How does a dead fly in a Canon EF 70-200mm f/2.8L IS II affect image quality?

Canon Rumors Guy

EOS 1D MK II
Jul 20, 2010
7,530
286
Canada
www.canonrumors.com
I bet the question of how a dead fly inside a Canon EF 70-200mm f/2.8L IS II affects image quality wasn’t something most of us would have ever seen tested, but alas, the folks at Lensrentals.com decided it was time to answer the query.
From Lensrentals.com:
So, this seems like a good time to do a blog post showing that 1) this big-ass fly had almost no effect on image quality, so that little dust speck you’re frantic about sure doesn’t, and 2) getting flies (or dust) out of a lens is a lengthy and difficult process that takes a long time.
Now I think we all agree that the fly really did need to be removed, but by the time you finish this post, hopefully, you’re going to agree with me that that dust speck in your lens probably is just fine right where it is. Not to mention, I bet there’s a really good chance that if we remove this fly, the...
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QuisUtDeus

EOS 80D
Feb 20, 2019
115
80
Meanwhile, ...Sony releases new firmware...
So you're saying you already knew about that from elsewhere and didn't need to read about it on a Canon-focused (SWIDT) site, and instead got alerted to a very interesting blog post? I assume you're meaning to thank CRG.
 

degos

EOS 80D
Mar 20, 2015
194
119
so that little dust speck you’re frantic about sure doesn’t
Of course it does, just not measurably so. But by the time we're using half-gigapixel sensors then we'll have to reassess.

I do hate the 'generalisation' of language. When I see a lens listing that says 'mark on objective has no effect on image', I know they're lying and I move to the next listing. Everything in a lens has an effect on image quality. Just because we can't see it right now doesn't make it acceptable to lie.
 

Metalex

I'm New Here
Feb 6, 2019
13
9
Of course it does, just not measurably so. But by the time we're using half-gigapixel sensors then we'll have to reassess.

I do hate the 'generalisation' of language. When I see a lens listing that says 'mark on objective has no effect on image', I know they're lying and I move to the next listing. Everything in a lens has an effect on image quality. Just because we can't see it right now doesn't make it acceptable to lie.
You think they're lying? Really?! That's a real stretch.

A "half-gigapixel" sensor would not render that dust-speck any more in focus and visible than today's sensors.
 

Ian_of_glos

EOS RP
Jun 12, 2012
236
20
England
Surely it depends on which lens you are using.
When I am taking pictures at rugby matches I frequently find that there are small splashes of mud on the front element of my 400mm lens but they never show up in any of the pictures. However, I once managed to leave a thumb print on the front element of my 8-15mm fish eye and you could see it clearly in all the pictures.
 
Jun 14, 2013
3
0
I upgraded my old 70-200 f/4L a while ago to the new II version. I had hoped to sell the old one in part exchange, but when the shop checked out the lens they noticed a piece of broken glass stuck somewhere between the rear lens elements. They showed it to me so I could see for myself. No question what it was, but how did it get there? Probably quite early on after buying the lens, I think. It dropped and got a nasty bash. I guess that the edge of one of the lens elements broke and got lodged there.

Did I notice it at all over maybe 10 years or more? No.
 

tvb

Apr 12, 2019
1
1
Objects located close to the lens surfaces usually are visible very clearly in bokeh circles :3 Sadly they didn't test it this way...
 
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stevelee

FT-QL
Jul 6, 2017
1,033
162
Davidson, NC
Supposed history of the waiter joke:

IN HER anthology, One Hundred Renaissance Jokes, Barbara Bowen identifies a Latin epigram by Sir Thomas More as a likely forerunner. At a banquet, a guest removes some flies from the loving-cup, drinks, then replaces them, before passing it on with the remark: 'I don't like flies myself, but perhaps some of you chaps do'.
 

johnf3f

Canon 1Dx
Oct 25, 2012
923
18
Wales
Had a tiny spider in the viewfinder when I had my 1D4 - ruined loads of images! It was just too much fun watching the antics of this tiny fella so I missed lots of birdies:(

I often wonder what happened to him/her - was it the Sensor Cleaning Monster:alien: