PDA

View Full Version : Zuiko 8mm Chromatic aberration


Trausti Hraunfjord
27th August 2009, 01:53 AM
So I finally received the 8mm fisheye lens today, and I am not happy with it at all.

It has quite terrible Chromatic aberration in the images:

http://flashificator.com/1/Diverse/ChromaticFisheyeErrors.jpg

... this may look bad, but it is far from the worst I have seen in the (few) images I have shot with the lens until now. And no, this is not from the edge of the image, but from a section close to the center of it.

The image this crop is taken from, was shot with the camera on a tripod, using a remote, so there is no shaking there (but it was a bit out of focus)

What am I doing wrong? Or is it the camera that is not cooperating... or could it be the lens?

You are the experts, I will listen.

snaarman
27th August 2009, 07:10 AM
That does not look like Olympus quality to me, especially if it is near centre shot. I would suggest trying another 8mm and comparing.

It may be your example has a mis-aligned element inside it..

Pete

Trausti Hraunfjord
27th August 2009, 07:32 AM
What I thought was Chromatic aberration, is not. It's Purple fringing. Here is a site that has addressed this very issue:

http://slash72.club.fr/gurl/Olympus/Copy%20of%20fisheye.htm

I have absolutely no way of comparing it to another lens, since this is the one and only lens of it's kind here in Peru. I bought it from the US, through a friend there... so I am truly stuck with it. I would however like to try it out on another Oly camera, and compare the difference... if there is any.

... then there is always the new successor of E-3 ... it will hopefully have a much better sensor and computing system, that can eliminate all unwanted purpleness and other baddies.

I have only done 3 pano tests with the lens here at home, and despite the purple fringing, and the complete disappointment it resulted in, I can see that with the lens/camera set up properly on the panohead, stitching and shooting times are going to be seriously reduced in favor of more life-time. So I will stick to this lens for my work.

Zuiko
27th August 2009, 08:49 AM
Sorry to hear of this problem' Trausti, it's a shocker. I suspect that the lens is faulty rather than the camera. Given that you've no way of comparing it with another lens the only long term solution may be to send it to Oly with some sample pics and get them to sort it, although I do appreciate the hassle this involves based on where you live.

I must admit I'm not familiar with this lens - are there any owners out there who can comment further to help Trausti?

Archphoto
27th August 2009, 09:28 AM
Just a hunch, this could be light bounching inside the mirror box.

Make from black card board a disk that fits the rear of the lens with an 16mm* hole in it at att it to the rear of of the lens with double sided tape and see what comes out.

I had some softness problems with legacy lenses on the E's and this solved it partly in Brazil without my having my own repair shop set-up that I have in Holland.

Peter

* you can experiment with the size of the hole, make it even smaller

StephenL
27th August 2009, 09:29 AM
I had the opportunity, a year or so ago, of shooting with one of these lenses on an E-510, and this problem never appeared. I can only conclude from this unscientific test that you have a faulty lens.

Ian
27th August 2009, 09:35 AM
I am a bit confused - is this a Zuiko Digital 8mm fisheye we are talking about or a legacy OM Zuiko circular 8mm fisheye lens?

Ian

Trausti Hraunfjord
27th August 2009, 10:34 AM
Zuiko Digital 8mm. Not the legacy one.

I will have to make a lot more shots and examine these... Of course, the crop I provided above, is only 460 or so pixels on each side, while the original is around 60 times bigger... so it is at relatively high zoom levels that the purple crap becomes really visible.

But since I have only shot less than 100 pictures with the lens, and not examined each and every one of those, I need more time for "accepting" or finding a way to "live with" this... if it is a genuine problem, that it could actually be, considering the info in the LINK (http://slash72.club.fr/gurl/Olympus/Copy%20of%20fisheye.htm) I provided earlier. Under good ligthing conditions, I hope there will be less purple fringes. But hope alone is seldomly enough to solve problems.

@Peter
Thanks for the suggestion, but the glass at the lens butt is only 16mm in diameter (maybe 17)... so there isn't much to move in there. I will block off the eyepiece for some tests, and see if that might help.

