Is My Lens Broke? Or Is It Me?

Hi -

recently I bought the EF 28-135mm zoom for my 350D Camera and since I have had I have not been able to take one image that was in focus. I have tried asking advice and people have told me it was my DOF which I thought ok I'l see if increasing it works. So I went and did a test today. I was outside (which is why I bought this lens so I could use as my walkabout lens) did some shots , processed them back into my computer and well to me they are out of focus. or not as sharp maybe? I don't know if it is the lens or my monitor or what.

Here is a photo taken with this lens today - (its the only file in the directory, full sized image but in JPG 5% compression so about 3-4mb)

http://www.22lies.com/mephoto/test/

Specs:

Shooting Mode : Manual Exposure
Shutter Speed : 1/250
Av : 18.0
Metering Mode : Evaluative Metering
ISO Speed : 400

Also when looking at the RAW image in my program and seeing where the AF points were. Almost all but one (the one at the very top vertical wise) was in the red, meaing they were in focus. So it is a mystery to me.

PPP,

That one shot looks OK to me. At least it seems to be in focus. When you view images at 100% (original size), they will look softer. Especailly if you are looking at converted RAWs where you haven't added any sharpening. Your original looks like many of my originals taken with consumer grade lenses. IOW, it's OK

FWIW, when doing these type of tests, F11 or so should be plenty good enough to minimize any DOF issues. When you use really narrow apertures (F16 and above), diffraction may become an issue.

Steve

--
Everyone has a photgraphic memory......some just don't have any film

http://www.pbase.com/slo2k
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http://www.photobird.com/steve

princess_peepee said:

processed them back into my computer and well to me they are out of
focus. or not as sharp maybe? I don't know if it is the lens or my
monitor or what.

Click to expand...

Looks like the focus lands on the metal rail betwen the plastic.

princess_peepee said:

Shooting Mode : Manual Exposure
Shutter Speed : 1/250
Av : 18.0
Metering Mode : Evaluative Metering
ISO Speed : 400

Click to expand...

I would guess this is with a flash, no? Any particular reason you went down to f/18?

I ask because that's what's making thing soft. There might be other factors as well; the 28-135 is a good but not a great lens, but on a 1.3x crop sensor, anything below about f/13 and you're going to see your images getting noticably softer from diffraction.

you certainly did not use a good photo to try to show focus.

to eliminate a lot of variables you could use the timer and a tripod and shot a picture of a chart.

http://www.pbase.com/llukee/inbox&page=37

Luke Kukovica said:

you certainly did not use a good photo to try to show focus.

to eliminate a lot of variables you could use the timer and a
tripod and shot a picture of a chart.

http://www.pbase.com/llukee/inbox&page=37

Click to expand...

I was trying to see if my images were blurry/out of foucs not necessarily trying to "show focus" in a technical manner , which a chart etc..

Forrest said:

I would guess this is with a flash, no? Any particular reason you
went down to f/18?

Click to expand...

No I did not use a flash for this. I have been getting advice from people telling me that the reason I was having focusing issues was cause my DOF was to shallow. THey kept telling me to increase it. So I have been experimenting and trying there advice. Normally I keep it around 10 so so.

Forrest41926 said:

I ask because that's what's making thing soft. There might be
other factors as well; the 28-135 is a good but not a great lens,
but on a 1.3x crop sensor, anything below about f/13 and you're
going to see your images getting noticably softer from diffraction.

Click to expand...

So keeping at 13 or lower would be good? Same goes my 60mm macro lens as well? Also what other lens would you recommened instead of the 28-135 for out and about shooting?

I own the same lens and it reasonable sharp lens.

1. I really do not think its not out of focus. It look pretty in-focus to me.
Thats not the problem IMHO.
2. The picture has some softness/ noise that might be the result of your
ISO400 setting in 100% view.
3. If you view a picture at 100% u have to step back from the screen or it
will always look. I you look at a big poster/billboard that near it is also
unsharp.
4. You say you see the red AF dots are all red beside on so u probably using
automatic AF point selection. Try to use manual AF point selection so
u and not the cam decide what needs to be sharp.
5. Try f/8 instead f/18. I agree on that with the previous posts.

