I've got a unhealthy mindset/mentality


NikonMI6

New Member
Nov 1, 2009
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#1
hey guys, just started out photog this year feb.. as an amateur.. didn't really have much
time or resources to go deep into it.. however, as i visit forums and read reviews, i've built up
a thinking that whenever a lens has an constant aperture of f2.8, i will think that lens is of
top grade..

but sometimes i wonder that there are lenses of variable aperture which produces images that
will somehow be better than some of those lenses with constant aperture? or is it really true
that those lenses with constant aperture will always be better than lenses with variable
aperture of similar focal length?

please help me understand the photog world better.. :) thanks!


EDIT: excluding prime lenses as none of them involves variable apertures! and this category totally slipped my mind..
 

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Sep 14, 2009
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#2
can't say anything for nikon but canon's 15-85mm performs well despite having variable aperture.

and i think your mentality is flawed, primes are top grade if u ask me :D
 

zac08

Senior Member
Feb 21, 2005
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#3
hey guys, just started out photog this year feb.. as an amateur.. didn't really have much
time or resources to go deep into it.. however, as i visit forums and read reviews, i've built up
a thinking that whenever a lens has an constant aperture of f2.8, i will think that lens is of
top grade..

but sometimes i wonder that there are lenses of variable aperture which produces images that
will somehow be better than some of those lenses with constant aperture? or is it really true
that those lenses with constant aperture will always be better than lenses with variable
aperture of similar focal length?

please help me understand the photog world better.. :) thanks! :)
It may be better in certain areas, but it's not always the better choice when you consider economics and weight/size.

And it's not always the case to be the same for all f2.8 lenses. For e.g. a Nikon 28-70mm f2.8 is much better in terms of optical quality than a Tamron 28-75mm f2.8. But the price difference is SO much. $2.5k to 2.6k vs $500-$600.

So would you want to spend such money for the optical improvement?? :)
 

night86mare

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Aug 25, 2006
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#4
constant aperture = better?

oh boy.........

the only thing that a constant aperture zoom offers is a constant aperture. that's all.

the faster constant aperture zooms are faster, that's all. it's just a name.

there are non-constant aperture zooms that work perfectly fine and are tack sharp stopped down.
 

fatigue

Senior Member
Sep 26, 2005
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#5
Here's the secret to the constant aperture.



There's a slanted slit that adjust the aperture as you zoom in and out.

You can try it yourself, observe the aperture of the lens as it zooms in and out.
The aperture will close a bit in it's shorter focal length. :)
 

NikonMI6

New Member
Nov 1, 2009
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.:North of Singapore:.
#7
constant aperture = better?

oh boy.........

the only thing that a constant aperture zoom offers is a constant aperture. that's all.

the faster constant aperture zooms are faster, that's all. it's just a name.

there are non-constant aperture zooms that work perfectly fine and are tack sharp stopped down.
hmmm.. so let's say we have Brand X have 70-200 f2.8 and 70-300 f4-5.6,
will an image taken @ 100mm f5.6 from 70-300 f4-5.6 be sharper than an image taken @ 100mm f5.6 from 70-200 f2.8?

p.s. please do not associate above examples with any brands :)
 

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NikonMI6

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Nov 1, 2009
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#8
It may be better in certain areas, but it's not always the better choice when you consider economics and weight/size.

And it's not always the case to be the same for all f2.8 lenses. For e.g. a Nikon 28-70mm f2.8 is much better in terms of optical quality than a Tamron 28-75mm f2.8. But the price difference is SO much. $2.5k to 2.6k vs $500-$600.

So would you want to spend such money for the optical improvement?? :)
if money is not an issue, why not? and in this case, i am comparing constant
aperture lenses and variable aperture lenses of similar focal length.. :) instead
of IQ of both constant aperture lenses.. :)
 

night86mare

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Aug 25, 2006
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#10
hmmm.. so let's say we have Brand X have 70-200 f2.8 and 70-300 f4-5.6,
will an image taken @ 100mm f5.6 from 70-300 f4-5.6 be sharper than an image taken @ 100mm f5.6 from 70-200 f2.8?

p.s. please do not associate above examples with any brands :)
it really depends, there are constant aperture lenses that are not really that sharp... if you don't know that, then you need to get out more.
 

Rashkae

Senior Member
Nov 28, 2005
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#11
Depends on the lens. The Sony CZ 16-80 is stupidly sharp at almost all apertures, quite frequently beating "constant aperture" lenses at the same aperture. Same with the Sony 70-300G.

The main benefit for constant aperture lenses is that the aperture is constant... Makes setitng and fixing the exposure easier too, as well as allowing for faster shutter speeds due to the extra stops of light hitting the sensor (assuming you're shooting at a larger aperture than the variable-aperture lenses are capable of). But sharper or better? Not necessarily, no.
 

Akatsuki

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Mar 2, 2008
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#12
I believe this is a phase that most of us underwent when we just started out in photography...

When i got caught on the heat of digital photography... i was like you and became obsessed with fast zoom and purchase the Canon EF 28-70 f/2.8L USM... Unfortunately, i sold it within 6months after acquiring it. It's still listed down on my list as my worse photography investment thus far ;p ... The only benefit it has is the convenience of a zoom at fixed f/2.8... and at a terribly prohibitive price!

Having say that, most important is know what you need. If you need a zoom at fixed f/2.8, by all means get the 24-70 or 70-200 f/2.8...

