"Home made" hood for the Lumix 20mm f/1.7 pancake

The Panasonic Lumix 20mm f/1.7 pancake is a brilliant lens, but it does not come with a lens hood. Flare is not a big issue with this lens, but a lens hood is still good for protecting the front element. Some people use UV protection filters for the same effect, however, adding another glass layer will reduce the image quality to some degree.

One option is to get a cheap third party hood designed for the Leica Summilux lens, to screw into the front 46mm filter thread. However, this hood adds some bulk to the lens, making it less compact. The compactness is one of the desirable features of the Lumix 20mm pancake in the first place.

In an attempt to find a low profile hood that looks more like the hood for the Pentax 40mm f/2.8 pancake lens, I bought a cheap 46mm to 37mm step down ring. The ring is essentially a short cylinder with 46mm threads on the outside, and 37mm threads on the inside.

The ring is made out of light metal, and is extruded on the rear side to save some weight:


Step up and step down rings should be used with care with the Lumix 20mm pancake. When powering down, the lens retracts the front assembly slightly into the chassis, which will jam and possibly damage the focus mechanism if you attach a ring which is too wide. The following picture shows that this step down ring is not too wide, and can be safely used with the Lumix 20mm pancake lens:


Looking at hoods, you will note that they are usually ribbed and matte on the inside. This is to avoid having light reflected into the lens. Since the inside of the step down ring is threaded, it already has the right shape. However, the metal is still a bit shiny. To make it more matte, I applied some matte black enamel paint on the inside threads. Wanting to retain the stealthy look of the lens, I also painted the front and the side of the ring:


Here is the lens with the "home made" hood attached. This hood does not cause any additional vignetting.


You will probably want to have a front lens cap as well, and you can get a 37mm cap which fits into the front threads of the step down ring. Both the step down ring and the front lens cap can be found on various auction sites.

Third party hood for the Lumix 20mm f/1.7 pancake

The Panasonic Lumix G 20mm f/1.7 pancake is a popular lens, and for a good reason. It is compact, sharp, focuses reasonably fast, and has a good maximum aperture. One drawback, however, is that there is no supplied hood in the box.



A hood is useful for keeping out stray light, light coming from outside of the field of view, which could otherwise cause flare in the image. A hood also protects the front lens element against objects touching it accidentally.

The filter thread is 46mm, and you can mount screw in hoods. One hood is easily available on various action sites for around US$10. It is made out of anodized aluminum, with a matte black finish to keep out stray light. You can find this by searching for, e.g., "46mm hood summicron".


This second picture shows that the inside of the hood is ribbed, for extra protection against stray light.


Front lens cap
When screwed into the filter thread of the lens, you cannot use the standard front lens cap. However, you can use a 55mm front lens cap inside the hood, as illustrated below, mounted on the Panasonic Lumix GH1 camera.


Vignetting
Originally made for the Leica Summicron 28mm, it is designed for a wide angle field of view. The Lumix 20mm has a field of view corresponding to a 40mm lens on a traditional film camera, which is narrower than what the hood is designed for. Hence, extra vignetting due to light loss in the corners should in theory not be a problem. Let's check this, however.

The image below consist of crops of the upper right hand corner of two pictures of the sky, taken with and without the hood mounted to the lens. Apart from the hood, the image parameters are the same.

As you can see, the amount of vignetting is roughly the same in both images, so using the hood is safe.
If you add a filter between the lens and the hood, you may need to check for vignetting again. The extra spacing of the filter will cause the hood to extend longer relative to the front lens element, and thus may cause vignetting.
Other lenses

The 46mm screw in hood can also be used on the Panasonic Leica DG Macro-Elmarit 45mm f/2.8 1:1 Macro lens, which shares the same filter thread diameter.

The to be launched 14mm f/2.5 pancake lens will also feature a 46mm filter thread diameter. However, with a 28mm field of view, this hood could potentially cause vignetting, so be sure to test before using it.
Other options
This lens hood adds significant bulk to the lens, contrary to the idea of a pancake lens in the first place. Another more slim option, is to use a step down ring as a lens hood.

Lumix G 20mm f/1.7 pancake

The Panasonic Lumix G 20mm f/1.7 pancake lens was launched in the autumn 2009, and became an instant classic even before it was widely available.

It is interesting that Nikon has launched a lens with basically the same properties for Nikon Z: Nikon Z 40mm f/2. As this lens is a full format lens, it has the same field of view as a 20mm lens on Micro Four Thirds.

Most people who had a Micro Four Thirds camera by this time probably already owned a kit lens which covers the 20mm focal length, e.g., the Lumix 14-140mm, Lumix 14-45mm, or Olympus 14-42mm. So why add another lens in the same range?

There are several reasons why a lot of people like this lens. The focal length corresponds to 40mm on an old style 35mm film based camera, which can be considered as a slightly wide normal focal length. While there is nothing magical about this "normal" focal length, it is considered to give images that look normal to a human observer, in terms of perspective. It sits between wide angle and tele lenses, and while different photographers have different tastes, it remains a useful focal length for a lot of situations.