Lens speed: Not always the best choice
 

On Fri, 10 Jul 2009 08:20:27 -0700 (PDT), RichA wrote:

People buy fast lenses for 2 reasons:
-The want the speed to capture action.
-They want the shallow DOF afforded by such lenses.

For for the first reason, speed is not always the best choice.
Shooting at a higher ISO sometimes works out better than using a lens
wide open and once you determine that it does for a specific lens,
then there is generally no reason to shoot a specific subject at the
wider aperture. The benefits are better image quality (fewer image
aberrations), possibly more accurate focus and the potential to use a
much cheaper lens. The downside is noise and giving up shallow DOF.

Here is an example of a shot at 800 ISO with a lens wide open and 1600
ISO with the lens stopped down. Shutter speeds were the same, so you
aren't giving that up.

The trick is to determine which lenses fall into this category.

http://www.pbase.com/andersonrm/imag...08342/original

I thought all lenses worked better if stopped down... Maybe a high quality lens
at f2 could beat a crap lens at f8... but the quality lens at f8 would be even
better.

What camera did you use for those shots?

|GG| Lens speed: Not always the best choice
 

Rich wrote:
On Jul 10, 10:16 pm, wrote:
On Fri, 10 Jul 2009 08:20:27 -0700 (PDT), RichA wrote:
People buy fast lenses for 2 reasons:
-The want the speed to capture action.
-They want the shallow DOF afforded by such lenses.
For for the first reason, speed is not always the best choice.
Shooting at a higher ISO sometimes works out better than using a lens
wide open and once you determine that it does for a specific lens,
then there is generally no reason to shoot a specific subject at the
wider aperture. The benefits are better image quality (fewer image
aberrations), possibly more accurate focus and the potential to use a
much cheaper lens. The downside is noise and giving up shallow DOF.
Here is an example of a shot at 800 ISO with a lens wide open and 1600
ISO with the lens stopped down. Shutter speeds were the same, so you
aren't giving that up.
The trick is to determine which lenses fall into this category.
http://www.pbase.com/andersonrm/imag...08342/original
I thought all lenses worked better if stopped down... Maybe a high quality lens
at f2 could beat a crap lens at f8... but the quality lens at f8 would be even
better.

A lens has to be pretty awful not to work well centrally at f8.0. But
some lenses are amazing wide open. Nikon's 14-24mm f2.8. Check out
the output from an Olympus 35-100mm f2.0, it's pretty amazing.
What camera did you use for those shots?

Panasonic G1.

What's the f/2 lens?

--
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Lens speed: Not always the best choice
 

wrote:
On Fri, 10 Jul 2009 08:20:27 -0700 (PDT), RichA wrote:

People buy fast lenses for 2 reasons:
-The want the speed to capture action.
-They want the shallow DOF afforded by such lenses.

For for the first reason, speed is not always the best choice.
Shooting at a higher ISO sometimes works out better than using a lens
wide open and once you determine that it does for a specific lens,
then there is generally no reason to shoot a specific subject at the
wider aperture. The benefits are better image quality (fewer image
aberrations), possibly more accurate focus and the potential to use a
much cheaper lens. The downside is noise and giving up shallow DOF.

Here is an example of a shot at 800 ISO with a lens wide open and 1600
ISO with the lens stopped down. Shutter speeds were the same, so you
aren't giving that up.

The trick is to determine which lenses fall into this category.

http://www.pbase.com/andersonrm/imag...08342/original

I thought all lenses worked better if stopped down.

Generally _most_ lenses are sharpset stopped down 2 - 3 stops from wide
open. Most diffract to a softer image beyond f/11, noticeably so beyond
f/16 or so - though in most common print sizes this not usually noticeable.

Likewise, the softer wide open shots only show as soft at 8x12" or so
(for a 35mm cropped sensor camera)

Lens speed: Not always the best choice
 

On Sat, 11 Jul 2009 12:23:51 -0400, Alan Browne
wrote:

wrote:
On Fri, 10 Jul 2009 08:20:27 -0700 (PDT), RichA wrote:

People buy fast lenses for 2 reasons:
-The want the speed to capture action.
-They want the shallow DOF afforded by such lenses.

For for the first reason, speed is not always the best choice.
Shooting at a higher ISO sometimes works out better than using a lens
wide open and once you determine that it does for a specific lens,
then there is generally no reason to shoot a specific subject at the
wider aperture. The benefits are better image quality (fewer image
aberrations), possibly more accurate focus and the potential to use a
much cheaper lens. The downside is noise and giving up shallow DOF.

Here is an example of a shot at 800 ISO with a lens wide open and 1600
ISO with the lens stopped down. Shutter speeds were the same, so you
aren't giving that up.

The trick is to determine which lenses fall into this category.

http://www.pbase.com/andersonrm/imag...08342/original

I thought all lenses worked better if stopped down.

Generally _most_ lenses are sharpset stopped down 2 - 3 stops from wide
open. Most diffract to a softer image beyond f/11, noticeably so beyond
f/16 or so - though in most common print sizes this not usually noticeable.