The Saint
27th August 2009, 11:04 AM
Trausti

I have a the ZD 8mm fisheye aswell as an E-3, E-620 and E-510 is there a simple test we could set up at our various locations to see if this is a generic issue with the lens or there is a fault in yours?

I have to admit I probably don't look at my images in as much detail as yourself, but I've never spotted the purple fringing in any of my images.

Regards

Simon

EH1
27th August 2009, 11:33 AM
I would have thought this is a fault with your idividual lens! I hope you get it sorted out somehow.

snaarman
27th August 2009, 11:48 AM
Trausti

I have a the ZD 8mm fisheye aswell as an E-3, E-620 and E-510 is there a simple test we could set up at our various locations to see if this is a generic issue with the lens or there is a fault in yours?
Regards

Simon


Here's a suggestion.. You could photograph a bright computer screen against a dark background (we can all arrange for both of those) and compare the results.. All you need is some helpful 8mm owner to do a comparison shot - doesn't even need to be on the same continent :-)

Pete

Trausti Hraunfjord
27th August 2009, 11:49 AM
Thank you Simon.

I put white paper on a turned off monitor (overhead light) and maked off the fringe areas on the monitor (other parts of the image have it as well, but for a test you can make too, let's focus only on the white paper and black monitor).

Here is a small image of it:

http://flashificator.com/1/Diverse/PurpleFringing2.jpg

And here is the full size image: http://flashificator.com/1/Diverse/PurpleFringing.jpg

Here is the exif for the image... if you want to set your camera to the same (or similar) settings:

http://flashificator.com/1/Diverse/PurpleEXIF.jpg

Trausti Hraunfjord
27th August 2009, 11:51 AM
Ok Pete... where is your spy camera placed? :cool: Looking over my shoulder, or reading my mind? We posted at the same time, but as you can see, I shot the picture minutes before you posted.

snaarman
27th August 2009, 11:58 AM
Ok Pete... where is your spy camera placed? :cool: Looking over my shoulder, or reading my mind? We posted at the same time, but as you can see, I shot the picture minutes before you posted.

Hehe.. satellite imagery is improving all the time my friend.. Always close your curtains :-)

P

The Saint
27th August 2009, 12:01 PM
I'm probably going to be in the office late tonight, but do a comparison over the weekend.

Regards

Simon

j.baker
27th August 2009, 12:09 PM
I have just taken a few images with my 8mm on the E30.

I do see purple fringing in similar locations....mostly towards the horizontal edges of the image. I do not see anything on the vertical. I did rotate my camera and took a shot if the same image. The purple fringing was also rotated and I could only see it on the vertical edges.

Personally I am not bothered with it. I knew that there would be distortion, but to the nature of the lens.

Trausti Hraunfjord
29th August 2009, 01:54 AM
Thank you John for testing.

I have (of course) done more shooting with the lens, and it is fringing... seems to be depending on the angle one has the subject in... in relation to the light sources hitting the subject.

Still I am disappointed in the quality, but on the other hand, I can now shoot a full spherical panorama in under a minute with only 7 shots (could possibly press it down to 6 shots... not tried that yet though).

Shooting -10 with 6 around and one up, leaves only the panohead rotating base to be covered up, and with my Flashificator, covering the panohead base with a company logo is done with 2 clicks of the mouse... so that's not a problem. If however I need a nadir shot, I will have to do that with using the nadir shot boom I made the other day, and it takes extra time to put it in place for use... but I guess I could just as well do some photoshopping to cover up the panohead base (using copy tool)... or shooting the nadir shot with another camera and photoshopping it in afterwards.... or changing the lens, removing the tripod and shooting the nadir with same camera... which is probably better.

After I have shot a pano with 7 images, from the moment I open the memory cover of the camera until I have the panorama stitched and converted to 6 cube faces, ready to be ran through Flashificator for panorama creation, only 5 minutes go by. Earlier, with the 30+ shots to be loaded from the memory card to the computer, loaded into the stitching software, aligned and matched between shots, stitched and converted to cube faces, would be at least 25 minutes... often more, if there were problems with the alignment. The panos I have made for testing, are done in a part of my home where I have had stitching problems with the 30+ shots earlier... and WITHOUT having aligned the camera on the panorama head accurately (only by "eye") I am having better results than ever before...

