In discussion groups and photography groups you see questions about lenses from shoppers and the number one thing they want to know is if a lens is “sharp.” What many beginning photographers don’t understand is that lenses are not sharp at every aperture value and at every possible distance (especially with zoom lenses). Therefore the responses one gets on these forums will likely be very subjective and based upon that photographer’s experience and how they use that lens. If a person reports a lens is "not sharp" they may not be giving you accurate information. Every lens has a “sweet spot” and sharpness is often confused with depth of field. This article will help clear up that confusion and help you figure out what your lens' "sweet spot" is and how to find it.
First, some background information, no lens is ever perfectly sharp. Lenses are designed for maximum performance based on what manufacturers believe the main function of that lens will be. For example, if you purchase a zoom 70-200mm lens, the manufacturer might assume that the main use of that lens will be at the 200mm end of the range and they will maximize its performance for that focal length. A lens that is a macro lens will be maximized for close up shooting distances. Never purchase a lens and expect perfect sharpness at every distance, aperture, and zoom level. Know what you will be using the lens for and buy a lens designed for maximum performance for that purpose.
Another common point of confusion for beginning photographers is understanding the difference between sharpness and focus (or depth of field). Sharpness is related to resolution and depth of field is related to how much of the image is in focus from foreground to background. When you are first learning photography you will probably hear the advice that if you want more of your image in focus to use a narrow aperture (larger f/# like f/11 or even f/16). While generally this is true, greater depth of field (or focus) does not always mean more overall sharpness.
A quick side note: Using smaller apertures will increase depth of field, but the depth does not increase equally in front of and behind the subject. Instead when you stop down your lens, the increase in the depth of field behind your subject will be almost twice as much as in front. In other words if the overall depth of field increases to 20 total feet, about 1/3 (~7 ft) of this will be in front of the subject and the remaining 2/3rds (~13 ft) behind the subject. (If you need a refresher or introduction to depth of field and hyperfocal distance check out our previous blog posts).
I took three photos of a flowering tree using f/4, f/5.6, and f/22. The photo at f/4 has the most narrow depth of field and the photo taken at f/22 has the widest depth of field, while the f/5.6 (not shown) would be somewhere in between. While there is more in focus (greater depth of field) in the photo taken at f/22, it is probably not as sharp compared to the in-focus parts of the same picture taken at f/5.6.
We can examine the sharpness by "pixel peeping" and looking at only the areas that were in the zone of focus. We should find that the image is sharper at f/5.6 and less sharp at f/4 and f/22. The image taken at f/5.6 will appear “sharper” even though more of the area of the scene (depth of field) is in focus at f/22.
Now let's actually take a look at those images below. The series of shots was taken from the same location and only the aperture was changed. These are parts of the same photos shown above that demonstrated depth of field taken at f/4 and f/22 (plus the additional shot at f/5.6). Note that the original images were already cropped and then I further cropped in on just one flower that was inside the depth of field (in the area of focus). At this "pixel peeping" level we can compare the sharpness. Remember that when not cropped to show detail, each of these photos "looked" sharp and in focus in this area of the image. The focus and focus point were not changed in between shots so any differences you see are not because of a focusing issue. We can see that none of the images are perfectly sharp, but the one in the middle is the best. The issue/difference between these images occurs because of the internal workings of the lens. All those glass elements have to align and at different apertures the quality differs.
Lenses are “softer” at both extremes of aperture – wide open and mostly closed. The details in an image won’t be as crisp or “sharp” when shooting at the maximum apertures like f/1.4 (or in the case above with my lens at f/4), or at minimum apertures like f/22. Both extremes are equally deficient when it comes to sharpness. As a general rule the maximum sharpness, or “sweet spot” of a lens is 2 to 3 stops from the maximum aperture of that lens. So for example, if the maximum aperture of a lens is f/2, then the “sweet spot” would be between f/4 and f/5.6.
The lens used for the photos above has a maximum aperture of f/4. Therefore the "sweet spot" should be between f/5.6 and f/8. The image at f/5.6 gave good results, but with further testing, I believe this lens would probably be sharpest around f/6.7 or f/7.1 which is about one and 1/2 stops above the maximum.
Once you know the range of where the “sweet spot” should be, it is easy to conduct a test to find it with more precision. To conduct the test you will need to use Aperture Priority Mode. In Aperture Priority mode we can set and test the aperture and the camera will set the ISO and shutter speed.
If you are unsure of how to switch to Aperture Priority and how to change the aperture settings in that mode, you may need to consult your camera manual (we have most manufacturers’ links here). If your camera allows you to use one-half or one-third stops, make sure that is selected in your settings.
