Wednesday, 14 December 2011

Lumix Leica 25mm f/1.4 and clicking sounds

The Lumix Leica DG Summilux 25mm f/1.4 is a premium large aperture prime lens for the Micro Four Thirds system. It is designed to work as a "classic" bright normal lens for a 35mm SLR system, which was typically rated as 50mm f/1.4. With the 2x crop factor associated with the 4/3 format, the Leica 25mm f/1.4 lens becomes equivalent to a classic normal lens in terms of field of view.


Many users have complained about clicking sounds when using this lens. This has left them worried: When they buy a premium lens, they expect it to function smoothly.

First of all: Don't worry, the clicking sounds are completely normal.

Having said this, let's look at why you experience these clicking sounds.

What's causing the clicking sounds is the change of aperture. In normal operation, the camera leaves the aperture at its largest value when using the camera, and only stops it down just before taking a picture. The aperture is opened up again afterwards. Since the sound of the shutter is louder than the actual aperture change, you don't normally notice the sound of the aperture changing.

I have examined the loudness of the aperture change with a number of lenses here. Generally, most lenses have a similarly loud aperture change. The Lumix G HD 14-140mm superzoom is marketed as a video lens, and is supposed to have more silent aperture change than usual.

However, the Lumix Leica 25mm f/1.4 is the brightest Micro Four Thirds lens so far. When using the camera, it is seeing the outside world through the lens, and relaying the information to you through the LCD screen, or the viewfinder. Unlike your eye, which is very flexible in terms of the dynamic range it can see, the camera sensor can only see a more limited range of brightnesses. When using a bright lens like the Leica 25mm, in combination with a bright surrounding, the light is simply too much for the sensor to process. It needs to stop down the aperture to show you a sufficiently good viewfinder image. Stopping down the lens causes a clicking sound.

Further, the camera cannot accurately focus with the lens stopped down. When stopped down, the depth of focus (Dof) is wider, hence the lens appears to be in focus in a large focus distance range. And this can cause misfocus.

So before focusing, the camera must open up the aperture fully, and then close down again afterwards, if the surroundings are very bright. Both opening up the aperture and closing down cause the clicking sounds. Hence, every time you focus the lens in a bright light, you will experience the click before and after the camera has achieved focus.

If you operate the lens in a dim environment, you should not normally experience the clicking sounds upon focusing the lens.

This can happen with any Micro Four Thirds lens, even relatively slow zoom lenses, given that you point the lens towards a strong light source. But since the Leica 25mm f/1.4 is unusually bright, it happens more often with this lens.

So to conclude: The clicking sounds are a normal part of the lens operation.

6 comments:

  1. When I first heard it after buying P20/1.7 I was afraid that the lens is broken ;)) simply, I haven't heard it before with kit :)

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    1. The kit lens has a smaller maximum aperture, hence, the camera does not need to stop down the lens during live view as often. If you point the kit lens towards the sun at maximum zoom, then I think that too will stop down, causing the noise.

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  2. Does this mean that if I constantly use my 25mm with a strong ND-filter (say 2-3 stops), that would reduce the noise?

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    Replies
    1. Yes, I think that would reduce the camera's need to stop down the lens, and, hence reduce the noise. However, it would also reduce the low light performance of the lens, of course.

      Some poeple like to use ND filters on fast lenses like this, to be able to use the maximum aperture in daylight.

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  3. Do you hear that sound when manually changing aperture from say f1.4 to f1.8? Because I hear it not only when taking a photo, but also whenever I change aperture.

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    Replies
    1. Yes, this is normal. The clicking sound is due to the lens changing aperture. So this could be during taking a picture, and also when changing the aperture for other reasons.

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