I have been using the longest telephoto setting on my EX3 and have noticed a fair bit of Chromatic Aberations. I know this is a lens issue and that even more expensive lenses have this problem, albeit maybe to a lesser degree.

Can anyone suggest a way to lessen the problem or is there a software application that will re-register the colours. I have tried to correct this in Photoshop CS4 & CS5 (Extended edition) and it does work to a fashion but is not perfect. I have also tried After Effects CS5.

Alister Chapman stated that the EX1 & EX3 cameras have electronic correction for C/A, I have searched for this feature and can't find it. Does anyone know where it is located?

Thanks in anticipation

AFAIK the electronic correction is in-built and works automatically - it detects what lens is mounted and goes through a software algorythm to correct for its known defects.
As you say, it's a fact of life to a greater or lesser degree with HD lenses, in fact all lenses.
I was always told that in post the problem could be corrected to a pretty big extent - more or less selecting the colour of the fringing and telling the software to de-saturate that colour, but I'm no editor.
In scientific terms from what I read the aperture used should make no difference to the amount of fringing, but a lot of people reported it being worse the wider the aperture, the consensus then being that it showed up more with a wider aperture because the fringing was wider as it was more out of focus, while with a smaller aperture it was more sharply defined so less pixels wide, so that may help, stopping down a little. But of course stop down too much and you'll start to get softness due to diffraction - lesser of 2 evils I suppose.
Steve

ps I love it how my computer keeps underlining COLOUR to tell me I've spelt it wrong!

Thank you for your detailed reply Steve. I have tried several techniques for correcting this problem using After Effects, and yes you can selectively desaturate the two colours (Magenta & Green) but this does leave a desaturated shadow which looks just as bad. I will keep experimenting, the shots in question are needed for a project.

ps. you can change your computers default language from US to UK spelling, that will cure your "Color" problem

Have always been aware of the telephoto CA but never thought it could be fixed. Will try your idea Steve. Only now noticed that when cutting EX1 material on an SD timeline with 10 year old Digibeta pictures shot on a Fuji 20-1 SD lens that there is CA on X2 wildlife close ups. So in one respect for this project they match!

Hi Vincent,

If you have access to the Vortex Media PMW EX3 Field guide you will find that page 117 mentions lens files including how to store and retrieve them. I have fiddled with the RGB Flare adjustments for my Nikon 300mm f4 and noticed no change over the full range of adjustments so I returned to the original settings. However I was only using the viewfinder image to make my judgements.

I am not quite following you on this one Alastair. I am fully aware of how to store files etc.

Have been experimenting further with Photoshop and After Effects. Photoshop CS4/5 does have a very good fix and has produced a better looking clip than After Effects, it's still not perfect but better than before.

I perfected the C/A using Photoshop, feeling very pleased with myself - UNTILL !!


I just realised that Filters and C/A corrections will only work on one frame at a time, back to the drawing board.

As a follow up to my Photoshop and C/A experience, have now found the sollution.

Using Photoshop CS4/CS5 (Extended edition) Select the Video workspace (top right hand corner drop down list). An empty timeline appears at the bottom of the workspace. Open a video file, I have converted my EX3 files to QuickTime MOV files. The movie appears in the timeline and your Layers palette indicates a single Layer 1. This next step was the misssing link for me, Convert this Layer to a Smart Object. Now any filter that you apply will be applied to the entire clip, not just the first frame.

I used the filter, Distort > Lens Correction, to correct my C/A problem. It has worked very well. Photoshop CS5 has more options for more precise corrections.

Note this video editing ability is only available in the EXTENDED edition of CS4 and CS5

Sometimes you can separate each RGB layer, and realign them, though sometimes you might have to add a warp too.

Stopping down does help somewhat, so you use more of the centre of the lens overall in the image. Things are more rectilinear there.

Just to finish off, here are the fruits of my day's labour.

The file WindFarm is a reduced full size frame,

The file C/A is showing the before shot

The File C/A corrected has been through the Photoshop workaround

Click on the images to view a higher magnification

[QUOTE=David C. Williams;1531191Stopping down does help somewhat, so you use more of the centre of the lens overall in the image. Things are more rectilinear there.[/QUOTE]

Stopping down doesn't mean you're using more of the centre of the image, only using a smaller sensor would do that.
Steve

Hi Vincent,

Looking at the before and after shots demonstrating the C/A, I am wondering if sharpening in camera is causing most of the problem, that is, of course if you have sharpening on.