To perform a test to find the “sweet” spot of your lens, first find the maximum aperture of the lens and add one half or one full stop to that number to use as your starting point. If your lens has a maximum aperture of f/3.5 (most kit lenses), then start at f/4.8 or f/5. If your lens has a maximum aperture of f/2, then start at f/2.4 or f/2.8.
Go outside in good sunlight. Use a tripod or something to stabilize the camera and to keep it in position between shots. You will need to take photos of something that is about 10 feet away (like my sample images of the flowering tree) and make sure your focus point is on that object. You will not recompose or refocus in between shots (after getting your focus point you can change over to manual focus to make sure your focus point stays set).
Start by taking a photo with the aperture at your starting point (from above). Then turn the aperture dial 2 or 3 clicks narrower (bigger f/#) and take another photo. Then turn the dial a few more clicks and take another photo. Take test shots from your starting point up to about f/11.
By taking a test shot every 2-3 clicks you will be sampling a range of f/stops that include some half and third stops. The “sweet spot” may not be at a full stop like f/5.6. If your camera only has full f/stops, then take sample test shots at each full stop.
Now it is time to "pixel peep." Upload your photos and zoom in on each one. Examine the area of the photo that contains the object you focused on (that was about 10 feet away) and examine that same area in every photo. You should be able to tell which aperture gave you the sharpest image.
You can then repeat the test using the range of apertures in 1/2 and third stops around that aperture to further narrow it down. In my test above f/5.6 was the sharpest, but to really narrow it down I would test again starting at f/4.8 using every increment up to about f/7.1 (I already had an image at f/8 that was not as sharp so I know I can stop before that point).
Once you know the "sweet spot" make a note of that aperture for that lens. Repeat for different lenses. Each one will have a different “sweet spot” but typically the maximum sharpness will be about 2 stops above the maximum aperture, somewhere in the range of f/4 – f/10.
If your lens is a zoom lens the sharpness and “sweet spot” may not be identical throughout the zoom. For example, I have a Tamron 18-400mm and the maximum sharpness at 18mm may not be the same aperture setting when shooting at 400mm.
We could not ever hope to detail all the possible parameters for every lens in the marketplace in a short article like this, but we can offer a little general advice. If you are ever out and about and need a sharp image and you are not sure what the “sweet spot” of a particular lens is, then use Aperture Priority Mode and take a series of photos from f/4 through f/11 and you will have all your bases covered!
Another often overlooked way to help improve image quality and sharpness is to use a tripod and a shutter remote. These reduce camera shake.
So in summary, shooting with a wide open apertures may result in reduced sharpness in your images. Additionally the narrow depth of field can be difficult to work with. At very low apertures this depth can be less than an inch and can cause one part of a face, like the eyes, to be in focus and the nose out of focus.
When examining your images to trouble shoot a “non-sharp” image, consider both the depth of field (focus) and sharpness (resolution) as separate factors even though both are related to aperture. Decide if the lack of “sharpness” you see is due to missing your focus point while using a very narrow depth of field, or if it is an overall resolution issue due shooting at the extremes of the lens’ aperture range.
Knowing that your lens has a “sweet spot” and how to find it can help improve your images overall, but much about photography comes down to compromise. Just because your lens has a “sweet spot” doesn’t mean you should always use that aperture. When out in the field you may have to decide which is more important; maximum resolution (sharpness) or depth of field. It may be that you want the wider depth of field for a landscape shot and to get that you may have to sacrifice some level of sharpness. Also, remember, that to see the difference in sharpness you may have to “pixel peep.” The actual difference in sharpness between two images in normal print sizes may not even be that noticeable to the naked eye (even though they are there). “Pixel peeping” can become a dangerous obsession. Don’t let the search for optimal sharpness interfere with your creativity and the fun and joy that photography can provide.
Are mirrorless cameras the way of the future? Are DSLRs going the way of the Dodo bird? Which is better?
The question of which is better, like so many other questions in photography, does not have a “right” answer and is subject to much debate. Similar to the debates of Canon vs. Nikon or film vs digital… there are merits on both sides.
Those that are pro-mirrorless will focus on the simple mechanics, fast and quiet shutter speeds, and slim lightweight design. DSLR fans will claim, the larger camera body is more functional to grip and that optical viewfinders are better than their electronic counterparts.
One thing I have learned over the years is that much of photography is about compromise. We compromise depth of field for lower ISO, or we sacrifice the crisp images of multiple prime lenses to be able to carry just one lightweight zoom in our camera bag. The choice between DSLR and mirrorless is no different.
Camera manufacturers are well aware of the pros and cons of both traditional SLR/DSLR and mirrorless cameras and are working to make adjustments to their new cameras so the gap between the two technologies is constantly narrowing. For example, Canon’s R5 mirrorless offers one of the best autofocus systems, which traditionally was a DSLR advantage.
