Monthly Archives: October 2014

Camera change

Camera change time. The 720nm e-PL1 has gone to a good home (the camera that taught me most of what I know so far on IR) and is replaced by a svelte e-PM2, which will be immediately off for a 660nm modification.

Image: Feeding duck

Feeding the ducks this lunchtime in Twickenham.

Full-spectrum Panasonic G2, UG1 filter (UV+IR mix). 3 composite HDR. Contrast and colour tweaked in Aperture.

All image rights reserved.

Hot spot lenses

A very helpful list of lenses that suffer, and don’t suffer, hotspot issues.

http://www.kolarivision.com/lenshotspot.html

Also a useful post on the www.mu-43.com site, for those like me using M43 lenses with their IR (original post link).

I can testify to the validity of the Oly 14-42mm II R, 9-18mm and the Panasonic 14-42. I have not seen it on my Oly 17mm f2.8, but I suspect that is because I have been using it wide open, rather than shut down – others report it having issues at f12 and above. 

Good Performers

Olympus 12mm f/2
Olympus 60mm f/2.8 Macro (hotspot @ f/9)
Olympus 9-18mm f/4-5.6 
Olympus 14-42mm f/3.5-5.6 ED
Olympus 14-42mm f/3.5-5.6 II R
Olympus 40-150mm f/4-5.6
Panasonic 8 mm f/3.5 (hotspot @ f/10)
Panasonic 14 mm f/2.5
Panasonic Leica 45mm f/2.8 Macro
Panasonic 7-14mm f/4 (hotspot @ f/9)
Panasonic 14-42mm f/3.5-5.6
Panasonic 14-45mm f/3.5-5.6
Panasonic X 45-175mm f/4-5.6

Poor Performers

Olympus 12-50mm f/3.5-6.3
Olympus 17mm f/2.8
Olympus 45mm f/1.8
Olympus 75mm f/1.8 (low contrast & hotspot @ f/4.5)
Panasonic 14-140mm f/4-5.8 (hotspots from 14-25mm)
Panasonic 45-200mm f/4-5.6 (low contrast)
Panasonic Leica 25mm f/1.4 (hotspot @ f/5)
SLR Magic Hyper Prime 12mm f/1.6
Voigtlander 25mm f/0.95

Mixed reviews (please let me know if you have these)

Olympus 45mm f/1.8 (one report of hotspot @ f/9)
Panasonic 12-35mm f/2.8

For my own tests, I used a full-spectrum GX1 with 850nm (Wratten 87C, B+W 093, Schott RG850) and 790nm (Wratten 87, Lee 87) long-pass filters, taking multiple exposures at all apertures of blue sky (> 90° from the sun’s direction) framed by light colored clouds or leaves. Loss of contrast and hotspots show very strongly in these conditions at wavelenghs above 800nm. 

Image: Out in the woods

Out in the woods today.

Full-spectrum modified Panasonic G2, with 660nm lens filter.

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Comparison of dual-band filters

A comparison of four different Schott glass types (used in bandpass filters), which combine UV and IR, and exclude Visible.

The UG11 looks very similar to the UG1 I already have (results blow); however, the UG5 and BG3 look to allow in greater levels of UV and a small amount of visible – potentially more blue and some green coming in.

I just need to find a source for these types of filters as they are hard to get hold of.

ug-1

Schott Filters

Nice ! Schott make data available for their filters, including the frequency graphs which are helpful in giving an indication of how colour will be influenced.

Schott Downloads

Time to see how a BG3 compares to a UG1. Just wish I could find a good local source for made filters with the glass.

Image: Ravenscourt Park

Managed to get some time this afternoon to play with the UV+IR pass filter – approx UV up to 400nm and IR from 700nm; cutting visible light from 400 o 700nm out.

Really like how it gives blue skies (with a little hue sliding form violet) and white foliage, without having to unsubtle colour swap and change all the image to a shade of blue. Allows the blacks and greys to be that and not a shade of blue. Like it.

Full-spectrum Panasonic G2 with a Schott UG1 filter.

All image rights reserved.

The first thing that stands out to me is how easy it is the take the UG1 image, UV+IR only (cutting out 400-700nm), and slide the violet of the sky into a nice blue, but still keep the white of the building and foliage). I this was a straight 720nm image, colour sapping the R<>B would have also tinted the building blue. Using UV and IR negates the need for colour swapping, which is a rather blunt instrument, and helps on the likes of buildings and general non sky or foliage.