Dust between lens elements

Bantu · 10 Oct 2016 at 16:26

Hi all,

I'm looking to get my travel lens and camera cleaned.

The lens is a Canon EF 24-105mm f/4L IS USM and, despite my best attempts at cleaning and keeping it safe, has acquired what looks like hair and dust somewhere near the rear element (have tried both air and microfibre cloth to remove it). Does anyone have any experience with London (or nearby) based photo shops? Or am i best off just sending it to canon? Would anyone know if this is part of a standard lens clean, or would i have to go for a pricier repair/servicing option?

The camera itself (5d mkii) also appears to have dust somewhere between the mirror and viewfinder (though a recent very windy trip to iceland actually helped to remove a bit of it). This doesn't affect picture quality at all, but I wouldn't mind getting it sorted if there's an easy way (without taking the camera apart). I always thought these bodies had a bit better weather sealing than this :/

JohnStewart · 11 Oct 2016 at 20:29

If it doesn't appear on the photos I wouldn't bother with professional cleaning. Dust on the internal elements is very common and in general has no noticeable effect on the resulting images.

My 24-105 suffered from the dreaded Err-01 a few months back due to the ribbon cable needing replaced. http://cam-rep.co.uk Replaced it and gave the lens a full clean and service for just £95 including insured delivery. Turn-around was just over a week and was much cheaper than some other places I asked.

D.P. · 11 Oct 2016 at 20:39

Dust near the rear element can show up in photos, and even when it isn't obvious it normally results in reduced sharpness or contrast. You certainly never see a big blob or anything.

Bantu · 12 Oct 2016 at 08:52

it shows up as lines and points against blue skies. i'll try and put up an example when i'm back home. Will give cam-rep a look.

Thanks,

Kei · 12 Oct 2016 at 09:06

The only time dust or debris will obviously show up in an image is if it is on the sensor. It would have to be a huge object in the lens to have a noticeable effect. Anything inside the lens will only be noticeable in the out of focus "bokeh balls" from point light sources. It's similar to the onion rings from ground aspheric elements but usually appears as a small spot.

Tbh, you fight a losing battle trying to keep dust out as it's impossible. Some lenses do seem worse for collecting dust inside but it always gets in eventually.

Bantu · 12 Oct 2016 at 10:08

Thanks for that. maybe i'll have another go at wiping the sensor (though i was sure i got everything off it!)

D.P. · 12 Oct 2016 at 18:00

Bantu said:
it shows up as lines and points against blue skies. i'll try and put up an example when i'm back home. Will give cam-rep a look.

Thanks,

As Kei says, that isn't due to dust in the lens but dirt on the sensor.

People seem overly protective of the lenses. As test, take a photo with you hand covering half of the front lens element. You probably can't see a difference, and the difference if it is exist is a reduction on contrast more than anything else. Dirt on the rear element has a bigger effect but its unlikely to show up as anything physical in the image.