So... better stitching results and faster stitching (as I had hoped for)... free up at least 20 minutes on every pano. That is a HUGE time saver. Shooting the pano takes less than 1 minute, compared to 5-20 minutes earlier (very much depending on people and moving objects close by... much less depending on that with the fisheye, since it grabs a lot larger area in every shot).

... so even though I could wish for MUCH better quality in the shots, I can live with the purple fringing, based on the enormous time savings gained.... even if I occationally have to do some purple fringe removal work in Photoshop.... there is enough time saved to make up for that.

... but I still hope for firmware update that may cure this... (a hundred years with chromatic aberration will probably not be resolved in the next firmware update), ... but a final solution in the next decade would be great.

Having got the fisheye lens, the kit lenses look and feel so small and incompetent... It's strange how quickly new equipment can feel "right", while older and more used equipment can feel "foreign". Just like my old Oly C-8080 wz... If I handle it these days, it just feels all "wrong". ........ "Nothing is where it should be" kind of feeling... and I have used that camera for over 200.000 shots in the past 5 years.

arrggghhh... sorry for pano-ramming you with my rant... forgot that I am not ranting in a pano forum :) (now someone is going to be glad I bombarded you with the rant, rather than them).

Zuiko
29th August 2009, 02:13 AM
You're right, Trausti, it's not a pano forum - but many here are interested in panos. Thanks for giving an insight on what that new lens can do for you.
It's a shame about the CA but maybe that's the trade off for such an extreme focal length.

I know what you mean about previous equipment no longer feeling right. Since I've got used to the E3 the E510 no longer feels natural whereas before it did. Weird!

Trausti Hraunfjord
29th August 2009, 06:07 AM
I will go bananas here:

http://www.rugift.com/photocameras/olympus-lenses.htm

Just look at this monster:

http://www.rugift.com/photocameras/telescope-1200mm-2000mm-for-olympus.htm

http://www.rugift.com/images/telescope-1200-2000mm.jpg

It's a powerful 1200mm objective focus lens. It should increase to 1800-2000mm for most DSLR.You can take impressive pictures of the moon, planets and other celestial objects. It also take extraordinary pictures of shy or wild animals or of a spectacular natural phenomenon as a volcanic eruption.

Olympus 4/3 Mount Film or Digital SLR Camera for : E-1, E300, E330, E400, E500, E410, E420, E510, E520 etc....

$375

The prices are so low that one really can't go wrong. I'd rather be disappointed by a $400 lens, than a $7000 dollar lens.

This is going to be my next next shopping stop for lenses. Anyone have experience with some of the models?

Pros/Cons?

theMusicMan
29th August 2009, 06:41 AM
Hi Trausti

I think if you don't mind losing or risking that amount of cash then fine - but it is almost guaranteed that this will be a very poor quality lens. The fastest aperture is f10, which is very slow indeed and will need all but the best light, it is a mirror lens meaning you'll get some interesting bokeh effects, and lastly... usually, if something appears too good to be true, then it usually is too good to be true!!

Sorry!

I also think that if you're into high zoom telephoto shooting, that you should consider a spotting scope rather than this. I have seen incredible results from an E-410 over on birdforum from a user (I think called Neil). He uses a quality spotter digiscope, probably Swarovski or Kowa, together with a digiscope adapter for his camera, as well as some additional tubes - to get incredible zoom ranges. Some of his bird shots are simply fantastic. There's a thread on it over there, specifically for his set up where he shows you what he uses, and how it is all set up etc. Maybe pop over there and take a look.

EDIT: Here's the thread: http://www.birdforum.net/showthread.php?t=116135

I have an Opticron scope, which is fantastic. I haven't used this for digiscoping as yet.

Hope this helps.

