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03-14-2020, 03:11 PM   #1
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Vented Lens Hoods ~ WHY?

While shopping around for new lens hoods for my Pentax 14mm DA F2.8 ED (IF) (77mm dia) and my DA 18-135 ED AL (62mm dia),
I came across 'Vented' generic lens hoods which caught my eye.
I'm sure the Pentax originals are the best, but prices are over the top for a little bit of plastic.

Has anyone used vented hoods?
And what is the use of vents all about anyway?
I would love to hear your opinions


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03-14-2020, 03:19 PM - 3 Likes   #2
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"They are meant for use on rangefinder and viewfinder cameras on which a normal, solid hood would block part of the frame when looking through the viewfinder."

"the vents allow you to see through the hood when it blocks a portion of the finder."

This is what I googled.


I also bought couple of them in the past. They are cheap and help to protect the lens against scratching, but sometimes dust can get to the glass through the cut-outs.
03-14-2020, 03:22 PM - 3 Likes   #3
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You want airflow over the front element to reduce boundary layer adhesion to the front coatings, which can change optical properties and increase flare.

There is an actual good reason for the original vented hoods but now it just looks cool.
03-14-2020, 03:30 PM - 2 Likes   #4
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QuoteOriginally posted by Postumus Quote
Vented Lens Hoods ~ WHY?
Because lenses need to breath, just like you or I!

Actually, it is to provide a small peek space for the viewfinder when used on non-reflex cameras. The photos below might help since both show the viewfinder window and the "vent" slot.





Without the slots, the edge of the hood intrudes into the viewfinder frame.

P.S. Ventilated hoods are seldom, if ever, used with focal lengths shorter than 35mm on 35mm film (24mm on APS-C) .


Steve


Last edited by stevebrot; 03-14-2020 at 04:19 PM.
03-14-2020, 03:36 PM - 1 Like   #5
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QuoteOriginally posted by Just1MoreDave Quote
which can change optical properties and increase flare.
Don't forget CA! Without the vents the coatings can't do their job to end CA!


Steve

(...no, not true...)
03-14-2020, 04:42 PM - 3 Likes   #6
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QuoteOriginally posted by stevebrot Quote
Don't forget CA! Without the vents the coatings can't do their job to end CA!


Steve

(...no, not true...)
And here I thought it was to cool the lens and prevent hot pixels!
03-14-2020, 04:50 PM - 1 Like   #7
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QuoteOriginally posted by photoptimist Quote
And here I thought it was to cool the lens and prevent hot pixels!
Are you sure it's not to reduce the massive weight of a metal hood?
03-14-2020, 04:54 PM - 1 Like   #8
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Hey, they just look cool!

03-14-2020, 04:55 PM - 4 Likes   #9
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QuoteOriginally posted by stevebrot Quote
Because lenses need to breath, just like you or I!
as we all know, lack of air causes purple fringing.
03-14-2020, 05:28 PM - 1 Like   #10
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if it is windy


does it cause a whistle ?

or just cut down in wind resistance ?
03-14-2020, 06:03 PM   #11
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QuoteOriginally posted by aslyfox Quote
if it is windy


does it cause a whistle ?

or just cut down in wind resistance ?
I have never heard one whistle, though if a cap is on the end (mine accept caps), wind resistance might actually be higher. Vented hoods tend to be somewhat bulkier than the non-vented type.


Steve
03-14-2020, 07:09 PM   #12
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Originally range finders. Let's not get bogged down in mythical trivia here. Ocam's razor stuff.
03-14-2020, 08:25 PM   #13
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QuoteOriginally posted by pacerr Quote
Originally range finders. Let's not get bogged down in mythical trivia here. Ocam's razor stuff.
As a user of camera's with non-reflex optical viewfinders (rangefinders being a subset), I can assure you that the original market is intact and that the practicality still exists for current production gear. Translation...not a myth, original usage is still intact, and more than just rangefinders.

As for the famed earl's tool, it does apply and the highest probability of being correct rests with the single assumption that practical application of the vent feature is limited to use with cameras having non-reflex optical viewfinders; that being to see through the vent slot. Translation...good for use on that class of cameras.

Concluded:
  1. They make poor whistles
  2. The vents are incidental to the hood's purpose as a hood and do not enhance optical performance in any way
  3. They only look cool on reflex cameras if you don't know what they are used for
  4. Are appropriate for both film and digital cameras with non-reflex viewfinders where a lens hood might intrude into the frame
This may be the end of the silliness, but perhaps not.


Steve
03-14-2020, 08:46 PM - 1 Like   #14
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QuoteOriginally posted by Postumus Quote
I'm sure the Pentax originals are the best, but prices are over the top for a little bit of plastic.
I know...all we did is answer your question about the vented hoods. What we did not help with is finding a suitable hood for your two lenses. The Pentax-brand hoods are designed to work with the lens and the strange "tulip" shape reflects that goal. It will be difficult to find an aftermarket hood for your 14mm ultrawide that will be effective without vignette. Similarly, the hood on the zoom is a compromise between wide and long ends and will be difficult to find a generic hood that does as well as the original for that lens as well.

I did a bit of Web search for "PH-RBH 77mm" and "PH-RBC 62 mm" in the hope that there might be third-party clones, but came up with nothing. Are the original hoods beyond hope?


Steve
03-14-2020, 09:32 PM   #15
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Honestly the situations where these are worse performance wise than a solid round hood are few. Also, in the event of a fall, these will take more of the beating, kind of like having a crumple zone.
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