Originally posted by billdotjr - The resolution seems to be significantly better at ISO 100 than ISO 200, but still the ISO 200 is way better than the photo from yesterday taken with the Sonnar
- The photo at ISO 200 seems to have little bit of motion blur, so I need to make more tests
- Although the IQ is worse in the ISO 200, the noise is not as pronounced. However when taken to Lightroom there is no noise at Sharpen 25 for the ISO 100 while it shows significant noise on the ISO 200 at the same setting. (Sharpen 25 only to demonstrate the difference.)
First of all, I applaud you for listening to the advice and opinions offered, acting on them, examining the results, and posting back to let us know how you got on. Many folks who get frustrated with such problems simply lose hope, or refuse to believe the problem isn't with the camera (it usually isn't
). So you've set an important example for others experiencing similar (or any other) problems. Thank you for that
It's very encouraging to see the improvement in your results. A few comments:
When shooting at 200mm with your Sigma zoom lens, bear in mind that almost every consumer-grade zoom lens (and even many mid-to-pro-grade models) will demonstrate poor (or, at least, reduced) performance at focal length extremes - so, at the very widest setting, or the very longest setting (or both). You'll almost certainly find that your Sigma performs better at 150mm than it does at 200mm, yet the field of view won't be hugely different. Similarly, for wide angle work, it may or may not perform all that well at 18mm, but could be much better at, say, 24mm. Experimentation is key, here... but we can almost-always say that a zoom lens set to maximum focal length won't perform at its best
Regarding motion blur... With 35mm film or so-called "full frame" digital cameras, the "reciprocal rule" states that you need to shoot at a shutter speed of at least
1 / focal length to avoid significant blur due to camera shake. Hence, if you were shooting at 200mm on a full frame camera, you'd ideally want to pick a shutter speed of 1/200s or faster. For an APS-C sensor camera such as your K-m, the formula is
1 / (focal length x 1.5). So, if you're shooting at 200mm on your K-m, you want a shutter speed of 1/300s or faster. If, instead, you're shooting at 50mm, you need a minimum shutter speed of 1/75s or faster. Of course, in-camera image stabilisation ("shake reduction") means you can often shoot at lower speeds, but what I've suggested is a good starting point.
Lastly, regarding noise and sharpening... It's fully expected that a raw ISO 200 image will be noisier than ISO 100, and images will become progressively noisier and less detailed as the ISO increases (the camera's JPEG engine will progressively apply more extreme noise reduction as ISO increases such that the difference is much less noticeable in JPEG files, but at the expense of detail). In post-processing with Lightroom, it's important that you switch off sharpening until you've completed all your other tasks. Then, set your sharpening as required - perhaps +25 - and set the "masking" level to +80 or thereabouts. The masking will reduce (though not eliminate) the amount of sharpening applied to noise, whilst still applying it fully to edges and larger details. In fact, there's an argument that you might not need any sharpening whatsoever in your raw processing. Instead, you can apply the necessary noise reduction, then export to JPEG at whatever size of image you require for final viewing, optionally with export sharpening enabled. And don't forget, viewing your images at 100% reproduction doesn't offer a meaningful assessment of image noise. If you can't see the noise when your image is resized to final output dimensions, it's irrelevant