It sounds like there is a lot of excitement about Panasonic’s new 4K camera – the Lumix GH4 – because I have received plenty of questions about it. Probably the most frequent question is what lenses should you get. So, I will make my recommendations here.
Before I do that, though, I want to make a few points about the Micro Four Thirds (MFT) lenses that this camera uses.
The MFT standard is designed for mirrorless cameras that have an image sensor with the crop factor of 2.0. This means that to get a lens with the same angle of view (or field of view) as a 50mm lens for 35mm (full frame) cameras, you actually need a 25mm MFT lens. So, keep that in mind. Multiply or divide by two to convert between the two standards.
If you are more familiar with APS-C sensor cameras like Canon 7D, Sony NEX series, the conversion number would be 1.25 for Canon APS-C cameras (crop factor of 1.6) and 1.33 for other brands (crop factor of 1.5). Again, you will need a shorter MFT lenses to get the equivalent field of view.
Now, due to the fact that you are going to be using lenses with shorter focal lengths, your depth of field will be greater/deeper. This sometimes will be to your benefit, but many times, it will work against you. In the situations when you want a narrow depth of field, you will have to open the aperture more than you would on cameras with smaller crop factors. Therefore, look for lenses with a low f/stop number.
Of course, lenses with low f/stop numbers are also fast – they let you shoot with less light. Therefore, it is nice to have such lenses anyway. The nice thing about the MFT is that fast lenses cost less than for other standards.
If you want to know how much more you will need to open the aperture to get the same depth of field as on other cameras, here are the exact numbers:
MFT -> 35mm/full-frame (crop factor 1.0): 2 stops
MFT -> APS-C Canon (crop factor 1.6): 0.64 stops
MFT -> APS-C other brands (crop factor 1.5): 0.82 stops
So, compared to cameras like Canon 7D or Sony NEX, you will need an extra 2/3 of an f/stop.
If you want to find out more about the depth of field for MFT cameras, check this post at luminous-landscape.com
Having said all that, I recommend you get the following lenses.
If your budget is under $700, then you should just get this one lens.
This lens is very versatile. You will loose out on speed and it will be more difficult to decrease the depth of field that is already deep on MFT lenses, but still, the lens provides a great value.
Now, if you can invest more money, go for prime lenses. You don’t need to buy them all at once. First get a medium, then a wide-angle, then a telephoto. And if you need to cut corners after spending serious money on primes, consider getting the cheap but versatile telephoto zoom lens that I list at the end.
Medium focal length prime lens
Wide-angle prime lens
Telephoto prime or zoom lens
The telephoto zoom lenses are generally slower, but give you greater flexibility, as compared to telephoto primes. You decide what is more important to you (and your wallet).