This is a difficult post to write. No matter what opinions or facts I share, it is going to be out of date in a matter of months. Some of it already is, and some of it depends on any critical specs clients require on a project-to-project basis, if they have any at all. I’ll try to keep it simple.
The higher the resolution, the better. Always, forever and ever, amen.
Shooting at extremely high resolutions in-camera–whether it is 4K, or 6K, or even 8K, all of which are now very prevalent and possible through many prosumer and/or high-end professional systems–in most cases is at the discretion of the producer or videographer (or, request of the editor). Right now, 4K has become the norm even though the industry is rapidly exceeding that standard, so I will use that as my main reference point even though ‘4K’ should quickly be interchangeable with ‘6K’ or ‘8K’ in the coming years.
From the client’s perspective, as a producer selling your gear or ability and intent to shoot in extremely high resolutions, the conversation sometimes gravitates to the question of, ‘well, why do we need to shoot 4K when we don’t really need to see it in 4K?’ It is true. In most cases, outside of extremely high end productions or clients with very specific criteria for their deliverable, you will not edit and export a project in 4K (or 6K, etc, etc.) Extremely high resolution capture is a tool meant more for the editor and post-production workflow than it is the necessity of a mid-market online promo video to be viewed in mentally absurd pixel resolution on the laptop or smartphone of the average online viewer.
Super high resolution image capture makes the editor’s work exponentially easier, even if it taxes the processing power of whatever system is being used for post-production. 4K or better image capture can turn a one camera shoot into a two camera shoot by allowing the DP or videographer to shoot wider than necessary for the editor to then punch in and out between 100% and 50% (or thereabouts) in post-production, thus creating more points for edits and flow corrections in a final timeline that will only be presented as a final export in 2K (or similar) resolution.
Extremely high original capture resolution also allows for greater depth of field with focus, and a tighter pixel density that benefits Warp Stabilizer (Adobe Premiere Pro & After Effects), or other stabilization plug-ins. For stabilization and 3D motion tracking in post-production, the more pixels, the more frames, and the better quality makes all the difference. The same rule is applied to footage shot in 60p (i.e., twice the frame rate quality of 30p, or ‘29.97’). If you have hardware that is capable of shooting 4K or better footage at 60p, 120p, etc., you are in a very, very wonderful place!
Finally, on the client/producer front, it should also be acknowledged that the discussion of 4K or other extremely high resolution image capture can be an item of concern when discussing budgeting and the price point of a project. Frankly, this should not ever be an item of concern. If you, as a producer, are not that the point where you can justify the expense of one extremely reasonably priced external hard-drive per-project to dedicate to the critical data of your client and reputation, you should not be advertising yourself as a relevant video production professional. As a client, you should expect your producer to deliver the best possible product, no matter the final deliverable resolution, and no-matter said producer’s choice of capture unless specified by you during initial scoping sessions and signing of contracts. Bottom line: unless it truly matters to one party or another, capture resolution or deliverable quality should never be a matter of price in this era of mid-market video production.