I might be wrong with all of that and you really have a bad copy but I', quite happy with mine.

Cheers

f11 maximum.

ed rader

--



'One often has mixed feelings about relatives, but few people could identify serious problems in their relationships with dogs.'

-- Anonymous

princess_peepee said:

So I have been experimenting and trying there advice. Normally I
keep it around 10 so so.

Click to expand...

You'll probably do best in the ballpark of f/8 to f/11 with that lens. Think of anything smaller than that ( and f/18 is definately smaller ) as an emergency mode, for when you're shooting macros or close-up landscapes with deep backgrounds.

But your scene is pretty flat ... you probably could have got by at f/5.6 to f/8, even if people disagree.

princess_peepee said:

So keeping at 13 or lower would be good? Same goes my 60mm macro
lens as well? Also what other lens would you recommened instead of
the 28-135 for out and about shooting?

Click to expand...

All lenses on a 1.6x crop body are going to show more and more softness beyond f/13 or so. What you're seeing is light bending as it passes through the aperture, and spreading out a litlte, striking the pixels next to where it was meant to hit, causing softness. The f-number is a ratio of the aperture and the length of the lens, so f/11 is the same at 10 mm or 100 mm.

The 28-135 IS is a fine lens for general shooting, unless there are specific things it's not doing for you - say letting you through the background out of focus enough, shoot sports in the dark, or whatever. There are sharper lenses, but do you really need to have one ... is it worth the money?

princess_peepee said:

So keeping at 13 or lower would be good? Same goes my 60mm macro
lens as well? Also what other lens would you recommened instead of
the 28-135 for out and about shooting?

Click to expand...

Ideally, you want to keep it below f11 if you don't want diffraction to cause softness - this is not a function of the lens, but of an 8MP 1.6x crop sensor. See link for information on diffraction.

http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

That said, just because you get softness above f11 does not mean you should not use a smaller aperture if you need greater DOF. You have to determine if the tradeoff is worth it. When shooting traditional macros (flowers, insects, etc.), you may have to use very small apertures to get the DOF you need, even if it means softness. You can then sharpen in PP.

Note, for consumer lenses like the 28-135 IS, it starts to get sharpest around f8. So, f8-f11 is the "sweet-spot" for most lenses. That does not mean you shouldn't use other apertures, though.

As for a better walk-around lens, you can always get the 24-105 4L, but that is about $1200 vs the $400 for the 28-135. But if you want to shoot at aperatures smaller than f8, you won't see much difference (the 24-105, like all L lenses are very good wide open compared to consumer lenses).

Based on your image, I'd say maybe an exorcism is in order. Reminds me of The Exorcist (movie). Then again, wasn't the message on the stomach in the movie written back to front, as if from the inside? You didn't flip this one horizontally when processing by any chance? ;^)

In all seriousness, if you want to show correct focus, you need to choose a much wider aperture to produce a much smaller DOF that doesn't hide the focus distance and effect so much, and that doesn't introduce diffraction artifacts like a very narrow aperture does, as others have suggested. Wide open may be too wide as that's probably going to be soft as well, but f/5.6 or so would show a lot more about focus than what you've tried.

--
Cheers from John from Adelaide, South Australia
John Harvey Photography http://johnharvey.com.au
Canon 20D & Fuji F10

John down under said:

In all seriousness, if you want to show correct focus, you need to
choose a much wider aperture to produce a much smaller DOF that
doesn't hide the focus distance and effect so much,

Click to expand...

But from what I understand, she wanted a large DOF to have everything in focus - hence the small aperture.

John down under said:

and that
doesn't introduce diffraction artifacts like a very narrow aperture
does, as others have suggested. Wide open may be too wide as that's
probably going to be soft as well, but f/5.6 or so would show a lot
more about focus than what you've tried.

