# 6d Banding/Posterization in Blue Sky



## bgran8 (Mar 20, 2014)

I just got a 6d with 24-105 from B&H in hopes of replacing my 5dii with 24-105. I really like a few things about the 6d, but there are a few issues I am dealing with.

1) See the attached images. They are screenshots of the same picture shot at 100 ISO and f22 to show the dust spots. There is noticeable banding in the blue sky when viewed in Lightroom 4. I have read in a review on either B&H or Amazon that someone else had this problem--has anyone else experienced this with the 6d? There are no issues with my 5dii.

2) There are also a number of dust spots on the sensor. These can be seen in one of the images. Is that common for a brand new camera?

Thanks in advance.


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## Sporgon (Mar 20, 2014)

1). This isn't banding, it's posterization caused by joey compression. Have you shot this on a small joey or converted it to high compression ? The 6D is actually a tad better than the 5DII in tonal graduation, superb for skies. 

2). Dust is a fact of photographic life; I wouldn't worry about it. 

2a). Oil splattering on the other hand is not, but as we're not Nikonians there's little to worry about


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## Lightmaster (Mar 20, 2014)

yep that´s not a 6D issue.

that what happens when you use JPG (or other formats) with only 256 tonal values per channel and higher compression. or when your editing has produced such posterization (levels, curves, spreading the tonal values can cause this).

in fine gradients like the sky or computer generated gradients this can even be visible with 16 bit TIFF files when viewed on 8 bit monitors.

that´s why, in my opinion, for serious image editing a 10 bit or better monitor is a must have.


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## MTSG (Mar 21, 2014)

Hi!
reg pt.1 i guess there is nothing to worry about i got it usually on sort of compressed pics, check it in RAW
reg pt.2, well i got 1 spot like that on my 6d and i am crazy about bcause i have no time to got fix in in service. i changed lenses - same, clean sensor with inbuild procedure - same,
finally, i tried to append dust data for correction and well, it reads the spot and clears it on... first shot image but on second shot image all comes back again.
My - the only one spot of dirt (?!!!) is located on "sky" part of typical image so is always visible (including video!!!) 
How the spot may come to my 6d? possib i shot before in marine environment of salt water sea and changed lens several times, however mirror is closed in such state... (???)
when shoting on completely white background you may really see the spots.
so my problem is similar to yours (spots), if somebody may encouter that and got fix - please help.


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## tolusina (Mar 21, 2014)

1) In the 6D's menus, bottom of the third page from left is Color space. Select Adobe RGB. You'll get the most pleasing results if the gamut of your monitor and workflow software also display in Adobe RGB or wider. 
2) Those don't look like dust spots to me but dried liquid residue.
Dust spots are usually well defined with hard edges, dried liquid residue spots are soft like the ones shown in your photo above.

I find sensor cleaning tense and tedious, one of my least favorite photographer's tasks. I've also accepted that it's necessary and too expensive to farm out.
It's not really very hard, clean, check, clean, check, repeat until satisfied.
---
I use a couple of tools.

Tripod, should be self explanatory, holds the camera while you work on it.

A $12 USD hand pumped garden plant sprayer from Walmart for my pressurized air source.
Canned air has propellants, some propellants are detrimental to the task, they're expensive.
I find squeeze bulbs wimpy.
The plant sprayer when fully pumped has good burst volume at low pressure. 
Since someone here is likely to jump on that low pressure statement, I just measured 25.5 PSI deadhead pressure. Spray pressure past the diffuser must be much lower. Still, back away from the closed shutter blades while spraying.
As soon as I've depleted the compressed air, I pump again so it's ready for next use.

For wet cleaning, I use Sensor Swab swabs, Eclipse solution.

I have the EG-S focusing screen, I use the included tool to remove the screen.
---
I lock up the mirror, remove the lens, blow out the mirror box with the shutter closed and sensor not visible.
I remove the focusing screen, blow out the area between the screen and the bottom of the prism, re-install the screen.
I clean the mirror box area first so as the (hopefully) remove any hidden dust bunnies from that area prior to exposing the sensor for cleaning, don't want those bunnies able to get to the sensor.

