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Microfocus tuning (or how to recognize the sharpest picture without looking at it)

Started Jul 5, 2017 | Discussions thread
OP George_pix Regular Member • Posts: 105
Re: Microfocus tuning (or how to recognize the sharpest picture without looking at it)

George_pix wrote:

Days ago I had some nice discussion on the significance of RAW file length:

https://www.dpreview.com/forums/post/59762583

Well, I am pretty sure that:

1) if the scene is exactly the same (tripod) with all subjects almost at the same distance

2) if the noise is low (ISO 100 or 200)

3) If there are no big exposure errors and differences (same exposure for pictures under comparison)

4) if the RAW file is lossless compressed (X3F are already lossless compressed)

THEN:

The picture with the highest detail is the one with the largest RAW file.

Looks like a good method to set microfocus on SD1.

Obviously I tuned the microfocus of the 105 macro at infinity. At macro distances nothing is in focus except something, so let's the camera decide ;-))

With SD1 maybe testing at your most frequently used focusing distance could be a better choice if that is easy to do.

For microfocus tuning, use maximum aperture, maximum focal length (if variable)...

But don't be lazy. Try yourself and confirm or reject.

Thank you for the interesting efforts and comments.

Right, Jpeg file length is also a possibility to evaluate, if compression ratio is adjusted to preserve the best quality, therefore if there is more detail in the picture, the file will be larger. Some jpeg compressor may be set to provide a predetermined file lenght, therefore in this case the lenght will give no useful information.

 George_pix's gear list:George_pix's gear list
Sigma SD1 Merrill Sigma 10-20mm F4-5.6 EX DC HSM Sigma 17-50mm F2.8 EX DC OS HSM Sigma 105mm F2.8 EX DG OS HSM
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