How to choose the right camera type
In the modern age of Digital acquisition the choices available in terms of recording medium are practically endless, helpful I know!
Unfortunately budget is going to be one of the large determining factors in what you end up shooting on, if you are shooting a Lo/No music video with friends for crew and no budget to speak of then the only way you'll be getting your hands on a Phantom Flex or Arri Alexa is if you happen to be best friends with an owner/operator. So budget is going to essentially set the 'bar' as to which price range (hire or buy, as the hire cost scale in a similar way to actual price)you will be looking in.
In terms of choice, it is important to define what you require from the camera, if you're doing a 'run and gun' indie production, hand-held, then you probably aren't going to want to carry a Panavision Genesis with full follow focus rig, matte box etc. and neither should you. However if you are shooting ChromaKey (green screen,while the portability of a DSLR may be great, the compressed nature of the recorded footage and the lack of dynamic range will make keying your subjects a nightmare.
So, long story short there are many camera's for many purposes, the key will be establishing what you require from the camera. For example, it would be relatively easy to access a DSLR, the images (e.g.) Canon 5D's shoot can be gorgeous, in the hands of a competent camera op, although the recorded data is not great for post production work, keying, grading and VFX. So if you are shooting a naturalistic piece or a Ob Doc a 5D may be a really great choice, cheaper and more 'beautiful' than a prosumer camera like a Sony EX3. IF you are shooting a highly stylised fantasy/drama, which you intend to colour correct beyond all recognition, then you want as much data as possible in your source image so you have plenty of latitude (high bit depth and lack of compression)for processing the images in post production.
Other technical consideration would be:
Audio, are you recording sync dialog? If so will you be recording this on camera or separately? Either way, are you working with a sound recordist, if so, can they send audio into your camera? If not, how will you sync sound to pictures after the shoot. From prosumer camera's upwards (e.g. Sony EX3, Canon C300, Sony F3, Panasonic P2HD or AVC)you will always have access to "profesional" audio inputs, generally 'XLR'. Any sound recordist should be able to send signal out of their mixer direct to the camera for recording, they can record you a safety on DAT or something similar. Even if you don't have a dedicated sound recordist, XLR inputs will give you access to professional microphone, ofter requiring 'phantom power' (The camera sends power to the mic as well as receiving the audio.)Using professional mic's will up the production values of your shoot and will hopefully decrease or eliminate any ADR work in post.
More expensive camera's tend to require more expensive lenses, a certain group of which are 'primes' and can cost upwards of £10,000. Prosumer camera's tend to only work with their full set of features with their specific 'stock' lens which will be a very flexible lens allowing for a variety of shots. Primes tend to be far less flexible, so moving from a CU to a WIDE requires a lens change. DSLR camera's, whilst cheap, give you access to professional photography lens' which are significantly cheaper than film primes, you can hire a box with 5-7 different focal lengths for as little as £100/day. This will mean you can use beautiful lenses which will really help your pictures along, for a fraction of the price of using an Arri Alexa with a selection of Prime lens'.
The size of the camera you are using will dictate which other equipment you can or can't use, rigs, cranes, sliders, steadicams and dollys will all be rated for certain weights so if you intend to use any of this equipment one choice will inform another.
Similarly, setting, lighting and style will also dictate certain choices, i.e. if you are shooting outdoors on a sunny day it is unlikely you will need a bank of 10K lights.
Different camera's will respond well to different conditions, I believe Sony camera's come WB'd to 5600k (kelvin)whereas Panasonic camera's to 6500k, so a Sony camera shoots 'bluer' images than a Panasonic. On the other hand, if you are shooting an interview at someone's personal location, business/home, that you've never Recce'd, how much space will you have? Can you fit all your lights and rig equipment in and still get the camera far enough away from the subject to achieve the desired shot?
Finally, are there any technical requirements and what is your delivery platform? For example, the BBC will only accept material captured at 50mbps (Mega-Bits per second), so a Sony EX3 shooting 35mbps would not meet the Beebs 'tech specs'. On the other hand, if the production is bound for web-based distribution, a lower bit rate would be fine.
What can the Budget afford? - This will inform rough price range, either Hire or Buy.
What does the production require?
- Audio? Sound recordist or not? No Sync?
- VFX? Green-Screen? Rotoscoping? Compositing?
- Grading? Simple balancing or really stylized?
- Grip equipment used? (Manfrotto fig-rig, dolly, crane)
- Setting? Studio, Location (Int./Ext.), Green Screen?
Are there any required supplier specifications?
What is the output format?
I hope this gives a good overview of the kind of questions you need to ask, either pre-production or when considering buying a camera. I understand that I've not told you which camera will best suit your given scenario but unfortunately requirements are as varied as the myriad of styles of production. Bear in mind that there is always a new/better/more desirable camera coming out, so the best camera for the job is the one you can get!
p.s. Follow fashion... Or don't. What I mean is that the Arri Alexa and RED Epic are the current darling's of the moment, every DP wants to use them and to be seen using them. What this mean's is that there are a bunch of hire facilities with RED ONE's gathering dust on their shelves and they can be hired for considerable discount.