Move over darling!

Lucky shot this morning... The skies cleared just before sunrise to allow for a portrait of Venus chasing the moon out of the morning sky. I have seen them closer together, even Venus disappearing behind the moon, but it always makes a nice sight.

On national television weather forecast, it looked like this:

A little clockwork

Last monday I put to service the iOptron Sky Tracker. This little device will be used on trips to dark skies to make guided pictures of the sky. It comes with an excellent iOptron polar scope (an iOs/Android app to calculate the exact spot of Polaris for a given time and location can be downloaded for a low fee - but other apps do the same for free).

The iOptron app on iPhone

The most recent version of the Skytracker features an altitude adjusment wedge to help aligning the mount to the pole. It works, but is a little wiggly. Locking it requires some force, with enough risk to lose the just achieved alignment. Maybe the better idea remains to use a heavy duty geared tripod head with fine motion (Manfrotto has one), surely if you want to use lenses like the Canon 200mm 2.8 in my picture. Swapping lenses or camera accessories must be done with some care, not moving tripod or Sky Tracker. Double check polar alignment after any change in the configuration.

The iOptron provides two tracking rates: half sidereal to combine star motion with not yet too blurred landscape backgrounds, or full sidereal. The half speed is very handy, but with a 50mm lens on full frame DSLR stars looked trailed after one minute - which is quite as expected. For the image of Gemini below, I captured about 45 minutes of data (in 2 minute single frame exposure) with a Canon 6D and 50mm 1.4 lens from my backyard. None of the single frames had stars trailing. From what I saw during the stacking process single exposures of 10 minutes must be possible.

Jupiter in Gemini