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Saturday, October 29, 2011

Weltenrausch - ein Gedicht (a poem)





Ich springe zwischen den Welten
Lange bleibe ich selten
Ich singe und tanze und taumle vor Glück
Über solche Vielfalt einfach entzückt.


Jeder Mensch ein neuer Planet
Wie er lebt, liebt, wie er geht
Was er glaubt, sagt, weiß über sich
Was ich lerne mit ihm über mich.


Zurück bei mir zuhause
Froh über die Pause
Atme durch von früh bis spät
Denke zurück so viel es geht.


Kein Spiegel mehr, kein du, kein da
Alles ist anders als es mal war
Mein Stern ist einsam ohne dich
Erinnerungen halten mich.


Die Zeit verfliegt in der Ferne
Ich lebe dort aber gerne
Ein Gast bei mir, spaziert umher
Als er ankommt glaubt er sich leer.


Nun singt er und tanzt er und taumelt vor Glück
Über solche Vielfalt einfach entzückt
Ich bin erfüllt
Geh nicht.




Copyright 2011 by Maria Kafritsas, all rights reserved.
Email: Maria.Kafritsas(@)gmail.com
Please replace the (@) with a @ to contact the author.

Wednesday, October 05, 2011

A Canon 7D under the stars

Please, sit down and keep cool. We are talking about a hot stuff tonight.


The system consists of a Canon 7D and a telephoto lense on a Losmandy G11 mount with the Gemini GoTo system. The system is guided with a Starlight Lodestar on a small Astro-Professional ED triplet refractor. This camera is a hell of quality. Magnesium alloy, hermetically sealed against dust and moisture, the large display, a professional long life shutter (150'000 cycles!), agile knobs everywhere and a beautiful body containing 18 million pixels. If you are an astrophotographer, you will never need more pixels in a APS-C format chip. We normally use the 7D at ISO800 for 7 min. integrations during the german summer. A handful shots are usually enough to capture faint nebulas of the Milky Way. We stack them with a freeware called DeepSkyStacker. Note, the software Aperture or Photoshop are excellent to process Canon's raw CR2 files. Oh yes, we are always working with 7D's 14 bit CR2 files to keep the dynamics high. When further processing with other software packages unable to read CR2 files is required, we use 16 bit TIFF files.


Did you know? A Canon 7D is upgradable to Da (a=astrophotography) in several shops here in Germany. Additionally, an IDAS LPS v2 filter can be attached on it, to block out the light pollution.
The clip version of his filter can be attached internally in the 7D. However, there is a normal 2" version  to attach it in the 48mm thread of your Canon<->WideT adapter! 

That's a hot deal, since the 7D with its small 4.3mu pixels is an ideal match for short focal length refractors and telephoto lenses. Since, the achieved resolution isn't trivial, we use a separate small telescope to guide the system. The guiding camera can be controlled by the software MaximDL or CCDSoft, the de facto standards in astrophotography.


A handmade "Hartmann Mask" (the mask having three holes in the photo above) is used for focusing. The micrometer screw at the left side of the telephoto lens facilitates precise focussing. Note, the 7D is remotely controlled from the laptop by using the supplied USB cable. The excellent "Canon 200mm f/2.8L USM II" telephoto lens is used at f/3.5 to take breathtaking wide field photos of large celestial objects (e.g. dark nebulas). This is the best 200mm camera lense for astrophotography, we have ever used so far, no donuts at the corners, no vignetting. Yes, why not, this dream lense could be also used on a full frame camera (e.g. Canon 5D MkII).

If you carefully look at the photos, you may find numerous parts being special customtailored products manufactured only on request.


This is the region around the star Tarazed in Aquila. Note, this is a crop of a 9 stacked (median) photos at ISO800 with 7 minutes each. No darks have been used.


Discover more details of this setup at dark.astrodigital.net

Thanks for reading.

Panagiotis Xipteras

Monday, October 03, 2011

Pleiades - The Seven Sisters

These are the Seven Sisters, the Pleiades complex, an open cluster in the Taurus constellation containing several blue giant stars. The most prominent of them, the Seven Sisters, are visible even with the n.aked eye.
See this photo in higher resolution at: dark.astrodigital.net. It's a single 13 minutes exposure with ISO400, at 385mm focal length (f/3.65) under suburban light pollution with an unmodified Nikon d3100 DSLR camera without any LPS filter. The photo processing has been entirely done in Aperture v3.1 (Mac).

It gets even better..
However, we experienced it get's even better if you stack many photos instead of using only one. So I did it, and I was astonished about the high quality the stacking can produce.
See my ultimate Pleiades (M45) photo in highest resolution at: dark.astrodigital.net

Data:
Median of 772+240+276+325+386+330 seconds
Nikon d3100 unmodified
FL=385mm, f/3.65, ISO400, No CLS filter
Urban light pollution

Exposure: Nikon d3100 unmodified in NEF (raw format)
Stretching & Histogram of each NEF photo: Aperture (Mac)
Alignment: MaximDL (2 stars manual)
Stacking: MaximDL (Media filter, default settings)
Histogram: Aperture (Mac)
Convert to JPG: Aperture (Mac)