The large and sparse open cluster in Ophiuchus called IC 4665, an object easy in binoculars. The star at centre is Celbalrai or Beta Ophiuchi. The 7.5 x 5° field is close to a binocular field of view. This is a stack of 9 x 4-minute exposures with the SharpStar 61mm apo refractor at f/4.5 and with the Canon R6 at ISO 800. Taken from home October 1, 2021 on a slightly hazy night with the field into the southwest.
Large and loose open cluster in Ophiuchus, IC 4665, in a wide-field image simulating the field of binoculars. Taken July 24, 2012, from home with the Canon 5D MkII at ISO 800 and Canon L-series 200mm lens at f/3.5 for a stack of 5 x 3 minute exposures.
IC 4665, the large and sparse open star cluster in Ophiuchus above the star Beta Ophuichi, aka Cebalrai. This cluster stands out well when scanning with binoculars, but is too large and sparse to be a good target for most telescopes. The telesphoto lens used here provides a field of view similar to binoculars. This is a stack of 6 x 2-minute exposures with the 200mm lens at f/2.8 and Canon 6D MkII at ISO 800.
