History, observatory and equipment

New start, new equipment and new possibilities:

AJ og teleskop 1969 009

It all started a long time ago.  When I was young. When I was a teenager.  The  local salesman gave me a small astronomy book when I laid sick in bed and the interest was born. 

Soon after I got my first telescope, a Unitron Polarex 2.4'' refractor.  This was followed by a Charles Frank 6'' Newton reflector on an equatorial mount.  In the  late sixties I started my first efforts as an amateur astro photographer.  These  were they days of 35mm film, noone have heard about a computer or a digital camera.  There was no "go to" options. I had to navigate the sky manually and learn from memory and from the use of start atlases where the objects were located. Interesting and funny days. 

The Charles Frank reflector is since long gone, but I still keep the Unitron in my observatory. (Photo left and below from 1970).

Orion omkring 1970 001

The interest for astronomy laid more or less dormant from 1975 until 1995.  I married, got two lovely kids and got involved in a lot of biology work, book publishing and fish farming. I also kept my full time job as a teacher.  The days were busy.

In the late nineties the CCD-revolution appeared and it became possible to observe and do astro photography in a completely digfferent way that I used to do back in the seventies. The motivation came back and in 1996 I bought a MEADE LX200 SC (below) and a CCD-camera from SBIG. The new equipment demanded a  permanent set-up.  Living close to the North Sea it was necessary to shelter the scope securley. Consequently I decided to build an observatory as part of our garage.  The light pollution is severe, the number of clear days are few and the wind and humidity can be terrible..... I live where the condistions for astro photography must be the worst possible..... nevertheless, the observatory became a reality in the Autumn of 1998.

I designed the observatory myself. My late friend Johnny Nilsen was a clever carpenter living next door.  He helped me a lot and the observatory could not have been built without him!  My other friens, Werner Jakobsen, who is a a tin smith, built the roof. Many thanks to Johnny and Werner!  In early 1999 the LX200 and other equipment were installed. The observatory is named Osmundstø Observatory after the place where our house is build on the island Hidra.

 Bygging observatorium sept okt 1998 014  Bygging observatorium sept okt 1998 015
 Bygging observatorium sept okt 1998 010  Ferdig observatporium feb 1999 005


Osmundstø Observatory is presented in detail in Springer Verlag's "More Small Astronomical Observatories" (Editor Patrick Moore) in 2002. I was surprised when Springer Verlag contacted me and asked for an article.  Apparently the unique design of the building was the main reason for including Osmundstø Observatory in the publication. The book is still available and here you can read the complete description of how the obseratory was built and operated.
Please click the pictures below for larger views.

 Observatory book 1  Observatory book 2


In 1995-2000 I invested in new telescopes and CCD-cameras.  An MEADE LX200 (f6.3) and a Fujigawa Achromatic refractor (f9) became the main telescopes. SBIG ST7 and later ST2000XM equipped with adaptive optics (AO7) and CFW8 were the main cameras.  LX200 was equipped with Van Slyke micro focuser and Van Slyke slider and off-axis guider. Late on came Optec's TCF-S electronic focuser, which is still in use today.

From 1998 until 2005 I experimented with CCD astronomy and achieved results that I could only dream off 15 years back when I observed the deep sky objects now photographed with my Unitron and Charles Frank telescopes. What an extraordinary progress the computer world brought to astro photography! 

Today the images from that period must be regarded as "low quality photos".  Now amateur astrophotographers can obtain astro photos thatb only the larger\st telescopes in the World could take 30 years ago.  Isn't it fun?

Below to the left LX200 with Unitron Polarex mounted piggy back and SBIG STV autoguider, prior to building the observatory. Right is the LX200 with Fujigawa refractor mounted in the observatory.

The equipment shown here was demounted in Spring 2019 and sold one year later.

  LX200 1
 CCD kamera001 Left:  Photo configuration used with LX200 around year 2000
Below left: Getting ready for imaging around year 2000
Below right: The longest exporsure I made with the LX200. A 5hrs 10 min image with ST7E of Messier 51 shot on the night between 22. and 23. April 2001.  The faintest star in the image is R-mag 20.72 (RA 13:30:21.634, DEC: +47:12:41.42). A total of 292 stars are recordet and at least 50 weak galaxies are detecable in the FOV, which covers about 13x20 am. (Many thanks to Arne Danielsen, Oslo for analyzing the image).
 Ferdig observatorium feb 1999 002  M51 73024



10'' RC
After 2005 I took a long break from astro photography and devoted my time to teaching biology and doing travel and nature photography, (which you can read more about on this web site).  But a deep interest never dies and in 2018/19 I decided to upgrade the observatory, getting hold of new equipment and develope my skills with astro photography further.

