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Sigma 24-70 2.8F Lens Query
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A quick question for all you lens buffs out there.
I?ve just bought Sigma lens (24-70 EX DG 2.8F). Indeed a lovely lens.
The lens has a constant aperture of 2.8F at all focal lengths.
So tell me … What mode should I be shooting in generally speaking, to get the best results?
Aperture Priority? (which would seem to contradict the constant 2.8F) Time Value priority? Fully automatic? Fully manual? Or does it even make a difference?
Am using a Canon 350D.
Prey tell good people???
Obliged v mucho.
Nif you’re good with figuring exposure then full manual with every lens. i use av (aperture priority) alot cause i travel with my parents and they like to rush me (or even worse, tell me what to take pics of while i’m trying to take pics of what i want)..
i’m not sure what you mean by this :Aperture Priority? (which would seem to contradict the constant 2.8F)
with aperture priority mode you pick the aperture and iso and camera figures the time..
bethHi Niallo,
I doubt very much that the lens will fixed to F2.8 It would make it very limited in its usefulness.
Generally the aperture information in the spec of a lens means that this is the widest possible aperture at a particular focal length. So in your lens you will be able to shoot with a widest aperture of F2.8 throughout the focal length range, but this does not mean you wont be able to shoot at smaller apertures. In aperture mode you should be able to change the aperture F8, F16 etc and the lens should respond accordingly (probably down to F32 or something like that).
In brief, stopping down to smaller apertures (the higher the number the smaller the aperture) will give you more depth of field to your photo’s.
Hope this helps
Gary
I understand about stopping down and shutter speeds in relation to apertures. The lens I bought is considered a ‘Fast’ lens. It’s for low light situations. It has a constant 2.8 aperture. which meant it is essentially a fixed lens but with a zoom.
It will mainly be used for wedding photography inside churches/reception areas without using a tripod. Yes, i’ll have a very short DOF all the time with it but that’s the idea. It’s for portraits and closeups of people.
So my query was because the aperture is ‘fixed’ at 2.8 (and can not be changed) does it make a difference in which mode I shoot in? Bearing in mind that I will be adjusting the shutter speed to suit the exposure.
Niallo wrote:
the aperture is ‘fixed’ at 2.8 (and can not be changed).
I’d kinda doubt that very much,
though I don’t know the lens-I’d say that it means that f/2.8 is your widest aperture throughout the range,
but smaller apertures should also be selectable-Though I don’t know about canon either-
Seems like I don’t know much, and I’m making up the rest-
not much new there then-j
hi niallo, this lens is not fixed at 2.8 – constant just means that you can have 2.8 at all focal lenghts. Some lenses require the aperture to narrow as focal lenght increases e.g would be marked as 3.5-5.6..if you just test put the lens in AV and turn the wheel you will see the aperture change and the shutter speed vary to compensate..
jb7 wrote:
I’d kinda doubt that very much,
though I don’t know the lens-I’d say that it means that f/2.8 is your widest aperture throughout the range,
but smaller apertures should also be selectable-Though I don’t know about canon either-
Seems like I don’t know much, and I’m making up the rest-
not much new there then-j
you got it right that the f/2.8 is the widest aperture for all focal lengths with that lens. and it holds true for canon. the aperture isn’t fixed, it can be changed.
heres a shot (not mine) taken with the same lens at f/13:
http://www.pbase.com/rb2105/image/27296310&exif=Y
bethI think I’m going to have to be found to be corrected on this one. I’ve just done more research on the web about it. All the reviews talk about the 2.8 aperture and nothnig else … Bar one! Some bloke gave a review about it in other aperture values. 8,11, etc right up to 32!
I cant check it just yet as I dont have it, am collecting it on Friday.
I’ll get back to you then to confirm if you wish.If it has a variable apertures then well and good. Just as long as it goes to 2.8 I dont mind.