John

j.baker
30th August 2009, 09:13 PM
For those that are interested, here is a shot taken today (sunday 30th Aug) at Crofton Beam Engine in Wiltshire.

http://e-group.uk.net/gallery/data/500/JB302683-small.jpg

Minor PP, and resizing.

Yes there is a small amount of CA, and I am aware that I would have centered the image better....but I was time limited. They could only keep the doors open for a few seconds.

j.baker
30th August 2009, 09:19 PM
Here are two from Bournemouth. Both taken from the pier on Saturday 29th Aug. Very windy.

http://e-group.uk.net/gallery/data/500/JB292408-small.jpg

http://e-group.uk.net/gallery/data/500/JB292403-small.jpg

Minor crop on one image. Minor RAW tweaking and then resized for web.

Trausti Hraunfjord
30th August 2009, 09:20 PM
Thank you for sharing.

There is purple fringing all over the image, and that is a great "relief" for me to know... because that confirms that it's not my lens or camera that is at fault... that's just how things are with these lenses in today's situation. It would be ideal if they came up with firmware that eliminated this problem... but that is not going to happen.

I can live with this... after having had time to adapt my mind to the facts.

Thanks again.

j.baker
30th August 2009, 09:23 PM
Yes there is purple fringing, but only in areas of contrast. The dark water and the sunlight as very noticable. For othershots its not too bad.

I like the 8mm lens. It allows me to get some very wide shots, and I also like the fisheye distortion.

That said, I wouldl like the 7-14mm :D:D.

I do not regret purchasing iit....which is a first for me :)

Archphoto
31st August 2009, 04:05 AM
Sory guys, did not expect this kind of "problem" with the digital 8mm, thought you were talking about the OM version.
Something for Oly to solve in a version II.......

I did some checking on shots that I made with the 7-14mm and found nothing disturbing (:D).

John, great shot, it is about time for some side by side shots with both the 8mm and the 7-14mm to see the real diferences and I know the 8mm costs about half of the price of the 7-14mm.

Peter

theMusicMan
31st August 2009, 06:07 AM
Sory guys, did not expect this kind of "problem" with the digital 8mm, thought you were talking about the OM version.
Something for Oly to solve in a version II.......

I did some checking on shots that I made with the 7-14mm and found nothing disturbing (:D).

John, great shot, it is about time for some side by side shots with both the 8mm and the 7-14mm to see the real diferences and I know the 8mm costs about half of the price of the 7-14mm.

Peter
Hi Peter

We could do this at the South Wales meet on Sat... *yes

Archphoto
31st August 2009, 12:07 PM
I would love to !!!!!!

That has to wait however: my flight from Sao Paulo to Amsterdam is on the 10th and after that I will need quite some time for my self (health issue) and other projeccts that are waiting for me in Holland.

An other time, but thanks for the invitation !

Greetings,
Peter

AlistairJ
16th November 2009, 04:47 PM
Sorry to re-awaken an old thread.

A while back I took this shot of star trails using the ZD 8mm, actually it was a number of exposures taken over about 45 minutes and added together (each 40s f/4 ISO 200)

There is quite noticeable fringing on the brighter stars out towards the edge. I tried to correct it using the tools in Lightroom but it soon became clear that its not caused by chromatic aberration. At the time I decided it was probably caused an internal reflection between some of the lens groups. Because the stars are quite bright in this image (completely blown out) and the camera is sensitive enough to pick up the reflections under these circumstances.

http://alistairj.smugmug.com/photos/599787907_6KQkM-XL.jpg

I could be wrong, but I suspect it is just a limitation of the lens design.

theMusicMan
16th November 2009, 05:04 PM
Interesting info there Alistair, I wonder what Ian's expert take on this is...? Ian...?

Ian
16th November 2009, 08:22 PM
I've only had very limited use if the 8mm fisheye. I do have some images in my Lighroom database at the office, so I will dig them out and check for this problem. A brand new on is on order for the lens hire stock and I will also check this as soon as it arrives.

