This is a post about two micro four thirds camera lenses. So in 35mm film terms you need to multiply the focal length by two. Which means these lenses are a 90mm equivalent and a 150mm equivalent.
So I should start by saying that I don’t hate the Olympus 45mm lens. Far from it. It is a great lens, especially at the price. It can produce astounding results like this picture (OK, not astounding, but I liked it):
However, it can also produce shots which are good but not great (no examples this time, I fear someone will point out user error). I’ve been raving about how good the Oly 75mm is since it turned up so I decided to try a quick and dirty comparison. First, the Oly 45mm:
A nice shot, I like it, another one for comparison:
What is to complain about with these two? They look pretty decent to me. Now let’s try the 75mm:
Not much difference, right? Wrong. If you open up the examples and look at the 75 check out the detail and the bokeh on the 75mm shot. Another example from the 75:
Finally one to show that while the 75 is a great lens, it is a long focal length. This one really would have been better if I had used the 45mm to be frank:
All shot with my Olympus E-M5. By the way, the musician above is Chloe Leigh and she is another participant in the Mayor of London’s Gigs contest. You can watch her here, she is very good: http://www.molpresents.com/gigs/vote/chloeleigh
Update 22 August: Just a quick additional edit, because I noticed quite a few people from Olympus club poland linking to this site. Hello! I think one of the downsides being considered on the posts on the site was that the 75 is somehow big and uncomfortable. It absolutely isn’t. It’s certainly heavy, but not uncomfortably so (it just feels like a quality lens). I have never felt the need to use the grip with it as Robin Wong suggested in his review. I do use a half case with my E-M5, but I think I would have noticed if the lens destroyed the handling as Robin suggested.
Update 1 September: Some (mostly on DPreview, though I note one has turned up here) have queried the sharpness of the shots, in particular those with the 45 but also the shots with the 75. Having looked at them personally I didn’t think they were unrepresentative of shots I have seen on the net elsewhere, but one constructive commenter noted he had found more significant sample variation in the Oly 45 than you might expect. I had tried a couple before selecting mine, but I’ve not been able to replicate sharpness of samples others sent me in tests. Interestingly, the G5 (without IBIS) produced the sharpest results with my copy. For the sake of argument I’ve ordered a new one from Amazon for monday.
In terms of querying the 75 shots I find that ludicrous. Perhaps the first isn’t critically sharp, but the second one is a fine shot IMHO – perhaps not as excellent as some of the other shots I’ve taken with it (see the links in my comment below) but very good. As these were all default settings RAW shots processed in Aperture, I thought I would see what one of them looks like cleaned up and processed using my usual mono methodology. Make of this what you will!
Update 4 September: See https://sgoldswoblog.wordpress.com/2012/09/03/olympus-45mm/ for the results of my testing of my 45mm
sgoldswoblog 
Sorry dude but none of these shots are sharp. I also have the Olympus 45mm and it kicks all your samples butt! Surprisingly even your 75mm shots look bad.
Samual,
Thanks for your comment and you are entitled to your opinion. Bear in mind this didn’t purport to be a review nor did it follow review conditions (all shots were hand held and from slightly differing positions). I’m surprised by your comment regarding the 75 though – even the low quality shots from the 75 (and I include this in that bucket) kick the 45mm’s behind.
If you continue not to agree (and I can see there could be some argument I had focused on the mic and not her face in the first example), check out the detail in the hair in the second example. Finally if that doesnt convince you I suggest you look at some of my other 75mm posts. The 75 equals or exceeds many M mount lenses (and I say that as an M9 owner…).
To follow my previous comment I heartily recommend you check out the following pictures at 100% if you still require convincing as to the 75’s abilities:
Oddly (perhaps), that last one where the singer was looking at you looks very sharp on my monitor. I much prefer the 75mm (which has character) over the 45mm (which is boring and rather flat in character). My m43 wishlist would be 15mm DG Summilux, 25mm DG Summilux, 42.5mm Nocticron, and 75mm D.Zuiko. Still saving up for the 75mm, and I doubt I will ever have enough reason to get the Noctilux, alas.
PS:
Love the two you posted in your comment above. The B&W one is superb, and the one of the lady in white looks very Leica like in colour and tone.