Wednesday, 27 January 2010

the Panasonic 20mm: do I really need one?

I want a normal lens which has shallow depth of field ... but I fear such a thing does not exist for the micro 4/3 format.

People who suggest that I'm over analyzing this, please just post me a Panasonic 20mm f1.7 and I'll just use it. But if I have to pay for it myself (and its not cheap) I'll be doing the analysis thanks all the same ... [post script ... I bought one 4 years later when they were reasonably priced used]

Well obviously the first question for me is what do I want it for?

The answer for me is photographs of people in places where I don't want the complexity of scenery to take over the image.


I just love the look of a normal lens, unlike wide angles lenses you don't get bucket loads of background and unlike telephotos' you don't get that compressed scale where the background is just a blur backdrop snuggled against the subject.

Having grown up on 35mm and then moved into large format, focal control was always a challenge of how to get more in view. Ownership of generic 35-80 zooms with apertures of f5.6 (often stopping down to f8 for clarity) seemed to make me feel my photographs were boring. I happen to read this comment a bit recently too . These zooms are a middle ground with nothing looking interesting some how (well, except for the subject matter) and I found myself graduating back to my two favorite primes a 24mm and a 50mm with my 35mm photography.

By 2000 I had more or less moved over into compact digital and large format. I always wanted a full frame DSLR and despite resistance eventually got a 20D. Beautiful images, but I'd beeen spoiled by lightweight compact cameras like my Coolpix 5000, so big and fat was not in.

However having used compact digital and then APS-C sized DSLR for some years, it wasn't until a couple of years ago I put some film in my 35mm camera and a 50mm on that I rediscovered this "style" and realized I really liked it.

Great subject isolation, and no funny telephoto "look" to the image.

Yes, this is what I'm after.

Of course having also come to work with Auto Focus in 35mm world (and know how fast it is compared to a compact digital) having a good AF system is part of my requirements too, as this can be a make or brake for a photograph. Get the focus wrong with a narrow DoF and the shot is transformed from great to delete it.

When I first got my G1 I was after a normal to do this, I tried the only options available to me, such as a legacy lens and an adaptor. I tried an FD 28mm and found that 2.8 wasn't enough.

Enter the Panasonic 20mm

So, back to my decision on the Panasonic 20mm, of course nothing you read (normally) helps you with making the decision like a hands on with the lens. I live in the boonies, so its not easy to get my hands on one, but I recently took a trip into the nearest store with one of these I could demo.

Since I have been making comparisons between my FD 28 f2.8 on my G1 and my 50mm f1.8 on my EOS I naturally took along an FD 28mm f2.8 for comparison with the 20mm.

Personally I've felt that the 20mm is a wee bit wide for a normal, and feel that the 28mm is a wee bit tele ( ... them being 40mm and 56 respectively) I'm told that the 40mm is the "perfect" normal so perhaps I'm just used to that wee bit more tele then. I have a Helicon 55mm f2 which I love (but I digress).

So, in at the shop I put my 28mm on my G1 and took a shot, without moving I then put the 20mm on and took another shot.

I used f1.7 on the 20mm and f2.8 on the 28mm

You can see quickly from this overview firstly how different their angle of view was. The colour balance comes from an issue I had with exposure with my legacy FD lens which I will go into later ...

Clearly there is some difference to take into account here. So to compare eggs with eggs I thought I'd "zoom with my feet" and walk that wee bit closer to the subject for the 20mm ... it was only another step after all. This is what I got:


Ok, so now we've got something to compare. Sure, the perspective changes by making a step forwards, but it does not stand out to me that there is significant difference between these two lenses in depth of field ... in fact that's not a real surprise to me as my calculations on DoF suggested that the 28mm @ f2.8 has a diameter of about 10mm and the 20mm @ f1.7 has a diameter of 11.7mm (remember DoF is based on aperture diameter not f number, please read my tutorial on this).

Add to this the (slight) change in perspective (subject / background distances) its really a close call. Examining them in detail its obvious there really isn't much in it ...


Since I know from testing that the 28mm @ f2.8 (on 4/3) does not have the pop of the 50mm @ f1.8 (on full frame) then after seeing this, I feel sure now that the 20mm offers me no optical advantages in my picture taking.

Getting back to the angle of view difference, I put the camera on the bench and took a picture of the cabinet on the wall with the 28 and the 20mm. I've scaled the image from the 28mm down to fit into the frame of the 20mm to show how much more the 20 captures.



more than the 8mm would suggest (to me, and perhaps to those used to working in 35mm land) and not inconsiderable if you ask me.


So what are the benefits?



?Well clearly its compact, and makes the G1 a very compact thing to poke in a backpack side pocket.

Using it simplifies operations, and I can comfortably hand the camera off to anyone with it set on Auto everything and be sure that the photo's come back as I'd expect.

I get very nice integrated manual focus operation which activates the focus assist zoom feature and all of the focus tracking nice features of the G1 will work with this lens well too.

