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Author Topic: Can a stock PhaseOne IQ4 shoot infrared  (Read 1101 times)

CMAmuseumbrich4d

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Can a stock PhaseOne IQ4 shoot infrared
« on: June 15, 2023, 04:47:01 pm »

I am wondering if the stock Phase One IQ4 can shoot infrared with a set of filters. I am not asking about the Achromatic. Thanks,
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Doug Peterson

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Re: Can a stock PhaseOne IQ4 shoot infrared
« Reply #1 on: June 16, 2023, 10:06:10 am »

I am wondering if the stock Phase One IQ4 can shoot infrared with a set of filters. I am not asking about the Achromatic. Thanks,

Hi, I have a lot of experience with this in a heritage context. Glad to speak with you about it. Or maybe you’ll be at IS&T this week?

Short answer: without the IR filter modified an IQ4 (color) can shoot IR but you need a ton of visible cut or you need a narrow IR output light source, and your exposure will be *several* stops (5+) longer than otherwise. With the IR filter removed it’s excellent at IR, especially longer band where all three channels respond very similar.

Achromatic of course remains the best possible option if budget and use case can justify.

Doug (DT)

Smoothjazz

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Re: Can a stock PhaseOne IQ4 shoot infrared
« Reply #2 on: January 19, 2024, 12:37:01 am »

Doug,
What type of filter would you be using on a normal (non-modified) Phase IQ4 digital back?
Thanks,

John
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yaya

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Re: Can a stock PhaseOne IQ4 shoot infrared
« Reply #3 on: February 06, 2024, 03:41:33 pm »

Doug,
What type of filter would you be using on a normal (non-modified) Phase IQ4 digital back?
Thanks,

John

A normal RGB IQ4 back has an IR-UV cut filter in front of the sensor so you're not able to see NIR.

BR

Yair
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Yair Shahar | Product Manager | Phase One - Cultural Heritage
e: ysh@phaseone.com |

Doug Peterson

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Re: Can a stock PhaseOne IQ4 shoot infrared
« Reply #4 on: February 14, 2024, 08:51:15 am »

A normal RGB IQ4 back has an IR-UV cut filter in front of the sensor so you're not able to see NIR.

BR

Yair

Yair you may have missed my reply above to which he was responding.

A standard camera (P1 or otherwise) strongly filters IR (at least, all of them after the Leica M8 residual-infrared-sensitivity disaster).

However, that just sets the bar for how strongly you must filter visible to shoot IR.

For example, simplifying things a bit to rough stops: if a given camera natively filters 7 stops of IR and you use enough lens filtration to filter 14 stops of visible then you'll be shooting infrared images.

Now it's extremely important to note that 1) you'll be stacking filters and that can degrade sharpness and 2) you'll be filtering an extreme amount of the total light so your shutter speed will lengthen by rather extreme amounts.

For example with "sunny 16" rule of thumb a bright mid-day photo would be roughly 1/100th of a second at f/16 at ISO100. So in the example above with 14 stops of light loss due to stacking IR-pass (on lens) with IR-block (on sensor) filters your new exposure is 160 seconds long. On the one hand that's patently absurd. On the other hand some people use ultra-strong ND filters to shoot long exposures during the day, and enjoy the temporal blurring that is a bit ethereal/unworldly/unusual. And if you open to f/2.8 and up to ISO3200 you'll be at ~1/15 which is vaguely hand-holdable with a wide lens and a very generous definition of "sharp enough".

Is any of this what I would do if I was deeply interested in infrared imaging? Absolutely not! Given the money I'd buy an IQ4 Achromatic without an IR filter, as several of our clients have bought from us. Given a lower budget I'd buy whatever camera I could justify and send it to max-max for IR filter removal.

But it can be done. And it can be an interesting foyer into infrared photography for someone playing around or those who like weird gear combinations. I'd put this roughly in the world of making a pinhole camera using your digital back, or doing direct shadowgrams onto your sensor, or mounting an old IMAX Cinema Projector lens to your IQ back - which is a lot of fun even if it's not what I'd call "deeply serious" or "technically appropriate".
« Last Edit: February 14, 2024, 08:55:40 am by Doug Peterson »
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