This blog post will discuss some of the pros and cons of each camera type. First let’s start off with defining the difference mechanically.
An SLR or DSLR uses a system that includes a mirror and a penta mirror (or pentaprism) which allows the photographer to see what is coming through the lens. The mirror reflects the view through the lens up and into the prism which then projects the image into the viewfinder. The mirror flips up and the shutter unit opens and closes when you take an image so the film (SLR) or sensor (DSLR) can be exposed.
A mirrorless camera does not have a mirror and penta mirror. Instead the light that is hitting the sensor is sent to an electronic viewfinder as a digital rendering of the image. The “live view” exposes the sensor when you take an image and there is no mirror in the way (so only the shutter must open and close).
The way the sensors work in both systems is the same, so the actual image quality between a DSLR and a mirrorless is theoretically identical (assuming the two cameras are using the same sensor type/size).
The type of viewfinder is thus the first area where we see pros and cons to each system.
DSLRs use an optical viewfinder to preview an image. This combined with the mirror and penta mirror give an exact view of what the camera will capture in the scene when the photo is snapped. Most DSLRs today also feature an LCD or Live View to preview images.
Mirrorless cameras use an electronic viewfinder or EVF to preview images. The EVF creates an electronic rendering of the scene.
Many photographers prefer the “real” view of the optical viewfinder versus the electronic or digital rendition. The rendering from an EVF is not as accurate as an optical viewfinder because the rendered image depends on the quality of the viewfinder panel. For example, the EVF may present an image with more or less contrast than the actual captured image. In the past, the resolution of EVFs was much lower, but the latest iterations of EVFs are much improved and almost match the quality of optical viewfinders.
EVFs may also lag, especially in low lighting situations. Following a fast-moving subject is much easier with a high-speed DSLR with optical viewfinder than with a mirrorless EVF. This may be especially important to wildlife, action, or sports photographers.
An advantage of an EVF is that you can view the image with changes to color settings and white balance, or exposure, instantly which you cannot do with an optical viewfinder (but you can snap a photo and view it or use Live Mode on the LCD). If you are learning manual mode this “what you see is what you get” feature of a mirrorless may be an advantage.
The technology of EVFs is continuously improving, but for now DSLR cameras have a slight winning advantage when it comes to viewfinders.
DSLR and mirrorless camera types can shoot at fast shutter speeds to capture many images in rapid succession. With the exception of high-end DSLRs, mirrorless cameras have an advantage in speed. There is no mirror that needs to flip out of the way so the simple mechanics of mirrorless cameras allows them to shoot at higher shutter speeds.
Unfortunately, the optical viewfinder creates a “blackout effect” when shooting continuous bursts of images. This makes it harder to track moving subjects. With an optical viewfinder you can continuously track your subject during a burst of images. Some mirrorless camera manufacturers have been working on this issue and higher end models, like the Sony a9, claim to have solved it.
The first mirrorless cameras did not include full-frame sensors, therefore at that time DSLRs were superior in image quality. Now manufactures use the same sensors (APS-C and full-frame) in both their mirrorless models and their DSLRs, so based solely on technology neither system has an advantage when it comes to image quality.
The selling point for mirrorless is that you can get that same image quality in an overall smaller size camera. However, just as bigger is not always better, smaller is not always better either.
Size & Weight
Because a mirrorless camera does not have a mirror and a pentamirror, the construction includes less parts and therefore they are lighter in weight and less bulky than DSLR cameras. However, the bulkier DSLR often feels better in the grip of one’s hands and has ergonomic advantages.
By making a mirrorless camera so compact, the controls must fit onto smaller rectangular shapes. Larger hands may not be comfortable with the smaller size controls. The touchscreens are also often smaller in size. The compact size of mirrorless includes a smaller battery which affects battery life (we will cover this aspect later).
The DSLR’s larger size makes the controls easier to read and see and makes changing camera settings easier (especially for those who are used to the DSLR shape and design).
One big disadvantage to mirrorless is that while the camera may be smaller, the lenses are not. Balancing a large lens on a small camera body – especially one with the very compact rangefinder-style shape – is awkward and uncomfortable over longer periods of time. Manufacturers can keep making camera bodies smaller, but lens size is determined by the sensor size. This means that to make lenses that match the quality and performance of DSLR lenses, the mirrorless lenses will end up almost identical in size (and weight). You can buy additional grips to make it easier to hold a mirrorless camera, but that defeats the “mirrorless is smaller” advantage.
So in this aspect, the advantage lies wherever your personal preferences lie. If you prefer lightweight, or are upgrading from using your phone for photography, then maybe the smaller mirrorless is the way to go. If you prefer a sturdier heft and grip, or use larger and heavier lenses, then a traditional DSLR should be in your camera bag.
