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jimsloy
24th of October 2003 (Fri), 15:42
Just bought a SIGMA 17-35 f/2.8 for the 10D. Came with what I think is called a lens hood. Why do I need that?

robertwgross
24th of October 2003 (Fri), 15:52
If you are shooting anywhere near the direction of the sun, and if the sunlight gets into the front of the lens, then you will get "sun dogs" which flare across the image. Typically, that ruins a perfect image, although some people use that to prove which direction the lens was aimed.

It does not have to be normal sunlight that ruins the image. It could be any really bright light from the side or the front. About the only time that you don't need a lens hood is if you are out shooting distinctly away from the sun, or in darkness.

Some people use the cheap lens hood as protection to the expensive lens.

---Bob Gross---

w10d
24th of October 2003 (Fri), 16:04
To avoid flare.

Simply: A strong light source (like the sun) can strike the front of your lens and cause flare on your image. Generally not good. But not always, hence the Lens Flare filter in photoshop. :D

This type of flare appears as bright discs, or octagonal shapes like the diaphragm in the lens (sometimes mistaken for UFOs).

Sometimes flare just causes a general softening in the image (which can cause you to start photographing rulers - don't ask).

The hood is a simple way of avoiding flare when shooting towards a light source, cheaper, but not always as effective as using an assistant to shade the lens with their hand. :)

HTH

CyberDyneSystems
24th of October 2003 (Fri), 16:20
And indeed it adds a level of protection to the front lens element as well as in some case the whole camera. I belive I read on this very forum of someone who dropped there camera,. it landed on the lens hood breaking that,. but both the lens and camera were fine.

When walkng in dense underbrush etc.. the hood will protect the lens (or even a pricey filter) from being cratched by a branch that would otherwse be able to drag across the element..

But yes,. the primary intended function is lens flare.
It can help with your images beyond obvious flare though... any light that is hitting any part of the front lens element that is not needed for the rectangualr film/ccd can be detrimental to some extent. The less extraneous light you have bouncing around within your lens elements the better. To what extent this light actually effects the image quality is debatable, but many insist that a hood can greatly improve image quality in certain situations.

EXA1a
24th of October 2003 (Fri), 16:25
Bob and HTH nailed it down. Maybe one addition: ANY light entering the lens system from outside the angle of view causes flare or artifacts in the picture. I read a comment of a professional who uses a lens hood for any shot just to be sure, and for lens protection.
Okay, the problem is getting smaller with very good multispectra coating of the lens surfaces, but it's still there.

--Jens--

iwatkins
24th of October 2003 (Fri), 17:12
Jimsloy,

All good advice above.

I have the same lense and use it more than any other. If you look at the front element of the lense you will notice that is is quite a prominent dome shape.

Now imagine shooting something with the sun almost directly overhead. The light (glare) from the sun will just touch the front of that dome. I.e. the front of the lense sees the sun even though it isn't in the frame you see through the viewfinder. Of course, that light is very bright and is going to bounce backwards and forwards inside the lense with some of it finding its way to the sensor.

I don't have any shots to prove it to hand but I've seen the effect of not using the hood in these situations. You cannot see any obvious flare, that comes when the sun is more towards the front, but you do see an overall "haze" over almost the whole image.

Only thing I don't like about the hood supplied is that it is quite difficult to turn a circular polariser with the hood on. Even so, I now never shoot without the hood on with this lense especially.

If you are not sure, basically don't shoot without it if any bright lights (sun, light, reflections) are anywhere close to being in front of you.

Cheers

Ian

HoldenMan
24th of October 2003 (Fri), 20:18
It will also help protect the front filter from sand, dust and other debri on a windy day. Additionally, if you ever shoot in the rain it will help keep the rain off the front element (which is a great way to ruin a shot :P)

jimsloy
25th of October 2003 (Sat), 21:22
Thanks everyone for the info. One more question these answers beg: Why is this lens the only one w/ a hood (that I own)? My other lens 28-105 didn't come with a hood. Given your replies, I should think they would apply to *all* lenses, no?

Or is it b/c the surface glass on the Sigma sticks out slightly beyond the body of the lens, and my Canon 28-105 glass doesn't?

Thanks again for all the quick replies.

CyberDyneSystems
25th of October 2003 (Sat), 21:29
Most quality lenses come equiped with hoods,. but Canon will make you pay extra in some cases.

Sigma ,. as a "number two" maker in town has to try harder. So there good lenses tend to come with all the bells and whisltels that others may make you pay extra for. (like tripod mounting collars on midrange telephotos,.. canon will charge you 150.00 AFTER you allready spent $1,700.00 on a 70-200mm IS,.. where as Sigma gives you a good onw with its $600.00 70-200mm

All my lenses came with hoods except for the 50mm f/1.8

jimsloy
25th of October 2003 (Sat), 21:55
So we can now effectively say that you can judge a lens by its hood!! It would appear that my 28-105 is circumsized and barely hits 6 inches at full length.