To my eyes it, has the appearance (effect) of "unsharp mask" where adjacent pixels of high-contrast values are pumped up.

-Andrew

No, I have all the sharpening in camera turned off (Detail = 0)

The shot was taken on a very hot day and there is a lot of atmospheric distortion creeping in, this is a nice effect when you see the full clip.

I am now more than happy with the end result. I must stress that under normal viewing of the entire clip the C/A is not that apparent. The shot is required for broadcast so it had to be right (one shot in a series).

Now for the next problem to solve, but that is for another day. :-)

One thing to bear in mind, certainly true on the big broadcast cameras, is that Detail Off and Detail 0 are not the same thing.
Steve

There are a bunch of threads on the topic of sharpening & crispening as it is called in Sony parlance. Here is an illuminating thread on the matter. (http://www.dvinfo.net/forum/sony-xdcam-ex-cinealta/473353-crispening-effect-noise-luma-range.html)

I'm not stating that the problem is sharpening but it is worth knowing and considering some of the counter-intuitive sharpening related settings in the Sony camera as it could have contributed to the color/contrast shifts on those dark thin lines of the hydro tower.

-Andrew

I didn't know you could work on video files in photoshop.
Is this done often?

Yes, the Extended edition of Photoshop supports video. It is not the best way of working with video, generally After Effects will be a better choice. However, I supply a lot of 10, 20, 30 second clips to a film library, these short clips work very well in Photoshop, especially as you can apply most Photoshop filters to a clip. I also like the fact that you can use multiple layers, blending modes and Adjustment layers without any great problem. Having said all this, I wouldn't want to produce an Epic movie using just Photoshop. Once finsihed editing you can use the File > Expot > Render Video to output your file.


See instructions for using video in Photoshop in my previous post on this thread.

Stopping down doesn't mean you're using more of the centre of the image, only using a smaller sensor would do that.
Steve

It does.

YouTube - Chromatic Aberration and Aperture Size (http://www.youtube.com/watch?v=yH7rbRu7Av8)

How does it David? The light is being taken in through the whole of the lens and only passes through the aperture blades at the rear element where it is focussed.
Surely if you're only using a central portion of the lens then you'll get a magnifying effect as you do when using a small sensor.
I'm not an optics expert I admit, so maybe I'm wrong.
I think the link you provides demonstrates longitudinal chromatic aberration, which is affected by aperture, it's translateral that causes colour fringing. Again, I'm no expert though!
Steve

Longitudinal also causes CA. As I said, "stopping down does help somewhat". Transverse can cause registration errors, which can be alleviated in cameras with CA processing, or in post.

As I also said, stopping down does cause the outer portions of the lens to not be used. Go argue with Penn State Uni, that's their video I posted.

As I also said, stopping down does cause the outer portions of the lens to not be used. Go argue with Penn State Uni, that's their video I posted.

I can't really argue, as I really am no expert as I said.
One thing that springs instantly to mind though is that if stopping the lens down reduces the amount of the lens being used this would mean that you could use for instance APS-C sized stills lenses on full frame bodies if you stop them down enough as you won't get vignetting as you're not using the outer edge of the lens. But this is not the case AFAIK.
Steve

The one thing that is not pointed out is that you are changing the colour and not actually removing the fringe. On my example shots posted earlier on this thread, I was left with a grey halo. Although I did change the grey to a sky colour, using the "From > To" feature. The end result on my footage was far from ideal, in fact the Electricity cables just looked too thick in places due to the replaced colours.

Photoshop and the Lens Correction filter gave the best results for my shot, as the colour channel was actually shifted to bring it back into register. However, on some other scenes with a less prominent sky backdrop, After Effects produced a good result.

I was unhappy with the Change to Color results the first time I tried it as well, but after spending more time with it I found I could get very good results. Remember to set Change to Hue & Saturation. I've found that useful numbers to start with are: Hue 20%, Lightness 5%, Saturation 5%.

FWIW-

The change to colour works well with some subject matter, especially if it is against a dark backround, but when it comes to tree branches and other fine detail against a light sky, then the whole thing falls appart. Thanks for the tips all the same.

There is realy no substitute for a good quality lens. Here are two examples. One was shot at the full zoom setting on the Sony stock lens, the other was shot with a 85mm Nikkor using Steve Schovlars Adaptimax adaptor. Look at the left edge of the pictures. Click on the images below to open them, then click on the image again to view at 1:1 magnification. The difference speeaks for itself.