Likewise, the softer wide open shots only show as soft at 8x12" or so
(for a 35mm cropped sensor camera)

This is only true for all poorly figured DSLR glass. The same cannot be
said for true diffraction-limited glass (the most precise lens polishing
that money can buy), as is found in nearly all higher-quality P&S cameras.

Simple test: If you open up your aperture wider at any point and the image
gets worse, that is NOT diffraction-limited optics. Meaning, it's just
poorly figured glass. DSLR buyers are so easily fooled. They still live by
that oft-disproved saying "you get what you pay for". The lens and camera
makers more than happy to take advantage of their naïveté and ignorance.

Lens speed: Not always the best choice
 

Praying They Don't Educate Themselves wrote:
Alan Browne
Likewise, the softer wide open shots only show as soft at 8x12" or so
(for a 35mm cropped sensor camera)

This is only true for all poorly figured DSLR glass. The same cannot be
said for true diffraction-limited glass (the most precise lens polishing
that money can buy), as is found in nearly all higher-quality P&S cameras.

LOL!

Simple test:

If somebody claims that a $400 camera has optics that are as good as
those in a $2000 lens then they are a liar or a crackpot.

--
Ray Fischer

Lens speed: Not always the best choice
 

Themselves wrote:
...true diffraction-limited glass (the most precise lens polishing
that money can buy), as is found in nearly all higher-quality P&S cameras.

Specific examples... ?

Lens speed: Not always the best choice
 

On 11 Jul 2009 18:58:47 GMT, (Ray Fischer) wrote:

Praying They Don't Educate Themselves wrote:
Alan Browne
Likewise, the softer wide open shots only show as soft at 8x12" or so
(for a 35mm cropped sensor camera)

This is only true for all poorly figured DSLR glass. The same cannot be
said for true diffraction-limited glass (the most precise lens polishing
that money can buy), as is found in nearly all higher-quality P&S cameras.

LOL!

Simple test:

If somebody claims that a $400 camera has optics that are as good as
those in a $2000 lens then they are a liar or a crackpot.

http://www.luminous-landscape.com/reviews/kidding.shtml

Lens speed: Not always the best choice
 

In rec.photo.digital.slr-systems Ray Fischer wrote:
Praying They Don't Educate Themselves wrote:
Alan Browne
Likewise, the softer wide open shots only show as soft at 8x12" or so
(for a 35mm cropped sensor camera)

This is only true for all poorly figured DSLR glass. The same cannot be
said for true diffraction-limited glass (the most precise lens polishing
that money can buy), as is found in nearly all higher-quality P&S cameras.

LOL!

Simple test:

If somebody claims that a $400 camera has optics that are as good as
those in a $2000 lens then they are a liar or a crackpot.

If the optical design playing field was level. Which it most certainly
isn't in this case.

Cost depends on the optical problems the lens has to solve. A DSLR
lens has to deliver its intended quality while leaving enough room
between sensor and rear lens element to accomodate the mirror. That
adds a lot to the cost of lenses of shorter focal lengths.

--
Chris Malcolm

Lens speed: Not always the best choice
 

Troll REALLY Is This Dense wrote:
(Ray Fischer) wrote:
Praying They Don't Educate Themselves wrote:

Alan Browne
Likewise, the softer wide open shots only show as soft at 8x12" or so
(for a 35mm cropped sensor camera)

This is only true for all poorly figured DSLR glass. The same cannot be
said for true diffraction-limited glass (the most precise lens polishing
that money can buy), as is found in nearly all higher-quality P&S cameras.

LOL!

Simple test:

If somebody claims that a $400 camera has optics that are as good as
those in a $2000 lens then they are a liar or a crackpot.

http://www.luminous-landscape.com/reviews/kidding.shtml

Q.E.D. Your'e a liar AND a crackpot who didn't even notice that the
web page you cite refutes your stupid claim.

--
Ray Fischer

Lens speed: Not always the best choice
 

Chris Malcolm wrote:
In rec.photo.digital.slr-systems Ray Fischer wrote:
Praying They Don't Educate Themselves wrote:
Alan Browne
Likewise, the softer wide open shots only show as soft at 8x12" or so
(for a 35mm cropped sensor camera)

This is only true for all poorly figured DSLR glass. The same cannot be
said for true diffraction-limited glass (the most precise lens polishing
that money can buy), as is found in nearly all higher-quality P&S cameras.

LOL!

Simple test:

If somebody claims that a $400 camera has optics that are as good as
those in a $2000 lens then they are a liar or a crackpot.

If the optical design playing field was level. Which it most certainly
isn't in this case.

Cost depends on the optical problems the lens has to solve. A DSLR
lens has to deliver its intended quality while leaving enough room
between sensor and rear lens element to accomodate the mirror.

And if you have a tiny sensor then you certainly can compromise the
lens quality to match the sensor's abilities.

--
Ray Fischer