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Author Topic: Digital Back for Art Reproduction  (Read 2286 times)

ben730

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Digital Back for Art Reproduction
« on: January 16, 2018, 12:53:11 PM »

Hi
I have to do a lot of art reproduction in the next time. I will use flash lights.
I can choose between my P40+ and my IQ150. I'm not sure which one is better for that work.
Lens is the SK72.
Which digital back would you use for it and why?

Thanks,
Ben

Doug Peterson

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Re: Digital Back for Art Reproduction
« Reply #1 on: January 16, 2018, 01:26:54 PM »

The IQ150 features a CH bespoke profile for art reproduction in Capture One. The P40+ does not. That, along with the improved Live View for assuring perfect focus, and the small but meaningful increase in resolution, makes it a no brainer: use the IQ150.

For more information please see the Cultural Heritage Art Reproduction Color Guide we wrote.

For results even better than flash, you might consider the DT Photon LED which has a higher CRI, CQS, consistency, and longevity than strobe.

Ken

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Re: Digital Back for Art Reproduction
« Reply #2 on: January 16, 2018, 01:44:02 PM »

What back to use is the least of your problem if you're concerned about the artwork and faithfully reproducing it.

If you're going to photograph artwork (especially someone else's) you should be aware that electronic flash emits ultraviolet waves that damage pigments, inks and other media. Also UV makes some pigments and other materials fluoresce. If your flash tubes are not coated to mitigate UV, you should use a UV filter on the reflector.

Not all electronic flash light is the same color temperature. Even various flash durations from the same unit can vary in color temp.

Ambient light will affect your color too, relative to the amount of it vs shutter speed and ISO.

In any case, you should run some test captures with both backs to see which one comes closest to reproducing the colors you see. Just like color film, different digital backs interpret colors differently. Even backs from the same manufacturer can vary.

A color checker such as those made by X-Rite or Datacolor would be the best to use for testing.
 
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Doug Peterson

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Re: Digital Back for Art Reproduction
« Reply #3 on: January 16, 2018, 02:03:06 PM »

A color checker such as those made by X-Rite or Datacolor would be the best to use for testing.

If you're doing work for government or high-end institutions you might also consider a professional target like the ISA GoldenThread series.

ben730

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Re: Digital Back for Art Reproduction
« Reply #4 on: January 16, 2018, 04:20:05 PM »

Thanks for your answers.
I will use the IQ150.
Of course I have a professional colour target.
My Broncolor Pulso G lamps have UV coated protection glasses and I thought the Graphits A4
are consistent in colour temperature and also bright and fast enough to eliminate 100% of the ambient light at 1/500s, F8.

Regards,
Ben

DP

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Re: Digital Back for Art Reproduction
« Reply #5 on: January 17, 2018, 01:54:50 PM »

For results even better than flash, you might consider the DT Photon LED which has a higher CRI, CQS, consistency, and longevity than strobe.

"Spectral Flatness:   Excellent", but no graph... why ? it will be really interesting to see it  ;)
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DP

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Re: Digital Back for Art Reproduction
« Reply #6 on: January 17, 2018, 01:58:05 PM »

Thanks for your answers.
I will use the IQ150.
Of course I have a professional colour target.
My Broncolor Pulso G lamps have UV coated protection glasses and I thought the Graphits A4
are consistent in colour temperature and also bright and fast enough to eliminate 100% of the ambient light at 1/500s, F8.

Regards,
Ben

you can simply switch the ambient light off... how about polar. filters ? and then - who will make you a bespoke profile for that ?
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Doug Peterson

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Re: Digital Back for Art Reproduction
« Reply #7 on: January 17, 2018, 02:01:41 PM »

"Spectral Flatness:   Excellent", but no graph... why ? it will be really interesting to see it  ;)

Few of our clients are scientists and many are not very technical. So there's a balancing act that has to happen between providing abundant technical information for those that are and ensuring the product is still easy to understand for those that aren't.

Part of the point of our system is you don't have to be a color science PHD to get excellent color if you use our system; we provide a complete system* that produces extremely accurate FADGI 4-star color right out of the box.

That said, you can find spectral emission graphs at around the 20 minute mark in the Cultural Heritage Lighting Webinar we cohosted with Robin Myers, an expert in color science in cultural heritage use cases.

*Lighting, sensor, lens, color profile, calibration, capture software, processing software, validation software)
« Last Edit: January 17, 2018, 02:14:14 PM by Doug Peterson »
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ben730

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Re: Digital Back for Art Reproduction
« Reply #8 on: January 17, 2018, 02:09:09 PM »

you can simply switch the ambient light off... how about polar. filters ? and then - who will make you a bespoke profile for that ?

