how much to clean oly lens?

[btfiend]

Originally Posted by wind30 The center crop looks pretty ok to me. My old 50-200mm is around this quality too. The fence looks wierd though but it is at the corner and maybe out of focus? but the ghosting is weird....

I forgot to mention that the oly tech told me the lense had been calibrated already too. Just waiting for the top glass replacement (to fix the scratch underneath) and it should be home free to its owner who paid $1.7k for it. YAY I can't wait.

Center region is generally OK but not fantastic. But theres a hint of yellow/blue chromatic aberration on some samples which is completely absent on another 50-200 test copy. Also strong green/red aberration is apparent on every single shot. Olympus' 50-200mm brochure claims "ABERRATION FREE IMAGE QUALITY".

Image quality degenerates quickly beyond the centre with some pretty serious ghosting (usually found on ultra cheap tele lenses). In the absence of strong contrasty objects, the entire image looks dull and soft. Compare these two samples taken by the Oly service tech, one with the lemon and another with a working copy (sample A and sample B) and see if you can tell which one came from the lemon. Hint: look at the railing. Out of focus objects should be soft all around and not smearing towards a particular direction.

Yet another one:


(click for full size image)

100% closeup crop of the bottom right

Look closely at the fella walking up the stairs and the rail.

[drakon09]

What if we all bring our 50-200mm, just to prove a point?

[drakon09]

Might it be light refraction through the scratch in the lens element?

If the ghosting still appears after the replacement of the glass then we might have a problem.

[btfiend]

Looks like an alignment problem with a certain lense element or a group. It is unlikely to be due to the scratch since the ghosting is affecting the entire area. A tech guy working for another major camera company tells me its virtually impossible to see the misalignment by naked eye. Have to send back to factory for overhaul and computerized alignment tests.

Haha...but what do I know right? Even people who fix lenses and cameras for a living are telling me off that its merely a calibration problem and as long as its sharp on the 2" LCD, its OK!

[wind30]

Originally Posted by btfiend Center region is generally OK but not fantastic. But theres a hint of yellow/blue chromatic aberration on some samples which is completely absent on another 50-200 test copy. Also strong green/red aberration is apparent on every single shot. Olympus' 50-200mm brochure claims "ABERRATION FREE IMAGE QUALITY".

The thing I remember about my 15-54 and 50-200 was that there are zero aberration which is quite remarkable.

Anyway aberration seems to be rather common with other lens. Even my nikon 85mm f1.4 shows significant aberration at f1.4. And still have slight fringing at f2.0.

Anyway here is a sample pic of my 50-200mm shot at 50mm wide open, ISO400 (so got a bt of noise)

http://pisduck.com/china/C271702.jpg

[cjtune]

Hmm, while we're still on the topic of cleaning lenses, anybody has any idea which camera shops are able to take apart and clean a lens inside-out, and how much do they charge for such a service?

Just got a 2nd-hand Vivitar f/2.8-4.0 70-210mm lens from EBay with somewhere between slight-to-moderate fungus infestation and I'm not quite sure what to do with it now. Everything else seems to be in good condition though but I can't really test the lens out until my OM-to-4/3rds adapter arrives. Thorough visual inspection only reveals that one lens element is affected.

I could try to sun it but given the monsoon season it'll be difficult (and wouldn't the multi-coats filter out UV too??), but I'm thinking of sealing it air-tight in a container with cotton buds soaked with hydrogen peroxide (common wound disinfectant) for a few days to see if it kills the fungus off.

[btfiend]

Originally Posted by wind30 The thing I remember about my 15-54 and 50-200 was that there are zero aberration which is quite remarkable. Anyway aberration seems to be rather common with other lens. Even my nikon 85mm f1.4 shows significant aberration at f1.4. And still have slight fringing at f2.0. Anyway here is a sample pic of my 50-200mm shot at 50mm wide open, ISO400 (so got a bt of noise) http://pisduck.com/china/C271702.jpg

Nice. Your foreground object softens out evenly and nicely without any CA or ghosting artifacts AT ALL. Even the branches and twigs on the tree are distinctly sharp from top to bottom. Mind if I show this to the Oly service centre drones?

My lemon has difficulty maintaining sharpness beyond 30-40% of the centre, and everything 'splits up' at the top, bottom and sides. Look at the plant leaves behind the blooming white gate pict. They should be softly OOF but instead there are GHOSTING into twins!



Here's another sample taken yesterday. This is the best that can be taken with this lemon under bright-lit condition. Looks GOOD FROM FAR (or from the LCD )...
E-500 + 50-200@200mm, 1/3000, f/4, ISO100; focused on the white railing.

(Click on pict to view full size copy)

...BUT ITS FAR FROM GOOD as closeup reveals everything starts to blur, with objects splitting into 'ghost twins' beyond the centre:



Centre sharpness is 'tolerable'. I can get far more detail from a $300 40-150.



Agree that the 4/3 system produce very good IQ and sharpness from corner to corner is the norm even with the kit lenses (...only if you don't get a lemon lense). This is rare on C&N systems, especially C which tend to be soft on wide angles and plenty of noticeable vignetting. Just that Olympus Singapore's tech support is an abysmal failure and leaves too much to be desired.

