Purpose of Lens Hoods?

[Sahil]

I am not clear about the uses of Lens Hoods. From what I know is that its used in day-light. Do their different shapes and designs mean anything?
I know these are way too basic questions but...

[Colin Southern]

Hi Sahil,

Their main function is to reduce or eliminate lens flare from strong light sources hitting the front element of the lens from outside of the lenses field of view. Their shape is determined by the field of view; if they're too deep then they will cause vignetting, but if they're too shallow then their effectiveness is reduced.

Some will argue that they also serve to protect the front element from knocks and pokes etc, but in my experience they're easily knocked off and a UV filter provides far better protection.

[Sahil]

Thanks, Colin.

[Donald]

Sahil

I also have an idea that for a lot of people, a lens hood is seen as something of a status thing - 'My gear (and therefore I) looks more professional if it has a cool looking lens hood'. Now, that may be very unfair of me. But, that's how it seems to be sometimes.

They are, of course, extremely valuable and useful in those situations where they are required. I find, however, that my adaptor rings and filter holders are more permanenetly fitted to the lenses than a hood. All depends on what it your are doing with the lens.

[Colin Southern]

Sahil

I also have an idea that for a lot of people, a lens hood is seen as something of a status thing - 'My gear (and therefore I) looks more professional if it has a cool looking lens hood'.

The other possibility might be that you see hoods on L-Series lenses more often because the lenses ship with them, whereas with non L-Series they generally don't.

[Sahil]

'My gear (and therefore I) looks more professional if it has a cool looking lens hood'

Lol!
I agree...
Any trade-off if they stay on the lens? And they should be used when pointing towards the source of light (Sun, Lamp etc.) or when in strong light?

[Steaphany]

Any trade-off if they stay on the lens?

Storage space & access of filters - Each of my Sigma lenses came with a lens hood and no two are the same. When mounted on the respective lens, the whole assembly is obviously larger and take up more space than I'm willing to provide in my already huge Pelican 1600 case. A problem that I have with these lenses is access to the filters. When a lens hood is in place, it is nearly impossible to reach down to add, remove, or in the case of my polarizer, adjust, the mounted filters. I'm not sure if this is universal to all lens brands or if I just happen to have purchased the worse offenders.

And they should be used when pointing towards the source of light (Sun, Lamp etc.) or when in strong light?

If the light source is within the field of view, as photographing a Sunrise or Sunset, a lens hood as no effect. Also, a lens hood is not needed if the light source is behind, where the lens body and possibly the camera body actually cast a shadow over the front element.

The greatest impact of a lens hood is when the light source is in front of the lens, but not actually within the field of view. This is because the light is actually falling on the front lens element.

I have read articles by photographers on lens hood use and some say to keep it on all the time. It's my view that a lens hood, just as with any addition to the front of a lens, needs to be a decision made by the photographer. There have been times when lens flare actually gave a nice effect to an image that would have been lacking if I used a lens hood. Unless I feel that I need a lens hood on a particular shoot, I keep my lens hoods at home in their boxes.

[benm]

Lol!
I agree...
Any trade-off if they stay on the lens? And they should be used when pointing towards the source of light (Sun, Lamp etc.) or when in strong light?

I keep mine on the lens all the time. And to answer your original question, the hood shape is designed to minimize extraneous light from entering the lenses (flare) without causing any vignetting. For a zoom lens the hood is obviously only most effective at the wide end. If you are going to buy a hood get one made specifically for your lens rather something generic.

[Dave Humphries]

Any trade-off if they stay on the lens? And they should be used when pointing towards the source of light (Sun, Lamp etc.) or when in strong light?

Clearly if the ONLY light source is the one already in shot, then, barring reflections of it off axis, the lens hood won't be any help - but if you see something out the corner of your eye and pan around to shoot that, the light source may contribute flare if no hood is fitted.

So my advice, and personal practice (until I start using filters and change my mind ), is always to fit it (facing the right way, not reversed for stowage).

When might I take it off?
When, using a macro lens, I am so close an insect that the extra length might cause the insect to fly, jump or hop off.

At least with Nikon, you always get a lens hood (in my experience).

Cheers,

[Dave Humphries]

I keep mine on the lens all the time. And to answer your original question, the hood shape is designed to minimize extraneous light from entering the lenses (flare) without causing any vignetting. For a zoom lens the hood is obviously only most effective at the wide end. If you are going to buy a hood get one made specifically for your lens rather something generic.

I agree with all this Ben,

The only time I have found a generic (rubber circular) lens hood useful is when you want to push the lens up against viewing glass to exclude reflections from behind and around you; e.g. with some aquariums and zoos with big enclosure windows.

