It’s All About Exposure

   Last night after sunset I set out to try and capture a picture of Venus less then 1o from the open star cluster M-35, near the feet of the Gemini Twins. Additionally the first quarter Moon was within about 1.5o from the star Regulus, the ‘heart’ of Leo the Lion, and also easily seen as the bottom of the backward question shape this constellation is best known for. Since my western skies are illuminated by the lights from an athletic field, and the eastern suburbs of Kansas City, MO. the limiting magnitude is around 2 or 3, meaning that the dimmest stars easily seen in that direction have to be at least 3rd magnitude or brighter. So with that in mind I took over 60 pictures with various camera settings but the skies were just too bright to capture the light from the stars making up M-35.

   Then I turned my attention to the Moon and Regulus. Regulus was close enough to the Moon that it’s light was nearly washed out by the Moon’s reflected Sun light. The difficulty of catching both has to do with camera settings. For example opening the shutter and increasing the exposure time washes out the Moon but allows Regulus to be seen.
   I use a Cannon Rebel EOS T7i with a touch screen allowing me to change settings very easily and see the effect in the change in real time.
   Camera settings: 300 mm; f/13; 1/40 sec.; ISO-400


   For this picture I increased the exposure time but left the other settings as they were. The Moon is larger in this picture because I zoomed in on the original before cropping it for this blog.
   Camera settings: 200 mm; f/13; 5 sec.; ISO-400

   
   
   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

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