Sonntag, 19. Februar 2017

Convenient life-hack for an entomologist - solution to troublesome pin holding

If you ever have tried to identify a pinned insect, you may have been either irritated that holding the pin in your hand to see all sides is exhausting your muscles, or have been irritated that the pin is fixed somewhere and you can't see the side you need to observe. This very simple aid solves the problem.

convenient entomology

Take a rectangular piece of polyethylene foam used as bottom inlay for insect boxes (or use something similar), about 5 by 5 cm. Take an apple corer and rotate very slowly with mild pressure into the foam to get the nice round hole in it. It exactly fits a finger! I usually use it on my forefinger or my thumb; sometimes I use two at the same time! And you can pin multiple specimens on one at the time and compare them. A very convenient life-hack for an entomologist.








Samstag, 26. November 2016

When do you throw your food away?


It is a challenge for all of us: we do not want to eat bad food, but neither we want to be bad for the environment or a shame to hungry people. So when do we throw our food away? When the date is expired, or when it looks or smells bad? Every person has its own way, but it makes sense to give it more thought. Therefore I made this diagram to make a fair and healthy decision.


Diagram to determine if your food is good or bad


Rule of thirds
When you buy a product, look at the 'best before' date. Count the days, weeks or months that is in the future and add one third: this is the more realistic date of expiration. So: the for milk you may have three days left, but you can probably use it four days; for a glass of vegetables for which you have 9 months will last 12, etc. Some products like flour, pasta, rice and some canned food will even last much longer. Meat that expires the next day, may last 0.3 day longer, but with such low margins you better stick to the date!

Why is it important not to throw it away on the expiration date? Because manufacturers reduce the expiration date every year silently and this seems an ongoing loop. So more and more food is wasted every year! See here (NL) and here (DE). Throwing it away on the expiration date is not very responsible.


The shelf life is actively reduced by manufacturers that set the expiration date earlier. As a result people are surprised that their food is expired earlier, but still throw it away, increasing food waste. They buy a new package instead. As a result sales go up. Now the manufacturers have an incentive to further reduce the shelf life of their products. Completely unnecessarily from the point of the food quality! Therefore it makes sense to use the diagram above to determine if you should throw your food away instead of the date!

Final notes
-  It is mostly safe to follow the diagram here, but it is on your own risk. Internet resources like this one can give you advice but cannot be hold responsible
- The manufacturer can be hold responsible for food going bad when it happens before the 'best before date'. Therefore it is logical to have the date early set, but there are not any legal rules for how early.
- Because the date is set earlier year by year, the rule of thirds is very rough and may be one day rather a 'rule of halfs'.

Sonntag, 13. November 2016

The supermoon of 14.11.2016 explained



Supermoon
The Moon has an elliptical orbit around Earth, and the Earth is not exactly in the middle (like the yolk in the egg). Therefore each month the Moon has a close position to Earth (Perigee) and a far position to Earth (Apogee). When it is close, it appears on average 14% larger (in diameter) and 30% (surface area) brighter when it is full moon. When both Perigee moon and full moon occur together, we speak of a supermoon (in far position of a micromoon).

The Earth has a similar elliptical orbit around the sun and also has a close and far position to the sun, together with the Moon. Hence, sometimes the gravity effect of the Sun is stronger than  other times, causing the Moon to vary in its far and close position. The close position varies roughly between
356.000 and 371.000 km while the far position varies roughly between 404.000 and 407.000 km.

supermoon dates
Far and close distances for every moon rotation from 2001 to 2100. Data Source: Moon Perigee and Apogee Table Courtesy of Fred Espenak, www.Astropixels.com. Full moons are in yellow, data Source: Keith Cooley, http://home.hiwaay.net/~krcool/Astro/moon/fullmoon.htm.

When the Earth would not turn around the Sun, the close distance would always fall together with a full moon. But because of the rotation around the sun, the light angle changes, causing a small shift in the cycle of full moon. After 14 moon cycles, both cycles are in the same position again, with a full moon in the close position, hence almost once every year! The interesting thing is that it is mostly never the same position relative to the sun, and therefore somewhere between 356.000 - 371.000 km as explained above. And that makes the the 14.11.2016 special; this full moon in Perigee position is closer than after most other 14 moon cycles. A super close, superbig moon! However this difference is much smaller than between a Perigee and Apogee month.

supermoon 14-11-2016
A close-up of the previous graph (only the very low band with full moons!), with the 100 closest moons from 2001 to 2100 and full moon in yellow and the dates everyone is talking about in orange. Closer moons will follow several times this century, so it is not so rare. And remember from the first graph: the distance and hence appearance diameters of all full moons in this graph do not much differ to the eye and are actually all supermoons!


