Thanks Barry.
Why the 30 second subs? Multiple reasons, first of all up here in hell, I mean the tropics, it gets hot and stays hot all night. According to the experiments I've done the single largest contributor to thermal noise when it's hot is time. 1 minute subs have twice the thermal noise at 30C of 30 second subs so why bother? Winter may change this for a short while during June/July.
The second reason is cloud. We get layers of cumulus at night that sweep over. Shorter subs means I can shoot in the cloud gaps. All of the above pics were taken in cloud gaps. Guiding would not have been possible due to constant loss of guide star.
Third reason, tracking error. While I can get 1 minute subs without guiding, the percentage loss of subs is greater. My two cats have been known to ruin a few subs too lol.
Fourth reason, the K-5 has an inbuilt interval timer. It only works up to 30 seconds. Yeah I know external ones can be bought. It's on the list.
Fifth reason, at F4 here in light pollution land, 30 seconds hits the noise floor anyway.
Sixth reason, it's just so easy! And I'm lazy lol. I have tracking gear and may drag it out during winter, if we ever get any.
Pretty well thought out excuses I think.
