Pages

Wednesday, November 16, 2011

How to capture a dancing planet

When Jupiter dances, you may need GRGB !
Since two years I capture the planets by using a powerful one shot color webcam, the TIS DBK21USB. It produces regular avi video files. After stacking the avi files with the software Registax, I produce FITS files, need sharpening. The sharpening step is done by using the wavelets function in Registax. Finally, I split the best FITS image in its three separate channels R,G, and B in order to use one of them as luminance, since my seeing conditions from my roof observatory are usually bad.

I need a luminance! But which one?
Depending on what kind of details you want to visualize on a specific planet (i.e. cloud or surface details), a suitable channel should be used as luminance. See below:

Jupiter and Saturn
I extract the G (green) channel in order to set it as a luminance.  It has a higher resolution than red or blue because of the RGGB mask placed on the camera sensor. Two of the four pixels in the RGGB matrix are green.

Examples on other planets:

Mars
I extract the R (red) channel in order to set it as luminance to bring out more albedo details under my poor seeing conditions.  The red channel does not suffer from seeing so much as the green and blue channel. It has a low resolution, since only one of the four pixels in the RGGB matrix is red.
If you want to visualize the orographic cloud structures on Mars you will want to use the B (blue) channel as luminance. You need very good seeing to get a sharp blue channel. These are very rare especially from roof observatories, where the local seeing also plays a role. Perhaps once a year? I think so.

Venus
I extract the B (blue) channel in order to set it as luminance as the cloud structures on Venus are visible in the blue/UV channel. As I said before, the blue channel suffers more from the seeing than the red or the green channel. Its resolution is also low.

NOTE: If your seeing conditions are excellent, the most accurate method for planet photography is simply RGB. You prevent sacrifying details both in the cloud structures and on the surface of the planets using the classic RGB method. See my latest results on Jupiter at http://dark.astrodigital.net.
If you are interested on how to process a RGB planet photos with the software GIOTTO and MaximDL please visit my homepage at: http://www.astrodigital.net

Photo shooting with IC Capture.AS
This is the software package I use with my DBK21 webcam. One of the advantages it provides is the live display of the RGB values. I pay special attention during the image acquisition, not to exceed the max. values of 255 in each RGB diagram. The screenshot above shows the settings, I always use. When the values tends to exceed the limits (255) during the session, I reduce immediately both the gain and the exposure time.

Jupiter rocks :-)
Jupiter rotates fast! Its rotation is easily noticeable at 3850mm focal length I use. I keep the time window for each avi video file short enough to prevent smearing due to its fast rotation. I developed an application to calculate the allowed time window to capture a given planet, taking into account your telescope/camera system! You can download it here for free. See also a screenshot of it:
Figure: My telescope, eyepiece and CCD calculator
/Panagiotis

Wednesday, November 09, 2011

I wonder (a poem)


I wonder

I wonder how come the angels fly high
while we are forced to walk

I wonder how come the stars always shine
but we see them only by night

I wonder how come six senses we've got
but we use only the eye

I wonder how come people don't ask
what's beyond the deep blue sky


---
(c) Copyright 2003 by Maria Kafritsas, all rights reserved.
Email: Maria.Kafritsas(@)gmail.com
Please replace the (@) with a @ to contact the author.

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)

Thursday, September 01, 2011

The supernova SN 2011fe in the Pinwheel Galaxy M101

This is the supernova, I didn't discover ;-) The SN 2011fe in Messier 101, also called Pinwheel galaxy.

Yesterday, it was possible to observe it even through my small 4 inches telescope from my light polluted suburban area in Stuttgart, Germany. In order to prove my observation, I attached my DSLR camera and I shot this photo, where the supernova is visible. This unguided, 30 second exposure reflects my visual experience through my 18mm TakLE eyepiece. This is the brightest supernova I've ever observed.

