Nowadays, users are more interested in the number of megapixels slapped into a smartphone’s camera when a new flagship is launched, be it from Apple, Samsung, Sony, Nexus and other brands. But one factor contributing to a camera’s quality of capture is often missed in product specifications: the aperture.
Aperture vs Megapixel
Oct 30, 2020 $499. Variable aperture. It's only f/2.8 at the wide end. At the long end it's f/4. However, it is 70mm @ f/4. Sigma17-50mm f/2.8 EX DC OS HSM. This is a constant aperture lens. It can be f/2.8 all the way through the zoom of the lens. But then it only goes to 50mm! It odes off image stabilization via OC. Sigma18-50mm f/2.8-4.5 DC OS HSM. Apple has updated its prosumer photo editing/management software Aperture, bringing it to version 3.4.2. The company has also released a new version of iPhoto, version 9.4.2.
For example the popular Kodak Anastigmat f7.7 (f-stop) was sold together with shutters with max. Aperture 4 (U.S. Some Kodak cameras with simple lenses had a simplified aperture scale 1-2-3-4, meaning (estimated) U.S. Stops 8-16-32-64. Link edit edit source A Tedious Explanation of the f/stop by Matthew Cole. Image Size: 6 3/4 x 8 5/8 inches. The River Po, Luzzara, Italy, 1953 Paper Size: 20 x 16 inches Image Size: 6 3/4 x 8 1/2 inches. The Family, Luzzara, Italy, 1953 Paper Size: 20 x 16 inches Image Size: 8 1/2 x 10 3/4 inches. Tir A’Mhurain, South Uist, Hebrides, 1954 Paper Size: 20 x 16 inches Image Size: 9 1/4 x 11 3/4 inches. On the camera front, the handset has a 5MP front camera with f/2.4 aperture. Users will get 13MP main sensor (f/2.25 aperture) and a 2MP depth sensor on the rear side. The device is backed by a 4,500mAh battery with micro USB charging port. Nokia 2.4 comes in Dusk, Fjord and Charcoal colour options.
As a freelance photographer, I believe cameras need less megapixel count and more of the aperture value, sometimes called the f-value, though they are not exactly the same (aperture is measured by the diameter of the lens opening while f-value is the ratio of the focal length to the lens opening’s diameter). That is, if you are not into the printing business. As I have mentioned in a previous article, megapixel only matters when you are printing large copies of your photos. That is so because large printing materials such as tarpaulins, billboards, etc.
Read also: Forget about megapixels, your smartphone’s sensor quality is what matters
The smartphone camera aperture – not the sensor size or the thing called MP – controls much of your photo’s sharpness, exposure, brightness and focus. Here is why. Like digital single lens reflex cameras, many mobile devices currently sprouting in the market as though mushrooms have improved imaging capability due in large part to the introduction of wide-aperture compact lenses.
Here are some of the high-end smartphones with wide aperture (rear camera only):
- Samsung Galaxy S9/S9 Plus, F1.5
- LG V30, F1.6
- Samsung Galaxy S8/S8 Plus, F1.7
- Samsung Galaxy S7/S7 Edge, F1.7
- Apple iPhone 7/7 Plus, F1.8
- HTC 10, F1.8
- iPhone 6S/6S Plus, F2.2
- Sony Xperia Z series, F2.0
- Nexus 6, F2.0
- Motorola Droid Turbo, F2.0
- Nokia Lumia 720/730/735, F1.9
- Xiaomi Mi 4, F1.8
Here is a photo taken using Samsung Galaxy S7 (f/1.7) and an iPhone 6S (f/2.2):
What is aperture?
For non-photographers, here is a quick guide: the smaller the f-number, the wider the aperture. Otherwise, you see a photo with relatively less focus, brightness and crispness. It means that a camera sensor’s ability to let in more light is dictated by the size of aperture opening. So the wider the aperture, the more light comes in. This is especially helpful in low-lit environments where you need to have as much exposure as you need for a good quality image. If your smartphone does not have a wide aperture, you will get underexposed and/or noisy photos. This can be aided with the use of slower shutter speed or higher ISO, but these settings are mostly used on DSLRs. Though some phones currently have pro modes where you can control the shutter speed and the ISO value, a majority of users don’t touch those settings and capture photos in auto mode only.
