Understanding lenstip mtf50 apsc vs FF results?

Started 10 months ago | Discussions thread
abera Regular Member • Posts: 103
Re: Understanding lenstip mtf50 apsc vs FF results?

vegetaleb wrote:

abera wrote:

vegetaleb wrote:


If we want to compare an apsc lens let's say the XF 16mm f1.4 to a FF one like the Z 24mm f1.8 in terms of sharpness, how can you do it by using lenstip charts results?

I thought that we could simply read them side by side but because the sensor size is different we have to make calculations right?

In general there are a couple of issues one has two consider.

First the enlargement: the measurements here are in line pairs per millimeter on the image sensor. If the image sensors have different dimensions, you have to scale accordingly as you want to compare outputs of the same size (e.g. A4 or whatever). In this case you'd multiply the FF figures by 1.5 or divide the APS-C figures by 1.5. Also in this context the blue dots of FF chart should be ignored.

The other issue is pixel count - I don't know how lenstip measures, but almost all sites measure systems, not lenses, thus one needs to consider pixel count - add pixels and you'll get higher lp/mm figures. If you just want to compare lenses this will be a problem, if systems it's not an issue.

The XF 16mm f1.4

The Z 24mm F1.8

I want to know if I get a Fuji x-t4 with the 16 f1.4 if the sharpness will be close to a z6 +24mm f1.8

According to the above charts the answer would be no.

But is the possible difference meaningful in real world applications you'd use the system is another question.

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