lens hood... do they work?

Ok so do lens hoods really work? when is the ideal time to use them?
i posted taking pics thorugh a fence.. it didnt work too great.. well i wasnt up on the fence.. next time...

but my 85mm does not have a hood...
iso 100
1/1000
f/1.8

BRIGHT PICTURES!!!!!!!!!!! ill get pics up later... but none are worth using unless i can get photoshop to darken them up ALOT.....

curious if i just need to get a hood for my lens...

Yes.
Almost always.
Hoods protect the front element and reduce or eliminate stray light.

TeleFragger wrote in post #11357661
BRIGHT PICTURES!!!!!!!!!!! ill get pics up later... but none are worth using unless i can get photoshop to darken them up ALOT.....

curious if i just need to get a hood for my lens...

Hoods don't correct for exposure errors...

I would never use a lens without a properly designed (for the particular lens) rigid lens hood attached.

A hood blocks stray light that can degrade an image. A rigid hood also provides a tremendous amount of protection from the daily dings that a lens will receive and the hood keeps the photographer's own fingers off the lens element.

I use a hood with older and less coated lenses (from the 1960's and prior to multi coated lenses). Some people debate the need for modern multicoated lenses.

I think of a hood as a baseball cap for my lens. Think of a time when you look into a bright light, such as towards the sun and a baseball cap (or hat with a brim) helped to see into the harsh light.

If I am shooting into the sun and do not have a hood, I will place my hand or piece of cardboard (a baseball cap works) over the top of the lens and near the front of the lens to reduce flair - assuming I do not want the flair.

Hoods can also help to keep rain or snow from the front surface.

I have a dedicated hood for each lens I own and it is always attached. Physical protection as well as protection from stray light. A hood has saved a lens from damage more than once.

TeleFragger wrote in post #11357661
Ok so do lens hoods really work? when is the ideal time to use them?
i posted taking pics thorugh a fence.. it didnt work too great.. well i wasnt up on the fence.. next time...

Wrap your fingers around the hood and use that hand to center the lens through one of the fence 'diamonds' for best results.

The hood will protect the lens from being scratched by the fance.

A hood will not change the exposure.

SkipD wrote in post #11357706
I would never use a lens without a properly designed (for the particular lens) rigid lens hood attached.

A hood blocks stray light that can degrade an image. A rigid hood also provides a tremendous amount of protection from the daily dings that a lens will receive and the hood keeps the photographer's own fingers off the lens element.

+1

Hoods are always on my lenses when in use, they improve IQ a lot of the time and add protection ALL the time.

gasrocks wrote in post #11357733
I have a dedicated hood for each lens I own and it is always attached. Physical protection as well as protection from stray light. A hood has saved a lens from damage more than once.

Gasrocks,

Where do you get hoods for the older lenses? Do you look for ones made for the lens or interchange them based on the focal length and filter size. Or is there some generic source you use.

Sometimes it is hard to get a hood with the lens when I purchase the older lenses.

For example, I am wondering if something like this will work for a 180 f/2.8. The filter size is 72, so I now it will mount. I wonder about the length of the hood or how to determine what will fit for a length.

http://cgi.ebay.com …m33598754bd#ht_​611wt_1139

Or a source such as this one.

http://www.camerafilte​rs.com/pages/lenshoods​.aspx

Actually, a hood can change the metered exposure because it does reduce the level of light that enters the mirror box...but it reduces light that you don't want to affect the measurement anyway. You don't usually want to count flare as measured light.

To answer the OP's question at a very basic level about how the lens hood works:

The lens projects a circular image into the mirror box (some lenses do have internal rectangular baffles which help a bit, but most do not). Obviously, the mirror box and the sensor are rectangular, which means a great deal of light that enters the lens isn't going to build the image on the sensor. Instead, it splashes around within the camera.

Some of it is absorbed by the black mirror box walls. Some of it bounces back out through the lens. But a lot of it bounces back to the sensor as overall flare.

If the level of unwanted light is very high--such as from a bright sky, or sand, or ocean background--it will be 'way too much light for the mirror walls to absorb. That's when you see it as noticeable flare. Notice, this is not just from a specular point source, but even from an overall bright background. The issue is not "point source" or "broad source," it's a matter of the amount of light being too great to be absorbed by the inner surfaces of the camera.

But a well-designed hood, such as the "petal" hood or a compendium (bellows) hood actually intrudes into the circular view of the lens so that instead of the lens "seeing" bright sky in those portions of its view that won't be part of the image, the lens "sees" only the dark interior of the lens hood petals. It's like the bill of a baseball cap cutting off the sky part of your own view. There is still a circular image being projected by the lens into the camera, but the extraneous portions are now dark instead of bright, and the mirror box is able to absorb that lower level of light.

I get lot of my hoods from HeavyStar on eBay. They are marked normal, wide or telephoto. Of course, if you are using a crop body you can and should use a longer hood than otherwise.

i think they do a lot, but it all depends on angles.

I have had a student drop my camera onto the concrete. They are still alive because the hood hit the pavement first, breaking apart into 3 pieces. Camera, lens were unmarked and worked fine. A little glue and paint and the hood is ok. Has happened more than once I am sad to say but the hood saved the day every time.

gasrocks wrote in post #11358037
I get lot of my hoods from HeavyStar on eBay. They are marked normal, wide or telephoto. Of course, if you are using a crop body you can and should use a longer hood than otherwise.

never heard of that.... so i should have a longer hood than a typical as i have a crop?

also just bought one on fleabay... dont know from who.. and yeah from china.. have bought a few things from china and has been fine...

$4.04 free shipping...

TeleFragger wrote in post #11358135
never heard of that.... so i should have a longer hood than a typical as i have a crop?

Unless the lens was specifically designed for a crop sensor (EF-S, etc), yes. The hood for the 17-40 is WIDE because the 17-40 is really wide on FF. On a crop, the hood isn't nearly as effective. Basically, a hood should block as much light as possible without vignetting.

Never go without a hood. My $.02.