The advantage, however, of wide apertures is that you do no longer need to adjust the shutter speed and ISO in low-lit environments, meaning your smartphone camera will be more flexible in different lighting conditions. A slower shutter speed, for example, is not applicable if you are shooting a person, especially a moving person or object. Linux mint arduino. You will need a relatively faster shutter speed to freeze the motion and avoid a blurry capture of your image.
Meanwhile, a higher ISO could sometimes lead to noisy images, or images with infinitesimal specks on it. It happens because you are, in effect, stretching the sensor’s light sensitivity to a level where there is no light anymore to detect, therefore resulting in digital aberrations that seem to register light where there is none.
As I have made mention above, the f-value is the ratio of the camera’s focal length to the diameter of aperture opening. So the focal length of a camera is another factor to consider when weighing in on the image quality of your smartphone camera. For comparison, I listed below some high-end smartphones along with their equivalent focal length and aperture:
- Samsung Galaxy S8/S8 Plus: 26mm, f/1.7
- Samsung Galaxy S7: 26mm, f/1.7
- Apple iPhone 7 Plus: 28/56 mm, f/1.8/2.8
- Apple iPhone 6S: 29mm, f/2.2
- LG G4: 28mm, f/1.8
From this comparison, we can see that the Samsung Galaxy S8 gathers more light than the rest of the competitors.
The size of the aperture opening is also responsible for the depth of field, which results in more or less bokeh: the isolation of the subject from the background. Here is the cheat: the smaller f-value, the more isolated the subject is from the background.
In the sample photos above, there is not much difference, though, in terms of isolation because the smartphone cameras used don’t go that far from each other when it comes to aperture. This is because of the crop factor of the image sensor. You can’t really expect much blur in the background using smartphone cameras because the shooter is much smaller in a mobile device than in a DSLR, so all you get is also a small image sensor. Here is the formula: the focal length and f-value multiplied by the crop factor.
Conclusion
So the next time you choose which smartphone best suits your taste when it comes to photography, look at the full specs of the device and head directly to the f-value.
Disclosure: As an Amazon Associate, I earn from qualifying purchases. The commission help keep the rest of my content free, so thank you!
Aperture 1.4.2
Over the last few years we have received several messages asking about and disputing the system equivalence that we are mentioning in our APS-C and Micro-Four-Thirds lens reviews. For the sake of efficiency, it was about time to write an article about it. This will surely not end the discussions but it illustrates our view on this - take it or leave it.This article is NOT an article promoting full format cameras. In fact, I am not using full format cameras by choice whenever I can. All systems compromise on something (size/weight/image quality/handling)- the important thing is that a system is right for YOU. YOUR preferences are the only ones that matter to YOU. I mention the obvious here because some people are really getting religiously defensive when it comes to a discussion about system equivalence.
Before diving into the details let's make a clear statement first - the focal length and aperture are static physical values. Citing Wikipedia:
No matter what we are going to discuss below - the focal length and aperture of a lens isn't going so change. e.g. a 50mm f/1.8 lens is a 50mm f/1.8 is a 50mm f/1.8 lens. Whatever we mention in our review, these physical characteristics are NEVER disputed.
Now the problem is .. you don't take images with a lens. A naked lens is nothing more than an expensive paperweight. A lens makes only sense in the context of a camera and THIS is where things are getting complicated when comparing different SYSTEMS. Equivalence is a SYSTEM discussion, not only a lens discussion.