At the moment (Sep. 1st, 2011), the ongoing supernova SN2011fe is brighter than the entire Pinwheel galaxy! It has a brightness of 10,5mag, that means it became 4 mag brighter in only 5 days, since on Aug.25th, 2011 it was significantly fainter with 14.8mag and thus only visible with bigger instruments. Note, each magnitude is about 2,5times fainter than the previous one, e.g. 11mag is 2,5 times fainter than 10mag!
I've heard from other colleagues in my astronomy club the detonation of this distant star could be strong enough to destroy everything in a radius of 30 light years around it. However this star is in a distant galaxy 19000000 (nineteen million) light years away from the Earth! So, don't worry about it. If you have a small telescope go out in the garden and don't miss this unique chance to watch a real supernova with moderate equipment. Note during your observation, you are watching a star in another galaxy! Normally, all stars you can watch with an amateur scope are in our Milky Way. But not this one.
/px

PS: New observation five months later on January 25th, 2012. Read more at: http://xipteras.blogspot.com/2012/02/pinwheel-galaxy.html
--
See also a wikipedia article about it: http://en.wikipedia.org/wiki/SN_2011fe
Learn how to find it at: http://www.astronomind.com
Watch it blinking in high resolution at: http://www.capella-observatory.com

Tuesday, June 28, 2011

Diamonds in the sky

This is the double cluster in Perseus. It is called h + chi and it contains over 600 blue giant stars. More information at: http://en.wikipedia.org/wiki/Double_Cluster
See my astrophoto in high resolution at www.astrovox.gr or at dark.astrodigital.net

When I am working on such delightful celestial objects, I sometimes think astrophotography is a pre-stage of poetry. The astrophotographer, invests all his experience trying to interpret a fact into a shapes and colors, so a poet tries to interpret his emotions after looking that pictures into wonderful words.

/px

Tuesday, June 21, 2011

My autoguiding settings are here :-)

Yes, it works! These are the settings for my autoguider. The graph is smooth (if nobody is jumping next to the mount ;-) and I could expect good photographic results with it.
..and now live during the download of the light frame ... (hertzklopf klopf klopf :-)))
The software "Point An Object" can be download here for free.

Sunday, April 17, 2011

Trying to capture Saturn with a color webcam

The planet Saturn has currently a brightness of 1.04 mag and an apparent size of 19.2". I tried to capture it using my TIS DBK21 One-Shot-Color webcam on my 21cm (f/11.5) Dall Kirkham cassegrain telescope in order to find out the most appropriate focal length for this application. The DBK21 cam uses the same chip as the popular Philips ToUcam 840k Pro. However both the electronics and the mechanical construction are excellent on the DBK21. Considering the low brightness of Saturn (compared to Jupiter, the Moon or the Sun) and the permanent bad seeing at my roof observatory, it was useful to get some experience on using this webcam to capture Saturn with my telescope. The goal is to find the "golden ratio" between the focal length and frame rate to get best possible results on Saturn.

f/11.5


Image 1: a single unprocessed frame

f/11.5 @ 27 frames per second. Focal length was 2415mm. No extenders. Notice: Quick enough to freeze the seeing. Too small planet disc but very bright. No problem to increase the frame rate.

The following data have been calculated with the free software AstroDigital.Net
Model: Takahashi Mewlon 210 (f/11,5)
Focal length [mm]: 2415
Critical Focus Zone [mu]: 290,95
Model: DBK 21AF04
Pixel size [x*y]: 5,6 x 5,6
Chip size [x*y]: 640 x 480
Chip diagonal [mm]: 6,08
Chip surface [qmm]: 18,26
Wavelength [nm]: 550
Telescope illumination power: 1,102345E-05
FOV: 0° 5' 6'' x 0° 3' 50''
Image scale: > 0,48 x 0,48


f/18.4

Image 2: a single unprocessed frame

Image 3: 5000 frames added and processed (AVIStack, Giotto, MaximDL)

Image 4: The setup

f/18.4 @ 19 frames per second. Focal length was 3864mm. The ExtenderNQ (1.6x) of a FSQ-106ED was used. It works excellent on the Mewlon! The planet disk is large and bright enough to show details under good seeing conditions. The frame rate is high enough to freeze the seeing.


Model: Takahashi Mewlon 210 (f/18,4)
Focal length [mm]: 3864
Critical Focus Zone [mu]: 744,83
Model: Takahashi Extender 1.6x
Model: DBK 21AF04/21BF04
Telescope illumination power: 4,306035E-06
FOV: 3' 11'' x 2' 23''

f/28.7
Image 5: a single unprocessed frame

f/28.7 @ 9 frames per second. Focal length was 6037mm. Televue Powermate 2.5x. Notice: Too dark on Saturn, too slow to freeze the seing. Big planet disk.

