Older MF Camera still "worth it" for commercial purposes?

Started Jun 28, 2018 | Discussions thread
Erik Kaffehr
Erik Kaffehr Veteran Member • Posts: 3,740
Re: Old comparison, long debunked


Not, I have not. Please keep in mind that SMI can be measured in different ways. The highest value I recall may have been around 88 and that was Phase One IQ3100. That figure came from Jack Hogan, who evaluated the Thrichromatic at around 80, if I recall correctly. But Jack used exposures made in non lab conditions, supplied by Dave Chaw (I hope I got the name right?!)

Some posters are a bit skeptical about SMI, as calculated by DxO-mark. Also, DxO-mark doesn't use the preferred method of calculating SMI which is using spectral data.

On the other hand, Tim Parkin has found a very good correlation between SMI data at DxO and his perfection of correct color. Several experts regard the Sony Alpha 900 to be best compromise, and it has a high SMI rating at DxO.

What we need to keep in mind is that SMI is a measure how well colors are converted using a simple matrix multiplication. So, it says a bit about how close a sensor is to Luther-Ives.

With LUT based conversion, there are more degrees of freedom, but it may also be easy to mess up.

Most raw converters may use matrix conversion with LUT-based "look".

Essentially, SMI is a measure about how well a sensor can reproduce color using an optimal matrix based conversion.

LUT based conversions are a bit arbitrary, they may work well but backfire horribly. I have myself encountered a horrible example:

This is a Capture One conversion of a deep blue purple flower on the P45+.

Using LR with Adobe Standard profile we get a pretty real world reproduction:

Adobe Standard gets it right.

So, what is the correct color?

This, measured with a spectro on the actual flower.

There are other factors. I would think that IR and UV cut off filters may play a role.

Some posters here have spent an immense effort analysing CFA designs. That was triggered by some unworldly explanations by Phase One about their new CFA design.

Names that come to my mind are foremost jack Hogan, Jim Kasson, Iliah Borg and Joofa, but there were many others.

Best regards


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Erik Kaffehr
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