The Right Filters to use with Phase One Achromatic Backs

[Digitalcameraman]

Just posted a new article with examples of how the various filters effect the look of the image with Phase One Achromatic Backs. I shot these images at workshops and trips around the US. Links below.

The Right Filters for Achromatic Shooting - Capture Integration

Phase One Achromatic Digital Backs are designed to allow you to have complete control over the image by choosing the correct filter for the desired look.

www.captureintegration.com

My Top Ten Achromatic Images from Phase One Cameras - Capture Integration

My Top Ten Achromatic Images from Phase One Cameras, by Chris Snipes.

www.captureintegration.com

 

[Jeffrey]

Terrific article and spot on accurate with the comments and examples of the IR Cut filters. By the way, who is that famous unknown photographer standing in the filed in the Palouse? Hahaha!

 

[olafphoto]

Very informative!

 

[Jacob Buchowski]

Thanks for the article. I routinely use the 486 filters. I sometimes venture into the IR territory and use 695 nm filters, but I haven’t decided if I like the results...

 

[docholliday]

That article isn't right...the B+W 486 is not a "486nm" filter. It's just a model number for an interference-type bandpass filter that is designed to only pass the visible range.

The 486 cutoff in the UV range is around 380nm with IR cutoff around 700nm.

I use them on all lenses 80mm and above to reduce UV/IR contamination in black objects as well as to reduce CA effects on some lenses. For all other lenses, I use 400nm blocking UV filters to reduce contamination and reduce CA, especially on the HC 50, since the 486 is an interference type filter which will cause weird color shifts on angles wider than 60° or so and therefore requires and absorbtion type filter.

 

[docholliday]

Mr Docholiday,

Are you using a Phase One IQ Achromatic Back?

Then none of your comments are valid above.

This is the filters I was discussing in my blog and how you can acheive different "looks" with different filters. The manufacture designates the wave length and thus that is how they are labeled.

UV-/ IR-Blocking

schneiderkreuznach.com

Heliopan describes and labels their filter the same.

IR RG 715 (88A) Filter

*Please note that this is a special order item and will take approximately 8-10 weeks for delivery. All special order items are non-refundable.The Heliopan IR RG 715 (88A) Filter is used for infrared photography with digital cameras and specialized infrared film. This nearly opaque filter blocks...

heliopan.com

Just FYI in case you do not understand these filters and how they work with specialized Achromatic backs like the Phase One designs.

I have a pile of the 486M filters here. I also use Heliopans. Some filters do list the number as the wavelength. However, the 486 is NOT one of them. Look at the response graph on the Schneider site you list...it is NOT a 486nm wavecut. It is 380nm-685nm bandpass.

In case you don't know...some of those filter numbers are actually correspondent to the Schott number. For microscopy and laser optics, you can order the Schott elements directly in those numbers, such as Schott's GG420 which is used by B+W and Heliopan for "UV 420". It is a 420nm highpass filter. But, only some are directly related, others are just a series/model number.

Typical Schott numbers that indicate wavelength are usually preceded by a code, like GG, RG, BG, UG, NG indicating the color of the glass. Even then, only some of the filters will have the wavelength in the number, like GG495 (yellow) or WG295 (clear).

It does not matter which back (or for that matter, film) is being used. I'm not discussing how it affects your images or what back(s), just that a "486M B+W" filter is a bandpass filter, which does NOT filter at 486nm. If you subscribe to the thought that the number is the wavelength cutoff, then please explain the B+W 090, 010, and 007 filters to me. The B+W 010M being one of their most common filters...

 

[tcdeveau]

Mr Docholiday,

Are you using a Phase One IQ Achromatic Back?

Then none of your comments are valid above.

This is the filters I was discussing in my blog and how you can acheive different "looks" with different filters. The manufacture designates the wave length and thus that is how they are labeled.

UV-/ IR-Blocking

schneiderkreuznach.com

Heliopan describes and labels their filter the same.

IR RG 715 (88A) Filter

*Please note that this is a special order item and will take approximately 8-10 weeks for delivery. All special order items are non-refundable.The Heliopan IR RG 715 (88A) Filter is used for infrared photography with digital cameras and specialized infrared film. This nearly opaque filter blocks...

heliopan.com

Just FYI in case you do not understand these filters and how they work with specialized Achromatic backs like the Phase One designs.