Model: Takahashi Mewlon 210 (/28,8)
Focal length [mm]: 6037
Critical Focus Zone [mu]: 1818,44
Model: Televue Powermate 2,5x
Multiplier [times]: 2,5
Model: DBK 21AF04/21BF04
Telescope illumination power: 1,763752E-06
FOV: 2' 2'' x 1' 32''
Image scale: > 0,19 x 0,19

Tuesday, April 12, 2011

Backnang's star party 2011

Dear guest, welcome to the photo gallery of our Star Party 2011 ..
..in Backnang, Germany.
The moon is still up and running
Vixen ED102 on a green Vixen GP
Two SkyWatchers are gazing the night sky
Happy faces, good scopes
Most of the guests were observing the planet Saturn at that night. The photo above corresponds to a typical view of Saturn through a big dobson telescope. It has been taken some hours after the event.
A 20cm f/5 newton telescope. Mike said, he had the best view of M42 in his life, as he observed it with this scope on the Alps/Austria 10 years ago.
A Meade LX10 ready to go.
Markus the APOD guy as he sets up his INTES 18cm Maksutov telescope.
Two Lightbridges look the sky.
Gerd at the 76cm dobson telescope. This was once the biggest portable telescope in Europe! John Dobson signed it during his stay in Fellbach/Germany a couple of years ago. It belongs to the Backnanger Sterngucker. You can observe some deepsky objects in color with it! (I'm not kidding!)
The eye of the tiger: a 400mm dobson telescope.
Mike is setting up his unbelievable 30cm dobson telescope.
Dennis with his fine tuned 37cm Dob.
An apple a day ... catches light at night! :-))))

Oh yes! My Nikon and me were also there ;-)

Kind regards and clear nights to the world wide astronomy community from Backnang, Germany. /Panagiotis

Friday, April 01, 2011

Observing Saturn with two different scopes

On March, 3rd 2011 I observed the planet Saturn trying to compare the views through two literally incomparable scopes; a Mewlon-210 reflector with a 25mm TAL Koenig eyepiece and a FSQ106ED (f/5) refractor with a 5mm Tak-LE eyepiece. Since the seeing was terrible and the sky was quite polluted at that night, the view through the refractor were steadier, sharper and more pleasant than through the reflector. However, I could observe one dim star through the Mewlon, that was invisible with the New-Q. Size does matter. The background had the same brightness on both scopes, but the Mewlon was equipped with a Baader Neodymium light pollution filter. I tried to go up with the magnification on Saturn. After trying to extend the native 530mm focal length of the refractor using a perfect Televue Powermate 2.5x, I observed some false color at 265x on Saturn. No, it was not the Powermate. Obviously, visual observers do need the Extender-Q accessory for planetary work. The Mewlon couldn't handle this magnification due to the atmosphaeric conditions.

Two weeks later, I decided to put the dedicated 1.6x NQ extender on the FSQ-106ED and try it on Saturn. Note, this magic part is much more than a simple barlow lens. It corrects the violet/ultraviolet spectrum for photographic applications, i.e. the blue stars do NOT bloat any more. Moreover, it provides a planet-friendly focal ratio of f/8 by also making the FSQ super-apochromatic and hence comparable with the TOA series. High magnifications of 236x are possible with the NewQ extender. Color free.
On Saturn the views are very sharp, crystal clear and a lot steadier than through a larger scope. One can see permanently Saturn's Cassini division on the entire field of view by using a 5mm LE eyepiece. This is amazing and in some way confirms the specification saying it provides a 44m flat field also suitable for photographic use.
Let's go back to the Mewlon again.. In fact, at that night I didn't want to compare it against the Q, since I know the abilities of the μ very well. The views are breathtaking when the seeing conditions permit it. I know what I am talking about. I have observed M13, M11, several galaxies and the planets with this reflector and I still can't forget the views through it. Aperture counts. So, I attached my old DBK21USB on it and I took a videoclip. After processing it with Giotto-software.de -a great german software piece for photo stacking- I was able to see the current storm on Saturn!!! :-) It's called "the Serpent Storm", see below:
Some astronomers say "the first four inches are the most important" but I think aperture still counts. That's the law of physics. cs px

