From left to right, exposure times are 60, 90, 120 secs. shot with Canon 400D(stock) with a 75-300 F/4.5 with a 2x tele-converter shooting at F/5.6. Tracked using a Celestron CG-5ASGT
![Image](http://xslegion.com/m42_grid.jpg)
It may be something on your sensor, or on the optics close to the sensor, or it may be something floating not far above you.AJ wrote:I am in Cincinnati(east side) and caught this sequence early morning Labor Day...
In support of Chris Pettersons analysis, the dark object itself is stationary during the exposures. The dark blob is in all three images of equal size, while the exposure times increase by a factor 1: 1.5: 2. If the object was moving with respect to the stars, the blob in the 120 s exposure should have been longer than in the 60 s exposure.AJ wrote: From left to right, exposure times are 60, 90, 120 secs. shot with Canon 400D(stock) with a 75-300 F/4.5 with a 2x tele-converter shooting at F/5.6. Tracked using a Celestron CG-5ASGT