For the sake of simplicity let's pick a concrete example that we'll use throughout this article:
See Full List On Slrlounge.com
Some of you may already shout in agony but let's swallow this for now .. :-)
Equivalent Focal Length
This is probably the least disputed topic of the whole discussion. The equivalent focal length relates to the crop factor of a smaller sensor relative to a full format sensor.| Format | Sensor size | Crop Factor (vs Full format) | Image ratio |
|---|---|---|---|
| Full Format | 36x24mm | 1x | 3:2 |
| APS-C | 24x16mm (*) | ca. 1.5x (**) | 3:2 |
| Micro-Four-Thirds | 17.3x13mm | ca. 2x | 4:3 |
(*) It is actually slightly less than that in real systems (e.g. 23.5x15.6mm on Nikon, 22.5x15.0mm on Canon)
(**) It is more like 1.55x to 1.6x in real systems
Simplistically the crop factor is just the ratio between the sensor width (or height) of a system relative to the full format (e.g. 36mm / 24mm = 1.5x for APS-C). Now you may notice that this is actually not so easy for Micro-Four-Thirds because the image ratio is different (4:3 vs 3:2). Most observers have settled for the 2x crop factor here (you can argue between 1.84x to 2.08x depending on how you look at it).
In order to compare the different focal lengths, we have to take crop factor and multiply it with the focal length:
| Format | Our Example Focal Length | Crop factor | Equivalent Focal Length |
|---|---|---|---|
| Full Format | 300mm | 1x | 300mm |
| APS-C | 200mm | 1.5x | '300mm' |
| Micro-Four-Thirds | 150mm | 2x | '300mm' |
Or we can phrase it differently - when using a smaller format, we have to use the same FOCUS DISTANCE using a SHORTER focal length in order to achieve the SAME FIELD OF VIEW in the final image (camera output) because only a crop of the full format image field is used. Which leads us to the next topic ..
Equivalent Aperture (Depth-of-Field)
Ok, so the above was (hopefully) easy .. let's move on to the equivalent aperture (depth-of-field) which is where the pain starts for some .. ;-)CLICK HERE to open a depth-of-field calculator.
Enter the specs that we have discusses so far and a focus distance of 10m (could be any):
Then observe the depth-of-field result - it is the SAME. Again, the FIELD-OF-VIEW is IDENTICAL here. Below is a summary:
| Format | Physical Focal Length | Physical Aperture | Focus Distance | Depth-of-field |
|---|---|---|---|---|
| Full Format | 300mm | f/5.6 | 10m | 0.37m |
| APS-C | 200mm | f/4 | 10m | 0.37-0.39m (*) |
| Micro-Four-Thirds | 150mm | f/2.8 | 10m | 0.37m |
(*) This value varies a bit because APS-C format sensors are not sized to the ideal 24x16mm. The calculator is also rounding a bit. Also APS-C f/4 * 1.5x = f/6 and not f/5.6. These are still tiny error margins in the grand picture really.
So despite having used a bigger physical aperture, the DEPTH-OF-FIELD is the same. Why? Because you have to use a shorter focal length to achieve the same result. So a 150mm f/2.8 (on MFT) is equivalent to a 200mm f/4 (on APS-C) is equivalent to a 300mm f/5.6 (on FF). Thus the equivalent full format aperture in our example is therefore .. f/5.6.
Note: This calculator simplifies things a bit - the so-called 'circle-of-confusion' is kept constant across all systems here.
Equivalent Speed
The next toad to swallow (one more to come thereafter) is speed. Some may argue that the 150mm f/2.8 (MFT) and 200mm f/4 (APS-C) are faster than the 300mm f/5.6 full format lens. Well, this is true for the naked lens but it is actually a debatable observation when comparing the SAME OUTPUT QUALITY - that is by taking the camera into the equation again.Let's assume that we have 3 different system cameras with 20 megapixels at ISO 200. I think we can agree on the fact that the image noise is best on the full format camera, followed by APS-C followed by Micro-Four-Thirds, right? Now .. what amount of increased image noise are we talking about here? There are, of course, variations due to different sensor technologies but let's assume for a moment that they all rely on the same ingredients. So ? Well, ISO 800 on full format will give you roughly the same image noise as ISO 400 (more like ISO 340 actually) on APS-C and ISO 200 on Micro-Four-Thirds. Or in other words - based on the same output quality - and this is the only thing that counts - full format has a 2 f-stops advantage over Micro-Four-Thirds and roughly 1 f-stop over APS-C.
