ham888
member
Reged: 11/06/2008
Posts: 190
Loc: Worcestreshire
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Hello
My lens has f/3.5-4.5 G IF marked on it. Why are there aperture settings on the lens.
Should I be forcing the camera's aperture settings to be within the f/3.5-4.5 range?
Or are they something to do with how the zoom affects the f/xx??
Help is much apprciated
Harry (newbie)
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Harry
My Flickr
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john_g
Pooh-bah Hoo-ha
Reged: 09/05/2007
Posts: 2190
Loc: Surrey
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This is just a way of saying how much light a lens can capture when the aperture is fully open. Zoom lenses often have a range of values, such as you've quoted, because the amount of light they can capture changes slightly depending on the zoom setting. You don't need to pay any attention to this when you use the lens - certainly it isn't telling you to only use the lens over that aperture range.
The reason it's important is:
1. Lenses that can capture more light are better at shooting in low light conditions (there are other differences too, but that's the main one).
2. Lenses that can capture more light cost loads more! For example, look at the cost of a 200mm F2.8 lens compared to a 200mm F4 lens - the former lets in twice as much light but will cost you a lot more, and be bigger and heavier because the glass elements need to be so much larger.
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John
The best things in life are not things.
http://www.flickr.com/photos/john_gass
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ham888
member
Reged: 11/06/2008
Posts: 190
Loc: Worcestreshire
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John
Thanks, very much appreciated. I'm on a BIG (and enjoyable) learning curve at present.
Harry
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Harry
My Flickr
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El Sid
Going potty
Reged: 14/04/2003
Posts: 9160
Loc: Sussex-by-the-Sea
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Quote:
Or are they something to do with how the zoom affects the f/xx??
Yes. Many, if not most, zooms do not have constant maximum apertures (which tends to be a feature limited to the 'best' lenses) and normally the effective aperture is smaller at the longer end of the lens. As a sort of rule-of-thumb the wider the maximum aperture and the smaller the variation the better the optical performance of the lens is likely to be (though it's no guarantee), the price also tends to go up too.
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Nigel
Completely BSRIPN 
ElSid Gallery
A camera in the hand is better than one in the cupboard........
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AlexMonro
addict
Reged: 05/06/2006
Posts: 689
Loc: Exeter, Devon (and Somerset so...
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I've just got myself one of these lenses (AF-S 18-70mm F/3.5-4.5) to go with my shiny new (well, 2nd hand  ) Fuji S3Pro. The things I particularly like about it are the good sharpness at pretty much any aperture and focal length, and the very good chromatic aberation. It's not quite so good for vignetting fully open at the wide end, and there is some distortion at wide angle, but these don't matter so much to me as I'm mainly interested in landscapes.
I found a very useful review with helpful interactive graphic charts at SLRgear, here.
CameraLabs gave it quite a good rating on their review here.
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ham888
member
Reged: 11/06/2008
Posts: 190
Loc: Worcestreshire
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Once again very useful and informative, thanks.
Heres another question - the hood (i guess thats what its called), the thing that snaps on the end to make you look uber proffesional.
What does it do exactly, should I be using it?
Harry
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Harry
My Flickr
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Benchista
Wich Tyler
Reged: 11/08/2000
Posts: 36431
Loc: Everywhere and nowhere, baby
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It does a number of jobs. It's designed to stop non-image forming light (flare) getting in, so a correctly-designed* hood can actually improve the quality of your pictures. It also helps protect the lens.
* Hoods for zooms are generally only really effective at the widest zoom setting.
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Nick
www.nbrphoto.com
Light and Shade II - the new blog
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john_g
Pooh-bah Hoo-ha
Reged: 09/05/2007
Posts: 2190
Loc: Surrey
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Yep. Imagine the sun isn't in the picture you're about to take, but it's close. In this case a lens hood effectively shields the front of the lens from any direct sunlight which might well cause flare or a general deterioration and softening of the image. I don't use them all the time - for example, when the sun is behind me, but there are times when they make an important difference and, don't forget, they can also be used to help protect the front of the lens from physical damage.
