I asked this question over at dpreview but they don't seem to want to answer my question.....!

[quote]

Being a newbie to dslr I wanted to know how important it is to have lens hoods on your lens.

  When would they need to be used and when would they not be needed....?

I have the 18-55 kit lens that came with my XTi/D400 and just received my new 28-135MM IS lens today. :) I did order the Canon hood for my 28-135 along with a UV filter.[/quote]

" *Being a newbie to dslr I wanted to know how important it is to have lens hoods on your lens. When would they need to be used and when would they not be needed....? "

Very

Always

Never

Using a lens hood will shade the lens from unwanted light leaking into the lens.  The effect of this light is to reduce the contrast and detail in what is captured. In the worst cases it will result in lens flare losing all detail and contrast in the parts of the image affected. The worst cases will be when shooting into/near the light or with studio lighting.

The hood will also give the lens some protection from knocks between shots. On the front of lens when shooting and when finished reversed to protect the barrel of the lens when packed away.   I prefer to protect my lenses this way rather than by putting on a filter which will reduce optical quality, even if only marginally if you use high quality filters.  

The only occasion I don't use  hood is if it would disturb wildlife when shooting macros up close - very rarely.

Thank you for answering my question.
  Guess no one at dpreview wanted to answer my question.  Must be a place for Pros only. :)

on wide angle lens the hood can creat problems.I try and notice any flares and use my free hand to block the offending light source

Quote - on wide angle lens the hood can creat problems.I try and notice any flares and use my free hand to block the offending light source

I disagree - the hood, even on my 10-20mm is useful, and it is only when i zoom in that i can actually use my hand to shade the lens without getting it in frame...

Also, just to add something here: with such lenses the use of a filter increases the effect of the glare as the filter is further out from the actual lens so is easily reacheable by light not needed to take the picture.

interesting discussion. So what is preferred, a UV filter to protect the lens, or a lens hood?

I think a UV filter is a MUST.

If you're doing night photography and there aren't a lot of stray lights about to mess up your shot I don't use the lens hood. I do use it on my new Ultra Wide Angle because you can pick up flare from anywhere. At the same time the hood is really only good for light from directly above, because of the design of the petal hood I find it pretty useless for flare from the sides.

I do like having my hood on when walking around crowds as Richard says it saves the knocks and bumps.

About DP review, I think it's pretty much like anywhere the more you contribute the more you'll be 'seen' and the more will 'see' you, if that makes sense?

This reminds me of an old say.  Different strokes for different folks.   I guess everyone does things different and what ever works and they are satisfied with is all that matters.

 I finaly did get some answers at dpreview. Maybe I was wanting things to fast.  Thanks everyone for you answers to my question. :)

You've gotta admit, a hood also looks pretty keen impressive!  I use one and folks believe I know what I am doing.  LOL.

Well that's the other reason Tom but I was keeping quiet about that

OK I gotta just pick up on a couple of points.

*"what is preferred, a UV filter to protect the lens, or a lens hood?"
*Personal choice -  I will present one scenario and you decide. 
You are photographing standing on some rocks and decide to move position. The camera (on it's neck strap of course) slips round your neck and is headed for an impact with a rock. We all think we will be more careful and it won't happen, but it does ! 
This impact is not going to be flat on the end of the lens, but a more likely spot of just on the front edge where there is no glass. 
With a filter the filter smashes and shards of glass go straight to where the actual lens glass is. The thickness and solid rim of the filter absorb very little energy on impact it will mostly pass down into the lens barrel and the camera body. 
With a lens hood on the same impact deforms the shape of the hood and it snaps off its bayonet fitting detaching from the lens. Lots of energy is absorbed in the hood and does not pass down into the barrel of the lens or camera body.  

*"the hood is really only good for light from directly above, because of the design of the petal hood I find it pretty useless for flare from the sides."

*Not so - a petal lens hood is the most efficient design there is. because the image you're capturing is not round but rectangular through a round lens. The petal hood allows the hood to be longer  while not causing vignetting in the corners.  If the hood were round it would have to be much shorter, if it were rectangular, which is as efficient as a petal hood, it would not be so convenient in use and practicality. 

*"a UV filter is a MUST"
*Why?

Most night photography I have done is in urban spaces where there are lots of stray lights around so I would use a lens hood for night photography in this case. I agree if you had one light source from behind the camera then you may be able to dispense with the hood for flare purposes but not for lens protection purposes. 

"I try and notice any flares and use my free hand to block the offending light source"
A rare skill indeed - there are some cases where I would use some other form of shade - hand, hat, card etc but these are in specialist fields of advanced photography and the original poster said they were a newcomer. 

*"on wide angle lens the hood can create problems"
*I'm same as Rich on this one. I have not encountered any problems and I use an ultra wide angle lens in landscape and architectural photography. 

As you said: Iloco -   Different strokes for different folks.
 

All valid point brought up, good discussion everyone. I remember some of my old lens hoods. There was a rubber one that popped forward and then could be collapsed back. Another was a metal sheath variety with 3 telescoping elements. All were perfectly round and I never noticed vignetting, though I might if I go back and look today. I always leave mine on unless I am doing close-up work.

Regarding the UV filter...Yes, I agree with Onlsow on this....it won't protect from a fall or good bump.  I also don't like the idea of another piece of glass in front of the lens....BUT in saying that, I DO use one most of the time...LOL.  It does give me some protection in case of finger prints, water spotting...or accidentally hitting a leaf with sap while taking a macro....

Regarding the lens hood....I know I should use them...but I find them to be a pain to put on and then reverse for storage.

Regarding the use of a free hand to block the light source....hasn't worked for me...I'd need to be an octopus....

One final comment on UV filters....Do NOT use them to take Aurora photos....I found this out the hard way...they create an interesting effect that resembles Newton's Rings on your image.  I  had this happen on my first attempt...thought the filter was touching the lens...NOT...Tried again loosening the filter thread..same thing. Tried without any filters...no rings.
 I did some research on the web and found others having the same result...something to do with the frequency...I'll see if I can find the link again.

For those interested in my experience with the UV filter/Aurora and the "Newton Ring" result, here is the link I mentioned in my thread above.....

http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00A5d5