I use polarized light but I don't know how to turn the daylight off......

digitaldog

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Re: Digital Back for Art Reproduction
« Reply #9 on: January 17, 2018, 02:10:36 PM »

Many graphs starting around 20 minutes into our webinar cohosted by Dr. Robin Myers, an expert in color science in cultural heritage use cases: https://dtdch.com/cultural-heritage-webinars/lighting-cultural-heritage/
Yes, Robin is indeed a major color geek and his software (SpectraShop) is invaluable. He's a doctor?
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Andrew Rodney
Author “Color Management for Photographers"

Doug Peterson

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Re: Digital Back for Art Reproduction
« Reply #10 on: January 17, 2018, 02:12:33 PM »

Yes, Robin is indeed a major color geek and his software (SpectraShop) is invaluable. He's a doctor?

My recollection is he is a PHD. If he is not, I apologize to PHDs everywhere for the mistake.

digitaldog

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Re: Digital Back for Art Reproduction
« Reply #11 on: January 17, 2018, 02:13:35 PM »

My recollection is he is a PHD. If he is not, I apologize to PHDs everywhere for the mistake.
Verify then trust  ;)
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Andrew Rodney
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Doug Peterson

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Re: Digital Back for Art Reproduction
« Reply #12 on: January 17, 2018, 02:14:48 PM »

Verify then trust  ;)

FWIW I've removed the "Dr." as I could be misremembering.

Regardless anyone who knows him or the field recognizes him as an expert.

digitaldog

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Re: Digital Back for Art Reproduction
« Reply #13 on: January 17, 2018, 02:19:25 PM »

Absolutely a major expert in the field and a super nice fellow too. Along with say Bill Atkinsion, Karl Lang and the last Bruce Fraser, there are few who are as savvy or have done more for the color industry. And everyone should listen to this podcast, at least his explanation of what color is. At 8 minutes in, well worth listening too!
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Andrew Rodney
Author “Color Management for Photographers"

Doug Peterson

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Re: Digital Back for Art Reproduction
« Reply #14 on: January 17, 2018, 03:33:53 PM »

Absolutely a major expert in the field and a super nice fellow too. Along with say Bill Atkinsion, Karl Lang and the last Bruce Fraser, there are few who are as savvy or have done more for the color industry. And everyone should listen to this podcast, at least his explanation of what color is. At 8 minutes in, well worth listening too!

Are you talking about the webinar?

If so, the "What is Color?" section was provided by me. His voice is the one that oozes sage wisdom. My voice is the other one :).

Thankfully for all involved, Robin covered the section on Metrics and the methods by which one can evaluate and characterize lighting and color accuracy.

digitaldog

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Re: Digital Back for Art Reproduction
« Reply #15 on: January 17, 2018, 03:41:55 PM »

Are you talking about the webinar?
Yes sorry for calling it a podcast.
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Andrew Rodney
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DP

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Re: Digital Back for Art Reproduction
« Reply #16 on: January 17, 2018, 04:40:44 PM »

I use polarized light but I don't know how to turn the daylight off......

I see... that will be an art outside under the open air then and night time shooting if a no-no, mea culpa - did not think about this ...
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DP

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Re: Digital Back for Art Reproduction
« Reply #17 on: January 17, 2018, 04:44:44 PM »

That said, you can find spectral emission graphs at around the 20 minute mark in the Cultural Heritage Lighting Webinar we cohosted with Robin Myers, an expert in color science in cultural heritage use cases.

this one =

I probably misunderstood the word "flat"  :)

and then how this =

corresponds with

Quote
Color Rendering Index (CRI):   98
Color Rendering Index (CRI-14):   98
Color Quality Score (CQS-Qa):   98
Color Quality Score (CQS-Qg):   100

???

am I looking @ the wrong place in the video ?

yes, I am - DT Photon starts @ 23 min - and looks better

this is really worth to be put picture-wise on the website itself, looks very good



« Last Edit: January 17, 2018, 04:54:14 PM by DP »
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Doug Peterson

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Re: Digital Back for Art Reproduction
« Reply #18 on: January 17, 2018, 05:27:18 PM »

am I looking @ the wrong place in the video ?

yes, I am - DT Photon starts @ 23 min - and looks better

this is really worth to be put picture-wise on the website itself, looks very good

Thanks! We put a ton of R+D time into creating an LED with as good a spectrum as possible.

I see you answered yourself... yes, several legacy light sources are described and graphed before the DT Photon is described and graphed, so I can see where you got distracted. Indeed some of those legacy light sources are pretty mediocre when it comes to spectral flatness/smoothness, CRI, and CQS.

DP

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Re: Digital Back for Art Reproduction
« Reply #19 on: January 29, 2018, 03:52:40 PM »

Thanks! We put a ton of R+D time into creating an LED with as good a spectrum as possible.

I see you answered yourself... yes, several legacy light sources are described and graphed before the DT Photon is described and graphed, so I can see where you got distracted. Indeed some of those legacy light sources are pretty mediocre when it comes to spectral flatness/smoothness, CRI, and CQS.

I finally remembered where I saw the similar curve... I bet Photon is using D50 leds from Yuji = https://store.yujiintl.com/products/vtc-series-d50-5000k-high-cri-led-2835-ribbon-120-led-m-unit-5m-reel



nice job with soldering that  ;D
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