Transmission of light through a filter is independent of whatever receives the light (achromatic, trichromatic, etc), it’s not accurate to say his comments aren’t valid if they don’t apply to an achromatic back. These filters will block transmission to the sensor of a back with a CFA as well.

As docholiday notes, the 486 UV/IR cut filter isn’t a “486nm” filter as in your post. He appears to be noting a minor typographical thing that doesn’t change the substance of the very helpful information you posted, which we all appreciate. It more accurate to refer to the 486 filter as a “486 UV/IR cut filter” and not a “486nm” filter, and even some of your images in your blog post have it labeled “486 UV/IR” and not “486nm”.

As you can from the spectral transmission of the BW site that you kindly shared, the 486 filter transmits 90% of greater of light 400nm and up, so it isn’t a “486nm” filter since the cutoff is not 486nm:



The 486 filter is more like a 380/400-680/700nm filter if we’re going by “nm” nomenclature according to the info on the BW site. Thanks again for sharing the information!

 

[Landscapelover]

Fantastic article Chris! Thank you for sharing. It's very educational. Pramote

 

[edmundphoto888]

Anyone has the experience with the Hot Mirror UV IR cut filter (the blue colour) with the achromatic back? Any different with the B+W 486 filter?

 

[tcdeveau]

Anyone has the experience with the Hot Mirror UV IR cut filter (the blue colour) with the achromatic back? Any different with the B+W 486 filter?

My understanding is a hot mirror can be synonymous with UV IR cut filter depending on what brand of UV IR cut filter, although google suggests some may reflect IR light only.

The BW 486 is a UV IR cut/hot mirror filter generally speaking. If you want “normal” B+W photography with a stock achromatic (that lacks a UV/IR filter over the sensor from the factory), then you’ll want to use a UV/IR cut filter, and the results should be similar to what Chris posted in the blog re: BW 486 filter.

That said, there may be differences among brands of filters. For example, Kolari vision says this regarding their hot mirror filter compared to the BW 486:

“ A note about wide angle: Unlike the B+W 486 filter (a popular hotmirror filter), this filter does not block light by interference, but instead uses absorbtion. This means that regardless of the angle of incidence, the color will not change. The B+W 486 will cause color changes on wide angles around the edges, ours will not.” (https://kolarivision.com/product/kolari-vision-color-correcting-hot-mirror-filter-uvir-cut-filter/)

Note too that not every achromatic back out there needs a UV/IR cut filter mounted on the lens since P1 can also install one on the back upon request. CI had an IQ260 Achromatic for sale last year that had a filter installed for example.

 

[docholliday]

To add to tcdeveau's comment... a "hot mirror" is just a common term from optics that referred to a coated surface that reflected the "hot" side of light, the infrared waves, to prevent heat build up at a destination. It worked by using the coatings on the glass which operate at certain wavelengths (hence the blue at one angle and magenta at another) to "bounce" wavelengths outside of the intended range. For the 486M, it allows all of visible light while bouncing off UV < 320nm and IR > ~685nm. The problem is that at extreme angles, usually greater than 50-60°, the light's incident angle striking it doesn't react properly and will cause weird color casts and darkening.

My Heliopan "Digital UV/IR" tends to block more on the IR side and less on the UV end whereas the 486M blocks more UV and less IR. The Rodenstock UV/IR that I have is probably the widest range block for "normal" UV/IR filters going from around 380nm-720nm visible. It's also the most incident angle sensitive filter I've used.

The absorbtion based filters don't have this incident angle issue, but since they are dyed-in-mass, the energy being filtered has to go somewhere usually being converted to heat (in this case, at the filter instead of the sensor being protected). Over time, the filter will fade or can even be destroyed (as when a high power laser source gets blocked) and must be replaced.

Normal optical glass blocks UV at some wavelength on it's own without any filters. Even normal "window glass" panes block UV. The difference varies on what the cutoff frequency is for different glasses. It's also the reason why the UV-Sonnar uses quartz with fluorite (and has no coatings), so that UV wavelengths won't be blocked.