AF100 Lens Comparison #1 – Sigma 12-24 vs. Lumix 7-14

Part of what makes the Panasonic AF100 so appealing is that its Micro 4/3 lens mount allows virtually any third-party lens to be used on the camera (with the correct adapter, of course). The “gotcha” is that the 4/3 sensor has a “2x” crop factor, which basically means that, with any given lens, the camera has a field of view that is half as wide as it would be on a full-frame camera like the Canon 5D.

If you’ve been shooting with a 5D Mark II, this 2x crop means that what the lenses you’re used to using now work in very different ways. One of my favorite lenses on the 5D is the Canon 20mm f/2.8. It’s wide enough to be very forgiving for handheld work, and to give a dramatic feel to scenics and lifestyle shots, but fast enough to use in conditions with limited light. On the AF100, however, I can only see the middle half of that 20mm lens image, as the rest is “cropped out.” That great, ultra wide lens is now just an okay, slightly wide lens.

A couple of years ago, I bought the Sigma 12-24mm lens, primarily for architectural interiors. Since it’s the widest lens I have (aside from a Peleng 8mm lens which is so soft that I haven’t been able to shoot anything usable with it), it’s been my go-to lens on the AF100, when I want to shoot wide, which is most of the time. However, I’ve been hearing good things about the dedicated Lumix lenses that Panasonic actually intended for use with the AF100, so I set out to do a head-to-head comparison between the Sigma 12-24 and the Lumix 7-14mm, to see how they stacked up against each other.

Speed

Neither of these lenses are fast: at 12mm, the Sigma will open up to f/4.0, and that drops to about f/5.6 at 24 mm. The Lumix is a little better – it will maintain f/4.0 throughout its 7-14mm range.

Field of View

Obviously, the Lumix is much wider than the Sigma. Here’s what that looks like, in a real shot. The camera was in the exact same position for both images; I only switched lenses.

In order to compare apples to apples, I shot a number of scenes with both lenses at 12mm. This allowed me to compare clarity and color in largely identical images.

Aperture Control

The drawback of using an EOS-style lens like the Sigma 12-24 on the AF100 is that there’s no way to control the aperture electronically. The adapter I purchased has a built-in iris, which allows for some control, but it vignettes terribly, and there’s no way to tell exactly what aperture you’re shooting at. It’s crude, but better than nothing. Often I juggle the Neutral Density (ND) filter and gain settings to get the exposure as close as possible, so that I can keep adapter-aperture adjustment to a minimum. For this comparison, I wanted to leave as many variables unchanged as possible, so I did not change the gain, which meant I had to be a bit more agressive with the adapter. As you’ll see in the comparison video, some of the Sigma shots exhibit quite noticeable vignetting. In my mind, that’s part of the reality of using this lens, so I think that’s fair.

On the other hand, using a Lumix lens forced me to use the AF100’s electronic aperture control, which is an extremely awkward plastic dial on the front of the camera. It was stiff and unresponsive, and I had to poke it with a fingernail to make fine adjustments. It gave me cleaner and more precise control than the EOS adapter, but I was surprised by how clunky and unfriendly the interface was.

Image Quality

When I was operating the camera, I didn’t notice any significant difference in the color or clarity of the image between one lens and the other. I did notice that the Lumix lens seemed slightly easier to focus, as it seemed to have more of an obvious difference between almost-in-focus and in-focus. Focus has been my biggest issue with the AF100 in general: the camera badly needs an expanded-focus feature. Even after shoots in which I’ve used an external monitor and carefully checked the focus of each shot to the best of my ability, I’ve discovered that some shots that were just slightly out of focus. After getting used to being able to jump in 10x on the Canon 5D2 to check focus, I find this limitation very frustrating.

When I got the footage into my computer, I looked at the clips more closely, and I found that the Lumix footage was significantly sharper than the Sigma footage. This is a little disappointing, but not particularly surprising: remember, everything shot on the AF100 with a 35mm lens is essentially zoomed in to the center of the image, because of the 2x crop factor. Here are a few frame grabs. Because of the EOS adapter, I wasn’t able to match the exposure precisely, but you can still clearly see that the Lumix shots (second image in each set) are sharper.

Color, on the other hand, seemed more natural and appealing on the Sigma. The Lumix lens gave a blueish cast to all the images (white balance was unchanged), and – perhaps because of the increased clarity – highlights appeared more harshly clipped. In general, I thought the Sigma gave a warmer, more filmic look to the footage, while the Lumix gave a cleaner, more HD-like look.

I was also a little surprised to see that the Sigma actually had less distortion at 12mm than the Lumix did. If you look at the frame grabs, you’ll see that, with the camera in the same position, there’s a slightly more pronounced taper to the architectural verticals in the Lumix shots (the second of each pair of images).

Conclusion

If I didn’t own either lens, and the AF100 was my primary camera, I would have no reason to purchase the Sigma. Although it’s $80 cheaper than the Lumix, it’s not as wide, it’s slower and softer than the Lumix, and being forced to use a lens adapter is a hassle. However, since I already own the Sigma, I’m not 100% sold on buying the Lumix 7-14. Although I’d like to be able to get those extra-wide shots, and I would like to have the sharpest glass possible, a maximum aperture of f/4.0 is pretty underwhelming for a dedicated $979 lens. And, although the level of distortion in the Lumix lens is not much worse than the Sigma, I would expect it to be better, so the fact that’s it even a little worse is a mark against it.

I enjoyed shooting with the Lumix, and I love how wide it is, but it’s a little too slow and a little too expensive for me to break open the piggy bank. I’d rather muddle through with my Sigma 12-24 until I see what else hits the market. If someone releases a reasonably priced 10mm f/2.8 that would be the equivalent of my Canon 20mm, I’ll snap it up. Until then, I’m adopting a wait-and-see attitude. After all, if I really need a wide shot, I can just put the Sigma Lens on my 5D Mark II.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s