[Geoff F]

I normally reverse them to fit within my camera bag. And I remove them when using the basic camera flash (not externally mounted 'real' flash) on macro subjects otherwise a flash shadow can occur.

I'm not sure if it is just my imagination but I think using the rather long (4 ins) hood on my 180 mm macro lens gives a better depth of colour. But I do wonder if it scares close insects or actually allows me to get closer because the lens, and any reflections, are hidden.

I was thinking about painting the outside of the hood with shades of green for insect work. Has anybody tried this?

[JK6065]

Just one more question from my side.

If a lens hood is to long (deep) than it causes vignettering, if it's too short it has no effect at all (that's clear to me), but what about when shooting with a (super)zoom lens? I have a sigma 18-125mm lens with a lens hood. When shooting at 18mm my shots don't suffer that much from vignettering. So assuming that the lens hood works well at 18 mm than am I wrong to think that at a focal length greater than 18mm the lens hood looses effect very rapidly? The field of view gets smaller when zooming but the lens hood doesn't (therefore a lens hood for a tele lens is much longer and narrower than one for a wide angel lens).
Is the lens hood than useful when zooming since it only start operating at a set angle from a centre line you could draw through your lens?

[Steaphany]

...am I wrong to think that at a focal length greater than 18mm the lens hood looses effect very rapidly?

No, your are not wrong, The geometry of the lens hood would need to change for every possible focal length that the lens can be set to. Obviously, lens manufacturers provide hoods for the widest field of view but rarely, if at all, for anything else.

I have seen some manufacturers who produce adjustable lens hoods which employ a bellows that is set to the field of view of the lens.

[Colin Southern]

No, your are not wrong, The geometry of the lens hood would need to change for every possible focal length that the lens can be set to. Obviously, lens manufacturers provide hoods for the widest field of view but rarely, if at all, for anything else.

Canon have come up with an interesting "work-around" with the EF 24-70mm F2.8L USM -- as the lens is zoomed OUT (to a wider angle), the front element moves FORWARD - so the hood, although quite "agressive", is none-the-less effective over a wide range of angles.

[Bill44]

At least with Nikon, you always get a lens hood (in my experience).Cheers,

About the only one that does not come with a hood is the 50mm 1.8D

As for lens hoods, I'm of the leave it on at all times school, only reversing it when it goes into my bag, but then again I'm an outdoor sports shooter.

[Sahil]

Thanks everyone for the replies, everyone.

Dave:-

At least with Nikon, you always get a lens hood (in my experience).

I didn't get any hood with my Nikon D3000. (18-55mm Kit Lens)

Actually, I will be meeting my cousin sis, who is getting me a 70-300mm lens, at the airport and we will be leaving for Ladakh, India. Its a cold desert and a BEAUTIFUL place. Heaven on earth! It is gonna be quite sunny there. So I wanted to take a lens hood along. As I have dealt with just one lens till now, I didn't know that for every other lens type one would need different lens hood.
And obviously I can't ask her, what make, type of lens is she getting.
But I guess my 18-55mm would be of more use for landscapes....

[Blazing fire]

Colin: "Some will argue that they also serve to protect the front element from knocks and pokes etc, but in my experience they're easily knocked off".

Under what circumstances did that happen? Did the hood break off or something?

Donal: "I also have an idea that for a lot of people, a lens hood is seen as something of a status thing - 'My gear (and therefore I) looks more professional if it has a cool looking lens hood'. Now, that may be very unfair of me. But, that's how it seems to be sometimes".

Agreed. I like the look of lenses with hood too.

[Colin Southern]

Under what circumstances did that happen? Did the hood break off or something?

I've knocked mine off a few times; the "problem"* is that the threads are relatively weak and with a medium to deep hood there's quite a lot of moment generated if you swing around and bang the side of the hood into something. On the other hand, if you drop a lens with a hood attached so that it lands hood first then there's so much enertia behind a relatively heavy lens that it just pushes the hood past the threads - so in my experience, as a protective device, it's about as effective as putting a sticking plaster on a gunshot wound.

* I say "problem" because this behaviour could well be by design.

At the end of the day, I've found lens hoods to be very effective against stray light, and UV filters VERY effective at protecting front elements.

[Bill44]

Most, but not all, Nikon lens hoods are attached by a bayonet type mount which is separate from the thread, and a lot stronger. Just one of the things that make Nikon superior to Canon.

[pwnage101]

I can normally tolerate flare for day-to-day snapshots, but if I'm looking for quality I'll shade the lens with my hand. Hoods are just too bulky for me, but that's me.