Ian

AlistairJ
16th November 2009, 11:02 PM
Yes, well if I am right then there is nothing fundamentally wrong with the lens or its performance. Really its my fault for over-exposing the shots.

Ian
17th November 2009, 09:54 AM
OK - here is a shot I took with an 8mm ZD fisheye and an E-3 a while back on one of the e-group meets. There is some high contrast edge detail that does reveal fringing right on the edge of the frame to the right. These are developed from the RAW file in Lightroom 2.5, taken at ISO 400, f/6.3:

http://e-group.uk.net/gallery/data/511/P4268956.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/19233)

Above is the full frame.

http://e-group.uk.net/gallery/data/511/fisheye-ca-notcorrected.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/19235)

Above is a 1:1 view if the area affected, without correction.

http://e-group.uk.net/gallery/data/511/fisheye-ca-corrected.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/19234)

And here is my attempt at correction, with red/cyan at -29, blue/yellow +100, and Defringe: Highlight Edges selected.

Any comments?

Ian

oly_om
17th November 2009, 06:27 PM
That seems to work well. I sometimes use the defringe settings on other lenses - pretty well any lens will exhibit fringing given very adverse conditions. This is particularly the case in situations of high contrast where you over-expose (in comparison to the metered value) to expose for a darker element of an image (e.g. bird against bright sky). Another trick, is to reduce the purple channel (in HSL/grayscale in ACR or LR) saturation and luminance (assuming you don't have a lot of purple in the image to begin with!).

Andy

Ian
18th November 2009, 08:53 AM
So what is the overall verdict? Is the 8mm fisheye unavoidably prone to CA or is the OP's example faulty?

Ian

oly_om
18th November 2009, 09:10 AM
I don't have the lens myself, but I would vote for "unavoidably prone to CA"

Andy

j.baker
18th November 2009, 09:22 AM
Andy,

I agree....and I own one :)

AlistairJ
18th November 2009, 10:05 AM
I disagree, its not CA.

I would say it does exhibit some purple fringing on high contrast edges towards the edge of the image.

oly_om
18th November 2009, 10:46 AM
I disagree, its not CA.

I would say it does exhibit some purple fringing on high contrast edges towards the edge of the image.


Strictly, purple fringing is a form of CA, as differentiated from lateral chromatic aberration (red/cyan or blue/yellow). Ian's example shows a bit of lateral CA and purple fringing.

Andy

Ian
18th November 2009, 11:18 AM
Chromatic aberration is where the lens fails to focus the different wavelengths of light at the same point. Lateral CA sees the different component colours remaining focused but separated on the focal plane. There is also another form of CA which is longitudinal, where the different colours are focused in front or behind the focal plane.

Purple fringing is subject to a lot of debate, but it is not CA in the strictest sense, although it does get mixed into discussions about CA. My personal feeling is that PF is more related to problems with digital sensors where very high contrast detail is not correctly managed by the de-mosaicing routine in the camera when the data is read off the sensor. In other words, saturation of the photodiodes along high contrast boundaries may result in spurious colour after the image has been processed. It may well be complicated by CA, so I suppose you can't necessarily mention one without the other.

Ian

Zuiko
18th November 2009, 11:54 AM
OK - here is a shot I took with an 8mm ZD fisheye and an E-3 a while back on one of the e-group meets. There is some high contrast edge detail that does reveal fringing right on the edge of the frame to the right. These are developed from the RAW file in Lightroom 2.5, taken at ISO 400, f/6.3:

http://e-group.uk.net/gallery/data/511/P4268956.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/19233)

Above is the full frame.

http://e-group.uk.net/gallery/data/511/fisheye-ca-notcorrected.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/19235)

Above is a 1:1 view if the area affected, without correction.

http://e-group.uk.net/gallery/data/511/fisheye-ca-corrected.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/19234)

And here is my attempt at correction, with red/cyan at -29, blue/yellow +100, and Defringe: Highlight Edges selected.

Any comments?

Ian

Er, is it my eyes or are these images posted the wrong way round? On my screen the corrected 1:1 (bottom image) looks significantly worse than the previous, uncorrected, version. :confused: