Sunday, 16 January 2011

GH2: Magnified focus with legacy lenses

The Panasonic Lumix GH2 represents an evolution from the original GH1, which not only includes better video quality, but also better ergonomics. One example is the possibility to use the click wheel to select magnified focus assist mode when using legacy lenses. With the GH1, this mode was available through two button presses: Left arrow key followed by the down arrow key.

On the GH2, it is much simpler. Normally the rear control wheel controls the aperture (in A mode), and the exposure compensation. Switching between these two is done by pressing the click wheel.


When using a legacy lens, however, the camera cannot control the aperture anyway, so the default function of the control wheel is to adjust the exposure compensation. However, Panasonic has added a new function on the GH2: Pressing the control wheel once brings up the magnified focus assist view. You can exit the magnified view by pressing the control wheel again, or by half pressing the shutter release button.

I will demonstrate how to do this.

To use a legacy lens, you will first need to make sure the camera operates when a non-compatible lens is attached. This is done by setting the "Shoot without lens" option. You'll find this option under the custom options (with the "C" and wrench symbol). Here is the location in the menu:


As an example, I am using the manual focus Nikkor 50mm f/1.8 AIS lens. This is a classic, cheap and light lens. It has a pancake characteristic, however, with the adapter it is still not very compact.

To attach such a lens, you will also need a Nikon to M4/3 adapter. Here's how to attach the adapter and the lens to the GH2 camera:



In the next demonstration video, you can see that I use the magnified focus assist view. In this mode, rotating the control wheel changes between 5x and 10x magnification. You can also use the arrow keys to move the enlarged area.



The magnified view can also be brought up by pressing the touch screen. However, since I usually have the thumb near the rear click wheel, I find it much easier to use this function for focus assist.

When focusing, you will normally want to use a large aperture. E.g., f/1.8 for the Nikkor 50mm f/1.8 AIS in my example. It is easiest to verify that the focus is correct when the aperture is large, since the depth of focus is the smallest.

On the other hand, when actually taking the photo, you'll often want to close down the aperture for extra sharpness. Hence, you end up adjusting the aperture ring on the lens back and forth all the time.

Virtually all cameras do this process automatically. But when using legacy lenses on a Micro Four Thirds camera, you must set the largest aperture manually when focusing, and then stop down the aperture before taking the picture.

17 comments:

  1. That's really cool. Do you set the lens aperature using the settings on the lens barrel itself? Or do you set the lens barrel wide open at 1.8 and then further reduce aperature (ex. F8) by using the camera body's settings?

    Thanks!

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  2. The lens aperture must be set on the lens. The camera cannot control the lens aperture, since there is no electronic or mechanical connection.

    This is one of the drawbacks with adapted legacy lenses: You would ideally use a large aperture (e.g., f/1.8) for focusing, and a smaller when taking the picture. This means that you must adjust the aperture back and forth manually every time you refocus.

    When using compatible Four Thirds or Micro Four Thirds lenses, the aperture is adjusted automatically when taking the picture.

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  3. The click wheel has moved from the front of the camera (GH1) to back of camera. Does this change handling? It appears that there is very little space left for a thumb. Are accidental button presses more likely?

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  4. Am I correct in saying that a single touch on the screen also enlarges the image when using a legacy lens?
    This is how it works on my G2.

    Excellent blog you have here, by the way!

    :-))

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  5. You're right that one single touch on the touch screen also brings up the magnified view on the GH2, when using a legacy lens.

    Personally, I much prefer to have the control wheel on the rear side. There is enough space for the thumb when not using the wheel, and I don't see accidental presses as a problem.

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  6. Here is short article I've posted on dpreview forum about easier focusing with legacy lens: http://forums.dpreview.com/forums/readflat.asp?forum=1041&message=37449012
    I've modified Minolta MD adapter so now I don't really have to use magnified view anymore. At least in 90% of shots.

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  7. Your adapter modification is interesting! I like these kinds of creative solutions.

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  8. I'm still amazed how easy is to focus with this little modification. New aperture lever is exactly under my middle finger when I put index finger and thumb on focus ring.

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  9. This feature of the GH2 has made the use of my Pentax lenses a snap! Inspired by your video, I've created a video of using the EVF with my 30 year old Pentax M50/F1.7

    Thank you for sharing your wealth of knowledge on your blog!

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  10. I'm very happy to hear that. I am an old Pentax fan myself, but I have to say that my photographs are much better after switching to Micro Four Thirds. Pentax still has a special place in my heart for making sensible, solid, photographers' cameras.

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  11. Hello,
    Usually I don't find it necessary to focus with the lens wide open. I usually dont have a smaller aperture than 1:5,6 and with the EVF (I do always use the EVF on my GH2 and Pen E-P2). On the GH2 it's very handy with the magnified view but with the EP-2 it's rather quirky so I try to avoid it. One of the advantages of the electronic view finders is that they don't become darker with smaller apertures on the lens. Last weekend I took a lot of pictures with the excellent FD Macro 3,5/50mm mostly at f5,6 and it was quite possible to focus at f5,6 and without magnified view with the EVF on the E-P2.

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  12. That is an interesting comment. For macro use, I definitively agree with you. f/5.6 gives a quite narrow depth of field at macro.

    And an advantage with using legacy lenses on Micro Four Thirds cameras is that you see exactly what you get. So if the focus looks ok in the viewfinder, why not just snap the picture?

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  13. I should have said that it was for macro work. I think it's as well possible with smaller apertures. When you take macro pictures free hand there is no use for the magnified view. I would like if it was possible to magnify just a small part of the view. I'm sorry for posting as "anonymous" as I don't know how to post otherwise.

    Regards,
    Per

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  14. I recently discovered this thumb pressing trick on my G2 which led me to your blog. However on G2 it's only good when using the legacy lens on certain mode such as A, P, etc, where pressing the thumb wheel don't have function for legacy lens. But on Creative mode (where you have lots of art filter choices), pressing the thumb wheel bring up the switcher for different art filter modes (just like when using pana lens) so no magnification trick here. I had to first put it in P mode for magnified focus, then switch to my Creative mode to take a shot. Any experience and suggestions? Excellent blog btw!

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  15. Sorry, I am not familiar with the G2.

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  16. How do you do this on the GH3?

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    Replies
    1. It's very easy. If you put the camera in MF mode (use the thumb switch on the rear), then you can press the focus mode button (Fn3) once to bring up the magnified focus assist mode. Inside this mode, you can scroll the control wheel to toggle between 5x, 10x, and 4x inside a smaller frame. These are very useful.

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