Saturday, 19 November 2011

GH2, ETC mode for macro video

The Panasonic GH2 has a very interesting feature, the ETC, Extra Tele Conversion mode. This is like a digital tele zoom. However, when used with videos, you still get the full resolution, with the centre of the sensor being used. This drawing illustrates the concept:


With this feature, you can record full HD videos with an effective 2.6x tele effect, with 2.6 being the fraction 2800/1080. Using the ETC mode, the Lumix G 100-300mm f/4-5.6 tele zoom lens gets an effective 1560mm maximum tele reach, in 35mm film camera equivalents.

However, this effect can also be used for even more enlargements when using a macro lens. Using the Panasonic Leica Lumix DG Macro-Elmarit 45mm f/2.8 1:1 macro lens gives you an maximum enlargement of 1:1. Using the ETC mode gives you a maximum of 2.6:1, which is very impressive. Keep in mind, though, that this only makes sense with videos, not with still images.

I have illustrated this effect with a macro video recording of my own eye. The following footage shows the same scene without and with ETC:



It was recorded using the "Manual Movie Mode", 1080p24, f/5.6, 1/25s. To get a sufficient exposure, I used ISO 1600.

As you can see, the depth of focus (DOF) is very thin, and it is difficult to keep my iris in focus. Setting a smaller aperture, e.g., f/8, would help here, but that would require an even higher ISO. And in my experience, there is significantly more noise with ETC mode compared with the ordinary video mode, especially at high ISO.

3 comments:

  1. Also consider that when you say "1:1" on a Four Thirds sensor, you're talking a much smaller subject than you would historically.

    1:1 on a full frame sensor shows a subject 36mm wide.
    1:2 on a Four Thirds sensor shows a subject 34mm wide.
    1:1 on a Four Thirds sensor shows a subject 17mm wide.

    The GH2's ETC crops the sensor down to its inner-most 6.5mm of width, so 1:1 with the GH2's ETC shows a subject 6.5mm wide. To get a 6.5mm coverage on a Four Thirds sensor would normally take a 2.6:1 lens. To get 6.5mm coverage on a full frame sensor would require a 5.5:1 lens... slightly closer than Canon's 65mm MP-E can take you.

    Of course there's no such thing as a free lunch; a 1:1 image from a 5DMk2 has more detail than a 1:2 image from any Four Thirds sensor (speaking as both a Canon/Panasonic/Olympus shooter), and using ETC would only increase the gap.

    M43 has great potential for macro, and is only let down by the complete lack of suitable macro lighting equipment. The STF-22 doesn't work right. The FL-50R and FL-36R can't tilt enough to use at 1:1 and thus need DIY off-camera brackets. The MAL-1 does not have enough output to shoot any closer than a kit lens can take you, and then only at wide apertures. And the Nahona macro lens has lighting doesn't go anywhere near 1:1, which makes it a specialized tool only.

    Micro Four Thirds needs a compact macro flash similar to the STF-22, MT-24EX, or R1C1. Take a FL-50R body and attach two small flash heads to it, then make it thread mount to the lens (for compatibility with non-system macro lenses). Then give us a cheap set of extension tubes ranging up to 25mm. The GH2 and EP3 are already great macro cameras on their own. With a little attention to complete the M43 system they could surpass full frame DSLRs as a macro system.

    C'mon Panasonic/Olympus, I've got an MT-24EX just begging to go on the auction block....

    ReplyDelete
  2. Yes, the Panasonic Leica 45mm f/2.8 lens allows for impressively close macro images, even without cropping.

    Lightning is a challenge for macro, I agree with that. I have used the FL360 (same as the Olympus FL-36) with a third party TTL extension cable. That makes for easy macro lightning, especially when combined with a light box/soft box. But it is hardly a perfect solution for macro use. A dedicated macro flash would certainly be easier to use.

    For macro video, lightning is even more challenging. With video, it is possible to push the ISO fairly high. But at ISO 1600, the quality does suffer a bit.

    ReplyDelete
  3. I'm using my FL-36R on a hot shoe cable, homemade metal bracket, and a Lumiquest Mini Softbox right now, and it works OK mostly (sometimes it's difficult to tame the side-lighting), but it's very bulky. My Canon setup (5DMk2 + 100/2.8 macro + MT-24EX) is easier to shoot with, despite being more than twice the weight.

    What I'm really after is something lightweight and compact that makes the camera easy to handle, sort of like a miniature version of the Nikon R1C1 system. All it would really take is two smal flashes like the FL-300R mounted to a plastic ring that screws into the front of a lens like the 45/2.8. The whole thing could even be triggered by the camera's flash, for those models with built-in flash.

    The Metz Mecablitz 15 MS-1 is close to this idea.

    As for macro video, I am in awe of those that can do it consistently. It's difficult enough to track insects to take still photos. Following them requires a level of fine motor control I do not possess!

    For what it's worth, I tried using continuous lighting for macro shooting on my GH1, and I couldn't get a sufficient amount of light to freeze the subject. I imagine some of the high-end video lights might work, but they are extremely expensive and still don't put out the power that even the cheapest flash can.

    I hope we get a solution someday soon. Micro Four Thirds could be a wonderful macro system if only a little attention were paid by Panasonic and/or Olympus. Given Olympus' excellent reputation for macro, I'm surprised all they've given us so far is a diopter and a hot-shoe-powered flashlight. It's a pretty weak showing.

    ReplyDelete