Canon Service/grit in lens

mackerski

Hi Folks,

Here's a sad story of some new kit. I have for a while been happy with my Canon EOS 350D which I bought with the 18-55mm kit lens. Recently I fancied some extra zoom range and maybe some better glass, so I went Ebaying and ended up with an original Canon 28-105mm Ultrasonic at a decent price (the 1:3.5-4.5 one, not the cheaper one).

The trouble is, I'm not at all happy with the image quality. The shots are quite blurry, especially when viewed at 100%. On inspection, there are some spots of grit, one quite noticable, visible behind the front element.

My questions: Could the grit alone be causing the kinds of effect I've described (at f5.6 and f8), or does this point to some deeper problem with the optics? Has anybody got experience of having problems like this repaired by Canon service or anybody else? And what can I expect to pay for the job?

Thanks for any help.

DotOrg

dirt/dust/filth inside the lens won't be visible on any pictures,most likely you've dust on the sensor, google it and you'lll get a million answers on how to fix it yourself

ladgie353

Is the 28-105 blurrier than the 18-55?
Did you use a tripod for the shots?

You could start by setting up a test (camera on tripod, static target) and take the same picture with both lenses at 50mm and f/8 and compare them.

While you are at it, take a picture of a grey card (or any uniform neutral surface) with both lenses.
Darker spots on the pictures will highlight dust and specs.
If these are present on both pictures, the dirt is on the sensor if not, the lens could be the problem.

mackerski

Thanks for the quick responses. On the dirty sensor issue, It's always possible, but it's a hell of a coincidence that my sensor got mucky more or less coinciding with me starting to use the new lens. I can check it for dust, but I don't see a dirty sensor applying a uniform blur over an entire image like that.

A comparison test between the lenses is well worthwhile and I did intend to try that. I can already tell you that the kit lens will be sharper, though, and on paper it should be the other way around. The 28-105mm lens (the version I have at least) is well-regarded and should absolutely yield better results than I'm getting. In fact, for my most recent shots I was also shooting with a crappy compact camera, which yielded sharper results.

So far, my tests have been hand-held, though my test shots today were at 1/250, which should be fine. I'll certainly try it on a tripod, though. It can't do any harm.

magicbastarder

might be the lens, but not down to the grit in the lens.
there are no signs of damage to the lens?
it could have got a knock in transit which misaligned an element or two.

Rojo

The diopter might have got moved by mistake... ?

Happened to me and ruined many photos...

PaulieC

I had that lens until recently and indeed it was a lot sharper than the kit lens. Quite a lovely lens in fact, just a pity it's not a 20- or 24-105 as it really wasn't wide enough

mackerski

Rojo wrote:

The diopter might have got moved by mistake... ?

You mean the diopter in the viewfinder? These were all shot on autofocus, many of them at infinity, so I can't see that being an issue.

prox

mackerski wrote:

On the dirty sensor issue, It's always possible, but it's a hell of a coincidence that my sensor got mucky more or less coinciding with me starting to use the new lens.

Unless of course you had to take off the old lens to put the new one on and some dust got onto the sensor. Then it wouldn't be very much of a coincidence at all at all.

Rojo

mackerski wrote:

You mean the diopter in the viewfinder? These were all shot on autofocus, many of them at infinity, so I can't see that being an issue.

just a suggestion...

mackerski

prox wrote:

Unless of course you had to take off the old lens to put the new one on and some dust got onto the sensor. Then it wouldn't be very much of a coincidence at all at all.

That'd be some dusty room... Sensors don't get that dirty that quickly, and certainly not all over the sensor. I will check it, but not before I try the kit lens again. If it yields sharp photos like it used to, then it can't be the sensor at fault.