With 12-40mm, Do I need still need primes?

duh

 

If shallow DOF is you want, the 45mm is the better choice, since it is both longer focal length and faster than the f/2.8 zoom. It's also cheaper than PL 25mm.

 

Only for subject separation and 1-2 stops better light gathering I would take a prime lens.

So if you need those, then it is only way. Just think carefully what focal length is required as with a same aperture, you get same depth of field as long your subject size stay same on the frame. So there is no difference between 25mm @f/1.8 and 45mm f/1.8 if subject is 1:1 by size. And there you get the extra with f/1.4 and in most cases you like more about normal lens than short tele as you can then always step back and crop later and achieve similar if not same DoF. But that extra 5mm (10mm) is not going to matter so much as just crop in post, rescale whole photo first if required too.

So I would personally go to f/1.4 if needed to choose from those two.

And for low light environments, I say f/2.8 is the required maximal aperture what is useful but f/3.5 is already too slow and with f/5.6 you really need tripod.

Like yesterday night I was shooting urban scenes and I chose to use two lenses only, this in street lights only. Samyang f/3.5 fisheye and f/2.8 Pro and I didn't have other "tripod" than one of those silly 10cm long $5 twisted leg ones with me to do long exposure HDR. Otherwise I shot handheld with mostly at 1-4 second shutter speeds and only 1/3 has little shakeblur but 2/3 are perfectly sharp.

Of course for me the 45mm would have been way too long tele and limited my shutter speed to 1 second, maybe two. But 25mm could be used in few cases but I would have enjoyed from its f/1.4 to freeze motion of subjects little more.

 

Personally, I would need the 45mm and either the P20 or the O17 1.8 In addition to the zoom.
But that's me...

 

There is still a place for 12, 20, 45 for me as much as I enjoy the convenience of 12-40 pro. I wouldn't call it a need.

 

If you shoot indoors or in low light conditions enough of the time, I find the fast primes are a must. If you need good subject to background separation, a fast telephoto is your best bet, starting with the 45 and 75, and ending with the Nocticron.

 

I think zooms are best for convenience, primes are best for quality. Simple as that.

 

To answer your question, only you know what you need. Just no one else can answer that.

If you only want short DOF and low light, 1.8 won't cut the mustard. Get the 1.4 or the nocticron, or an adapted lens with a booster.

 

Seems like you've answered your own question and just needed to talk it out

 

The 12-40 makes a great landscape and general-purpose/walk-around lens. The 45/1.8 is a great portrait lens. They do compliment each other. If you can afford it, the Nocticon is even nicer. Both the 12-40 and Nocticron balances very well on the E-M1.

 

I have all the fast primes including the PL25 f/1.4 and the 12-40. I would not get rid of the 25 for anything. Love that lens. The extra speed and DOF is noticeable. Love the pictures I get from that lens. The 45 well, ... I'd sell that one but wife likes it. I just don't use that focal length. Get the 25. It compliments the zoom nicely! The 75mm compliments it very nicely as well. Just in case you wondered.

 

I didn't recommend the 25 over the 45 partly because I was never a fan of the normal/standard lens and have always preferred the 12/17 (24/35) and 45 (85) focal lengths. The 45/85 is ideal as a portrait lens and it does a great job of isolating/blurring the background so you get a nice separation at f1.8 … something you cannot do as well with an f2.8 lens if you are shooting from the same distance. For portrait work, blurring out the background makes a huge difference as your subject will pop because of the less distracting/sharper background. The 75 does this job best actually … even better than the f1.2 Nocticron. Only problem with the 75 for portraits is that you need to be further away from your subject. Other than that the 75 is a fantastic lens that is sharp across the frame wide open. It was my favorite lens before the Nocticron came along. But I would never part with the 75. I am willing to sell my 25/1.4 as the rattle-snaking noise bothers me somewhat, and frankly I don't enjoy using that lens so much - I enjoy using the 45/1.8 more.

And when it comes to subject separation I do think the 45/1.8 does a better job of bluring out the background than the 25/1.4 … in much the same way that the 75/1.8 does a better job than the f1.2 Nocticron. The longer the focal length the more out-of-focus is your background, given the same or similar f-stop and the same distance from your subject.