Jump to content
UltravioletPhotography

IR Spruce against Cloudy Sky


Recommended Posts

Pentax K1-converted + Asahi Ultra-Achromatic-Takumar 85/4.5 + RG1000

f/11 for 1/50" @ ISO-1600

 

That is a rather dark filter to shoot through. Needed lots of ISO for f/11-f/16 shots. The sky was very overcast so you only see streaks of the expected RG1000 dark sky. Sharpening was only applied to the tree because it brought out too much noise at such a high ISO. I did like the final artistic (more-or-less) effect but I'm not totally satisified with this photo.

 

I am trying to learn to use the UAT on its native Pentax body. Lots to learn - mostly about the camera settings. Using an old manual lens on a digital body is much easier on a Nikon who expects you might actually do that on rare occasions. I had to learn by trial and error how to get exposure feedback from the K1 for an adapted M42 lens. So much for RTFM. The info was just not there. :D

 

Added: Thanks, Bill, for the ID !!

 

PNTX0016pnFinal.jpg

Link to comment
Yes, I'm going to try various experiments with my cool Longpass filters on this UAT.
Link to comment

I did some comparisons between RG850 2mm thick, and RG1000 1.25mm thick, and I didn't see any differences, other than exposure time which is almost identical.

Ask Bob Friedman about 1mm thick IR longpass filters. He was the first person to show results using thin RG glass, and has more experience with that than I do.

Planning on some RG1000 1mm thick soon.

At the bottom is a photo shot with RG1000 1.25mm thick. Exposure is the same as shot with RG850.

Also some comparison graphs.

What I should point out about the 'flat line' in these graphs is it represents the lowest recorded tested data for that glass type @3mm thick, which is OD5 for all these types,

so one should disregard the flat line because the diminishing transmission continues lower than the flat line, I show an example of this with the Ti graph 'estimation' line.

Note that the first two graphs are shown in T, the other graphs are shown in Ti.

 

Transmittance Diabatic

post-87-0-35102800-1499125356.jpg

 

Transmittance Linear

post-87-0-94743600-1499125465.jpg

 

Internal Transmittance Diabatic and Linear

post-87-0-88368000-1499125397.jpg

 

Internal Transmittance Linear

post-87-0-99976000-1499125515.jpg

 

RG1000 1.25mm thick (cloudy). Close to Sweet Creek Falls (near Mapleton, Oregon, USA).

post-87-0-60064100-1499125841.jpg

Link to comment
Bill De Jager
I've had good success with a 1000nm filter in bright sun and low humidity. The tree in post #1 is actually a spruce (Picea sp.); pines have much longer needles in bundles.
Link to comment
Thanks, Bill !! I could not get close enough to see if the needles were square in cross-section. I'll change my title. I probably should have recognized it as spruce, but I really don't know trees. Too many flower IDs stuffed into the old brain pan, I guess. :D
Link to comment
Bill De Jager
You're welcome, Andrea. The cones are a big clue. Some other Pinaceae such as Pseudotsuga have somewhat similar cones, but even those look different. Besides, there's just a certain look to Picea that one learns with practice. I'm also assuming that this photo was taken somewhere within 2000 km of your home, not on the other side of the world where there are some different conifers I'm not familiar with and which might fool me. (Granted, there are plausible foliage imposters for your area such as Abies pinsapo, but at least that one has very different cones.)
Link to comment

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
×
×
  • Create New...