Click to expand...

Well, for the lens that she has (28-135), f5.6 is wide open at the long end. The photo doesn't have any EXIF information, so I don't know what FL it was taken.

I would suggest that she shoots at f11 to get the look that she wants (large DOF and maximum sharpness). Of course, this is different than how I like to take photos (which is wide open to get a narrow DOF).

a shot from around f8-f11. But from what I see and considering that it's F18 - which as Forrest said will soften things a bit - it looks to me like your getting normal consumer-grade-lens quality combined with some ISO 400 noise which doesn't help either. In other words, it looks like your lens is performing as I would expect that lens to perform with those settings.

--
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Even if you can't donate, please help spread the word.

I'll read the Economist after you pick up a book on optics.

Have a great day.

Erik Gordon said:

I'll read the Economist after you pick up a book on optics.
Have a great day.

Click to expand...

My god, I seem to have offended you. Tell me what you don't agree with in the post above.

I've read "The Camera" several times, a book by Ansel Adams with a section on optics, as well as whatever good material I've been able to find. All of this agrees with my experience shooting about 50,000 digital photos through a variety of lenses.

Tell me what's not clear to you on optics, and I'll do my best to help you understand.

dave_s93 said:

Ideally, you want to keep it below f11 if you don't want
diffraction to cause softness - this is not a function of the lens,
but of an 8MP 1.6x crop sensor. See link for information on
diffraction.

http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

That said, just because you get softness above f11 does not mean
you should not use a smaller aperture if you need greater DOF. You
have to determine if the tradeoff is worth it. When shooting
traditional macros (flowers, insects, etc.), you may have to use
very small apertures to get the DOF you need, even if it means
softness. You can then sharpen in PP.

Note, for consumer lenses like the 28-135 IS, it starts to get
sharpest around f8. So, f8-f11 is the "sweet-spot" for most
lenses. That does not mean you shouldn't use other apertures,
though.

As for a better walk-around lens, you can always get the 24-105 4L,
but that is about $1200 vs the $400 for the 28-135. But if you
want to shoot at aperatures smaller than f8, you won't see much
difference (the 24-105, like all L lenses are very good wide open
compared to consumer lenses).

Click to expand...

Thanks for the info. I was looking at the L series of lens but at the time could not afford to get one. I am hoping that for Xmas I can con someone into getting it for me.

Forrest said:

Forrest41926 said:

So I have been experimenting and trying there advice. Normally I
keep it around 10 so so.

Click to expand...

You'll probably do best in the ballpark of f/8 to f/11 with that
lens. Think of anything smaller than that ( and f/18 is definately
smaller ) as an emergency mode, for when you're shooting macros or
close-up landscapes with deep backgrounds.

But your scene is pretty flat ... you probably could have got by at
f/5.6 to f/8, even if people disagree.

Forrest41926 said:

So keeping at 13 or lower would be good? Same goes my 60mm macro
lens as well? Also what other lens would you recommened instead of
the 28-135 for out and about shooting?

Click to expand...

All lenses on a 1.6x crop body are going to show more and more
softness beyond f/13 or so. What you're seeing is light bending as
it passes through the aperture, and spreading out a litlte,
striking the pixels next to where it was meant to hit, causing
softness. The f-number is a ratio of the aperture and the length
of the lens, so f/11 is the same at 10 mm or 100 mm.

The 28-135 IS is a fine lens for general shooting, unless there are
specific things it's not doing for you - say letting you through
the background out of focus enough, shoot sports in the dark, or
whatever. There are sharper lenses, but do you really need to have
one ... is it worth the money?

Click to expand...

I really appraciet the info/ time. Looks like I need to go back to the books and learn more. I seem to get really confused about FL etc.. even though I read up on it I keep forgetting about it. Normally I just stick with my 60mm which I love and works great for me (as I do a lot of in studio shots) but lately I have been trying to get out and thus why I bought a diff lens. Cause the 60mm does not do well when handling (to much shake even at a good shutter speed) I guess I just have to keep working at it with this lens.