I needed a scope that could be permanently mounted in the observatory and suited for doing high quality imaging of deep sky objects.  Searching the internet and especially looking at the many interesting setups shown at AstroBin, I finally decided to buy a  GSO 10'' Truss Tube FL2000mm (f8) Ritchey-Chretien (RC) reflector (bought from astroshop.eu) and mount it on iOptron CEM60EC (also from astroshop.eu) equatorial mount. This set-up would fit exactly into my observatory, but the pier had to be modified (below). ZWO's cameras ASI294MC Pro (colour) and ASI1600Pro including their filter wheel (EFW) would make up the main cameras, (items bought from First Light Optics, UK). 

A second plan was to purchase a mobile equipment for wide field imaging later on.

 RC april2020

10inc RC specifications

73156 D

: 10''RC in operation April 2020.

Top right:  Telescope specification (the focuser has been replaced with Optec's TCF-S)
Bottom right:  10'' RC first image. 14 hrs of NGC891

In order to get the best possible view with the new scope, it was necessary to raise the pier about 40 cm.

The original pier built for LX200 consists of two steel tubes thread outside each other where the inner tube is ancored in the concrete base.  The outer tube moves smoothly around the inner one with grease in between. This allows rough polar adjustment. My friend Kjell Nagy (Flekkefjord) built the pier for me, many thanks to him!

The photos to the right (click for larger view) show how the pier was expanded and how steel wires with turnbuckles are mounted to minimize vibrations.  The two circular alu plates are 10mm thick and the 45 cm long steel bolts are 16mm i diameter.  The 4 bolts that originally mounted the LX200 superwedge, now lock the bottom alu plate to the top of the original pier.

The photo below shows how the ioptron 130mm top pier plate is mounted to the upper alu plate. iOptron CEM60EC is in turn mounted to this plate as seen below right.

Far below are photos showing the scope mounted for testing prior to anti vibration wires were mounted (right), and the finially mounted and equipped scope in October 2019 (left).

 Mount modification 1
Top pier plate


 RC 061019 RC 140719

The large backfocus distance (250 mm) of the RC allows a lot of equipment to be added.  This is a great advantage and gives me the oppurtunity to experiment with different photo configurations. Adapters like a "collimation tilt adapter" can be added without killing the focus point. The large backfocus distance gives configuration flexibility.

I have replaced the original focuser with Optec TCF-S that was originally bought for use with the LX200.  A chip upgrade had to be done and a special adapter made for mounting the focuser had to be built. (Specially made adapters can be ordered online from PreciseParts (USA)).


1) Configuration with ZWO cameras, filterwheel and viewing or off-axis guiding option

This configuration (among other used for the NGC891 photo above) allows me to fine tune focus from the PC, observe visually if wanted, install a LP-filter, use the ZWO EFW and do imaging with ZWO ASI294 or ASI1600. Drawing and photo to the right outline the set-up.

The TCF-S focuser eats 88.2 mm (3.5 inches) of the total 250 mm backfocus distance and has an adjustment range of 15.1 mm (0,6 inch).  It can be operated manually through the control unit (which is mounted on my desk) or from the pC.  I usually controll the focus through the imaging software Astro Photography Tool (APT) that I normally use. The focuser also has a temperature control option.

A 2'' draw tube fits inside the TCF-S and can be moved back and forth for a rough focus adjustment

A masterpies of equipment built by Paul B. Van Slyke, Founder & Director, Black Forest Observatory (BFO) and VSI, Colorado, USA, is the Van Slyke Versa Port Slider. This beautifully made optical manifold gives you an steerable off-axis guider port and a separate eyepiece port with a slide mirror to divert light to the eyepiece or allow it to pass straight through to the camera. You can observe and switch to imaging in a second!

The photo below shows the 2'' eyepiece version, I use the 1.25'' version.

