IQ4 Achromatic - Nighttime Filter Comparison (IR; UV+IR cut)

[tcdeveau]

I usually don't care for comparisons because it takes the fun out of photography for me....especially since at one point in my life I was a scientist so I got to do comparisons all day, and the last thing I wanted to do was experiments with proper controls in my free time.

That said, I thought this might be of value to someone out there and I haven't seen anything like it on the interwebz so I figured I'd share.

One of the nice things of the P1 Achromatic backs out of the box is the lack of a UV/IR filter in front of the sensor, which opens up lots of creative possibilities. I've pretty much had an IR filter glued to my lenses most of the time since getting the IQ4 Achromatic, but haven't played around with it much at night. I tried once and noticed a ton of lens flair and tonight had the sense (and patience) to take off the IR filter and throw a UV/IR cut filter on instead....the difference for this type of photography was pretty dramatic so I thought I'd share in case anyone is curious (settings are otherwise identical - STC, 70HR, ISO 250, 15sec exposure, f9):

695IR filter



UV/IR cut filter:



Pretty dramatic difference right? Maybe one day I'll remember to level the camera but today wasn't that day.

 

[tcdeveau]

These are posted in another thread somewhere but just for posterity thought I'd repost them here too....

Very specific use cases but someone may find it of value. Both with the STC and 40HR, exposure settings identical except for filters on lenses.

With UV+IR cut filter:



No filter on lens:



Once again my horizon leveling skills are poor but at least these were taken at 330am-ish after waking up with my son to give him a bottle so it's a little more excusable haha.

 

[guphotography]

How useful would IR cut filter be in daylight? I'm intrigued with the differences shown.

Most searches tend to focus on astro work at night, do you have any experiences in daylight?

Many thanks

 

[Pemihan]

How useful would IR cut filter be in daylight? I'm intrigued with the differences shown.

Most searches tend to focus on astro work at night, do you have any experiences in daylight?

Many thanks

I have lots of images shot with IQ260 Achromatic and IQ3100 Achromatic here all shot with IR cut filter.

 

[Makten]

How useful would IR cut filter be in daylight?

Unless you want IR "contamination" in your images, an IR cut filter is the norm. Most (virtually all?) consumer cameras have an UV/IR cut filter in front of the sensor to get decent colors, but on a monochrome camera there might be reasons to not include it.
My guess is that you will get brighter foilage and not so deep blacks with IR lowering the contrast. Sharpness will also probably be worse because of the longer wavelength, causing diffraction at much larger apertures. And possibly flares and/or sensor reflections that you would otherwise not see.

 

[tcdeveau]

How useful would IR cut filter be in daylight? I'm intrigued with the differences shown.

Most searches tend to focus on astro work at night, do you have any experiences in daylight?

Many thanks

Not too many experiences in daylight because I usually have the 695 IR filter glued to the lens.

I'll be out and about this afternoon and evening and will try and get some daylight comparison shots

 

[JeffK]

I keep the UV/IR cut filter on all the time, unless I'm specifically shooting an IR image. The I remove the UV/IR cut and add a filter that only lets in IR.

 

[Pemihan]

I keep the UV/IR cut filter on all the time, unless I'm specifically shooting an IR image. The I remove the UV/IR cut and add a filter that only lets in IR.

Same here.

 

[Chris C]

I have lots of images shot with IQ260 Achromatic and IQ3100 Achromatic here all shot with IR cut filter.

Peter,
Being curious about what others had to say about UV/IR-cut filters I strayed into this thread, and then to your website to see if I would recognise a filtration signature. I wasn't prepared for how enjoyable your work is and left hungry for more. Among others, Grand Staircase Escalante, Utah, 2010 is fabulous. Oh; ever since the Leica M8 I've kept UV/IR-cut filters on my lenses, and for M10, P, & R, cameras too. Go make more pictures please.

............. Chris

 

[guphotography]

can anyone recommend a decent make of the uv/ir cut filter please? i'd love to get one and see for myself.

thanks!

 

[alistairsimmons]

can anyone recommend a decent make of the uv/ir cut filter please? i'd love to get one and see for myself.

thanks!

Heliopan or B+W are your options. Heliopan easier to source in the UK.

 

[ThdeDude]

I wonder whether there are any situations/circumstances where using an aggressive UV/IR cut filter on a chromatic camera (IQ3-100, iPhone) would offer an advantage?

According to "Why UV Filters are Basically Useless on Modern Cameras", https://tinyurl.com/467bp46w, "a very aggressive UV filter with a 420nm cutoff point could help ... cameras that generally have slightly weaker UV filters built in".

Yes, much can be done and fixed in post, but if the sensor doesn't see/record it clearly, it takes work and artifacts can become an issue.

 

[tcdeveau]

I wonder whether there are any situations/circumstances where using a UV/IR cut filter on a chromatic camera (IQ3-100, iPhone) would offer an advantage? Maybe if also a skylight filter.

Yes, much can be done and fixed in post, but takes work and artifacts can be an issue. (If the sensor doesn't see/record, say, because of haze, recovery in post can be tricky.)

My understanding is most color cameras have this....the cover glass in front of the sensor has a UV/IR coating. So it's already there

The strength of the coating can differ. I thought I remember reading that the old Leica M8 needed an additional UV/IR filter because the coating on the cover glass wasn't strong enough, which, on the other hand, made it ok for IR photography.

Full-spectrum conversions for color cams remove the sensor cover glass with the UV/IR coating.

 

[ThdeDude]

My understanding is most color cameras have this....the cover glass in front of the sensor has a UV/IR coating. So it's already there

Yes, you are correct. I should have written that. I slightly revised my posting.

 

[Pemihan]

Peter,
Being curious about what others had to say about UV/IR-cut filters I strayed into this thread, and then to your website to see if I would recognise a filtration signature. I wasn't prepared for how enjoyable your work is and left hungry for more. Among others, Grand Staircase Escalante, Utah, 2010 is fabulous. Oh; ever since the Leica M8 I've kept UV/IR-cut filters on my lenses, and for M10, P, & R, cameras too. Go make more pictures please.

............. Chris

Thank you so much Chris, really appreciate it.

 

[weldonbrewster]

Chris Snipes has a great article on the different filters for an Achromatic back. https://www.captureintegration.com/the-right-filters-for-achromatic-shooting/

 

[ThdeDude]

Just in case of interest. PhaseOne wrote me that the sensor filter on the IQ3-100 is S8612 - SCHOTT Advanced Optics, https://tinyurl.com/5et3h6ey

 

[tcdeveau]

Here's a quick [unscientific] comparison between (1) no filter; (2) UV/IR filter; and (3) 695nm IR filter during the day. Had to adjust the exposure with the IR filter but settings are otherwise identical. IQ4 Achromatic/STC/70mm HR, B+W brand filters. They're downrezzed quite a bit so I wouldn't judge sharpness much based on these....and again forgive for my poor leveling skills haha.

(1):

(2):

(3):


The foliage is definitely a little softer in the "no filter" image but I didn't really notice any sharpness differences with the buildings. The 695nm IR buildings appear a little softer than the other images but that could be due to focus shift.