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06-30-2019, 03:21 PM   #1
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butchblack's Avatar

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Lens hood on 50mm lens

Quick question. I was looking through my old accessories and found a 50mm lens hood that fit my F 50mm F 1.7. fine. I also found a lens hood for a 100 f4 macro. Just for fun, I put it on. I did not see any vignetting on my KP. I took a photo and opened in Photoshop and could not see any vignetting. Even with the conversion factor, the hood should be too large for the lens. Am I missing something, or was the macro hood purposely shorter than a non-macro hood for a 100mm lens? I will do some further tests, but it would be nice if it works. Any ideas or feedback?

06-30-2019, 03:33 PM   #2
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QuoteOriginally posted by butchblack Quote
Quick question. I was looking through my old accessories and found a 50mm lens hood that fit my F 50mm F 1.7. fine. I also found a lens hood for a 100 f4 macro. Just for fun, I put it on. I did not see any vignetting on my KP. I took a photo and opened in Photoshop and could not see any vignetting. Even with the conversion factor, the hood should be too large for the lens. Am I missing something, or was the macro hood purposely shorter than a non-macro hood for a 100mm lens? I will do some further tests, but it would be nice if it works. Any ideas or feedback?
Some of the macros have a very recessed front element, so the hood may not need to be as long. This is a somewhat educated guess, do you know what series it was from? (Takumar, K, M, A ?) I don't know how many series had a 100/4 macro)

edit:
I just did a search through the lens databases and I guess it must be from a Takumar or the A series which have 49MM filter threads, for the hood to fit your F50. Those both appear to have well recessed front elements.

Last edited by ramseybuckeye; 06-30-2019 at 03:41 PM.
06-30-2019, 03:51 PM   #3
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A lens hood for a 50mm generally shouldn't cause vignetting on a longer focal length (but there's a slightly higher chance of having flare in photos), but most likely will cause vignetting on a wider focal length (e.g. 35mm).

I know the lens hood I have for my 50mm lens when put on my 35mm lens starts vignetting slightly when focused around the 3 foot mark and onward, getting more obvious when near the infinity mark.
06-30-2019, 03:51 PM   #4
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Your initial logic that a hood for a 100mm lens would probably vignette on a 50 mm lens, even on APS-C is basically sound. The only "missing something" is that hoods are designed to suit both the focal length and what is known as the entrance pupil of the lens. The entrance pupil is the optical location and size of the aperture inside the lens where all the rays of light that are captured by that lens will pass through. A lens with an entrance pupil that is deeper inside the lens will need a larger diameter or shorter hood than one with a shallow entrance pupil. The 100 f/4 has a pretty deep entrance pupil so the hood is probably a bit wider & shorter than might be expected.

But all this theory doesn't matter if the hood designer was lax or overly aggressive about shading the lens. The vignette test (a shot of a blank wall done at infinity both wide open and fully stopped down) will reveal if the hood works or doesn't.

Enjoy your discovery!

06-30-2019, 07:47 PM   #5
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I use takumar metal hood designed for 135mm f/3.5 and 200mm f/5.6 on my 50mm f/1.7 (SMC-M) lens on K-5 w/o problem (and I did check it at infinity w/ lens at smallest f stop). It also is a nice hood for the 85mm f/2 (SMC-M) lens. But this was not with a filter!
07-01-2019, 09:43 AM   #6
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If that hood isn't vignetting...use it! I used to make a habit of snatching up any odd lens hoods I'd come across at garage sales and thrift stores, especially any by Pentax or Nikon. Now that things have gone digital, I've been able to move up to much deeper hoods on my older lenses due to the crop factor. I operate on the principal that it's best to use the deepest hood you can get away with using.
07-01-2019, 11:02 AM   #7
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my experience with experimenting with the non original lens hood for F28 / 2, / 8 and F50 / 1.7 and the combination of AFx1,7 + F50 / 1,7 and on FA 80-320 / 4,5-5,6,proven good and cheap solutions for the non original lens hood:

F28 / 2, / 8 + 2 ring step up 49-55 + 1 ring step up 55-58 works perfectly (left part of the photo)



F50 / 1.7 + 1 step up ring 49-52 + metal lens hood 52mm with ebay for $ 2 works perfectly (right part of the photo), this combination is also suitable for AFx1,7 + F50 / 1,7=F85/2,8 (not soft):



FA 80-320 / 4,5-5,6 + metallic lens hood 52mm with ebay for $ 2 works perfectly


Last edited by mbukal; 07-01-2019 at 11:20 AM.
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