VanSlyke slider 1

Read a S&T test report (2002) of the Versa port Slider HERE.

Sadly a firer destroyed Van Slyke's Digital Machine Shop and VSI is no longer in business. The VSI Versa Port Slider to me is a fantastic tool that I would not sell for any price....period!

The large back focus distance also gives room for two extension tubes with the possibility to mount a screw-in 1.25'' IDAS LP-filter.  If other equipment needs to be inserted in the image train (such as a 15mm collimator-focus-ring that can be installed in front of the focuser and will allow collimation of the focuser) these adapters can be replaced or removed to allow precise focus.

Photo right
: 8.8 hrs LRGB of Messier 81 with the above configuration.


Config 1

M81 (73161 D)

2) Configuration with Nikon D850, flat fieldner and filter holder

 Being a nature photographer I luckily hold a lot of Nikon photo equipment, including the full frame 45.7 Mp D850 DSLR camera body.  A full frame body gives sever vignetting on the 10'' RC.  However, the TSRC Flat2 corrector corrects for most of the distortion without altering the scope's FL.  Here was an option to use the high resolution DSLR for astro photography.

The flattener requires an exact focus distance of 109 (+/- 1.0) mm behind the back M48 thread.  The camera body and it's required T2-adapter eats 55 mm of this distance, leaving 54 mm left.

The flattener fits inside the TCF-S.  An M48/T2-thread adapter is needed and the configuration and steels 16.5 mm. The config also gives room for the UFC filterholder (15 mm), which is great for adding either a LP-filter or a narrowband filter.  Two extension tubes (15 mm and 8 mm) complets the image train and fulfills the 109 mm distance.

As you can see from the photo below, there is still vignetting, but not more than can easily be removed by cropping.

TSRC Flat2 spec

 D850 and TSRCFlat 010220 1

RC and D850 january 2020

 IC405 D850 RC konfig
Above: a singel 300 sec exp of IC 405 with the above configuration
Right: Cropped version of 84x300 sec (7 hrs) IC 405 image

 IC405 (73157 D)

Imaging with Nikkor 600mm f4E FL ED VR
The Nikon 600 mm f4 lens is about four times as expencive as my 10'' RC scope! A once in a life time investment. It is a optical masterpiece, highly valuated by nature photographers worldwide and regarded as one of the best optical lenses ever made.

f4 makes it a superfast lens and even equipped with Nikon TC14 (1.4X teleconverter) it is still fast (now f5.6 and FL=840 mm) and the images are super sharp.

I decided to end the season 2020 trying this lens with the TC14 in combinition with ZOW ASI294MC camera.  This would give a FOV of 79 x 53 am (vrs 110 x 75 am without the TC14) large enough e.g. to frame M81 and M82 in one photo.

ZWO produces a lens adapter for Nikon (as well as for Canon lenses) that gives the exact necessary 6.50 mm backfocus needed for their cooled ASI294 and ASI1600 cameras.  The adapter splits in two where you can use the 20.5 mm part to include the EFW in your configuration. This is neat if you want to do narrowband imaging.

The results turned out great I think.  However, you have to manually focus the lens, which can be a difficult task.  The focus point is very narrow, a little off and the image is ruined.  It was necessary to spend some time learning and to test and retest the focus before starting the image session.  Once focus is achieved, a little tape on the lens' focus ring secures the focus.

 20054 AFS 600E FL front
 M101 (73159 D)  Config 2
Above: Nikon 600/TC14-configuration
Left: 7.1 hrs ASI294 colour image of M101 using the above configuration
Below: The Nikon 600mm set-up on CEM60EC with ZWO mini guidescope and ASI120 mini  guide camera
Nikon600mm 1

A second mounting - iOptron GEM45EC

In April 2020 I decided to modify an old telescope pier that was mounted in our backyard and to equip it with a second equatorial mount that could also be used as a portable mount to bring along in our car.

I did choose a the new iOptron GEM45EC that was relatively light (7,2kg) but could still carry 20 kg payload.The mount is designed to operate on latitudres from 14 to ~68 degrees N, which in this case was perfect.

Eight 10mm bolts were cemented to the top of the concrete pire and used a 20x20cm 10mm aluminium plate to which I fastened the iOptron top-pier plate (easily visible on the photo). This allowed the GEM45EC to be fast and securely fastened to the pier and also allowed an easy demount of the mounting when necessary. 

