Quality and workflow

[rogertb]

Hi - I've been attempting to submit some shots to a photo library and keep getting refused because of artefacts - believe me this is not a moan - I agree with their strict quality requirements but would like to reduce the refusals. There are so many places where artifacts can be introduced from too high ISO settings 'in-camera' and it seems the slightest 'tweak' in ACR. I shoot in raw using the manual, Tv or Av setting, convert to dng, open in Adobe Camera Raw and use the default settings (ie not "auto") though even these default settings seem to be introducing some problems eg brightness and contrast are punched up a bit, there's a little sharpening and color noise reduction and a small adjustment in 'curves' - at last to my questions - should I just accept what ACR is doing to the dng and is my workflow correct ? The still I've attached is, I think, a little "dull" - shot on my 400d with a Sigma 18-200mm is it acceptable quality for this camera and this lens ? Many thanks for your time Roger

http://www.rogerburton.co.uk/cow/400dtest.jpg

[nicksan]

Did you use a tripod for this shot?

144mm 1/15" = too slow

f20 probably doesn't help in your cause as well.

I would open up some, which would also give you extra stops of shutter speed.

[ssim]

Have you tried doing some comparative conversions using other converters. You got DPP when you got your camera. I don't use DNG but I would also run some conversions against the original RAW file.

The image that you supplied doesn't seem to have issues with artifacts, it is just too soft for a stock agency to accept.

[rogertb]

Thanks nicksan - yes I used a tripod and the self timer and I thought closing down would help sharpen things up a little ... also thanks ssim ... is it really possible that dng is so bad that I could find a significantly better converter for the eos 400d ? and any tips as to why it's so soft - I obviously have a lot to learn. Thanks for taking the time - Roger

[Bollan]

For a stock image library that image is way to soft and slightly underexposed. Also it is a bit flat and lack some punch. Is it a crop or the full image?

Try your lens at f8 instead. Even if the Sigma is not the sharpest glass around you should get better results than this.

[miklav]

Start with putting sharpening/detail to 0 in RAW converter (default in Adobe Camera RAW is 25 for each) and watch the picture at 400% zoom - preferably solid shade areas without little details. If you see overall smooth color with some sharp spots here and there, those are the artifacts (it's not the same as digital noise/grain). As you increase sharpness, you'll see more of them. Increasing level of "Masking" in Adobe Camera RAW helps to keep artifacts under control (I usually use value 15). And you always have more artifacts in shadow areas.

So a) don't underexpose b) sharpen as little as possible in ACR and use masking, and then c) you can reduce artifacts in post-processing if you don't have too many of them.

One method I use is free deJPEG plugin from TopazLabs. Although the artifacts we are talking aren't JPEG artifacts, plugin can reduce them quite well. Use at low value (3 to 5), without any sharpening.

Another easier method is to duplicate picture layer, apply Gaussian Blur with radius 0.2-0.3, and put layer opacity to 40-60%. Again, check at 400% zoom.

[rogertb]

Hi Bollan - thanks for responding - yes it was a crop, probably representing 20% of the total picture area. I can address the exposure the softness and the lack of "punch" (which I totally agree with) are different matters, is it possible that the lens IS soft - I know that it was pretty cheap, maybe I should start saving for better quality - also thanks to miklav for some excellent advice though I don't quite understand "masking" (I have ACR 3.7) - good of you both - regards Roger

[miklav]

ACR 3.7 used another RAW conversion engine indeed than the recent version, so it has much fewer options. Nevertheless start from minimizing sharpening (provided you have well exposed RAW file shoot with low ISO).

As far as I know, majority of lens are most sharp in the range f8-f11. Even cheap Canon "kit" lens (EFS 18-55) is reasonably sharp in that range.

[rogertb]

Great tips again miklav - I'll do some tests across the focal length range at f8-11 and check them out. Roger