Steve Spencer
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 p.1 #18 · Thinking out loud: thoughts on cropping, zooms & primes | |
Lethimcook wrote:
Here are some of my thoughts after getting into photography very recently. I went through a lot of opinions here and elsewhere (Youtube, DPR, etc.). I struggled a lot with camera selection and lens selection. Especially on the topic of cropping, FroKnows adamantly rejects cropping, and he's a massive if not the biggest Youtube photo creator. So I wanted to write some of my ideas down in hopes that other beginners can read and veterans can also chime in:
If photography is a bike in an analogy, zooms would be a race bike, primes would maybe be a fixie or a dual speed, and not cropping would be like riding without a seat. You can do it, but it could be very challenging!
With a race bike, you technically have the 'optimal' set-up to tackle a variety of terrain. The correct gears for every speed and angle of elevation or ground. Pro's spend a lot of time learning the skills of when and how best to switch up and down gears.
With a fixie bike or dual speed bike, you get one or two gears and that is it. I say potentially two gears because there are tangible benefits to shooting in APS-C mode even if you can achieve the same looks in post-processing. Aside from reduced file-sizes that lead to a bigger camera buffer which is important for sports and on cameras such as the 120fps Sony A9iii, there are tangible benefits to the auto focus system. Using a sports shooting environment again, when shooting an athlete at an event with spectators, the focus system may sometimes hunt onto someone in background, resulting in missed focus. This can be partially addressed by managing auto-focus settings, but it does not change the fact that using APS-C mode to tighten the frame does help eliminate the possibility of the focus system attempting to hunt a face or point of focus in what would have been a wider field of view. In short, you get reduced file sizes and less area for your auto-focus system to make an error.
Now onto cropping. Whether you choose to ride a race bike (zooms) or a fixie (prime), the ability to crop in post-processing is invaluable and allows you to make up for times where you have missed a photo due to poor framing. While it is likely true that you will make less framing related errors with a zoom, that does not mean that you will never make such an error, and in such cases cropping is the option which can save a photo for those moments that cannot be restaged. Let's say for arguments sake that riding a race bike without a seat makes you lose balance less than riding a fixed bike without a seat. Both can be ridden with just standing on the pedals. Inevitably you may lose balance, and the consequence of potentially falling back without a seat will lead to negative consequences. Again, missing shots is never good, but cropping may sometimes help to salvage a photo.
So I am firmly in the cropping camp. And I think with the development of high mega-pixel cameras, it is becoming more and more acceptable to do so. I also prefer primes over zooms. The main reasons for this preference are the superior image quality, low-light performance and weight. I will also address the very common (and valid) counter-argument that Zooms offer more flexibility, which is factually true.
Historically image quality on primes have been better than Zoom counterparts, nowadays with the development of high-end zooms with fast apertures, the gap in image quality has been somewhat bridged. High-end primes are often marginally sharper, and that contributes to the decision to choose primes, even if the performance gap is not particularly large. When you combine high-mega pixel cameras with cropping, you will need sharp lenses. No amount of cropping can fix an image with inadequate sharpness. How much sharpness is necessary for different levels of cropping is something I do not know. However seeking out ultra-sharp lenses will guarantee you preserve as much image quality as possible when you do end up cropping, and in such cases the gap between zooms and primes will widen. For evaluating a lenses sharpness, you can look at MTF charts provided by the manufacturer or by a third-party testing site such as LensTip which uses a more transparent and rigorous testing methodology.
Low-light performance. At the time of writing there are no f1.4 aperture zooms in standard zoom ranges (16-35, 24-70, 70,200). While an aperture of f2.8 can work in certain lighting the environments, the reality is that a faster aperture offers more flexibility to shoot in challenging lighting environments while also simultaneously allowing for more creative options with depth-of-field. A sports photographer may only ever need a f.28 if all they shoot is professional sports in well-lit venues. But if the same photographer was offered to work to shoot in high school gyms which are often poorly lit, they may find themselves needing a faster aperture to achieve the image quality they desire.
Weight. I will not go too extensively into this topic as I think it's relatively straight forward. Zooms with fast apertures will always be heavier than primes with equally fast or faster apertures unless manufacturers somehow find a way to break the laws of physics. For those jobs that require a day's worth of shooting and lugging around equipment, the factor of weight will impact the ergonomics of your work. Weight is also subjective, what is heavy for one person will be different for another. However when all other factors are equal, less weight is always better. There are also situations where using several primes to cover a focal range that could be covered by a zoom will actually lead to more weight for a prime user. Your mileage may vary.
If zooms are like race bikes, maybe primes are track bikes that Olympians compete on. Such bikes are ridden purely for performance at top speed.
Now the counter-argument that Zooms offer more flexibility is true. However I personally value image quality and the other factors mentioned above over zooms. Lens switching is something prime shooters have to factor in and practice when shooting. And not every environment can allow for lens switches to happen safely. Obviously in such harsh environments, the act of not needing to change lenses skyrockets in value relative to other factors. That is not to say that there are no solutions. Using primes with two or multiple camera bodies is also a possibility. You will take a hit in the weight category but you also are likely to achieve better image quality and low-light performance with primes.
The decision to choose primes over zooms lies solely with a persons needs. I believe the above points to be factual, but what is best for you depends on the types of shooting you are doing, what workflow you want to have, and what you deem to be acceptable image quality, weight, and overall performance.
On a final note, I do not know if a cropped image taken with a prime lens will offer higher image quality than an uncropped image with a zoom lens. Obviously if you magnify a 50mm focal length to a 500mm field of view equivalent and compare it against a zoom with a 500mm focal length, the latter is better. However where the scales tilt is beyond me. Is an 85mm prime cropped to 100mm still sharper than a 70-200 zoom at 100mm? I am not aware of testers who look into this....Show more →
First let me welcome you to the forum. You have been gracious as you have gotten some tough feedback to your post. I hope that tough feedback, however, has helped you learn a little bit. I hope you continue posting here and if you continue in your gracious responding you will have no problems in my view. One thing I think you should know is that some of us, and I include myself here, think "Fro," is a bit of a clown and more flash than substance. Like many people on the internet, the fact he is popular and gets a lot of views doesn't establish his expertise. He is not wrong about everything and in fact gets a lot right, but I think his analysis is often tuned to get more views and be controversial at times rather than carefully examining issues. For me personally I can't stand to watch his videos just because I have to sit through him hawking his what I see as thoroughly mediocre post processing presets.
All that said, welcome and let me add one thing about cropping. Keep in mind that people use sensors with a lot of different sizes. A lot of people here, myself included, use bigger than full frame 35mm (which is 36mm X 24mm), 44mm X 33mm sensors. Others use micro 4/3rds sensors that are 17.3mm X 13mm. All of these cameras can produce very nice results in many circumstances, but the 44 X 33 sensors have an area of 1,452 square mm, whereas the micro 4/3rds sensors have an areas of 225 square mm. That difference is the same as a 2.5X crop (a crop of FF 35mm to micro 4/3rds is at least a 1.85X crop), and if you crop that 44 X 33 sensor (or a FF 35mm sensor) that far you will get results that look just like a micro 4/3rds camera and shots that would work with such a camera will work the same even with a crop that deep. So depending on the sensor size you start with, you might be able to crop a lot more than you are suggesting--at least in some situations--and if Fro is so anti cropping then he isn't describing that reality very well.
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