In the past, the winner for autofocus speed was the DSLR. For now, higher end DSLRs still have an advantage, but newer mirrorless cameras have made great strides in this area and are quickly diminishing this difference.
Mirrorless cameras mainly use contrast-detect AF. While this type of AF is precise and accurate, it is also slow and inefficient. The camera focuses through a trial-and-error to-and-fro process that is time consuming (comparatively speaking) versus the DSLRs phase-detection AF method.
Phase-detection AF compares two versions of the scene from two angles and quickly decides which way to focus and how far. This happens very quickly.
But just as quickly as that camera can focus, mirrorless camera manufacturers recognized and tackled this issue to try and find a solution. Now some mirrorless cameras use a hybrid AF with phase-detection built into the camera sensor and contrast-detect AF for precision. This makes the AF accurate and fast. This on-sensor phase-detection is now also being added to traditional DSLRs as well.
If you need the fastest autofocus speeds (wildlife, race cars, sports) and your budget allows you to buy the very highest-end cameras, then you should get a DSLR, otherwise, this category is a tie.
Since DSLR cameras have been around so long, there is a plethora of lenses available for them. Including the third party manufacturer lenses available, the selection is comprehensive. By comparison, the selection of lenses for newer mirrorless cameras is small.
Of course, the availability of lenses is growing as these cameras gain popularity. In the micro four thirds mirrorless, such as those from Olympus, there is more lens selection. Additionally, third party manufacturers are also making lenses for mirrorless cameras now and there are several new adapters on the market that allow photographers to use DSLR lenses, as well as legacy lenses, on their mirrorless camera bodies.
At this point, the DSLR cameras probably still have the advantage for lens selection, but not for long.
DSLRs and mirrorless cameras a both shoot video. Mirrorless cameras, because of their design, are intrinsically better for the constant “live view” mode for video recording.
Mirrorless typically have better and more accurate focusing for video. This is because very few DSLRs have on-sensor phase detection points (as previously discussed). Currently, both mirrorless and DSLR can film in HD, but if you want to shoot in 4K, or even 8K, you will more likely find it in a mirrorless camera.
Professional filmmakers will probably elect to purchase cinema cameras instead of mirrorless or DSLR cameras, but for bloggers or vloggers a mirrorless camera is a clear winner. Additionally, the R&D into video is focused mainly in the mirrorless market, so the technology will only improve from where we are today. Many of the newest lenses for mirrorless also include silent autofocus motors, a technology designed for filming. These quiet technologies can be an advantage for wildlife photographers.
If you are mainly a photographer (other than perhaps wildlife), who only needs video on occasion, then a DSLR may still be the way to go.
Stealth & Quiet
You can never get rid of sound completely because when you take a photo the shutter curtains will open and close regardless of whether you are using a DSLR or mirrorless. The mirrorless camera will be quieter because it does not have mirror. On a DSLR, when the mirror moves out of the way and then returns to its starting position it makes two “clapping” noises in quick succession. If you shoot where quiet is key, such as around skittish wildlife or in public libraries, then you will appreciate that mirrorless technology eliminates some of the sound. Some DSLRs dampen the sound, and some offer silent live view modes, but if you want to be assured that your photo taking will be as quiet as possible, then mirrorless is the way to go. (Side note: some mirrorless cameras have a mirror “clapping” sound effect that you can turn off in your settings.)
Mirrorless cameras drain your battery faster because they require the electronic viewfinder (EVF) or LCD to take photos. Therefore a DSLR battery can easily last twice as long or for twice as many shots. The smaller design of mirrorless cameras also means smaller batteries. This creates an even further limit on their capacity. If you don’t mind carrying an extra battery or two, this might not be a deal breaker.
There is no debate when it comes to battery life. DSLRs win hands down.
Cost / Investment
Mirrorless probably is the way of the future, but that is still a long way off. Mirrorless cameras are still catching up and while they can compete with DSLRs on almost every level, a DSLR is still the cheapest way to get into serious photography.
Finding a mirrorless APS-C with a viewfinder for same price as a new beginner DSLR like a Canon Rebel or Nikon D3XXX series is almost impossible. Unless you are willing to compromise and buy a used mirrorless that is more than 5 years old, a DSLR is the best option when you need something budget friendly.
The Final Tally
As with all debates in photography, sometimes there are no real winners and it comes down to personal preference and your shooting style. Which is “better” will really be determined by where you are willing to make compromises, not because one technology is actually intrinsically better than the other, but because each has its own distinct advantages and disadvantages. There may be one or two aspects to a camera system that are crucial to your photography that make the difference in your decision.
So When Should You Choose a DSLR?
So When Should You Choose a Mirrorless?
Hopefully this article has clarified the differences between DSLR and mirrorless and will help you decide which camera system is right for you.
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