I planned to use this mount with my new Celestron RASA 8 as well as with my SkyWatcher Esprit 100ED, SkyWatcher Skymax 180 Pro (used for moon- and planetary imaging) and for the Nikon 600 lens, which is superbe for astro photography.These will mostly be optics for widefield astro imaging in contrast to what went on in the observatory (see above).

The mount contained iOptron's iPolar Electronics Polarscope and could easily be polar aligned using the corresponding software.  I managed to get perfect alignment in 10 minutes. 

A water proof and insulated cover was made in order to be able to leave the device mounted in all sorts of weather.  Telescopes and electronics were stored in a small operating room in the near by garage and a 10 meter USB 3.0 cable connected the mount and other gear to a laptop via a 7 port USB 3.0 hub.

 In this way the mounting, focusers, guide scopes and cameras can all be operated from a cosy and heated room in the garage.  If weather conditions are stable, I cover the complete rig with heavy duty plastic covers in order to more easily resume imaging the following nights.  

From left to right:
GEM45EC mounted inside the waterproof shelter when this was under construction allowing the mounting to be viewed from the top.
The completed waterproof shelter made of waterproof wood with styropore inside and plastic-coated aluminium outside allows the mounting to be permanently stored outside in all weather.
The set-up covered with waterproof bags for short-time storing when qweather is favourable for more-nights-in-a-row imaging.


LEFT:  SkyWatcher Esprit 100ED mounted on GEM45EC
RIGHT:  Controllroom in the garage where imaging is done
BELOW: Celestron RASA8 on iOptron GEM45EC

Celestron RASA8
There are few clear nights here at Hidra.  To compensate for this, I need to make the most out of a few sessions.  This was the major motivation for buying the superfast (f2) Celestron 8''Rowe-Ackermann Schmist Astrograph (RASA8).  

The astrograph is compatible with many ZWO cameras, including the ASI1600, ASI294 and ASI2600, that I use and can also be used with mirroless cameras, but not with full frame sensor cameras. (To use full frame cameras, you need to upgrade to RASA11). It is also dresigned for photographic purposes only and cannot be used for visual observations.

RASA 8 has an aperture of 203mm, a focal length of 400mm and a focal ratio of 2,0, which gives it a light gathering power 843 times faster than the human eye. The backfocus is 29mm, which is critical to achieve focus and ~zero vignetting.  With a tube weight of only 7,7 kg, it fits nicely on my GEM45EC, allows guide scope and other equipment to be added and is also highly useful as a portable scope (although a transport case had to be made).

Starizona sells a filter slider very useful with 6,5mm backfocus ZWO cameras (like the ASI1600 and ASI294) and a filter holder useful with ZWO' 17,5mm backfocus cameras like the ASI2600.  Both items will allow you to use NB-filters or light polution filters with RASA, while traditional filter wheels cannot be used due to RASA's short backfocus (29mm). Read a review of the astrograph HERE.

An f/2 system delivers images of the same exposure depth as an f/10 system in just a twenty-fifth of the time. By using this fast instrument I should be able to capture in seconds what my f8 RC would capture in minutes. A challenge can be to avoid "bun out" of lighter parts of an objects, e.g. the core of bright galaxies.

I did install the Celestron focus motor for SCT, EdgeHD and RASA8, which has prooven to be most useful when operating the scope from my controllroom.

Also I had to make my own dew shield to block out lights and to be able to place a flat-filed-box in front of the scope without moving the camera.

I was excited when downloading the first frame taken with RASA 8, a 30x15sec (7,5 minutes)  unguided image of M13 - and what a result!  Take a look below and scroll down to see a few other early images with this scope.


  RASA8 "first light".  7,5 minutes (30x15 secs) of M13 on 27. August 2020 with ZWO ASI1600 on iOptron GEM45EC. No darks, no flats.

                                                      Celestron focus motor
Western Veil Nebula (NGC6960). 101x180sec (5 hrs) Ha-OIII-SII with ZWO ASI1600 on RASA8


  M31. 233x30secs (1,9 hrs) with ZWO ASI294 (colour) and RASA8. Sept. 18th 2020.




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