Now I enter the Sensor cleaning> Manual mode which opens and holds the shutter, exposing the sensor, blow it off.
I stop and take a test shot, stopped all the way down in AV, ISO 100, focus at infinity. I'll shoot plain paper or notepad in full screen, view the shot in full size on the PC, scrolling around looking for problem spots. 

If there's anything left after dry cleaning, it's wet clean time.

No more than two or three drops of solution on the swab is needed or desired. Full strokes from one side to the other, swab makers insist only one pass should be made with each side of the swab, I always exceed that recommendation.
This is the part I find nerve wracking even though I've never caused myself additional issues.
Quick quick as you can after swabbing. air blow the sensor.

Check and repeat. And repeat. Repetition until satisfied is the tedious part. 
---
My most recent cleaning job left one small dried wet spot, barely visible at f22, couldn't see it at f11 so I left it.
---
FWIW, my 6D, brand new in the camera store had dust visible on the camera's screen, icky. Fact of life I suppose, no sense complaining, just deal with it.







.


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## sdsr (Mar 21, 2014)

This may not be very helpful, but I've never noticed posterization via my 6D. As for dust spots, it's perhaps silly but while I expect to get a few over time, and while they're seldom a problem for me, it annoys me quite a bit if a new camera arrives with them. My first 5DII arrived with a large dark dust spot (much more intrusive than yours) that showed up at much wider apertures than f22 (as I never shoot anywhere near f22 I wouldn't care what showed up at that aperture anyway) that didn't go away easily, so I returned it; the next one was perfect (as were my subsequent 6D and 5DIII). 

Of course, this is nowhere near as bad as the infamous Pentax K5 sensor stains (which couldn't be cleaned off, but at least they acknowledged the problem) or the far worse Nikon D600 problem (which they refuse to acknowledge expressly, issuing the D610 instead). But if it annoys you, and if you regularly shoot at apertures where you can actually see the spots in your photos, send it back and try another.


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## dendowling (Mar 21, 2014)

The banding issue is not due to your camera it is due to your Lightroom previews. 

If you look at a photo in Lightroom's Loupe View you are not seeing the full quality image, you are only seeing a JPEG preview version of your image and is likely to have banding. If you want to see a fully rendered version of your image go to Develop mode and zoom into 1:1 (wait for render) and zoom back out. 

There is also a preview setting in Lightroom Catalog Settings under File Handling. Make sure you have Preview Quality on High. Even with that on High, I'd still suggest going to Develop mode 1:1 for a proper rendering of your image. 

It may also be possible to have banding if your camera is set to shoot JPEGs instead of RAW. Avoid shooting JPEG, make sure your camera is set to RAW mode if you want the full benefit of post-processing in Lightroom, Photoshop, etc.

Dust spots on the sensor should be rare for a brand new camera. If it's sensor dust you would see small dark spots on images shot at small aperture like f/22 and up and, faint fuzzy spots at mid apertures like f/8. 

Lots of places to find sensor cleaning recommendations. Before (or after) you try a sensor cleaning, you can do a sensor dust test by shooting a blurry photo of nothing. 

Set your camera to a low ISO like 100, use Aperture Priority and your smallest aperture like 22-32, set your lens to manual focus at infinity, and shoot a plain solid color wall just a few feet away (deliberately OOF, tele works better than wide angle). The small aperture should give you a very slow shutter so, it helps to move the camera around a little while the shutter pops to avoid getting a clear shot of anything on the wall. When you import the photo use auto white balance and turn up the contrast to get a better view of the spots. 

If you don't have the tools or time to clean your sensor it's a good idea to shoot a sensor dust test before an important shoot so, you can use it as a reference of dust locations when trying to determine if your good photos have dust spots. 