Thursday, March 17, 2011

The Marcarian Chain in Virgo

This is the star field around the Marcarian Chain in the constellation of Virgo: click here for full resolution (10 MB). The exposure time was only 2 x 100s ! The equipment used is listed below. The photographer used an unmodified Nikon d3100 DSLR camera without any light pollution filter in suburban area to shoot this photo.
The jet of the galaxy M87 is almost visible, if you zoom in the photo above. Follow the yellow lines below:
Here is a flow chart how to process your DSLR photo material:

Thursday, March 03, 2011

A Nikon d3100 camera under the stars

After five years of astrophotography with a light sensitive, mono astro camera (ST-7XME), I started looking for a more productive one with a larger color sensor. My old CCD camera had a tiny chip, my telescopes were screaming for something larger and any dedicated astro camera did not fit my camera budget.

Image 1: Nikon d3100 with solar filter

I just wanted to shoot pretty pictures in a fast and easy way without the need to spend a lot of money. Hence, I decided to attach my unmodified Nikon d3100 DSLR on the lenses I had at that time.

Image 2: These scopes were acting as lenses for the Nikon

I was wondering why astro cameras represented a long-time capital investment ;-) Although, normal astro cameras were simpler and easier to build than normal DSLRs but they were much more expensive. In the meanwhile, I have given up hope that this fact will change someday.

Image 3: H+χ Persei. (Nikon D3100 at 530mm focal length)

Anyway, at a cold clear night I had the chance to test this DSLR on the FSQ106ED equipped with the dedicated f/3.65 focal reducer. The recommended adapter train consisting of a Nikon->WideT->CA35(Sky90) has been used to mount the DSLR on the scope. This has been done in order to keep the optimal distance between the CCD sensor and the reducer. Fortunately, this adapter combination is sturdy, compact and easy to use.

I observed a hint of vignetting on the RAW photos, but it was negligible. Fortunately, the Nikon sensor was correctly built in the camera body, so there were no orthogonality issues even at f/3.8.
I used the optional remote cord to take the pictures.

Image 4: The Moon at 300mm focal length

Although the Nikon (as every consumer camera) has no active cooling, its sensor is known for its low dark noise, i.e. typical deep sky exposures of 3..5 minutes at ISO 200 are no problem in the cold winter nights. During imaging of the Moon or the Sun you may however notice mirror vibrations, especially when you are firing at long focal lengths (>1000mm). A workaround is to work with a remote cord, in silent mode settings, at ISO800.

Image 5: The Orion nebula at 386mm

If deep sky photography is your only application area, you can modify your Nikon at special shops like Optic Makkario in Germany. They set your Nikon in a so called "undefined state" by removing its internal daylight filter and making it able to register all frequencies. An IDAS LPS D1 light pollution filter is mandatory then. It is available in numerous sizes at TS.

Nikon also excels in the photography of planetary nebulas, the moons of the outer planets, and dark nebulas. An apochromatic refractor with 800..1400mm focal length and 100..150mm aperture are perfect for doing this. Example: the moons of Uranus.

My astro images are usually taken under heavy light pollution (LP). Since, I initially did not own a LP filter, I had to reduce the exposure time, increase the ISO (>400) and to process the results harder with Aperture 3 on my Mac. I captured all astro photos in NEF (Nikon's RAW) format in order to prevent data loss, a well known problem of JPG files. Nikon's NEF format offers more processing options and greater dynamics in later stages. Apple's Aperture 3 fully supports Nikon's NEF format. You can see an example here (size 3,5MB). A cropped version of M13 is shown below:


Image 6: Messier 13 - The globular cluster in Hercules captured at 385mm focal length

In August 2011, I reshot M13 at 820mm focal length (f/8). It is a crop of 3x30s stacked exposures at ISO1600 in NEF format. A high resolution photo is available here.

Image 7: Messier 13 captured with the Nikon d3100 at 820mm focal length

Photoshop users: NEF files must be converted in DNG format to be further processed in Photoshop. A good converter is here: http://www.adobe.com/support/downloads/detail.jsp?ftpID=4923

Nikon's ViewNX software can also convert the NEF files in a photoshop readable format.

Many findings in this review can be more or less also implied on newer Nikon models. Hence, if you want to buy one, you could go for the newest model as well. The Nikon D5500 was introduced in January 2015.

More astro photos with the Nikon D3100 are available in my site at: http://dark.astrodigital.net/nikond3100

Thanks for reading

Panagiotis Xipteras