[SimmoW (SIMON)]

Hi, last night I got cocky and tried imaging with my 200mm Canon lens and camera, mounted on the NEQ-6.

I'd read some handy tips about polar aligning with a mobile phone, so used a compass app to help me align the tripod to true south. The mount causes a bit of interference with the compass, so I just stood directly behind the rear tripod leg and aimed the tripod carefully in alignment to where the compass was pointing. Far more accurate than I'd previously done with a 50mm lens and getting 1 min okay subs.

I aligned the altitude using another phone app, firstly levelling the tripod (on grass, i know that's bad but that's all I got right now), then using the phone to fine tune the azimuth. Freaking phone has a curved back, so it's pretty hard to get dead right, I know.

I even managed to do a 3 star alignment, and the mount slewed to objects very well.

BUT with the 200mm lens, any exposures over 15 secs revealed quite large star trails. With 30 secs it was ridiculous and the object was visibly moving in each subsequent image.

What's going on? Am I asking too much of the mount with the 200mm lens? Is the camera too light, are there speed settings I might need to adjust? Do I really need to be within 1 second angle accuracy? Not sure what to do from now, other than keep working on drift alignment/further tweaking of alignment accuracy.

I need to take the scope inside every night, so I'm afraid I can't have a permanent setup. I did set up a compass guide, crude! Just lined up a pot to the point of the house pointing south, so I can line the tripod up within reasonable limits. The Azimuth alignment, I figure, should be permanent, using those adjusting knobs.

Any help appreciated.

Simon