A final consideration is that medium and telephoto lenses generally yield better optical quality for similar price ranges.
FOCAL LENGTH & HANDHELD PHOTOS
The focal length of a lens may also have a significant impact on how easy it is to achieve a sharp handheld photograph. Longer focal lengths require shorter exposure times to minimize blurring caused by shaky hands. Think of this as if one were trying to hold a laser pointer steady; when shining this pointer at a nearby object its bright spot ordinarily jumps around less than for objects further away.
This is primarily because slight rotational vibrations are magnified greatly with distance, whereas if only up and down or side to side vibrations were present, the laser’s bright spot would not change with distance.
A common rule of thumb for estimating how fast the exposure needs to be for a given focal length is the one over focal length rule. This states that for a 35 mm camera, the exposure time needs to be at least as fast as one over the focal length in seconds. In other words, when using a 200 mm focal length on a 35 mm camera, the exposure time needs to be at least 1/200 seconds — otherwise blurring may be hard to avoid. See the tutorial on reducing camera shake with hand-held photos for more on this topic.
Keep in mind that this rule is just for rough guidance; some may be able to hand hold a shot for much longer or shorter times. For users of digital cameras with cropped sensors, one needs to convert into a 35 mm equivalent focal length.
ZOOM LENSES vs. PRIME LENSES
A zoom lens is one where the photographer can vary the focal length within a pre-defined range, whereas this cannot be changed with a “prime” or fixed focal length lens. The primary advantage of a zoom lens is that it is easier to achieve a variety of compositions or perspectives (since lens changes are not necessary). This advantage is often critical for dynamic subject matter, such as in photojournalism and children’s photography.
Keep in mind that using a zoom lens does not necessarily mean that one no longer has to change their position; zooms just increase flexibility. In the example below, the original position is shown along with two alternatives using a zoom lens. If a prime lens were used, then a change of composition would not have been possible without cropping the image (if a tighter composition were desirable). Similar to the example in the previous section, the change of perspective was achieved by zooming out and getting closer to the subject. Alternatively, to achieve the opposite perspective effect, one could have zoomed in and moved further from the subject.
|Two Options Available with a Zoom Lens:|
|Change of Composition||Change of Perspective|
Why would one intentionally restrict their options by using a prime lens?Prime lenses existed long before zoom lenses were available, and still offer many advantages over their more modern counterparts. When zoom lenses first arrived on the market, one often had to be willing to sacrifice a significant amount of optical quality. However, more recent high-end zoom lenses generally do not produce noticeably lower image quality, unless scrutinized by the trained eye (or in a very large print).
The primary advantages of prime lenses are in cost, weight and speed. An inexpensive prime lens can generally provide as good (or better) image quality as a high-end zoom lens. Additionally, if only a small fraction of the focal length range is necessary for a zoom lens, then a prime lens with a similar focal length will be significantly smaller and lighter. Finally, the best prime lenses almost always offer better light-gathering ability (larger maximum aperture) than the fastest zoom lenses — often critical for low-light sports/theater photography, and when ashallow depth of field is necessary.
For compact digital cameras, lenses listed with a 3X, 4X, etc. zoom designation refer to the ratio between the longest and shortest focal lengths. Therefore, a larger zoom designation does not necessarily mean that the image can be magnified any more (since that zoom may just have a wider angle of view when fully zoomed out). Additionally, digital zoom is not the same as optical zoom, as the former only enlarges the image through interpolation. Read the fine-print to ensure you are not misled.
INFLUENCE OF LENS APERTURE OR F-NUMBER
The aperture range of a lens refers to the amount that the lens can open up or close down to let in more or less light, respectively. Apertures are listed in terms of f-numbers, which quantitatively describe relative light-gathering area (depicted below).
Note: Aperture opening (iris) is rarely a perfect circle,
due to the presence of 5-8 blade-like lens diaphragms.
Note that larger aperture openings are defined to have lower f-numbers (often very confusing). These two terms are often mistakenly interchanged; the rest of this tutorial refers to lenses in terms of their aperture size. Lenses with larger apertures are also described as being “faster,” because for a given ISO speed, the shutter speed can be made faster for the same exposure. Additionally, a smaller aperture means that objects can be in focus over a wider range of distance, a concept also termed the depth of field.
|f-#||Corresponding Impact on Other Properties:|
|Required Shutter Speed||Depth of Field|
When one is considering purchasing a lens, specifications ordinarily list the maximum (and maybe minimum) available apertures. Lenses with a greater range of aperture settings provide greater artistic flexibility, in terms of both exposure options and depth of field. The maximum aperture is perhaps the most important lens aperture specification, which is often listed on the box along with focal length(s).
An f-number of X may also be displayed as 1:X (instead of f/X), as shown below for the Canon 70-200 f/2.8 lens (whose box is also shown above and lists f/2.8).
Portrait and indoor sports/theater photography often requires lenses with very large maximum apertures, in order to be capable of a narrower depth of field or a faster shutter speed, respectively. The narrow depth of field in a portrait helps isolate the subject from their background. For digital SLR cameras, lenses with larger maximum apertures provide significantly brighter viewfinder images — possibly critical for night and low-light photography. These also often give faster and more accurate auto-focusing in low-light.Manual focusing is also easier because the image in the viewfinder has a narrower depth of field (thus making it more visible when objects come into or out of focus).
|Typical Maximum Apertures||Relative Light-Gathering Ability||Typical Lens Types|
|f/1.0||32X||Fastest Available Prime Lenses
(for Consumer Use)
|f/1.4||16X||Fast Prime Lenses|
|f/2.8||4X||Fastest Zoom Lenses
(for Constant Aperture)
|f/4.0||2X||Light Weight Zoom Lenses or Extreme Telephoto Primes|
Minimum apertures for lenses are generally nowhere near as important as maximum apertures. This is primarily because the minimum apertures are rarely used due to photo blurring from lens diffraction, and because these may require prohibitively long exposure times. For cases where extreme depth of field is desired, then smaller minimum aperture (larger maximum f-number) lenses allow for a wider depth of field.
Finally, some zoom lenses on digital SLR and compact digital cameras often list a range of maximum aperture, because this may depend on how far one has zoomed in or out. These aperture ranges therefore refer only to the range of maximum aperture, not overall range. A range of f/2.0-3.0 would mean that the maximum available aperture gradually changes from f/2.0 (fully zoomed out) to f/3.0 (at full zoom). The primary benefit of having a zoom lens with a constant maximum aperture is that exposure settings are more predictable, regardless of focal length.
Also note that just because the maximum aperture of a lens may not be used, this does not necessarily mean that this lens is not necessary. Lenses typically have fewer aberrations when they perform the exposure stopped down one or two f-stops from their maximum aperture (such as using a setting of f/4.0 on a lens with a maximum aperture of f/2.0). This *may* therefore mean that if one wanted the best quality f/2.8 photograph, a f/2.0 or f/1.4 lens may yield higher quality than a lens with a maximum aperture of f/2.8.
Other considerations include cost, size and weight. Lenses with larger maximum apertures are typically much heavier, larger and more expensive. Size/weight may be critical for wildlife, hiking and travel photography because all of these often utilize heavier lenses, or require carrying equipment for extended periods of time.
For more on camera lenses, also visit the following tutorials:
- Using Wide Angle Lenses
- Using Telephoto Lenses
- Macro Lenses: Magnification, Depth of Field & Effective F-Stop
Want to learn more? Discuss this and other articles in our digital photography forums.
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