Also, if you use the Spot Removal tool in Lightroom you can also Sync the spot correction from one photo you corrected to any other photos that have the same composition (tripod shots) - as long as the image area at the sample points is the same from one image to the next.

As usual, avoid changing lenses in windy and/or dusty locations. Dust in your mirror box and dust on your rear lenses may eventually make it's way onto your sensor.


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## dendowling (Mar 21, 2014)

tolusina said:


> 1) In the 6D's menus, bottom of the third page from left is Color space. Select Adobe RGB. You'll get the most pleasing results if the gamut of your monitor and workflow software also display in Adobe RGB or wider.



Keep in mind the camera's Color Space setting only affects JPEGs. Photos shot in RAW mode do not include any color space adjustment. But, it's still a good idea to set the cam to AdobeRGB just in case you accidentally shoot some JPEGs.


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## Sporgon (Mar 21, 2014)

dendowling said:


> tolusina said:
> 
> 
> > 1) In the 6D's menus, bottom of the third page from left is Color space. Select Adobe RGB. You'll get the most pleasing results if the gamut of your monitor and workflow software also display in Adobe RGB or wider.
> ...



That's very misleading. Whilst it _is_ true that colour space doesn't effect the raw capture, you always have to convert the raw file to _some form_ where you can view it as an image, and in this viewable form colour space will apply.

However at the present time most people are just going to give themselves issues by shooting in adobe rgb due to the fact that virtually all display mediums are srgb.


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## dendowling (Mar 21, 2014)

Sporgon said:


> That's very misleading. Whilst it _is_ true that colour space doesn't effect the raw capture, you always have to convert the raw file to _some form_ where you can view it as an image, and in this viewable form colour space will apply.
> 
> However at the present time most people are just going to give themselves issues by shooting in adobe rgb due to the fact that virtually all display mediums are srgb.



sRGB was designed back in the 1990s when everyone had low quality monitors and low quality printers. Current computers and displays have much better color quality plus ICC color management and higher quality printers. So, most people are able to see images displayed in higher quality than the sRGB color gamut. 

Generally, you'd want to capture images in camera in a high quality format and downgrade later only if necessary. Post processing software always has the option to convert color space on export so there's no need to shoot in sRGB. It'd be better to capture in RAW or AdobeRGB and only downgrade to sRGB if needed in post process export. It would seem odd to spend a lot of money on a pro grade camera and then shoot images in a low quality format.


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## Lightmaster (Mar 21, 2014)

dendowling said:


> Sporgon said:
> 
> 
> > That's very misleading. Whilst it _is_ true that colour space doesn't effect the raw capture, you always have to convert the raw file to _some form_ where you can view it as an image, and in this viewable form colour space will apply.
> ...



nope. unfortunately that is not the case.

most TFT displays sold today does not even reach full sRGB gamut.

the majority does not buy wide gamut displays.
they buy cheap 100-300 euro displays.

popular monitors for photographers from the last years, like the dell 2711 or 2410, have 100% sRGB and around 95-97% Adobe RGB coverage.

new TFT models, aimed at photographer, normaly offer 100% sRGB coverage these days.
but wide gamut or adobe RGB is far from being "standard".
even some more expensive models (like the samsung S27B970D) have only 96% sRGB coverage and around 69% Adobe RGB.

the brand new NEC P242W-BK covers 98% of sRGB.

cheap TFT´s often cover only 87-95% of the sRGB colorspace.
the samsung S24C450MW from 2013 for example barely covers 87% of the sRGB colorspace.


as for printing i agree.
todays printer often have wider gamut for some colors then sRGB offers.

so while these printers don´t have the full Adobe RGB colorspace, it makes sense to use Adobe RGB for print.

as for my own workflow.
i shoot RAW.
i do some basic image editing in LR.
then i send the files to photoshop when they need local adjustments or further editing.
the end result is a 16bit Adobe RGB TIFF file (with layers).

my monitor is a wide gamut 10bit eizo.

but for "normal" people who are no so much into computer and image editing i recommend a full sRGB workflow. less to worry about. and you won´t notice a difference on flickr or facebook anyway. 



