Questions about wide-angle and macro lenses!


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babykailan

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#1
hello boys and girls!
i have these questions which had been burning me up since last night!

1. wide-angle prime lenses!
i understand prime lenses when wide open at biggest apertures tend to have a relatively small area of focus compared with the rest of the image ie. background all oof. i thought when using wide-angle lenses, you want to take it all in with everything in sharp focus and doesnt that mean having to stop down to achieve overall sharpness for the whole image? that defeats the purpose of having a big aperture in the first place isnt it?

2. macro / zoom / tele lenses!
let's consider the 70-300 lenses from both canon and sigma. the sigma lenses states clearly it is capable of macro shots but the canon doesnt. can the canon lenses take good macro shots? in the case of the sigma, what is its primary function - a zoom, a tele and then to throw into the mix, a macro lens? what is this ratio thing for macro lenses, 1:1, 1:2, etc.?
 

bluemoon

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Jan 25, 2005
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#2
1. Yes it's true when you shoot landscape you want everything from the fore to the background to be in focus, so you stop it down to as small an aperture as possible. But all lenses have a range of apertures you can use, from big to small, from the range of 1.4-4 to 22 or 32 or even 64. Wide-angle lenses can be used for other applications besides landscape photography, where you want to have less depth-of-field

2. The macro mode on the SIgma allows you to shoot at a shorter minimal focusing distance (1m as compared to 1.5m or something like that, you can check the lens specs for the exact distances), which means you can go closer to the object and hence it is bigger on your shot.

SHooting at 1:1 means that the size of the image on the 35mm film will be exactly the same as the size of the object in real life. 1:2 means that the size of the image will be half, and so on. There are lenses which go up to 5:1 which means the image is 5 times the size of the object on the film. This is on the film itself so when you enlarge the film during developing it becomes even bigger.

Hope that answers your questions :D
 

Liew

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#3
for wide angle shots, normally you'll be using a tripod to get the best capture. however, there might be times at low light that you need to handheld a wide angle lens. result might not be as sharp as f/5.6 photo, but you get what you need. normally, the lowest best apperture is 2x the widest apperture of the lens.

if everyone is shooting at f/11, the quality of the photos does not make much difference. so wide apperture is for just in case you might need to use it case...and it's convinient
 

creampuff

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Jul 11, 2006
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#4
hello boys and girls!
1. wide-angle prime lenses!
i understand prime lenses when wide open at biggest apertures tend to have a relatively small area of focus compared with the rest of the image ie. background all oof. i thought when using wide-angle lenses, you want to take it all in with everything in sharp focus and doesnt that mean having to stop down to achieve overall sharpness for the whole image? that defeats the purpose of having a big aperture in the first place isnt it?
Understand that depth of field is a function not just of aperture size but the focal length of the lens and focusing distance. So if you have say a 50 mm lens versus a 24 mm set say at f2.8 and focused at the same distance, the wideangle will exhibit greater depth of field. That's why with a wideangle lens the hyperfocal distance for a given aperture will always be shorter than a normal or tele. Yes stopping down will increase sharpness and DOF but with a wide angle lens you'll find there is quite significant DOF unless one is focusing at very near objects.

A large aperture for a wide angle is certainly useful in low light situations. But such wideangle lenses don't come cheap.

2. macro / zoom / tele lenses!
let's consider the 70-300 lenses from both canon and sigma. the sigma lenses states clearly it is capable of macro shots but the canon doesnt...
These aren't true macro (needs to go 1:1 or lifesize) but merely have a low minimum focusing distance. In other words, marketing hype.
 

creampuff

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Jul 11, 2006
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#5
for wide angle shots, normally you'll be using a tripod to get the best capture. however, there might be times at low light that you need to handheld a wide angle lens. result might not be as sharp as f/5.6 photo, but you get what you need. normally, the lowest best apperture is 2x the widest apperture of the lens.

if everyone is shooting at f/11, the quality of the photos does not make much difference. so wide apperture is for just in case you might need to use it case...and it's convinient
Actually a tripod would be much more needed on a tele than a wideangle. I don't know where you got the idea about the lowest best aperture is 2X the wideset aperture of the lens. So if a lens has an aperture of f2, the optimum aperture to get the sharpest image is f4? Not a reliable rule to follow.

A faster lens has the big advantage of a brighter viewfinder which help focusing a lot.
 

Liew

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#6
Actually a tripod would be much more needed on a tele than a wideangle. I don't know where you got the idea about the lowest best aperture is 2X the wideset aperture of the lens. So if a lens has an aperture of f2, the optimum aperture to get the sharpest image is f4? Not a reliable rule to follow.

A faster lens has the big advantage of a brighter viewfinder which help focusing a lot.
telephoto definately needs a tripod, i.e 200-600mm but if you're serious about capturing a good architacture or wide angle photo, a tripod is needed to get the balance between the horizon and etc.

i'm not saying that if the lens is f/2, the best aperture is f/4 but most of the time, the LOWEST BEST aperture, (meaning the lowest aperture to get the sharpest image) would be at f/4. at f/2, normally, it would not get the sharpest image, but for certain lenses, such at the f/2.8, it would still be sharp, never as sharp as it would be at f/4. it's not super reliable, but it's a guide.

and i don't think lens with larger aperture has anything to do with fast focusing at all. corrent me if i'm wrong but all my f/2.8 lenses focuses better than the f/1.8
 

babykailan

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#7
thanks all, still digesting the infomation.

but can the canon 70-300 take good macro shots?
my heart wants the canon lenses but my pocket says no.

there is not much price difference between the canon 10-22 and the sigma 10-20. so i will probably go for the canon one. ;p
 

fireframe

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#8
there is not much price difference between the canon 10-22 and the sigma 10-20. so i will probably go for the canon one. ;p
Wah, few hundred leh.. 'not much' ah.. :bigeyes:
 

tmfwy

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Feb 14, 2005
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#9
thanks all, still digesting the infomation.

but can the canon 70-300 take good macro shots?
my heart wants the canon lenses but my pocket says no.

there is not much price difference between the canon 10-22 and the sigma 10-20. so i will probably go for the canon one. ;p
Taken with a Canon 70-300mm IS



Not much of a macro, but you get the drift.

It takes beautiful shots with vivid colours. What is good about it is that it has IS....
 

babykailan

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#10
Wah, few hundred leh.. 'not much' ah.. :bigeyes:
the context in which i made this statement is from the comparison of 2nd-hand prices between these two types of lenses - wide-angle & 70-300.

based on the observation of the BnS forums, the difference betw the canon and sigma wide-angle lenses is about $100-200+, which is 'not much' relative to the difference betw the 70-300mm lenses that can be as much as 3.5 times - canon ~$900+, sigma ~$250+ ...

hence i am thinking of going sigma for 70-300 and canon for wide-angle.
 

tmfwy

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Feb 14, 2005
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#11
the context in which i made this statement is from the comparison of 2nd-hand prices between these two types of lenses - wide-angle & 70-300.

based on the observation of the BnS forums, the difference betw the canon and sigma wide-angle lenses is about $100-200+, which is 'not much' relative to the difference betw the 70-300mm lenses that can be as much as 3.5 times - canon ~$900+, sigma ~$250+ ...

hence i am thinking of going sigma for 70-300 and canon for wide-angle.
Well, the canon variant has Image Stabiliser for the 70-300mm. IMO, you cannot compare the Sigma to the Canon variant with IS.

If you are looking at cheap teles, the Sigma 70-300mm macro takes my vote over the canon 75-300mm

For wide angle either the canon 10-22mm or sigma 12-24mm are great choices. :)
 

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