Here's a new image of Comet C/2012 S1 ISON, as seen on May 1, 2013 by Ernesto Guido and Nick Howes of the Remanzacco Observatory. They used the 2 meter La Palma Telescope. Their initial approximation of the tail length is around 28 arcseconds, which Howes told Universe Today is bigger than some recent reports from smaller scopes.
As of May 2, Comet ISON was approximately 3.885 AU from the Sun, which is about 581 million kilometers (361 million miles) distant from the Sun. ISON will makes its close approach to the Sun when it passes within 1.2 million km (730,000 miles) of the Sun on November 28, 2013.
Explore further: Comet ISON shaping up to be a spectacular display