Phase One Trichromatic In Depth Article with Raw Files

[GrahamWelland]

It's the only explanation that matters.

Doug’s explanation helped a lot. It explains why as a Brit I’ve struggled for decades with capturing the accurate colour of our blue bells. They always end up pink or purple, the IQ3 trichromatic definitely nails that colour aberration with all current cameras.

 

[f8orbust]

From the available info it seems that expense, and slightly more noise at high ISO, are the only real downsides ?

But knowing that using a CFA is a zero sum game, some colors must render worse for others to render better.

Jim

 

[dougpeterson]

Thanks Doug for these pieces. I found them very informative. I am waiting on shipment of my Phase One kit with Trichromatic back, and an accompanying Alpa STC kit for good measure, this week. Haven't shot MF in almost three decades, but am looking forward to it again.

I look forward to your hands on testing and feedback! I hope you'll post some photos!

 

[ErikKaffehr]

Some reflections lime fruit colour

Hi,

This is a bit a technical posting.

Anyway, Doug Peterson has posted two articles describing the differences between the Thrichromatic and traditional designs. The most obvious example he shows is lime fruit, shot on the Trichromatic:

and the IQ3100MP

That would indicate the rendition of lime fruit is critical because the surface of the lime has high near IR content, while the fruit is very green. I don't own either the IQ3100MP or the Trichromatic, but I could buy a couple of lime fruits at the grocery. I also have a few cameras with traditional CFA designs. The cameras i chose for this small comparison were:

• Phase One P45+ on a Hasselblad with Zeiss Sonnar 180/4, the P45+ is known to be a bit tricky in colour.
• Sony Alpha 900, the camera that a few colour experts regard to have the best CFA design amoung the commercially available cameras, used with a Sony 70-300/4.5-5.6 G lens.
• Sony Alpha A7rII, my most used camera, with the Zeiss 35-135/3.3-4.5 Sonnar mounted on the HCam Master TSII adapter.

I included a ColorChecker Passport in the setup. It was used for three purposes:

• Setting white balance
• Adjusting exposure so we would get similar mid tones
• Generating DCP profiles for each camera setup

Development was in LR CC Classic, the P45+ image was also developed in Capture One. The results are shown below:

• Top left: P45+ with LR CC
• Top right: Sony Alpha 900 with LR CC
• Bottom left: P45+ with Capture One
• Bottom right: Sony A7rII with LR CC

One possible observation is that the Capture One processed image has more snap, but that is probably due to it using a higher contrast tone curve.

I am more concerned about the rendition of the lime fruit peel, and that seems to be very accurate on all the images. How can I tell? Because I have measured the colour inside the marked areas with a spectrometer. In all the images a small area was selected, where "a" and "b" channels (in Lab mode) were replaced with "a" and "b" values calculated from spectral data. So, texture is coming from the original image but colour is actual colour of the fruit peels. I have done this on the lime in front and the one in the back. The A900 image (top right) has thin green marker on the patched areas.

These patches are not really different from the rest of the fruit, that indicates that colour reproduction is near perfect.

I used two Elinchrome flashes with soft boxes for illumination and in this light it seems that near IR contamination of the greens was not a problem, at least not with my setup. I don't know what light source Doug has used.

What my samples illustrates is that a wide variety of traditional CFAs handle lime green very well, at least under studio flash.

Best regards
Erik

 

[Erik Lundqvist]

I'm starting to think being color blind is maybe not so bad after all