Newbie question re. sharpness

Hi,
I have what is hopefully a pretty basic question. I have a Canon 350D
with the two kit lenses:

* EF-S 18-55mm 1:3.5-5.6 II
* EF 75-300mm 1:4-5.6 III USM

As a test, I tried taking the "same" photo with each lens; that is, I
framed a still object as closely as possible with each lens and used
the same settings: Manual mode, 1/100s, f/5.6, ISO-100, Flash
(Speedlite 430EX pointed ahead), tripod. Obviously I had to move the
camera back to get the same shot with the 75-300. The only other
difference was of course the focal lengths: 45mm vs 75mm.

The picture taken with the 75-300 came out much sharper than with the
18-55. What accounts for that? I ask because, in general, I'm able to
get better looking pictures out of the 75-300.

Thanks in advance!

gwperil wrote:
Hi,
I have what is hopefully a pretty basic question. I have a Canon 350D
with the two kit lenses:

* EF-S 18-55mm 1:3.5-5.6 II
* EF 75-300mm 1:4-5.6 III USM

As a test, I tried taking the "same" photo with each lens; that is, I
framed a still object as closely as possible with each lens and used
the same settings: Manual mode, 1/100s, f/5.6, ISO-100, Flash
(Speedlite 430EX pointed ahead), tripod. Obviously I had to move the
camera back to get the same shot with the 75-300. The only other
difference was of course the focal lengths: 45mm vs 75mm.

The picture taken with the 75-300 came out much sharper than with the
18-55. What accounts for that? I ask because, in general, I'm able to
get better looking pictures out of the 75-300.

Better lens.

Can you easily post the two photos?

--
John McWilliams

Can you easily post the two photos?

--
John McWilliams

I'd like to see them also.

"gwperil" schreef in bericht
ups.com...
Hi,
I have what is hopefully a pretty basic question. I have a Canon 350D
with the two kit lenses:

* EF-S 18-55mm 1:3.5-5.6 II
* EF 75-300mm 1:4-5.6 III USM

As a test, I tried taking the "same" photo with each lens; that is, I
framed a still object as closely as possible with each lens and used
the same settings: Manual mode, 1/100s, f/5.6, ISO-100, Flash
(Speedlite 430EX pointed ahead), tripod. Obviously I had to move the
camera back to get the same shot with the 75-300. The only other
difference was of course the focal lengths: 45mm vs 75mm.

The picture taken with the 75-300 came out much sharper than with the
18-55. What accounts for that? I ask because, in general, I'm able to
get better looking pictures out of the 75-300.

Thanks in advance!

Both lenses are not producing very good pictures 'at the ends'.
So, don't use 18 and 55 or 75 and 300mm
Same for the aperture. Stay away from the ends.
Compare them again in the middle sections, ergo around 35mm and around
150mm, both with f8.
I think the difference will be less.
(beware that the largest apertures will become smaller when zoomin in. f5,6
will be wide-open in tele, dont't use it)
br
Aad

"gwperil" wrote in message
ups.com...
Hi,
I have what is hopefully a pretty basic question. I have a Canon 350D
with the two kit lenses:

* EF-S 18-55mm 1:3.5-5.6 II
* EF 75-300mm 1:4-5.6 III USM

As a test, I tried taking the "same" photo with each lens; that is, I
framed a still object as closely as possible with each lens and used
the same settings: Manual mode, 1/100s, f/5.6, ISO-100, Flash
(Speedlite 430EX pointed ahead), tripod. Obviously I had to move the
camera back to get the same shot with the 75-300. The only other
difference was of course the focal lengths: 45mm vs 75mm.

The picture taken with the 75-300 came out much sharper than with the
18-55. What accounts for that? I ask because, in general, I'm able to
get better looking pictures out of the 75-300.

Thanks in advance!


Can you repeat the experiment without using the flash, use ambient light in
an open area?

Rudy Benner wrote:
"gwperil" wrote in message
ups.com...
Hi,
I have what is hopefully a pretty basic question. I have a Canon 350D
with the two kit lenses:

* EF-S 18-55mm 1:3.5-5.6 II
* EF 75-300mm 1:4-5.6 III USM

As a test, I tried taking the "same" photo with each lens; that is, I
framed a still object as closely as possible with each lens and used
the same settings: Manual mode, 1/100s, f/5.6, ISO-100, Flash
(Speedlite 430EX pointed ahead), tripod. Obviously I had to move the
camera back to get the same shot with the 75-300. The only other
difference was of course the focal lengths: 45mm vs 75mm.

The picture taken with the 75-300 came out much sharper than with the
18-55. What accounts for that? I ask because, in general, I'm able to
get better looking pictures out of the 75-300.

Thanks in advance!


Can you repeat the experiment without using the flash, use ambient light in
an open area?

Thanks for everyone's comments on this.
I will take the advise of dropping the flash and going outside on a
cloudy day. Then I will find a place to post the photos.

Part of the reason for these tests is that I do not (yet) have the
experience to differentiate between bad technique and inferior
equipment... so as I consider a new lens, I want to measure the quality
of the two kit lenses as a reference point. There are a lot of strong
opinions out there with respect to lens quality. For example, I'm
interested in the EF 28-135mm F/3.5-5.6 IS USM lens. Research is all
over the map: "Perfect walk-around lens." "Way too soft." "IS is a
life-saver." "IS is not worth the money." And my personal favorite:
"Watch out for bad copies." Bad copies? There goes some more hair...