One thing I can say I learned to love when I transited from Manual Focus to Auto Focus was that fast accurate AF is essential when trying to get sharp images of people in natural unposed situations. With MF I had to prepare and be ready for things, AF (and reliable metering) opened up a whole new world of 'grab' shots which all too often were hit and miss using MF lenses.

But the same can be said of the Kit Zoom ...

So at €399 the slim and light weight 20mm raises the question for me of "what's it good for" and further raises the question of what am I trying to accomplish with my micro 4/3 system.

Well my main criteria has been a high quality compact and light weight camera system. What I'm wanting to add to it here is shallow depth of field in a 'normal' lens , and quite clearly this lens does not provide enough to meet my desires.

If I am photographing across a dinner table then the kit zoom at something like 14mm will provide good background separation too.

So (already having EF 50 and EF24mm and an OM 21mm from my film days), I could instead put this money (the €399) towards a used Canon 5D camera and get exactly the look I am seeking (that of a 50mm f1.8) by using a 50mm f1.8 (I already have two). If I also then sold my 9-18mm and added that to the 399 above that would probably even fully pay for a used 5D.

I already know that I prefer the Bokeh of my Olympus 21mm on full frame to the ZD Olympus 9-18, so perhaps I would be better off in wide angles than I am with micro 4/3 too.

hömötinttiBut its then not just about one lens, its about a system. Do I want a 5D for just two or three lenses?

Thinking about other lenses, I find that the micro 4/3 system lacks quite a lot in that department. There are no native telephoto lenses which have IS or fast AF. While I have had some really good images from my G1 and legacy lenses like the FD 300 f4 (the bird image to the left) I'm not sure that this is something I really want to live with.

Again I find myself drawn back to the Canon EOS system, but its not without costs.

While I could source an EF 300f4 with IS in as new condition with a case even for US$1000, I only paid US$200 for the FD300f4 used above.

Sure theres no IS and no AF but I have managed to get quite a few good images from this G1 based system...


I need to balance this against the truth that for shots of people or things further than 5 meters away the differentiation between background and subject will diminish with a any lens, so perhaps my criteria is for a small set or working conditions. I really need to work out this aspect carefully before making the decision to go with Godzilla after coming to like Bambi so much. Stuff like the swivel screen and ease of review of shots in bright light using the EVF will be absent on a 5D ... it feels like stepping back in time.

I just know I'll want to grab the G1 over the 5D when off for the weekend ...

I don't know, perhaps I should regard the micro 4/3'rds as being what I expected it to be from the start, a good light weight camera for taking great pictures when I'm on the move and not as a replacement work horse for everything ... its just that the micro 4/3'rds cameras are so bloody good at stuff that one feels that they could be good at everything.

Perhaps I should just use my 4x5 film camera for static shots where I need better depth of field and have more control over it in the first place


forget about the 5D and just revel in the G1 ... after all, you can't have everything?

can you?

6 comments:

Noons said...

I am amazed at the difference between the FD 28 and the Pana 20!

The perspective difference in the detail shot 20VS28closeup.jpg is incredible!

I'd say there is a bit more at play here than just the 8mm difference.

Perhaps a side effect of the FD adapter or the retro design?

obakesan said...

I'm going to be really boring here and say that its down to stuff like "tan" which is "opposite over adjacent" ... so as the adjacent shrinks (the sensor lies effectively on the line represended by the adjacent, and the focal length is essentially the opposite here) the relationship grows in a non linear way. Considering that angle of view is what we are calculating for.

shit, isn't it time for a coffee yet?

You know, if my high school maths teacher could read this he'd think I'd been abducted by aliens and replaced ...

Noons said...

LOL!
Mate, my high school maths teacher *WAS* an alien: I think his name was Ford Prefect and he was from Beetlejuice!

Yeah, I think I understand what you said: it's gotta be non-linear.

And the adapter and retro-focus design throw the tan over the adjacent.
Or was that the sunlight over the back?
(reaching for the coffee cup...)


word verification: polingsh
How appropriate, sounds like the language I was using!

david said...

Not quite relevant, but this link fits about halfway between this post and your one about large format and m4/3. It includes a DxO comparison between a GH1 and a Canon 7D.

http://www.dxomark.com/index.php/eng/DxOMark-Sensor/DxOMark-reviews/DxOMark-review-for-the-Panasonic-Lumix-DMC-GH1

obakesan said...

David ... real interesting though ... I knew that I liked my G1 a lot, its nice to know that others find also that it performs as well as I do. I must say that the GH1 is now quite an alluring choice ... get video too!

juarez_j said...

20mm is slightly wide for 4/3. The image sensor is 17.3mm x 13mm, which makes the diagonal 21.6mm. If you shoot in 2:3 aspect ratio, then it's closer to 20mm (20.8, almost perfect). Still, this is much closer to perfect normal than 50mm on a 35mm camera.

35mm film has an image size of 36mm x 24mm, which gives a diagonal of 43.2mm. So if you're accustomed to shooting with a 50mm on full frame, that's a little long. But it's what everyone considers "normal" in the vernacular, so it's what people have come to expect.