Friday, 12 March 2010

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Originally made for the Leica Summicron 28mm, it is designed for a wide angle field of view.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.

16 comments:

  1. The lens hood defeats the form factor-purpose of a pancake, imo. But the 45mm/f2.8 Leica Macro-Elmarit lens while having the bayonet mount lens hood, also has a 46mm thread, and may look good on it. Also the stock 45mm Leica lens cap can probably be used with this hood as well as it looks like the lens hood has a extension ring built in.

    No objection if the hood actually reduces vignetting.

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  2. Yes, a hood makes the lens larger. But some people like to have a hood on a lens, for the reasons stated in the article.

    No hood will reduce the amount of vignetting.

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    Replies
    1. Mismatched hoods can cause vignetting...

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  3. B+W sells a retractable rubber hood that I found to be extremely useful for this lens. The advantage is that it hardly adds to the buld of this lens.

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  4. Will de freitas8 October 2010 02:37

    The main problem is that the lens motor is attached to the lens thread piece. If you bash or knock the lens hood it's quite likely that the motor focus motor maybe damaged.

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  5. I went as far as ordering one of these hoods from an ebay trader based in China and it failed to arrive after six weeks. I do agree to an extent that it partly defeats the object of using a pancake lens in the first place, which is to reduce size. However, why Panasonic did not supply one in the first place remains something of a mystery. Certainly my G1 and GF1 cameras especially are susceptible to blown highlights and anything I can do to reduce that would be helpful.

    Thank you for the review.

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  6. If you haven't received your package within six weeks, then I would suggest that you contact the seller. Probably, he will resend a new one for no fee.

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  7. Well, as luck would have it, the hood arrived literally this morning. It's exactly the same as the one you reviewed and screws into my UV filter thread without the need for over-tightening, which had been a slight concern. I actually received a refund last week and so have paid for it again. It doesn't take up much room in my smallest camera bag and will be a useful addition.

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  8. Sounds good! Some times, the shipment from China takes ages. It's mostly surface mail, so no wonder.

    Don't expect the ring to solve your blown highlights problems, though. It might keep out a little light if the sun is in the corner of the frame. But with this fairly wide lens, you might be photographing with the sun or a bright object in front of you, in which case no hood can help you. I use the hood mostly as a protection against damage to the front lens element. It makes me feel safer, compared with having the glass element exposed.

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  9. For safety, I bought a UV-filter but I do a lot of shooting with the LCW Fader ND-filter.

    But I have noticed when shooting in the direction of the sun, the image becomes washed out, no matter how much you stop down. Your hood would solve that, I guess? (well, partly...)

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  10. I think the hood would not solve that. The hood only protects against some light that comes from outside of the frame. If there is a light source in the frame, or even in front of the camera, the hood does not do anything.

    In my experience, adding filters to the lens will dramatically worsen the performance with strong light sources in front of the lens.

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  11. Almost all off my pictures are taken with panasonic Gf1 and the 20mm and a lens hood, and i think it works perfect for food pictures, i also use 2 small led light to make the light soft, never use flash, i think it gives the motiv a lot of strengt and persenality. See all the pictures on my web-site: www.dinkok.dk

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  12. Skipper, I am very impressed with your food photography using the GF-1+20mm. What a lens this is for the money! I think I'll get the hood, cheap enough on ebay etc. and though a bit bulky, not heavy if it's aluminium.

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  13. Personally, I like a dome type of lens hood better. There are also simple straight metal lens hoods without the vents. I like those better too. They look more like a lens hood and less like some hyper modern UFO.

    http://www.japanexposures.com/shop/product_info.php?products_id=435

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  14. Personally, I love this lens hood! It small and looks very good. Great service from this Japanese company too.

    http://www.un-ltd.co.jp/products/camera/lens_hood/unx5281/index.html

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  15. I get pretty much the same effect by using a 46-37mm step down ring, which can be bought on Ebay for next to nothing. A 37mm front lens cap is also needed.

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