Canon 100-400 dust specks

EMA747

EMA747

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Andy
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I just received my Canon 100-400mm from a sale on fleabay. It appears on close inspection to have about 3 dusl spot on the top left of where the glass narrows inside the lens. I know about the 100-400 being called the dust pump but what I want to ask is are the dust specks really a problem to image quality?

If not I will just leave it but if they are I might email the seller as it wasn't descibed as having dust speck inside the lens. Other than that it seems like a nice lens.

I'm not trying to scam the seller or be over picky I am just interested to know what effect the dust has and if you guys think I should do anything about it. ;)
 
Tripod mount, use self timer and set aperture to F16 point at blue sky:eek: and check results. if you can live with the results and can edite them out then I would be happy.
 
I have the same lens with three large dust specs on the inside of the front element, unless I stop well down they do not show in my images, but I have enquired at Lehmans to have the lens serviced and the cost is £130! Might be worth asking fleabay man for some money back towards this cost.
 
there's a thread on here somewhere showing a lens with a smashed front element which was still capable of producing usable images. A couple of dust specks really aren't an issue :)
 
Mine has some noticeable dust inside the front element but it has never caused a problem for me. Seems to happen alot with the 100-400.
 
sbowler579 said:
Tripod mount, use self timer and set aperture to F16 point at blue sky:eek: and check results. if you can live with the results and can edite them out then I would be happy.
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Is there a test that I can do indoors as it's snow tomorrow in my part of the country. :bonk:
 
To be honest whether it makes a difference to the IQ is neither here nor there .. if not then all well and good but personally I would be on to the seller anyway. The lens is obviously not as described and I would be wanting a partial refund for any loss that will be coming in the future should you decide to sell and have to advertise it correctly.
 
How much did you pay relative to a new pristine lens, I don't think you can expect 'new' quality when buying secondhand, and in any case I doubt it will make an iota of difference to your images.
 
There is no test you can do that will show the effect of dust inside an individual lens. If it is very severe (like dozens) it would show up as flare and slighly reduced contrast all over the image, not as individual specs. But only if you compared side by side it against a pristine lens.

If you start shooting plain walls at high f/numbers, as suggested above, it will frighten you to death as you will see loads of sensor dust marks.

All lenses that change length as you zoom suck in air. The only way to avoid it is not to use the lens. If you use it, you will get dust specs sooner or later.

I agree that it's not what you want to see inside your fine new lens, but in terms of image quality it would have to be very bad to make any noticeable difference.
 
swivelonit said:
I have the same lens with three large dust specs on the inside of the front element, unless I stop well down they do not show in my images.
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It is very likely that when you stop down the dust you see is actually the dust that is on your sensor, not the dust that is on the front element.
 
If you are really paranoid don't forget to get the atmosphere between you and your subject cleaned before pressing the shutter as well :D
 
RJL2005 said:
Mine has some noticeable dust inside the front element but it has never caused a problem for me. Seems to happen alot with the 100-400.
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I've heard this and at the moment I use this lens every weekend at Rugby in all weathers and never had this problem.
 
RJL2005 said:
Seems to happen alot with the 100-400.
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Not really. I have 30 of them, which I think is enough to be statistically meaningful - or at least one step above the usual level of "I read it on the internet so it must be true". The push-pull action might put more dust on the sensor than other lenses, though I don't have any data to confirm or refute this. However it is very clear to me that this lens does NOT suffer very much at all from internal dust. Some other types of lens (and not necessarily the ones you'd expect) are far, far worse.
 
Well I have email the seller and just stated my findings. I've not asked for a refund yet so I will just wait and see what he says. If he offers a refund I will take it. If not I might ask for a little cash back.

As Mike.P said, the main problem is reselling if I ever want to. The dust would knock the price down some I bet.
 
I'd expect so. One of the lenses I was looking at had dusk in so I was looking at a £100 reduction in price to cover getting it cleaned.

Are you sure it's internal?
 
I find it very hard to believe that this will have an effect on the final image unless it is really severe. We used one in Namibia and looking through it afterwards it had loads in it but the pictures are all fine.

as has been pointed out the 100-400 is no worse than any other lens that changes length.

If there were a 100-400 with internal focusing it would be better, but wouldn't it be rather big?
 
Byker28i said:
I'd expect so. One of the lenses I was looking at had dusk in so I was looking at a £100 reduction in price to cover getting it cleaned.

Are you sure it's internal?
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I'm sure it's internal. It's just where the narrow part of the glass starts (the part that's about an inch diameter).
 
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