April 2025

[ARTUROARTISTA]

Another from my last riverside hike. The low water level exposes mud flats and depressions in the silt where organic matter decomposes to make a rust-coloured film across the surface. In IR, these areas come out very bright.

Nikkor 40mm f/2, Z5 with Kolari 720nm clip-in filter. I had really to fight the colour unevenness caused by the filter in the post-processing stage. A bit strange this not-so-wide lens triggers the filter to behave badly, unless this behaviour is due to the combination of stopping down and near infinity focus.

I like seeing the Norwegian landscapes. When I was 10 or 12, I read all of Knut Hamsun's books, and I knew the country even though I hadn't been there.

[Fons Baerken]

aPRIL\ 19

sunny day

Zf  -  Z 28mm f/2.8

[Bruno Schroder]

Tipulae, Easter holidaying on a balcony at sea.

Iphone16 Pro

[KarlMera]

Few lenses are so specific that you can tell them apart.

Sorry, but that is very interesting for me. The differences between a fisheye or wide angle lens and tele lenses are visible for me.
But "normal" pictures like my "perfectly clear" could not tell the lens/brand/lens age/focal length/exposure time/aperture.

Do you need to see the bokeh of a lens?

[Øivind Tøien]

Another from my last riverside hike. The low water level exposes mud flats and depressions in the silt where organic matter decomposes to make a rust-coloured film across the surface. In IR, these areas come out very bright.

Nikkor 40mm f/2, Z5 with Kolari 720nm clip-in filter. I had really to fight the colour unevenness caused by the filter in the post-processing stage. A bit strange this not-so-wide lens triggers the filter to behave badly, unless this behaviour is due to the combination of stopping down and near infinity focus.

Another very nice reflection, Birna. Could the color unevenness struggles be related to the rather strange, large and flat rear element (but concave on the inside) of the Z 40mm that almost looks like a protective glass covering up the surface of the baffle? Are similar problems encountered with a UVIR cut clip-in? If the IR pass filter is a dichroic filter perhaps there is a problem with steep angle of incident light (i. e. possible close proximity of the exit pupil to the sensor).

[Birna Rørslett]

There is no UV clip-in filter available at the moment

Your comment can lead to a testable hypothesis, so very interesting. I'll try to follow this up comparing front- and rear-mounted filtration with various lenses.

[Birna Rørslett]

Sorry, but that is very interesting for me. The differences between a fisheye or wide angle lens and tele lenses are visible for me.
But "normal" pictures like my "perfectly clear" could not tell the lens/brand/lens age/focal length/exposure time/aperture.

Do you need to see the bokeh of a lens?

If we had seen the original files, more differences had been disclosed. The bokeh behaviour is one of several clues, like signs of, or lack of, CA, or spherical aberration. Night shots tend to disclose presence of coma. Harsh lighting show tendency to flare and also image contrast.  Close-ups indicate any issues with field curvature. And so on.

[Birna Rørslett]

aPRIL\ 19

sunny day

Zf  -  Z 28mm f/2.8

Fons is in contrast mode

[Birna Rørslett]

I had similar thoughts re the clip-in filters, Colin.

Apparently the focus offset is handled within the latitude of the focusing system of the camera, at least with the lenses tried so far. I'll add a few more longpass or narrow-pass filters before I conclude.

What I have seen is that my 400/4.5Z copes better with the clip-in filter than front-mounted filters, as the latter definitively can cause very uneven light field or even a hot spot. Impression so far is also the Fisheye Zoom 8-15mm f/3.5-4.5 likes rear filtration better (front filters are hardly feasible any way with this optic). Still collecting field data.

[Birna Rørslett]

I like seeing the Norwegian landscapes. When I was 10 or 12, I read all of Knut Hamsun's books, and I knew the country even though I hadn't been there.

Norwegian landscapes are highly diversified. Hamsun wrote of the middle North. I live in the more gentle landscapes of South-Eastern Norway, so have the nearest mountain ranges some distance away. On the other hand, there are wide inland forests towards the Swedish border, plenty of lakes and rivers, and the endearing coast line further south.

[KarlMera]

If we had seen the original files, more differences had been disclosed. The bokeh behaviour is one of several clues, like signs of, or lack of, CA, or spherical aberration. Night shots tend to disclose presence of coma. Harsh lighting show tendency to flare and also image contrast.  Close-ups indicate any issues with field curvature. And so on.

Thank you, I know what you mean, I think my question is too difficult to get answered

[Bent Hjarbo]

On a dull day with overcast, why not photograph the easter eggs

[Akira]

Tipulae, Easter holidaying on a balcony at sea.

Iphone16 Pro

Amazing shot, Bruno!

[Birna Rørslett]

Thank you, I know what you mean, I think my question is too difficult to get answered

Not difficult, just complex with no simple answer.

[John Geerts]

Colorful Sunset

D850  AF-D 200/4 Micro Nikkor