Originally posted by Dartmoor Dave Thanks, that's useful info that confirms that it's best to use the correct original hood with the Tak 20 on full frame. The one in your ebay link is the correct hood.
The only thing that really bugs me about the original hood is that you have to remove the rectangular part to be able to put a lens cap on the step-up ring -- either that or remove the entire hood, including step-up ring, and put a cap on the lens itself. What I'd really like is a rectangular cap that could be pushed onto the front of the hood while the whole thing remains on the lens. I suppose it would be possible to 3D print one, but I haven't got a clue how to go about it.
Edit: For anyone who might not be familiar with the original hood, I've just done some quick snaps.
The lens with no hood:
The lens with the original step-up ring:
The lens with the full original hood:
I would like to clear up some misinformation about the 20mm and 24mm lens hoods. The Ebay item indicated that the hoods were the same and that is incorrect. Both lenses have a filter thread of 58mm so while the 24mm hood will fit on the 20mm it will vignette. The 20mm hood comes in 3 pieces to allow 77mm filters to be inserted.
I have an excellent version of the 24mm lens complete with hood and cases. I don't have a 20mm lens.
Here are the details of both lenses and their filters from Gerjan van Oosten's book The Ultimate Asahi Pentax Screw Mount Guide. I have a copy from the original 1500 print run and, no, you don't have enough money to buy it from me.
[/url][url=https://flic.kr/p/QWTKWp]Super Takumar 20mm_ACD[/url] by [url=https://www.flickr.com/photos/rayallen/]Ray Allen[/url], on Flickr" target="_blank">
[/url][url=https://flic.kr/p/2dBgYn3]Super Takumar 24mm_ACD[/url] by [url=https://www.flickr.com/photos/rayallen/]Ray Allen[/url], on Flickr" target="_blank">