If not, you can get fast primes and zoom with your feet! Cheaper, lighter and better optical quality! ;)
 

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scorpioh

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Jul 17, 2007
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#13
I am almost a total prime shooter. F2.8 is actually quite slow in my opinion. But that's about as fast as zooms can get right? Yeah, right.
 

sfoto100

Senior Member
Nov 29, 2009
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#15
hmmm.. so let's say we have Brand X have 70-200 f2.8 and 70-300 f4-5.6,
will an image taken @ 100mm f5.6 from 70-300 f4-5.6 be sharper than an image taken @ 100mm f5.6 from 70-200 f2.8?

p.s. please do not associate above examples with any brands :)
the answers are in the lens review...

it all depends on what u shoot... if u shoot landscape.. u usually use smaller aperture ... to have wide dof... in this case, constant aperture does not help... and even cheap lens becomes sharp when stop down...

anyway, no need to be so sharp la... look at those film pics by great pg in the past... not sharp, but got feel... i love them..

content is more important...


pls see http://www.lebeck.de/

not so sharp right?

fyi, in photozone.de canon kit lens 18-55 is very sharp... kit lens nowadays can really produce good results... dun play play...
 

NikonMI6

New Member
Nov 1, 2009
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.:North of Singapore:.
#17
Depends on the lens. The Sony CZ 16-80 is stupidly sharp at almost all apertures, quite frequently beating "constant aperture" lenses at the same aperture. Same with the Sony 70-300G.

The main benefit for constant aperture lenses is that the aperture is constant... Makes setitng and fixing the exposure easier too, as well as allowing for faster shutter speeds due to the extra stops of light hitting the sensor (assuming you're shooting at a larger aperture than the variable-aperture lenses are capable of). But sharper or better? Not necessarily, no.
hmmm.. so for those who doesn't require constant aperture,
there are lenses out there for them which are cheaper and
produces better image quality than those with constant aperture?
 

NikonMI6

New Member
Nov 1, 2009
71
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.:North of Singapore:.
#18
I believe this is a phase that most of us underwent when we just started out in photography...

When i got caught on the heat of digital photography... i was like you and became obsessed with fast zoom and purchase the Canon EF 28-70 f/2.8L USM... Unfortunately, i sold it within 6months after acquiring it. It's still listed down on my list as my worse photography investment thus far ;p ... The only benefit it has is the convenience of a zoom at fixed f/2.8... and at a terribly prohibitive price!

Having say that, most important is know what you need. If you need a zoom at fixed f/2.8, by all means get the 24-70 or 70-200 f/2.8...

If not, you can get fast primes and zoom with your feet! Cheaper, lighter and better optical quality! ;)
oh.. tot I am only one of the few out there who has
this kind of mentality.. haha.. I know primes are good
but I believe having a zoom lens is good in case there's
a time when switching between lenses is almost impossible.. :)

and prime with long focal length don't come cheap I believe..
 

NikonMI6

New Member
Nov 1, 2009
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.:North of Singapore:.
#19
the answers are in the lens review...

it all depends on what u shoot... if u shoot landscape.. u usually use smaller aperture ... to have wide dof... in this case, constant aperture does not help... and even cheap lens becomes sharp when stop down...

anyway, no need to be so sharp la... look at those film pics by great pg in the past... not sharp, but got feel... i love them..

content is more important...


pls see http://www.lebeck.de/

not so sharp right?

fyi, in photozone.de canon kit lens 18-55 is very sharp... kit lens nowadays can really produce good results... dun play play...
hmmm.. I think I should read more reviews.. most of the reviews I've
read usually compare lenses of the same class, that is, same focal length
and of constant aperture.. if not when they review the lens individually,
they seldom relate it to other lenses..

on the other hand, I can't always be stopping down to achieve that particular
sharpness, sometimes one do require that extra stop of light.. unless shooting
landscape with tripod..

I will bookmark the link first, surfing with my phone now.. can't view that site
correctly..
 

wildcat

Senior Member
Sep 8, 2004
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Bedok
#20
hmmm.. so let's say we have Brand X have 70-200 f2.8 and 70-300 f4-5.6,
will an image taken @ 100mm f5.6 from 70-300 f4-5.6 be sharper than an image taken @ 100mm f5.6 from 70-200 f2.8?

p.s. please do not associate above examples with any brands :)
Actually, it might. Generally lenses are not at it's sharpest wide open, and optimally, you need to stop down lenses by one to two stops at least to see the full potential of the lens. This is just a general number as each lens has it's own optimal sharpest aperture.

I used to own a Panasonic m4/3 len 45-200mm f/4-5.6 that was sharp at 45mm only from f/6.7 onwards. I didn't know at that time and wondered why pics I took with wider apertures kept coming out looking a bit "OOF" (actually was soft) but reviews from a number of people and websites have since confirmed that.

If I had a 45mm f/2.8 and I shot at f/4, it would have in theory given me a much sharper image than the other lens at f/4.

There are lenses which some reviews like to say "sharp wide open" but even so, stopping them down will generally still yield even sharper images.

On a separate note, if you shoot wide open and there is a choice between zoom lens of f/3.5-5.6 and a constant f/4, the reason why f/4 would be superior is when you zoom in and out, you still get the same amount of light in. Several photographers I've talked who have a penchant for using manual everything, having that means you can set your manual setting and not have to worry about different amount of light when you zoom in and out with aperture fully opened. Personally, I would just let the camera adjust the exposure automatically but yes, the camera has to do that by slowing down your shutter speed when you zoom in... and you know that when you zoom in, you need even higher shutter speed to compensate for shakes and stuff, right? If the camera slows down the shutter speed, then the shakes become even more apparent, blah blah... you get the point.

And yet one more thing, when you shoot at widest aperture, f/2.8 and f/3.5 may not seem like much but when you zoom in, f2.8 and f/5.6 has significant amount of light going in. Imagine bokeh (if you're into that) for a 100mm f/2.8 vs a 100mm f/5.6!
 

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