Thus .. assuming the SAME OUTPUT QUALITY (same megapixels, same sensor noise) the SYSTEM SPEED is identical for a 300mm f/5.6 on a full format camera, a 200mm f/4 on an APS-C camera and a 150mm f/2.8 on Micro-Four-Thirds. You may argue that image stabilization plays a role but then just take e.g. the Sony A7 II as an example - thus a full format camera which can take advantage of in-body IS plus in-lens IS. Whatever you can do in a smaller format is technically achievable in a bigger format. Current advantages are just a snapshot in time - eventually all systems will pick up new technologies and catch up (or they disappear as Darwin told us).
Wonna have a visual here? Try the comparometer over at dpreview. If you click the link it'll give you a new window showing a comparison between the Nikon D750 (full format, 24 megapixel Sony sensor) and the Nikon D7200 (APS-C, 24 megapixel Sony sensor). Select RAW & ISO 3200 for the D750 and RAW & ISO 1600 for the D7200 (or ISO 6400 vs ISO 3200). Observe the image noise. Result: pretty much identical thus a 1 f-stop advantage for the full format camera here.
Size ..
Very often you can read that smaller sensor systems give you a substantial size advantage. But keeping the discussion above in mind .. is that actually true? Of course, there'll be many variations depending on the specific comparison (and e.g. whether a lens has been underdesigned or not) but let's pick one:| Format | Lens | Equivalent to .. | Size | Weight |
|---|---|---|---|---|
| Full Format | Sony FE 70-300mm 4.5-5.6 G OSS | 70-300mm f/4.5-5.6 | 84x143.5mm | 875g |
| APS-C | Pentax DA 60-250mm f/4 ED SDM | '90-380mm f/5.6' (f/6.2 actually) | 82x167.5mm | 1.04kg |
| Micro-Four-Thirds | Olympus M.Zuiko 40-150mm f/2.8 ED | '80-300mm f/5.6' | 79.4x160mm | 760g (w/o tripod collar) |
The Pentax lens doesn't really fit there but I couldn't find a more appropriate APS-C example. The Pentax lens is longer but then the equivalent aperture is f/6.2 if we are precise there (f/4 * 1.55 = f/6.2).
Well? Ok, the Sony lens is a little heavier but the Olympus lens is actually a bit longer. We have to take off the tripod mount in case of Pentax - thus 100g or so. However, you may notice that the difference is not huge - it's certainly not a factor of 2 (MFT vs FF).
Another one maybe?
| Format | Lens | Equivalent to .. | Size | Weight |
|---|---|---|---|---|
| Full Format | Sony FE 35mm f/2.8 | 35mm f/2.8 | 37x62mm | 120g |
| APS-C | Fujinon 23mm f/2 | '35mm f/2.8' (f/3.1) | 51.9x60mm | 180g |
| Micro-Four-Thirds | Leica DG 15mm f/1.7 | '30mm f/3.4' | 36x58mm | 115g |
One more?
| Format | Lens | Equivalent to .. | Size | Weight |
|---|---|---|---|---|
| Full Format | Sony FE 28-70mm 3.5-5.6 OSS | 28-70mm 3.5-5.6 | 72.5x83mm | 295g |
| APS-C | Pentax DA 16-45mm f/4 | '24-70mm f/5.6' (f/6.2) | 72x92mm | 365g |
| Micro-Four-Thirds | Panasonic 12-35mm f/2.8 OIS | '24-70mm f/5.6' | 68x74mm | 305g |
Surprising, isn't it? Not really. Why? Well, because in order to achieve the same output characteristic in the final image, you have to increase the physical aperture correlated to the smaller sensor. Bigger aperture = bigger glass = higher weight.
Let's do a quick calculation just for fun - a bit more precise this time (for equivalent lenses):
What is the diameter of the aperture in mm? 17.8mm .. in all three cases. Now if we assume an idealized lens .. what does this mean ? Right .. :-)
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