Why do some lens hood have slits holes?

[peter_kim2]

I know about tulip shades for zooms but I noticed some lens hood

have flared ends that have slits in them anyone know what these are

for? I have seen them on the new lenses for the Bessa cameras and

some leicas. I'm guessing maybe its cause the lens hood blocks the

rangefinder and the slits gives you at least some view of the

blocked image?

 

Just curious...

[Ed_Ingold]

Not knowing what you have seen, I can only describe something familiar to me.

 

A hood for the Leica 50/2 Summicron is shaped like an inverted cone, with open segments in the base. The openings allow you to see through the viewfinder with the hood in place. The angle of the cone presents a thin edge to the viewfinder. Older hoods blocked a significant portion of the view. The rangefinder is not blocked in either case.

[michaelging]

Peter that is a very good question ,I have noticed the same thing and wonderd why myself.

[dan flanders]

A response on another thread suggests that the ventilated hoods are cooler!

[charles_stobbs3]

Also a cone shaped lens shade would reflect light into the lens if it weren't painted dull black. They really only cut off light from outide the image area while tending to somewhat reflect light in the image area into the lens. The reverse cone solves this problem.

[alex_lofquist]

Edward is exactly correct. I have used one of these cutout hoods on my Leicas for many years.

[Jochen_S]

Mamiya TLR Hoods are the same. They are square but the upper Part can be liftet afew degrees to allow mare view with the viewing lens through a slit.