Link below if you’re interested.
http://www.photographyreview.com/cat/lenses/35mm-zoom/sigma/PRD_88759_3128crx.aspx
Thanks folks. I’ll now toddle off into a dark corner and listern to the masses behind me shouting “I told you so!”
Looks like there’s a bit of confusion here regarding the term fixed, so let me offer this explanation to try and clarify.
There are fixed aperture lenses which one can get where the aperture is literally fixed, i.e., it cannot be changed. These lenses are typically mirror lenses and their method of construction means that it’s not possible to incorporate an aperture in them. They were popular in the eighties but I haven’t come across them much in recent times as lens technology has moved on significantly.
These days when someone loosly refers to a fixed aperture lens when talking about a zoom lens, they generally mean that the lens’ maximum aperture remains the same throughout the zoom range. A more correct term, which has already been used above is “constant aperture”. This is usually a sign of a better quality lens, with an price tag to match. Cheaper zoom lenses will have a different maximum aperture across the zoom range. So if for example, you had a 28-75mm, f/3.5-5.6 lens it means that the maximum aperture at 28mm is f/3.5 and goes right down to f/5.6 at 75mm. What is essentially happening is that the lens is getting darker as you zoom it in to 75mm. This is down to simple physics – as you zoom in, you increase the magnification and an increase in magnification results in less “light gathering power”. Macro shooters would be particularly familiar with this problem. A lens that doesn’t change it’s maximum aperture like this has to have additional functionality designed into it in order not to get darker as you zoom in.
There was also mention made above of “a fixed lens but with a zoom”. That’s a contradiction in terms! A fixed lens is a fixed lens and by virtue of this fact has only one fixed maximum aperture. A zoom lens doesn’t become a fixed lens simply because it has a non-variable maximum aperture across the zoom range.
As to how to use it, well, use it as you would any other lens. It will only have a very short DOF if you choose to use it at it’s maximum aperture. If you do so, that’s your choice. But there is nothing to stop you using it at f/4.0, f/5.6, f/8.0, etc. And there is no reason why you can’t use it in Av, Tv, Prog, or Fully Manual modes.
Now I know I’m probably not going to be too popular for saying this, but I believe in calling a spade a spade! Let me preface it by saying that I think more people should be asking questions like this. (Isn’t it better to look stupid and become clever than to look clever and remain stupid!) Having said that, do you really think you are ready to photograph one of the most important events in a persons life if you have to ask a question like this? You owe it to yourself and to your customers that you can use your equipment blindfolded before you tackle a wedding. I don’t get the feeling here that you are in that position just yet.
[EDIT] – Looks like a whole lot of useful replies came in whilst I was drafting mine, so it makes some of my reply somewhat redundant!
jb7 wrote:
Seems like I don’t know much, and I’m making up the rest-
Forgive me for saying so, but I very much doubt that!
Thorsten wrote:
(Isn’t it better to look stupid and become clever than to look clever and remain stupid!)
I like it…. is this Thorsten original or a something from Confucius?
Also thanks Thorsten for enlightening me on the existance of a true fixed aperture lens, whether relevant or not in this instance.
Banter banter. Marvellous stuff.
Thorsten, you’re a living encyclopaedia of photographic knowledge.
Joseph, you’re a self-deprecating cad… and I always laugh.:lol:
Rob.
Having said that, do you really think you are ready to photograph one of the most important events in a persons life if you have to ask a question like this? You owe it to yourself and to your customers that you can use your equipment blindfolded before you tackle a wedding. I don’t get the feeling here that you are in that position just yet.
well said thorsten
Thanks Thorsten. Ok, I dont think I made myself clear in my posts. So without going through everything again, I’ll just bow down gracefully.
Point taken about photographing a wedding an not knowing my gear inside and out. However, I certainly wouldn’t attempt to shoot somesomes wedding without firstly knowing my gear inside and out, (and all my equipment to date, I know inside out.) In relation to this newer lens (of which I have no experience with as yet) … well, I’ll have gotten to know that inside and out too, before any big day arrives.
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