I knew that Canon 28-105 was a cheap ass paper weight that magnifies light onto a CCD sensor behind it!!!! :)

HoldenMan
26th of October 2003 (Sun), 04:55
I heard off somewhere that sigma are more likely to include lens hoods, something to do with marketing or something like that.

You can get a lens hood for all your lenses, they don't cost a great deal for the smaller lenses, on canon's website it says which hood to buy

k_s_rajeev
27th of October 2003 (Mon), 20:57
Does any one know about the LENS hood for a

ZENOTAR Fisheye.

Thank you.

Jesper
28th of October 2003 (Tue), 05:19
jimsloy wrote:
Thanks everyone for the info. One more question these answers beg: Why is this lens the only one w/ a hood (that I own)? My other lens 28-105 didn't come with a hood. Given your replies, I should think they would apply to *all* lenses, no? ...


Yes it applies to all lenses, but Canon just wants you to pay again for the hood. I had to order the hood for my 28-135 IS USM, it took a month before the store got it and it cost a fortune (€ 45 - about US$ 52 for a piece of plastic). Only Canon's expensive "L" series lenses have the hood included.

PrimoFelis
28th of October 2003 (Tue), 12:42
I just wish Canon would come out with a new set of lens hoods sized for the 1.6x cropping factor for 10D, D Rebel, etc, especially for the more flare-prone zooms and wider EF lenses.

The current hoods for EF lenses are obviously sized for the 35mm full frame, and so they are a bit less effective than they could be when used on a DSLR with less than the full 35mm format sensor.

To avoid possible confusion between the different format sizes, maybe they could use a different color on the outside of the new hoods (rather than the usual black), perhaps? How about pink. (Kidding.)

(To Canon: Hint, hint.)

DaveG
28th of October 2003 (Tue), 13:17
PrimoFelis wrote:
I just wish Canon would come out with a new set of lens hoods sized for the 1.6x cropping factor for 10D, D Rebel, etc, especially for the more flare-prone zooms and wider EF lenses.

The current hoods for EF lenses are obviously sized for the 35mm full frame, and so they are a bit less effective than they could be when used on a DSLR with less than the full 35mm format sensor.

To avoid possible confusion between the different format sizes, maybe they could use a different color on the outside of the new hoods (rather than the usual black), perhaps? How about pink. (Kidding.)

(To Canon: Hint, hint.)

I would agree if I thought that these potential new lens hoods would actually shade the
lens. Even with a regular Canon film camera and the 24x36 mm format, the current
shades are way too short.

There are any number of reasons to doubt that effective shades for the smaller CMOS
will ever be made: First, the shades would have to be much longer than they are now and
that would make transportation more difficult. Then they may also be too long to store
inverted on the lens as Canon shades are now. And for the zoom lenses it's obvious that
the shortest part of the focal length - say 70 in a 70-200 zoom - would have to be what the
shade is optimized for to prevent vignetteing; but it would call into question that shade’s
effect at 200 mm.

The path of least resistance for me was to buy a Lee bellows shade. It’s very light so I
don’t feel like it’s stressing out my lenses like my Lindahl does on my Mamiya Pro-TL. I
have 58, 67 and 77 mm adapter plates so other than my non USM 100 mm macro lens
(which seems to have a built in lens shade) I can use this hood on all of my lenses, from
the 16-35 (well from about 21 mm out) to the 200 part of my 70-200.

I should also say that I have and use the regular lens hoods for all of these lenses (16-35,
24-85, 50, 70-200) and I use them when for whatever reasons it's inappropriate to use the
Lee. I do this since an inadequate shade is better than no shade at all.

PrimoFelis
28th of October 2003 (Tue), 15:53
DaveG wrote:
...
There are any number of reasons to doubt that effective shades for the smaller CMOS will ever be made:
...


Okay. In that case, I will settle for a cheap DSLR with a full 35mm frame CMOS sensor, so there won't be a need for different lens hoods for (small CMOS) DSLRs. :)

But seriously, I guess I subscribe to the notion that every bit helps. So I find myself still wishing for a simple but resized hood for my 17-35mm lens on DRebel, for example. At least for this lens, I'd estimate that the larger/different size wouldn't be prohibitive or impractical.

Not that I'm holding my breath for it. And if I wanted it badly enough, I'm sure I could fabricate one myself. Maybe I will... (Especially if the current hood is that ineffective even for the 35mm full frame.)

Fixed-size lens hood for a zoom is always a (big) compromize. The Lee bellows shade does sound like a good idea for many lenses based on your account. Too bad it won't work for

DaveG
28th of October 2003 (Tue), 17:01
But nothing works with a true 21 mm lens or my 16 either.

For fun I put the Canon lens shade from my 70-200 f2.8L onto the 16-35 f2.8L just to see what would happen. On the 10D - and it's obvious that it would be a lot worse on a full frme SLR - the 70-200's hood only started to vignette when I was about 24 mm (effectively what, about 35 mm?) or wider.