The moon illusion
People often think they see a supermoon. But in fact they are victim of the so called moon illusion! A very good explanation is on Wikipedia.


Macro photography in millimeter range: microscope vs DSLR camera

In this small review I compare two imaging methods, the VHX2000 microscope and a Canon EOS 7D camera with a reverse ring, for an object of a few mm in size.



This motive, a 30 million year old ant trapped in Baltic amber, is about 3 by 4 mm. Wit a normal macro lens or extension tubes, it is not possible to get such a small object so detailed captured. Reversing a wide angle (zoom) lens with an adapter (reverse ring or retro adapter) gives high magnifications and it is possible to get a good picture (right two images). I also had the opportunity to use a microscope with camera, the VHX2000 from Keyence, which is specially built for imaging small objects. I found that both are not perfect solutions, which makes a comparison meaningful.

Before I get to the differences, some words on what they have in common. Both work with lenses and a digital sensor. The depth of field is very limited and both require a stack of 10-20 images from bottom to top that are either merged in a stacking program like CombineZP or Photoshop*. They both disappoint in image quality and detail for printing on a A3 format. For more detail you need to zoom in and make a mosaic composite**. The ant image is based on a single stack image.

VHX2000 DSLR
Stability
Stable platform present Need to stabilize camera and object carefully
Image Quality
1600 x 1200 (3200 x 2400) pixel resolution 5184 x 3456 pixel resolution
Compressed/filtered data Raw data
Crisp sharpness difficult Crisp sharpness difficult
Details such as hairs visible Details such as hairs visible
Photo stacks by software Photo stacks manually
Optimal stacking


Non-optimal stacking
(movement of camera possible when turning wheel)
Light
Artificial light Natural and artificial light possible
Light from all sides (adjustable) Light from one side (with natural light)
Light can work 'flat' Lighting very flexible in giving depth
Clipping of light areas Fewer clipping areas (with Raw data)
Other
Zoom under 1 mm possible Zoom limited (here to about 2 mm objects)
Relatively fast Time consuming
Expensive Not expensive, when camera and lens are already in possession

Conclusion:
The pictures with either a VHX2000 or a reverse ring are slightly different, especially concerning color. The reverse ring method is more complicated and time consuming but gives an image quality that can keep up with a microscope image (apart from small lens distortions that are not considered here). For the price and quality, a reverse ring is a very attractive alternative to a microscope, when the object is not smaller than about 2 mm.

* On digital stacking:
1) CombineZP (freeware for stacking) gives nice results with the pyramid weighted average method. The idea is that the software reconstructs the 3d depth of the object. From the bottom layer, the sharpest is considered and build up to the top layer with complex algorithms.
2) Photoshop can also yield nice results with a different method. It just keeps the most sharp part from each layer. Sometimes the result is nicer than CombineZP, sometimes not. To do this, choose File => Scripts => Load files into stack. In the layer palette, select all layers. Then choose: Edit => Auto-Align Layers, followed by Edit => Auto-Blend Layers. Sometimes the result is better without Auto-Align (eventually manual align).

** Mosaic composite:
E.g. a mosaic of 6 image columns by 6 image rows with overlap in area for stitching gives at most 3 times more detail. With 20 stack layers per image, you need to manage 36x20=720 images (which I only did once). First you stack each mosaic part with the favored software, after which the mosaic is stitched together. This is time consuming because it often requires manual adjustments, and is only justified when an image is indeed to be presented at A3 format.

Montag, 31. Oktober 2016

De koffiespecht en de treinreis (NL)

 

De koffiespecht - ik kom er zo op.




