Infrared with the M system

petrochemist wrote:

Larry Rexley wrote:

petrochemist wrote:

With my full spectrum cameras I've found a fair number of old photographic filters can work well. Practically any of the red/orange yellow filters for black & white film will be long pass filters equivalent to high color/super color etc.

Blue & green filters are much more variable not all pass IR & this can vary between filters supposedly of the same type. Some that have worked well on one occasion have been quite useless a few months later (possibly from varying IR in the sunlight)

A variable ND can be very good allowing the visible portion to be adjusted while constantly seeing ~800nm plus (stacked with appropriate coloured filters the affect is the same as the variable wavelength filters on e-bay)

I'll try any strongly coloured filter I come across (colour correction & warming/cooling types tend to be too weak)

A few types of 'technical glass' can be effective too, but many of these are hard to get in sizes above 50mm, tend to come without any mounts & don't have guaranteed optical flatness. Still my 25mm Schott BG3 & U330 filters have worked well on lenses small enough for them to cover. They were among a set from work that were no longer used

Thanks for those observations. I have discovered some of those principles such as the strongly colored filters seem to be the most useful for IR and the 'correction filters' less so, although they can be used in conjunction with stronger filters to create a particular effect.

Here's a link to a thread where folks stacked multiple filters including 80A and 80C filters to get 'candy pink' effect, it is quite interesting. There are other threads on this as well.

https://www.dpreview.com/forums/thread/4639879#forum-post-66403437

I get fairly similar 'candy pink' results quite easily using my old SD14 bodies, the Foveon sensor sees IR in the red, but sees other things fairly normally. (The red is often be more intense)

Foveon IR shot (dust trap removed, X1 filter & fluorescent WB)

I've also had similar results with a 590nm filter & hue adjustment: https://flic.kr/p/25BAv9s & https://flic.kr/p/2abeHbN

I don't want to find a reason to collect CC filters too, I've got far too many filters to play with already

Interesting result.

I hear you about collecting filters, I have 15 or so already.  eBay is great for treasure hunting.... I'll buy any new filter that looks promising for IR for $5 - $10 on a super discount, knowing I can resell and not lose money.  I'll pay $15 - $20 if the filter normally sells used for $30 - $40 as many of the larger 67 and 77mm filters do.

Just found someone selling a set of 4 identical Hoya Green X0 filters which pass much more IR than the Green X1 in 55mm size for less than $10 which includes shipping!  I can keep one and resell the rest.