The professional approach there is to have an off the camera shade (a flag) that just aims a shadow at the front of the lens. This implies that either the whole thing is locked down with stands and tripods, or more likely that an assistant holds the flag.

PrimoFelis
28th of October 2003 (Tue), 17:08
Re. EF Lens hood optimized for smaller CMOS size.

A thought occured to me that perhaps the lens hood for my Canon EF70-200 f/2.8 L would fit on my EF17-35mm f/2.8 L.

They looked about the same size where they mated with the lens.

Guess what? It perfectly does! (Duh!)

I run a quick test with my Digital Rebel, and found that the hood works great on the 17-35 + Digital Rebel combination at focal lengths greater than about ~22 mm. At the focal length 22mm the hood barely shows at the edges of frame. Of course at focal lengths less than 22mm the lens hood shows at the edges of the image.

(Your mileage may vary a bit.)

So, conceivably, I COULD just buy another lens hood for the "wrong" lens, carefully reshape it with a Dremel tool until it no longer showed in the image at the 17mm end, and end up with a lens hood optimized for the smaller CMOS size? Anything wrong with this idea?

Or, there might even be a different existing Canon lens hood that fits and works better (for the smaller CMOS sensor size).

Thank you DaveG. I wouldn't have thought of this without your comments. :)

(To Canon: Never mind about my previous hints.)

PrimoFelis
30th of October 2003 (Thu), 18:37
Re. Better Canon lens hoods for smaller CMOS sensor sizes

I see that we both thought of trying the same thing at about the same time. :)

I don't want to stray too far off the original topic, but as a followup (in case anyone else is interested), potential candidates for swapping for the Canon 83mm size hoods are as follows:

For the Canon 83mm hood mount size series:

1. EW-83 (II) (Originally for EF20-35mm f/3.5-4.5)
2. EW-83B (II) (EF28-70 f/2.8L)
3. EW-83C (II) (EF17-35mm F2.8L)
4. EW-83D (II) (EF24 f/1.4L)
5. EW-83E (EF16-35mm f/2.8L, 17-40mm f/4L)
6. EW-83F (EF24-70 f/2.8L)

7. ET-83 (II) (EF70-200 f/2.8L)
8. ET-83B (II) (EF200 f/2.8L II)
9. ET-83C (EF100-400 f/4.5-5.6L IS)

(Compatibility is not guaranteed.)

Experimentation is the only way to determine which one will fit and work best as is or as a starting point for a modification. For example, I understand that EW-83B hood for 28-70 lens is, rather unexpectedly, only slightly shorter than ET-83 for 70-200. This is apparently because the 28-70's front element moves forward relative to the hood as it zooms wide. For my own use, EW-83F (for 24-70mm lens) looks promising for 17-35mm + DRebel/10D combination, but I don't know for sure.

I read somewhere that EW-83B for 28-70 does fit fine on 17-35, so as a starting point for a mod it would even be a better choice than ET-83 for 70-200 that I previously mentioned.

For other Canon lens hood sizes, here is a current lens hood list as a PDF file:
http://www.usa.canon.com/eflenses/pdf/spec.pdf

And the photo of each lens hood (not all) here:
http://www.usa.canon.com/eflenses/accessories/

and more at this Japanese site here:
http://cweb.canon.jp/camera/ef/accessary/hood/index-j.html

slin100
30th of October 2003 (Thu), 20:12
David Burren confirms (http://www.burren.cx/photo/ew83d.html) that the EW-83DII works on the 16-35 and the 17-40 when used with a 10D. I wonder if that has anything to do with the EW-83DII being out of stock everywhere? I can't seem to find one. :-(

He also speculates on a few other lenses, too. Check the link.

PrimoFelis
30th of October 2003 (Thu), 23:15
Steven thanks much for the useful link.

I just did a search and found this thread from 6 months ago, that adds more thoughts on this topic:

http://www.photography-on-the.net/forum/showthread.php?t=14986#78115

FYI.
---
PS. and here too:
http://www.mail-archive.com/eos@a1.nl/msg20959.html

slin100
31st of October 2003 (Fri), 13:01
Oh yes, I'm remember seeing that article, now. I would never consider cutting up a EW-83B II to fit a 17-40. I'll wait for B&H to get an EW-83D II in stock.

CyberDyneSystems
31st of October 2003 (Fri), 15:08
I was not using the EW83b on any other lens,. I got the used one for $10.00 from MarinePark (risky!) and have indeed "cut it" a bit...

it works hreat. It is my 17-40 lens hood. It was amazing how little I had to trim it to get it to function wthout vignette on the 17-40mm.

A simple temporary fix would be to take a peice of black heavy card stock paper and wrap it around your exisiting lens hood. Trim the leading edge of the card stock to match the profile of the "petals" on your lens hood. Then start to slide the paper tube forward,. beyond the edge of the hood,. keep going untill you see the first sign of vignette,. then back off a fraction.

Ths is sort of how I figured out where to cut the EW 83B...