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John
The best things in life are not things.
http://www.flickr.com/photos/john_gass
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TimF
Senior Member
Reged: 30/07/2001
Posts: 15968
Loc: Herts/Beds border
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Yes, but as Nick says, the ones for zooms are usually only effective at the wide-end (although there are a handful of honourable exceptions). The wider the short end is the more of a problem this is. For a 17-35mm type I'd generally leave the hood in the cupboard as they are pretty useless, being so short. In those circumstances it might be worth trying a french flag instead.
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Tim BSRIPN
The camera makes everyone a tourist in other people's reality, and eventually in one's own - Susan Sontag
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Benchista
Wich Tyler
Reged: 11/08/2000
Posts: 36431
Loc: Everywhere and nowhere, baby
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Quote:
In those circumstances it might be worth trying a french flag instead.
I wonder how many here know what you're talking about there? 
What he IS talking about, gentle readers, is a piece of card or similar on an adjustable arm that can be positioned to block out the worst of the flare. I've got a variant called a Flarebuster with a flexible arm and foam rubber discs that does a perfectly OK job, but I don't know if it's still made, and I've not actually seen any alternatives on sale for a long while - perhaps I'm just not looking in the right place. Useful thing to have, and you only need one for all your lenses.
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Nick
www.nbrphoto.com
Light and Shade II - the new blog
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ham888
member
Reged: 11/06/2008
Posts: 190
Loc: Worcestreshire
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Quote:
Yes, but as Nick says, the ones for zooms are usually only effective at the wide-end (although there are a handful of honourable exceptions). The wider the short end is the more of a problem this is. For a 17-35mm type I'd generally leave the hood in the cupboard as they are pretty useless, being so short. In those circumstances it might be worth trying a french flag instead.
Hehe, now you know I'm a noob. French flag, a proper photographic term, a joke, a......? What is that.
Thanks again for all your help, I like it a lot.
I took a look at some of the poster Flicker / web pages - wow, some of those shots are awesome.
Hope to be that good one day,......and know about a French flag, let me think could it be the colours...??
Harry
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Harry
My Flickr
Edited by ham888 (20/06/2008 10:42)
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NorthernNikon
Bulls Hitter
Reged: 16/12/2005
Posts: 5312
Loc: Harrogate, North Yorks
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Quote:
Quote:
In those circumstances it might be worth trying a french flag instead.
I wonder how many here know what you're talking about there?
French flag - it's a bit like a French letter but looks better on your pole.
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www.BarneyAllen.com the new home of ComicShots.
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Norman
Reged: 23/09/2004
Posts: 1547
Loc: West London, UK
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Quote:
I've got a variant called a Flarebuster with a flexible arm and foam rubber discs that does a perfectly OK job, but I don't know if it's still made, and I've not actually seen any alternatives on sale for a long while - perhaps I'm just not looking in the right place. Useful thing to have, and you only need one for all your lenses.
Here ya go!
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Regards,
Norman
www.photobox.org.uk
A woman has the last word in any argument.
Anything a man says after that is the start of a new argument.
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ham888
member
Reged: 11/06/2008
Posts: 190
Loc: Worcestreshire
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Quote:
Quote:
In those circumstances it might be worth trying a french flag instead.
I wonder how many here know what you're talking about there?
What he IS talking about, gentle readers, is a piece of card or similar on an adjustable arm that can be positioned to block out the worst of the flare. I've got a variant called a Flarebuster with a flexible arm and foam rubber discs that does a perfectly OK job, but I don't know if it's still made, and I've not actually seen any alternatives on sale for a long while - perhaps I'm just not looking in the right place. Useful thing to have, and you only need one for all your lenses.
Ah, we posted simultaneously. You were answering my question at the same time I was asking it.
Spooky
Thanks
Harry
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Harry
My Flickr
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zx9
old hand
Reged: 22/06/2007
Posts: 830
Loc: London
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Lens hoods help keep the rain of your front element too.
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Regards
ZX9 (Keith)  
My Flickr Pictures
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