Jul 22

ISS – experimental 4800mm of focal length first light

Although I live in London, sometimes I visit my home country Hungary for short holidays. This summer my 10″ dobson telescope was coming with me too, mainly because I desperately wanted to try out imaging the ISS under mostly calmer and clearer hungarian sky. Usually I use a TeleVue 2.5x powermate and recently had the opportunity to test a 4x TeleVue powermate on ISS as well. When I am using the 4x focus extender with my current telescope, I can do imaging at 4800mm of focal length instead of the currently applied 3000mm.

Before this attempt I had one semi-successful try, sadly the expo/gain values were not correct (yet). But it still gave me very useful information which I could use during my next opportunity. So this time I used shorter expo value and slightly lower gain then previously. The result above feels very pleasing – especially because this was my last chance to capture SpaceX’s Dragon CRS-15 cargo spacecraft berthed to the station. On the downside though by the time the overhead pass happened, only a midsize but shrinking clear patch remained in the sky, rest was cloudy. So this is still only a partial success with a few good frames in the bag.
Still every opportunity is a great chance to gain more useful information about camera settings. Once the appropriate camera settings are found you only need to use them. No more experimenting!

Taking images of ISS is not just a photographic challenge alone, image processing also can be a very hard work too. After a few years of ISS imaging I am fairly good at identifying the orientation and the main structural elements of the station. The orientation of ISS at the time of capture is crucial, we don’t know what we are going to see.  I’m often confused especially with lower passes (between 50º and 70º elevation) and takes a little time to actually understand what I see.
So in this post I’d like to offer you some help with the identification.
At the moment quite a few spacecrafts are berthed or docked to ISS so I have made a drawing (in Windows Paint) to replicate what can we find and where on the station. Hope this helps to identify all the fours vehicles currently attached to ISS.


This is the first time me drawing anything really. I am glad for the result as I have never done it before, still the positioning is not 100% perfect. Hopefully good enough to show the position and the angle of Progress cargo vessels. Especially MS-09 looks super cool as it stands there at a funny angle. Also the round shaped bottom half of SpaceX’s Dragon is very recognisable.

Berthed spacecrafts can be identified after the drawing, from right to left the bright white spots on the main structure:
– SpaceX Dragon (NASA contract)
– Soyuz MS-09 to carry humans (Roscosmos)
– Progress MS-09 to carry cargo (Roscosmos)
– Progress MS-08 to carry cargo (Roscosmos)

Skywatcher 250/1200 Flextube dobson
Zwo ASI224MC camera
TeleVue 4x powermate
MANUAL tracking


Leave a Reply