I guess there's no substitute for just plunking down the $$$ and trying
it out.

Part of the reason for these tests is that I do not (yet) have the
experience to differentiate between bad technique and inferior
equipment... so as I consider a new lens, I want to measure the quality
of the two kit lenses as a reference point. There are a lot of strong
opinions out there with respect to lens quality. For example, I'm
interested in the EF 28-135mm F/3.5-5.6 IS USM lens. Research is all
over the map: "Perfect walk-around lens." "Way too soft." "IS is a
life-saver." "IS is not worth the money." And my personal favorite:
"Watch out for bad copies." Bad copies? There goes some more hair...

I guess there's no substitute for just plunking down the $$$ and trying
it out.

Or, you can use modulation transfer curves and make decisions based on how
you will most often use a particular lens:

http://www.usa.canon.com/consumer/co...mode lid=7445

By the way, the sharpness freaks can lead one astray. I have run tests
between two similar Canon zoom lenses, one of which was L-glass, and was
underwhelmed with the difference in sharpness. It was definitely there ...
I could see it; but honestly the difference was modest. Just me.

I'm not saying that L-glass is not worth it, by the way. Auto-focus
acquisition time and ruggedness are certainly worth having and paying for if
one has deep pockets or is a pro.

Not sure if I missed it in the other posts, but a tripod is a must for
such a test!
- Take photos at smallest F stop and F8 (at least)
- At min, max and middle of the zoom range

Shoot a brick wall/ facade or the like and review the results at 100%
in photoshop.

yes, I also always loved the "Watch out for bad copies."";-)) However,
there are as many results as testers. Someone had a kit lens that was
sharper than his new 24-105 F4L IS if I remember the post correctly. I
would be pi#%d off ;-))


T
http://tr-photo-blog.blogspot.com/


gwperil wrote:
Rudy Benner wrote:
"gwperil" wrote in message
ups.com...
Hi,
I have what is hopefully a pretty basic question. I have a Canon 350D
with the two kit lenses:

* EF-S 18-55mm 1:3.5-5.6 II
* EF 75-300mm 1:4-5.6 III USM

As a test, I tried taking the "same" photo with each lens; that is, I
framed a still object as closely as possible with each lens and used
the same settings: Manual mode, 1/100s, f/5.6, ISO-100, Flash
(Speedlite 430EX pointed ahead), tripod. Obviously I had to move the
camera back to get the same shot with the 75-300. The only other
difference was of course the focal lengths: 45mm vs 75mm.

The picture taken with the 75-300 came out much sharper than with the
18-55. What accounts for that? I ask because, in general, I'm able to
get better looking pictures out of the 75-300.

Thanks in advance!


Can you repeat the experiment without using the flash, use ambient light in
an open area?

Thanks for everyone's comments on this.
I will take the advise of dropping the flash and going outside on a
cloudy day. Then I will find a place to post the photos.

Part of the reason for these tests is that I do not (yet) have the
experience to differentiate between bad technique and inferior
equipment... so as I consider a new lens, I want to measure the quality
of the two kit lenses as a reference point. There are a lot of strong
opinions out there with respect to lens quality. For example, I'm
interested in the EF 28-135mm F/3.5-5.6 IS USM lens. Research is all
over the map: "Perfect walk-around lens." "Way too soft." "IS is a
life-saver." "IS is not worth the money." And my personal favorite:
"Watch out for bad copies." Bad copies? There goes some more hair...

I guess there's no substitute for just plunking down the $$$ and trying
it out.

"t_rust" wrote in message Shoot a brick
wall/ facade or the like and review the results at 100%
in photoshop.

yes, I also always loved the "Watch out for bad copies."";-)) However,
there are as many results as testers. Someone had a kit lens that was
sharper than his new 24-105 F4L IS if I remember the post correctly. I
would be pi#%d off ;-))


Canon DSLRs have a low pass filter in front of the sensor that limits the
resolving power anyway by blurring the image. Any hard black to white
transition seems to take about 3 pixels to occur fully and this is often the
limiting factor in determining lens sharpness.

gwperil wrote:
Part of the reason for these tests is that I do not (yet) have the
experience to differentiate between bad technique and inferior
equipment...

At least you realize the difference. That's 90% of the problem solved!


I want to measure the quality
of the two kit lenses as a reference point.

If you really want to "measure" there are charts and tools that can
help:

http://www.imatest.com/
http://www.normankoren.com/Tutorials/MTF5.html
http://www.graphics.cornell.edu/~wes...res-chart.html

The main problem with these is that they are not used under the same
lighting/distance as most real-world photographs.

For example, I'm
interested in the EF 28-135mm F/3.5-5.6 IS USM lens.

Note that these focal lengths are a bit long on an EF-S 1.6x crop
camera. The 17-85mm is the EF-S equivalent.

Research is all
over the map: "Perfect walk-around lens." "Way too soft." "IS is a
life-saver." "IS is not worth the money."

And guess, what? All of these opinions may be true! A lot depends on
how you use a lens and what you expect (and even what camera you use it
with!).

Bad copies? There goes some more hair...

There are two solutions for this:
1) buy where you can return if not satisfied
2) be able/willing to send in the lens for calibration repair (ideally
under warranty).

I guess there's no substitute for just plunking down the $$$ and trying
it out.

You can also often rent lenses you cannot afford to buy - even via the
internet in the U.S.
http://www.rentglass.com/

--
Erik