[btfiend]

Originally Posted by cjtune Just got a 2nd-hand Vivitar f/2.8-4.0 70-210mm lens ...with somewhere between slight-to-moderate fungus infestation

that fungus growth looks pretty serious. Definitely need to be physically cleaned. Doubt H2O2 or UV treatment will do anything at this stage. The coating on which the fungus is feeding on is cfm gone.

[cjtune]

Originally Posted by btfiend that fungus growth looks pretty serious. Definitely need to be physically cleaned. Doubt H2O2 or UV treatment will do anything at this stage. The coating on which the fungus is feeding on is cfm gone.

Aaah... Note to self: no more impulse buys from EBay.

Then I guess it would be a fun project to start learning DIY lens disassembly and servicing now... otherwise how can I admit to being a mechanical engineer?

[wind30]

Originally Posted by btfiend Nice. Your foreground object softens out evenly and nicely without any CA or ghosting artifacts AT ALL. Even the branches and twigs on the tree are distinctly sharp from top to bottom. Mind if I show this to the Oly service centre drones?

sure but I don't have the 50-200mm anymore. Sold to a fellow CSer 1 year back. And it is on a 5meg E1 cam so viewing at 100% is like viewing at 80% for the E500. And I shot at 50mm not 200mm. And you must understand this is one of the sharpest pics I have and I have samples that are worse than your cathedral shot, due to a variety of reasons like slight shake, slight misfocus.

Your second pic is better than the first one with weird ghosting. But "sharpness" without an objective measurement is quite hard to argue.... what seems sharp to someone may not be sharp to another guy.

wonder how does oly Singapore measure the sharpness of the len? Surely they have some form of objective measurements locally? I have read how some lens review sites are measuring it (MTF values) and it doesn't look expensive or technically difficult. Maybe you can ask for some objective data.

[cjtune]

Originally Posted by wind30 wonder how does oly Singapore measure the sharpness of the len? Surely they have some form of objective measurements locally? I have read how some lens review sites are measuring it (MTF values) and it doesn't look expensive or technically difficult. Maybe you can ask for some objective data.

I would think (or rather, EXPECT) that they'd employ standard targets such as those mentioned in links below:
http://www.normankoren.com/Tutorials/MTF5.html
http://www.edmundoptics.com/onlineca...productID=2287

[btfiend]

Originally Posted by cjtune I would think (or rather, EXPECT) that they'd employ standard targets such as those mentioned in links below: http://www.normankoren.com/Tutorials/MTF5.html http://www.edmundoptics.com/onlineca...productID=2287

These charts will test the sharpness of the lense but it won't reveal ghosting artifacts caused by internal reflections (eg.an element or a group is very slightly off axis and reflecting light all over) or the ghosting on bright fore/background objects.

Unless super bright lights are used to lit the test target.

[cjtune]

Originally Posted by btfiend These charts will test the sharpness of the lense but it won't reveal ghosting artifacts caused by internal reflections (eg.an element or a group is very slightly off axis and reflecting light all over) or the ghosting on bright fore/background objects. Unless super bright lights are used to lit the test target.

Well, somewhere along the lines of a target, for resolution, ghosting and whatnots.
Key word is 'standard' so that there can be no miscommunication as to the procedures used, and can be redone for verification. Not rule-of-thumb or gut feel or personal experience.

[Blu-By-U]

Looks like my cheapo Sigma 55-200 may give a better image. Maybe all E users should troop into the Oly service center and demand better service.

Another thing, you better demand for extended warranty and if you are not satisfied with the lens, ask them to be in the position to replace the lens.

Shot taken with the cheapo Sigma..at full zoom. Resized for posting only.

[btfiend]

Originally Posted by Blu-By-U Looks like my cheapo Sigma 55-200 may give a better image. Maybe all E users should troop into the Oly service center and demand better service.

I took another shot of the same thing sometime back using a $300 40-150mm (at 1/2000, f/4.5) and it was way sharper and detailed than this. ZERO ghosting and sharp from corner to corner. Its probably sharper than the lemon 50-200mm even if I resized it up to match the 200mm shot.

[Blu-By-U]

When will they deliver it back to you? When it's back, then do a test again and if possible, same cam but another similar lens for comparison. I am sure there are other Oly users near you willing to help.

[btfiend]

Originally Posted by Blu-By-U When will they deliver it back to you? When it's back, then do a test again and if possible, same cam but another similar lens for comparison. I am sure there are other Oly users near you willing to help.

Borrowed a loaner from Oly service centre today (looks like another beat up lemon...dust and stains INSIDE the lense... this kind of lense dare show customers ...Oly SG no pride at all). Took some test shots with the loaner 50-200mm and another (VERY good) 50-200mm copy.

Original / Loaner / Good copy:





Original: 1/3000 f/4
Loaner: 1/2000 f/4
Good copy: 1/2000 f/4

Loaner/Good Copy taken around 3.50pm, 22 January 2007.

The loaner is better than the lemon but still exhibit slight ghosting and softness.

[btfiend]

The 'blooming fence test':

The original:



The loaner:



OOF is more even on the loaner. Still slight ghosting although it isn't half as serious as the original lemon.

[btfiend]

Another 3 comparison test shots:

Lemon/Loaner/Good Sample:

[cjtune]

A world of difference when comparing between the lemon/loaner/good copy's images.