Mike,
If you have not used the Focal, then perhaps it would be good to familiarise yourself prior to start throwing the weight around. That’s not what a scientist will typically would do.
8 AFMA point is only a very approximate number. I you used Focal a lot, you would what it makes to the image. Just an example: if your peak QoF is around 1800, then -20/+20 point AFMA QoF will be in around 1000 points only
I.e. If you detune you Camera by 20 AFMA points, you may expect the QoF value to reduce from 1800 to 1000
From experience, detuning by 8 AFMA points would typically result in QoF decrease of around 15%.
QoF curve typically looks like a parabola with its highest value being positioned on horizontal axis where your AFMA adjustment value is. Step to the left or right by 8 points and you QoF value is came down from the peak value by approx 15%. - for illustrative purposes only.
Hence my example. From 1900 QoF value of 80D down to 1690 value on 5DsR
Yes, I can demonstrate the difference as you requested. You have not looked in the report for have provided you need to look at the QoF Test result pages.
I provided 3 reports in PDF format. Please download 5DsR and 750D reports.
Scroll through pages and locate image of the cropped area that Focal used to analyse RAW file for accutance (crispiness, edge sharpness or whatever...)
You can compare this image with the same you find in 750D report.
Evaluate visually as you do your images at 1:1 magnification for blurriness, sharpness, crispiness, edge sharpness, whatever you would like to call this.
You cannot make this stuff up as you will see with your own eyes that even 750D image was crispier around edges.
I use this word deliberately. I hate buzz words though.
AlanF,
I analysed two files per each given camera.
Very small number, I know. However deviations of result for any given camera is also very small. All results are very close to each other. Please refer to 2x 5DsR report files I have provided.
There is a correlation between edge sharpness, accutance QoF value of Focal software and real world image sharpness or crispiness.
Many forum members relies on Focal to achieve peak focus = peak sharpness for their images.
Mikehit said:
SecureGSM said:
I am sure that you used FoCal before and aware what the before and after calibration images look like.
Imagine that your lens was Out of tune before calibration by 8 AFMA points. Now imagine what difference does it make if you were to compare before and after calibration screen
5DsR image at 1:1 magnification will look blurrier than 80D image at 1:1 magnification by approximately the same ammount. It is up to you to decide if this relevant or not.
You can compensate for the loss of image acutance / edge sharpness by using a much sharper lens or image down sampling if it matters to you at all.
You cannot make this stuff up as you will see with your own eyes that even 750D image was crispier around edges.
I use this word deliberately. I hate buzz words though.
AlanF,
I analysed two files per each given camera.
Very small number, I know. However deviations of result for any given camera is also very small. All results are very close to each other. Please refer to 2x 5DsR report files I have provided.
I am not 'throwing my weight around' I am asking the person who has presented a set of numbers, and who is giving an interpretation of those numbers, how those numbers can be used and the limitation of those numbers.
You say
I.e. If you detune you Camera by 20 AFMA points, you may expect the QoF value to reduce from 1800 to 1000
From experience, detuning by 8 AFMA points would typically result in QoF decrease of around 15%.
So does a shift of 8 AFMA points result in a 15% reduction in QoF, or does it result in a reduction of (taking your 80D vs 5DSR as an example) a reduction of 310 every time in every comparison? This is vital to understand what your numbers mean - are QoF relative or absolute? Are AFMA relative or absolute?
Are you saying that QoF is a direct and qantitatice measure of image sharpness?
These are the scenarios where we would need to consider your numbers:
Take the same picture with two FF cameras: One a Nikon D810 and one a Canon 5Diii: can we compare the numbers between the two, especially considering they will use different lenses with different characteristics that will affect what we get off the sensor? I am not convinced.
Take the same picture with two Canon FF: the 5DIV and the 5DSR. You would take the same picture with the same lens from the same position. You would frame the picture in the same way, even crop it in the same way. No matter what you do, you are downsampling the 5DSR compared to the 5DIV and that would override any 'Pixel level' sharpness.
Take the same picture with APS-C and FF: if the framing is the same then producing the images at the desired size means you are magnifying the APS-C more and I am not sure how that will affect your numbers - and from your comments neither are you
Take the same focal-length-limited picture with APS-C and FF and use the same lens on both cameras. The crop the FF to APS-C FF. This is about the only situations your numbers become a major factor.
I do appreciate your time answering my questions because understanding offers a chance of another bit of information in selecting gear.