Is there any book you would suggest to read? I took a class as part of my collage degree course and have one book "Photography 7th ED" but obviously need to know more.

felixreichardt said:

I own the same lens and it reasonable sharp lens.

1. I really do not think its not out of focus. It look pretty
in-focus to me.
Thats not the problem IMHO.
2. The picture has some softness/ noise that might be the result of
your
ISO400 setting in 100% view.
3. If you view a picture at 100% u have to step back from the
screen or it
will always look. I you look at a big poster/billboard that near it
is also
unsharp.
4. You say you see the red AF dots are all red beside on so u
probably using
automatic AF point selection. Try to use manual AF point selection so
u and not the cam decide what needs to be sharp.
5. Try f/8 instead f/18. I agree on that with the previous posts.

I might be wrong with all of that and you really have a bad copy
but I', quite happy with mine.

Cheers

Click to expand...

Actually I do pick manual AF points I was just trying a bunch of stuff that day. I would really rather be doing manual focus instead of any AF point etc... but this camera sucks at that. I need to get one I can manual focus with.

princess_peepee said:

I really appraciet the info/ time. Looks like I need to go back to
the books and learn more. I seem to get really confused about FL

Click to expand...

Let's take your 60 mm f/2.8 Macro for example.

It's a 60 mm lens, because that's how far the light travels. The front element - the glass you can clean with a soft cloth, gathers light from the outside world and sends it backward towards your CMOS chip, which records a picture. Anyway, 60 mm is the focal lenght, because it's the lenght of the "light path." That also determines how much "reach" it has; more than a 50 mm but lens than a 100 mm lens.

Now let's take aperture, but first we'll do a quick thought experiment. Imagine looking yourself in the mirror on a bright sunny day, versus the middle of the night. In one case your pupils are going to be pinpoints, closed down really tight to block sunlight and not go blind, but in the other, they'll dilate, or get really big to take in as much light as possible so you don't walk into anything. This is the aperture in your eyes.

Say you're shooting your ( 60 mm ) lens at f/10; that means the pupil is going to be 10 mm wide. If you shot at f/20, it'll be 5 mm wide. It's just the focal length / the f-number. That's a circle inside the lens that all of the light passes through.

But light tends to bend if it passes too closely to something; you can see this if you ever walk through a long, dark train tunnel. You can also see it in your photos. As you stop down, the opening inside your lens gets smaller, so more of the light you record has passed very close to it, and bends a little. That's called diffraction, and it makes your photos less soft. You'll always have some amount of it, but more at f/18 than at f/8, because f/18 is a 3.3 mm opening, whereas f/8 is a 7.5 mm opening. That's why f/18 is softer; smaller hole, more light gets diffracted.

princess_peepee said:

Is there any book you would suggest to read? I took a class as part
of my collage degree course and have one book "Photography 7th ED"
but obviously need to know more.

Click to expand...

Personally, I really enjoyed "The Camera" by Ansel Adams, but parts of it are really technical. You seem to have a pretty good grasp of what's going on - more, say, than this guy called Bulb Mogul who has $50,000 worth of lenses and hasn't used any of them - so even more than reading a book, I would suggest taking lots of photos at different settings, and looking at the results.

Especially, take the photo you showed us at f/4, f/8, and f/16, but with everything else ( except the shutter speed or ISO ) the same. Then you can get a better idea of how just one variable changes the picture.

But also don't hesitate to ask questions here ... that's what this place is for. You'll get a little bit of flack from rude people, but you'll also get answers from smart people who've learned a lot from others, and want to pay back their "debt to society" by helping people, too.

princess_peepee said:

Actually I do pick manual AF points I was just trying a bunch of
stuff that day. I would really rather be doing manual focus instead
of any AF point etc... but this camera sucks at that. I need to get
one I can manual focus with.

Click to expand...

Well manual focus is not as easy anymore since they took away the split focus screens.