What's with a "VENTED HOOD?"

[Trankster]

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45 minutes ago, Jskywalker said:

Agree with the “venting” part. 
Do you notice any difference in image quality between a round and square hood ?

I have not tested one versus the other, but have experienced no loss of image quality.  I would think it is the same as going hoodless, except for the flare protection. 

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[erl]

6 hours ago, Jskywalker said:

Agree with the “venting” part. 
Do you notice any difference in image quality between a round and square hood ?

Here is a theoretical answer for you, based on real life practice with Hasselblad cameras. The same theory applies to all lenses, regardless of camera used.

In another life I did a lot of studio work and a lot of field work. There were times when lights or the sun or any other light source would cause lens flare. The only way to prevent it is with an effective lens hood. Hasselblad made a bellows compendium that fitted most of their lenses and was adjustable in length to suit a specific scenario. The increase in contrast could be seen through the viewfinder when the bellows was correctly adjusted. It even included masks to be inserted at the from of the bellows for very long lenses, to exactly match the viewing angle of the lens. To this day, that bellows compendium is still in my Blad kit bag. Occasionally, I curse afterwards that I did not fit it when I should have, instead relied on the standard lens hood.

So, it is a balance between convenience and perfection. Watch professional videographers and film crews. They nearly always use a compendium lens hood!

[Woodstock]

I have always been led to believe that anything other than the bellows type hood beloved of cinematic photographers was a compromise in terms of flare and ghosting avoidance, but recently came across one of Hudson Henry's YouTube postings in which he posited that for almost all “domestic” situations, the coatings on modern optics mitigated against such problems occurring even when shooting directly into the sun. He didn’t specify the Q3 as an example, but was holding one as he spoke, and has made many posts about it, so it may be related. He did specifically mention studio lighting as one area where in his experience it might be more prudent to rely on a significant hood, but otherwise suggested that with modern optics a hood's main benefit was physical protection of the front element, rather than flare protection.

[erl]

5 hours ago, Woodstock said:

I have always been led to believe that anything other than the bellows type hood beloved of cinematic photographers was a compromise in terms of flare and ghosting avoidance, but recently came across one of Hudson Henry's YouTube postings in which he posited that for almost all “domestic” situations, the coatings on modern optics mitigated against such problems occurring even when shooting directly into the sun. He didn’t specify the Q3 as an example, but was holding one as he spoke, and has made many posts about it, so it may be related. He did specifically mention studio lighting as one area where in his experience it might be more prudent to rely on a significant hood, but otherwise suggested that with modern optics a hood's main benefit was physical protection of the front element, rather than flare protection.

It will always remain a balance between perfection and convenience. The only difference between a 'domestic' and 'commercial' situation will be the need to comply with an accepted standard. Both situations will experience the same effect from external light sources. The difference is usually how it is dealt with. Modern lens coatings are a great thing, but modern lenses will still benefit from effective shading. An extreme example that I encounter periodically, is in the use of my 50mm f1.0 Noctilux lens. The built in lens hood is virtually useless for shading. I do get lens flare from it, partly because the UV lens attached does catch more side flare/reflection. I live with it because in that case there is no practical solution.

[Woodstock]

Entirely happy to agree with your point that there is a “balance” to be reached, not only between perfection and convenience, but also of course with the effect of coatings on the physics of transmission versus reflectance. To be fair to Hudson, I don’t think he was advocating that we should as a matter of principle throw our hoods away unless we want physical protection, more that he was pointing out that modern coatings have gone some considerable way to mitigate what was previously a more major problem.

[S Maclean]

I use the polar pro flip hood, identical to the leica but it flips open and allows for fast filter changing.  Also use the hood as a visor sometimes when I stack filters