Technically this should be a part of my review of the C/P 25/1.4, but I couldn’t wait to share my latest observations with you, so here you go
This is not a scientific comparison, nor has it the aim to be exhaustive – it is merely to show some of the differences between the two lenses under certain conditions. Those conditions are:
- Indoors setting with available light
- Close focusing for maximum bokeh
- Aperture wide open on each lens
What I want to compare here are the following points:
- Bokeh (i. e. rendering of out-of-focus areas)
- Optical qualities (vignetting, distortion, sharpness, colour)
The setup I used for this comparison was pretty simple – in fact I simply shot away at a scene that happened to just be there by chance – a teapot and a salt shaker on our kitchen table, with some light reflections from kitchen stuff in the background. This proved to be a quite usable setting for checking the three above mentioned points.
Now without further ado, here are the resulting pictures. Click them each to view a larger version that also contains a 100% crop showing each lens’ sharpness performance.
First, the Lumix 20/1.7:
And next, the Cosmicar/Pentax 25/1.4:
Right away I think it is worth noting that both lenses perform exactly the same in terms of speed. Both pictures were exposed for 1/125th of a second, and both are equally well exposed. This can only mean one thing, namely that the Cosmicar/Pentax’ maximum aperture setting, which is nominally 1.4, is in fact (only) a 1.7(*). It does show significantly more bokeh though, but this might at least in part be due to its greater focal length of 25mm vs. the Lumix’ 20mm.
Speaking of bokeh, I personally find that the C/P’s rendering of out-of-focus areas is much more pleasing. Not only does it offer more, it is also quite different from the Lumix’. The Lumix’ bokeh is – as most other aspects of the Lumix – very clinical. It is more of a consistent blur of things, with rather harsh transitions between in-focus and out-of-focus areas. The C/P, on the other hand, has a much more ‘alive’ bokeh. There seems to be action going on, the transitions are smoother – simply put, it has a certain magic to it that I find (Ashwin Rao might beg to differ here) the Lumix lacks – at least in this particular case.
As I said, the Lumix’ performance is quite clinical (to me). It is a great performer technically, as can be seen from the pictures: there’s only the slightest distortion (if at all), no vignetting worth mentioning, it’s sharp – it’s good. Whereas the Cosmicar/Pentax shows strong barrel distortion, it has vignetting at every aperture setting, it has terribly soft corners – but then again it wasn’t designed to be used with sensors larger than 1″, was it? But there are also areas where it performs better than the Lumix. First, it is sharper, at least in the center. Now before you shoot me for such heresy, let me say in my defence that I did not do a thorough sharpness comparison between the two. I know that the Lumix has a sweet spot somewhere around f/2.8-3.3 where its sharpness is stellar, but it is a tad soft wide open, which the C/P isn’t. You can see this in the 100% crops, although I have to admit it is a bit unfair since I autofocused with the Lumix and it didn’t hit exactly the same spot that I focused on with the C/P. But I can tell you from other pictures I took that it is sharper than the Lumix wide open.(**) The other aspect is color signature, which is a bit warmer with the C/P. I personally find that much more pleasing – in fact it always bugged me about the Lumix that it renders a bit too cool for my taste.
To sum it up: The Lumix is the better performer technically speaking, but I think this was to be expected (it does cost more than twice as what the C/P + adapter cost new, and it was designed for MFT). My personal impression though is that the Cosmicar/Pentax has a lot more character. Even with all its flaws it just gives the pictures a certain uniqueness, as if it were to say “I know I’m not perfect, but isn’t that what’s so loveable about me?” And that’s exactly it. I love the Cosmicar/Pentax 25/1.4 for how it renders – not so clinical, not so perfect, but with a certain charm of its own.
That’s why I do indeed prefer it over the Lumix as my everyday-walkaround-take-pictures-of-everything-in-any-situation lens, although the Lumix still has the advantage of autofocus, which might come in handy from time to time
*) I could secondarily verify these findings by pointing both lenses at the same well-lit scene, first wide open and then stopped town to f/2, 2.8 and 4. Both performed identically, giving 1/3200 sec. at their initial aperture setting, then 1/2000 @ f/2, 1/1000 @ f/2.8 and so forth.
**) dpreview Forums user madmaxmedia pointed out to me that there might be something wrong with my sharpness rating for the two lenses. So I did another test and I have to admit that this time the results contradict what I originally stated – the C/P is in fact not sharper than the Lumix wide open (I may have mistaken a crispy sharp shot from the C/P for having been taken with f/1.4, where it was in fact f/4!). But I find it is a close call, and the C/P does get really really sharp when stopped down, which is amazing for such a small lens. (Sharpness samples of the C/P will of course be included in my final review soon!)
So here are two 100% crops that show how each lens actually performs in terms of sharpness wide open, for you to compare (click the links to open each picture):
Cosmicar/Pentax 25/1.4 @ f/1.4 | Lumix 20/1.7 @ f/1.7
Buy the Pentax 25mm f/1.4 C-mount TV lens from B&H Photo Video Audio!
Buy the Panasonic Lumix G 20mm f/1.7 lens from B&H Photo Video Audio!