> It would seem odd to spend a lot of money on a pro grade camera and then shoot images in a low quality format



well... that´s a bit like in the analog days.
many people like to take photos but not everyone want´s to setup a darkroom. 

my father loves to photograph.. but he does not want to spend time editing RAW files.


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## Sporgon (Mar 21, 2014)

Lightmaster said:


> dendowling said:
> 
> 
> > Sporgon said:
> ...



Yes, this is a detailed explanation of what I was referring to. 

For Building Panoramics work, where the _raison d'etre_ of the pictures is printing onto large canvases, I have my settings on one of the camera custom functions, and this includes Adobe RGB. The program I use to convert to 16 bit TIFF is set to carry over the camera's settings to the file. When these images are posted on the web they have to be converted to sRGB.

Unless I'm looking at serious printing I shoot everything else on sRGB now; it's a case of if you can't beat 'em, join 'em, because despite the fact that this colour space comes from the days of the digital Ark it is still the universal standard, and that is going to take some shifting. 

There are many reasons why someone needs a 'high end' camera, but the availability of Adobe RGB ain't near the top of the list.

Also regarding the OP's original question on posterizatiion, using Adobe RGB isn't going to have made a half cents worth of difference in this case - in fact it could have made it worse but that's opening a whole new can of worms  ;D


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## dendowling (Mar 22, 2014)

Sporgon your building and landscape photos are awesome - I can't imagine shooting those as JPEGs. 

Yeah, if a beginner is shooting with a cheap point & shoot it's fine for them to use sRGB JPEGs. But, I thought we were talking about experienced photographers using dSLRs here. If someone is into photography and buys a nice dSLR I would never recommend shooting JPEG. There is too much loss of image detail on JPEGs. It's like buying a nice HD1080 video camera then shooting everything at SD480.  

Even if the user plans to only upload photos to websites it's still not necessary to limit captures to sRGB. The photo processing software like Lightroom or iPhoto is always going to automatically convert the color profile on export, no effort required from the user. 

I would not recommend photographers downgrade their original captures in order to match the low grade equipment of the average web surfer or an outdated image standard. Don't aim for the lowest common denominator. Photographers should be capturing their originals in a higher quality format and only exporting a low-grade version as necessary for web use. 

If we want to move beyond the old sRGB standard we need to stop adhering to that standard and start capturing and processing in a higher quality format.


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## Sporgon (Mar 22, 2014)

dendowling said:


> Sporgon your building and landscape photos are awesome - I can't imagine shooting those as JPEGs.
> 
> Yeah, if a beginner is shooting with a cheap point & shoot it's fine for them to use sRGB JPEGs. But, I thought we were talking about experienced photographers using dSLRs here. If someone is into photography and buys a nice dSLR I would never recommend shooting JPEG. There is too much loss of image detail on JPEGs. It's like buying a nice HD1080 video camera then shooting everything at SD480.
> 
> ...



Thanks ! That's very kind of you . Yes I shoot all these in RAW then convert to a 16bit TIFF in Adobe RGB. ( Actually there is one that was accidentally shot on medium jpeg - The Cellarium at Fountains Abbey. I'd been taking scouting shots in unsuitable weather, just seeing where the best views were going to be, and of course I shoot these in jpeg, and forgot to change. I've overcome this now by having all B-P's stuff set up on a custom setting). 

However all web based images have to be changed to sRGB. You're quite right about it being an digitally archaic colour space but there is massive inertia now because of it being a worldwide standard.


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## dgatwood (Mar 22, 2014)

Sporgon said:


> 1). This isn't banding, it's posterization caused by *joey* compression. Have you shot this on a small *joey* or converted it to high compression ? The 6D is actually a tad better than the 5DII in tonal graduation, superb for skies.



Autocorrect?


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