Infra Red technical details

I wish to take IR images of faint graphite inscriptions on C19th prints. So I am considering converting one of my Olympus cameras (P5 or M5ii) to full spectrum by removing the IR cover filter (using a commercial service). Advice would be welcome. The OM help service was not able to provide anything.

Specifically:

Is the IR wavelength/ sensitivity of the sensors known? Is the IR wavelength/transmission of the 60 and 30 mm macro lenses known? Will the auto focus work with IR?
i.e. would it work? If so, which body would have better properties?

As an aside, are these details known for UV wavelengths, to which the conversion would also provide access?

Thank you

cvhmanchester wrote:

Specifically:

Is the IR wavelength/ sensitivity of the sensors known?

I have never seen an analysis of this data, so at least it's not known to me.

Is the IR wavelength/transmission of the 60 and 30 mm macro lenses known? Will the auto focus work with IR?

I have shot infrared with a 720nm filter on the Olympus 60mm lens. It does transmit infrared light, and my non-scientific understanding based on using a range of lenses on different IR/full spectrum cameras over the years is that I've never seen a lens be the limiting factor on infrared wavelength capture. This is anecdotal, not rigorously tested.

Autofocus works fine.

i.e. would it work? If so, which body would have better properties?

It should work for near infrared (i.e. near 720nm and a bit longer). It won't work for far infrared/thermal imaging.

As an aside, are these details known for UV wavelengths, to which the conversion would also provide access?

From personal experience, it is nearly impossible to capture UV wavelengths with modern lenses- their designs and coatings block nearly 100% of UV from hitting the sensor. I've been trying to capture UV light with a full-spectrum converted sensor for years and I have yet to find an affordable way to do it, with the most promising solutions being scientific lenses specifically designed for UV transmission. Even the B+W Ultraviolet Pass filter I've used has transmitted far more IR than UV, to the point that the weak IR completely swamped whatever UV light may have made it through.

Thank you

Tcvhmanchester wrote:

I wish to take IR images of faint graphite inscriptions on C19th prints. So I am considering converting one of my Olympus cameras (P5 or M5ii) to full spectrum by removing the IR cover filter (using a commercial service). Advice would be welcome. The OM help service was not able to provide anything.

Specifically:

Is the IR wavelength/ sensitivity of the sensors known? Is the IR wavelength/transmission of the 60 and 30 mm macro lenses known? Will the auto focus work with IR?
i.e. would it work? If so, which body would have better properties?

As an aside, are these details known for UV wavelengths, to which the conversion would also provide access?

Thank you

It always disappoints me that dpreview does not have an infrared forum. However for what it’s worth I have been shooting IR with both Olympus and Panasonic converted cameras for several years. I use a fairly full range of filters covering about 450 to 950nm and they perform equally well on all my lenses. The lenses include the Olympus 30mm macro but not the 60mm macro. Certainly auto focus works correctly with IR. I don’t know what you mean by a body having better properties?

Whoever you choose to do the conversion will tell you more about the sensors than I can, but selecting full spectrum means you don’t need to specify a wavelength for your sensor, it is all taken care of by the external filter.

If you are based in the UK, I can recommend Protech Repairs as a very helpful company who will explain the details to you, in order to help you make any decision. In the US, the big name is Kolari but I have only used their sales service for filters.  I’m afraid I can’t help with your specific application but either of these companies should.

Avoid UV, It needs special sensors.

You might also ask for advice from one of the infrared Facebook pages.

Good luck!

Maggie

cvhmanchester wrote:

Is the IR wavelength/ sensitivity of the sensors known?

All sensors block IR rays over 1300nm. Between 720nm and 1300nm, 96% of the sun’s IR rays are between 720nm and 950nm. In other words, less than 5% of IR rays are over 950nm.

Is the IR wavelength/transmission of the 60 and 30 mm macro lenses known? Will the auto focus work with IR?

Not all μ4/3 lenses can autofocus on an IR camera. The Lumix 20mm can’t on my wide-spectrum IR camera. But the Lumix 30mm macro lens and the M.Zuiko 60mm macro lenses work perfectly.

If so, which body would have better properties?

Any body camera should work.

If you were doing _colour_ I.R. as I do, you would see that the colour obtained with Olympus lenses are not _exactly_ the same as the colour obtained with Panasonic lenses, probably because they use different mineral coatings.

JeanPierre Martel wrote:

cvhmanchester wrote:

....

......

Is the IR wavelength/transmission of the 60 and 30 mm macro lenses known? Will the auto focus work with IR?

Not all μ4/3 lenses can autofocus on an IR camera. The Lumix 20mm can’t on my wide-spectrum IR camera. But the Lumix 30mm macro lens and the M.Zuiko 60mm macro lenses work perfectly.

....

Lumix 20mm/1.7 (and also wider lenses) can focus on wide spectrum camera but all of these depends on the conversion and specifically the critical point is the adjustment of the sensor when service throw off the AA filter .

In addition to what others have said:

INFRARED

Ultravioletphotography.com has an infrared area with useful info: https://www.ultravioletphotography.com/content/index.php?/topic/712-sticky-ir-photography-cams-mods-lenses-lights-links/#comment-26624.  Unfortunately it does not address MFT lens performance.

I'd like to stress the IR hot spot issue.  This can be a real killer with some lenses, but plenty of lenses do reasonably well.  List of lenses known to hot spot, though it's not comprehensive:  https://kolarivision.com/articles/lens-hotspot-list/

Yes, different cameras, especially from different manufacturers, will give slightly different color infrared results.  The differences are probably mainly with the dyes in the Bayer filter matrix, but could also be caused by subtle differences in the IR transmission of the microlenses and the inner coverglass of the sensor.

UV

Ultraviolet photography is best for seeing subtle surface effects like faint scratches or inscriptions.  While it's hard to find common lenses with decent UV performance there are some out there that are usable. Refer to https://www.ultravioletphotography.com/content/index.php?/topic/1654-sticky-uv-capable-lenses/#comment-44959.  Personally, I mostly use an EF-mount 40mm f/2.8 STM as my walkaround UV lens.  I've also used the Sigma 60mm f/2.8 DN (on E mount but it was also made for MFT) for UV photography.  There are a couple of them in MFT mount on KEH right now.

UV-pass filters are expensive.  The best is the Baader-U but it's especially expensive and has a non-standard thread meant for use on scopes. It can be adapted but it's a bit of a pain.

The thick cover glass on MFT cameras doesn't make UV photography any easier, and will adversely affect the performance in outer regions of the image area for wider-angle lenses not made for that format.  That should not be a big problem with the 60mm since it's telephoto.

Once again DPReview members have come up with an excellent range of useful answers.

I shall put a toe in the water by trying a 720nm filter on my (unconverted) E-M1 ii, starting by checking hotspots on the macro lenses I have, 2 Olympus, a Canon, and a Nikon.

Thank you to you all.

john isaacs wrote:

https://www.lifepixel.com

Their web site also has quite a few articles discussing the technology. Well worth spending some time reading up. Also the DPR "Photographic Science and Technology" forum, https://www.dpreview.com/forums/1061

Sterling
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Lens Grit