The differences between Nikon and Fujinon are impressive. I would be very interested to know if the lens file for the Fujinon is set to its optimum. The menu provides for adjustment capabilities but so far I have not seen an account of the best way or even any way to effect the procedure. Even the local Sony repair centre cannot offer assistance.

I haven't touched any of the lens file settings other that doing an Automatic Back Focus from time to time.

The Nikon lens used is the old style manual Nikkor, i.e. not the rubberized grip type. I have a whole set of Nikkor lenses ranging from 20mm through to 500mm, you can pick these lenses up for a song on e-bay or other sites as most people want auto focus and up to date lenses. Optically they are still superb lenses as you can see in my sample.

The stock lens at full magnification is roughly equivalent to the Nikkor 85mm.

I'm a massive fan of the old Nikon lenses. The more I shoot and learn, the more I appreciate the importance of the glass. I looked at an old 600mm f4 the other day, a monster, 14 pounds of metal and glass, the image it made was beautiful. But, I moved from my EX1 to an EX1r instead of an EX3, mainly because of the form factor, so my only option for more reach is an extender. I have to be very conservative with it. If I push it in terms of the lighting or contrast of a shot I'm pretty much guaranteed CA, I can usually fix it in post but not always. Not an ideal situation. My next camera will definitely allow for changing the lens.

Quote: - I haven't touched any of the lens file settings other that doing an Automatic Back Focus from time to time.


Hi Vincent,

I am not suggesting that you have changed any of your lens file settings but no doubt since you have owned the Fujinon it has been subjected to normal usage that may have detracted from its performance. No doubt there is some wear of threads, cams and other components that do the internal adjustments hence my interest in whether or not its lens file settings are still set to their optimum.

I have not looked very closely at my own EX3 but have got as far as noting that the Fujinon lens file can be recalled and I assume that the settings can be readjusted if deemed necessary.

However I have looked at the finder image when using a Nikon lens and tweaked the flare settings. As I did not see anything happen I returned the settings to their original levels. Since then I have been trying to find a good procedure for using this interesting feature of the EX3, I am sure that Sony must have good reasons for including it. For a start what does one need to display the EX3 image directly on to a high resolution computer screen?

I had only just got the Stock lens when I shot the footage examples so no wear and tear - this lens was a replacement to my first lens which unfortunately tried to mate with a concrete floor.

I too am rather puzzled by the numerous adjustments that are available, I don't even understand what half of them are supposed to do. I just try to shoot everything as clean as possible and then adjust colours etc. in post.

For my editing work I use Adobe Premiere CS4 & CS5 on a system that has a Matrox RTX2 card fitted. I use a 24" Samsung SyncMaster 245a as my working screen, i.e. the application interface etc. and a Samsung 24" SyncMaster T240HD for true High Definition monitoring, The Matrox card provides the HD signal. I also have a JVC 15" studio monitor for final colour correction, although I find the Samsung HD monitor does a good enough job on this.

I don’t pretend to know what all the lens file adjustments are. However I assume that they are provided so that one can get the best results possible from any particular lens. If the lens is set to its optimum this could well save time in post.

It would be also interesting to know whether the same lens file is used for all the standard EX3 Fujinon lenses (for example) or whether an individual file is prepared for each lens in the factory. If it is the latter the file may need to be modified if a replacement lens becomes necessary.

Interesting you say that Alastair, I do have two lens data files on the camera, under Recall, VCL-614B2X and XS8X4AS-XB8. Do you or other users also have two files under the File > Data > Recall section?

Hi Vincent,
I have exactly the same files plus four user files and I have not had to replace my lens (touch wood).

I have had another fiddle with the flare adjustment on my EX3, there is a choice of R,G and B which I guess refer to Red, Green and Blue. For a subject I used a red bodied pen with white lettering and for a lens I used a Nikon f4 300mm. There seemed to be a very small of red bleeding into one of the the white letters which I am sure was an artifact seen by the lens and not myself. Changing the R flare setting over its full range produced no observable change in the image on my 27" iMac. Admittedly I was only using an S-video cable so the image was not very good anyway. After all this I am none the wiser.

Are any of us wiser than the Sony guy who incorporated these adjustable settings in the first place. Maybe he doesn't know either, hence the lack of information.