Eerst even dit. Laatst zat ik in de trein en hoorde wat ik vaker hoor. Er werd omgeroepen 'Deze trein rijdt niet verder als...'. Wacht even, ver - verder - verst, DAN!, verder dan...
Tenzij de trein natuurlijk niet verder als stoptrein rijdt, maar als sneltrein (in de hoedanigheid van), dan is 'verder als' dus wel goed. Maar bij de vergrotende trap hoor je gewoon 'dan' te gebruiken, dat hebben we zo afgesproken. Toch wordt het misschien ooit 'verder als'. Als iedereen namelijk hetzelfde steeds fout zegt, dan is er een soort consensus dat het goed is. Afspraken, zoals bij de vergrotende trap, kun je veranderen.
Anders ligt dat bij grammaticale logica. Deze sneltrein word stoptrein, zonder t, is echt fout. Ook als iedereen het fout schrijft zal het nooit correct worden. Dit is namelijk logica afgeleid uit een algemene afspraak dat voor vele werkwoorden geldt. Als je dit zou toestaan omdat veel mensen het fout doen, dan zou dat op alle andere werkwoorden ook toegepast mogen worden. Dan krijg je gekke dingen als 'de trein stop niet bij het volgende station'.
Er zijn nog andere uitspraken die om logische reden onjuist zijn. Bijvoorbeeld 'de trein rijdt omhoog'. Dat kan niet. Een trein kan alleen maar in tekenfilms direct omhoog rijden, want 'omhoog' is een verticale beweging, net als omlaag. Zo zijn 'vooruit' en 'achteruit' de horizontale beweging. Een trein kan wel schuin omhoog rijden; mooier is echter 'de trein reed de berg op'.

Nou vooruit, nog een regeltje dan. 't Kofschip, 't fokschaap en xtc-coffeeshop hebben de medeklinkers t, x, k, f, s, c, h en p. Als de stam van een zwak werkwoord hierop eindigt dan gebruik je in de onvoltooid verleden tijd -te en -ten, en anders -de en -den. Het blijven rotwoorden. Wie onthoudt die nou? Dus kan er nog wel eentje bij; ik introduceer 'koffiespecht'.



De koffiespecht drinkt wel een kopje mee als het om de Nederlandse taal gaat! Gezelliger kunnen we niet maken ;-).



Mittwoch, 12. Oktober 2016

Free desktop backgrounds




A small present from Naturemoods.com, a package of backgrounds for you computer in the formats 1920x1080, 1280x800, 1366x768 and 1024x768. Download HERE.



A smaller fit can be elegant, supply a better overview of your icons and save energy with a black background.

How to use (Windows 10):
- Open the downloaded zip
- Copy the folder Backgrounds1 to "Pictures" (This PC)
- Go to your desktop and right-click on an empty spot, and choose "Personalize"
- Here you can set Background to "Picture".
- Important: Set "Choose a fit" to "Center" first! (Backgrounds are not made to stretch, span, etc.!)
- Click on "Browse" to choose you picture. Navigate to the folder Backgrounds1 in Pictures where you have put it.
- Now you can try different backgrounds to find out what your favorite is, in the size of your desktop. You can choose one that fits your background, but you can also choose a smaller one (as above in the example) when you wish.
- If you are done and still in the settings window, you see a list on the left. "Background" first and "Lock screen" as third. Go there, and select a picture here as well. You can also set "Show lock screen background picture on the sign-in screen" to ON.

Rainbows and butterflies in dutch agricultural landscapes - 30 years ago



Rainbow



Aglais Io - The European Peacock
on Lythrum salicaria - Purple loosestrife


Along ditches: purple loosestrife, nettles, and other plants preferring nutrient-rich soils


Along the maize monocultures; quite some diversity, including Anthriscus sylvestris - Wild chervil.

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These pictures were my very first, when I started photography. Now they are a time document from about 1988, almost 30 years ago.
Yes, it seemed so idyllic when I grew up. Some biodiversity between the agricultural fields; different weeds and at least 5 different butterflies flying regularly around each year. At that time I did not know the truth. Decades of fertilizer already destroyed most of the biodiversity. These were the species remaining! But it was the world I knew (my 'zero' reference). And it would become worse soon... New pesticides were being used and by 1992 the purple loosestrife disappeared completely from this area where I lived, along with the butterflies and bees visiting them. For who is not depressed enough: This happened AFTER 1992.

This change that I observed was definitely one of the reasons to dedicate a part of my life to nature conservation in agricultural landscapes. It seems I have to continue for a while...



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