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I have two questions here, firstly I just submitted 4 images for QA and 2 failed for CA, now thats not a complaint they both do have CA, but I could not really see it untill I got past 400% zoom, so my first question is should we be doing that to check images before submitting or do I just have bad eyes not good enough monitor (probably not this) or something. Clearly there was a problem but what lengths should we be going to to find these problems and fix them.

 

OK so accepting I had a problem I did some research and it seems that the lens used has a tendancy to give some CA at the extreems of its zoom and aperture, so is it normal to have to remove CA as part of my workflow, or do I need to spend thousands on really good lenses. I hasten to add that the ones I have are not cheap and are reviewd well.

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This has been said many times before, but your QC submission should be of very conservative images free of any faults- f8, tripod, sunny day probably. Subsequent submissions are not as closely scrutinised. QC only examine at 100% so you should look into this. Get to know when the CA is noticeable and try to avoid those situations. I must have submitted dozens of images with a bit of it and it's only once been a problem in a backlit shot, but that one was SoLD anyway. I use kit lenses.

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Hi Stephen 

 

You dont say whether you are taking RAW images or not - If you are not, then I would strongly recommend you do, and then when you do the initial RAW processing, in ACR or Lightroom or whatever software is used, always look at a few parts of the image (borders between light and dark areas) at at least 300% to check for chromatic aberration, and remove it with the tools provided.

 

Most lenses have some degree of CA, even the best, and it is well worth removing it at the processing stage

 

Kumar sriskandan

Edited by Doc

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To a newcomer I would say that for me the returns from here don't justify the effort raw processing would take and I have always shot jpeg for Alamy. A bit heretical but there you are, even David Kilpatrick recently mentioned he'd consider it now with the new cameras.

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Doc yes I always take raw and I have seen the idea that the first 4 should be safe images and to be honest I thought they were the problem wasin tree branches against a sky which on reflection is not safe at all so I have resubmitted different images, I was really just curious about the process as you really need to zoom in further to see the CA and its going to be there in a lot of images so it will need removing.

 

Thanks for the fast responses they confirm my assumptions.

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To a newcomer I would say that for me the returns from here don't justify the effort raw processing would take and I have always shot jpeg for Alamy. A bit heretical but there you are, even David Kilpatrick recently mentioned he'd consider it now with the new cameras.

 

Mark,

I too only shoot high quality JPEGs (with RAW 'backup') for submission to Alamy and my track record is pretty good. I agree that the returns of processing RAWs, converting to TIFFs then JPEGs doesn't seem worth it.

 

My sales record seems to agree too!

 

I'll probably get some abuse for not doing things 'properly' though now!

 

John

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Sorry to disagree but I have shot in RAW for some years now and never looked back there is so much control gained from RAW that I don't really get why people shot jpeg it's such an unstable format. However I guess it's working for some of you as sales say it all here I guess.

Sorry to disagree but I have shot in RAW for some years now and never looked back there is so much control gained from RAW that I don't really get why people shoot jpeg it's such an unstable format. However I guess it's working for some of you as sales say it all here I guess.

Edited by Stephen Barney
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Thinking about it I note for the first time that LR2 deals with my RAWs quite well so I may have another go. Not sure I want to quadruple my disk space but maybe for the odd tricky sky it might save all that bracketing. Thanks for the heads up.

Edited by spacecadet
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I use Lightroom 4.1 as my RAW converter and I find it excellent on CA. Magical in fact. :)

All my lenses will show CA in some circumstances including my best Zeiss lens. Lightroom deals with them all equally well.

 

Christine

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RAW plus LR4 correction fixes almost all CA problems. My main config is 5 D III pls canon 17-40 lens. No problems whatsoever with CA since LR4 appeared on the scene. I also use a couple of pimes, a Canon 50mm f1.4, and on my 7 d's the Canon 60mm macro, again though, no CA problems with LR4, and the EF-S 10-22 wide zoom.

 

There are othe alternatives in PS to fix CA, google is your friend here.

 

Ken

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I'm quite surprised you can see it at 400% but not at 100%. If that really is the case then Alamy should not have failed it as, we are told, they look at 100%.

I don't know what camera you have but Nikon Capture and Lightroom both have pretty good automatic CA removal tools. I use them most of the time. All my lenses will produce CA if given the opportunity so it's more or less a standard part of my processing.

 

This 400% thing really doesn't seem right to me. Are you sure you are looking at 400% and are you sure there isn't something more obvious somewhere else?

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My process is to shoot RAW with Canon equipment and use DPP (supplied with Canon) to remove CA. Does an excellent job too.

 

When shooting with other makes I use LR3, and PSE11 with Adobe RAW processing to remove CA.

 

Allan

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I'm quite surprised you can see it at 400% but not at 100%. If that really is the case then Alamy should not have failed it as, we are told, they look at 100%.

I don't know what camera you have but Nikon Capture and Lightroom both have pretty good automatic CA removal tools. I use them most of the time. All my lenses will produce CA if given the opportunity so it's more or less a standard part of my processing.

 

This 400% thing really doesn't seem right to me. Are you sure you are looking at 400% and are you sure there isn't something more obvious somewhere else?

It was probably me and my eyes now I am more aware ill be more careful good news is my latest four passed QA so I am very happy

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I have two questions here, firstly I just submitted 4 images for QA and 2 failed for CA, now thats not a complaint they both do have CA, but I could not really see it untill I got past 400% zoom, so my first question is should we be doing that to check images before submitting or do I just have bad eyes not good enough monitor (probably not this) or something. Clearly there was a problem but what lengths should we be going to to find these problems and fix them.

 

OK so accepting I had a problem I did some research and it seems that the lens used has a tendancy to give some CA at the extreems of its zoom and aperture, so is it normal to have to remove CA as part of my workflow, or do I need to spend thousands on really good lenses. I hasten to add that the ones I have are not cheap and are reviewd well.

 

May I please take a minute and ask you and all newbie members to do a few things before post a question? 

 

First read everything Alamy has given us about preparing and submitting images:  http://www.alamy.com/contributor/help/prepare-images.asp

 

Please tell us about the equipment and software you're using. And tell us your normal workflow—RAW, tiff, jpeg or something else.

 

Welcome to Alamy, Stephen. 

 

PS: I'm shooting a lot with NEX cameras now, and using LR4. The first thing I do is click on the "reduce chromatic aberrations" button.

Edited by Ed Rooney

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I've never had anything fail because of CA, and I can't afford expensive lenses. I currently shoot RAW and correct CA with a program called PTLens after images have been converted to 16-bit TIFs. PTLens does a decent job. However, one of these years, I will upgrade to LR.

 

The example of CA that Alamy gives in their submission guidelines is woefully inadequate IMO, as it only shows "purple fringing."

 

As far as Alamy vetting images at 100%, my guess is that QC people will zoom in on an image if they see potential problems such as CA.

 

I hope that QC continues to smile on you, Stephen.

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I shoot Nikon and raw and tend to have a pretty good look at images at 100%,  I have used either lightroom or Capture NX for converting raw/nef files and find that I can sort out most CA.. I sometimes get a quite bit of CA with my 50mm 1.4 or my 35mm 1.8..but if I cant completely get rid of it I wouldn't submit the images.

 

Steve.

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Having found out that LR has a CA slider and that it works well on jpgs I'll be sticking to them.

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