Sub length limits

[Alien 13]

As you might guess its cloudy again and i was thinking about sub lengths, up to now i have not lost many subs because of poor tracking but have had many discarded for other reasons listed below.

Satellites in the FOV.

Clouds.

Meteors.

Aircraft.

Security lights.

Dew.

Pet hairs moving about on the sensor.

I can manage subs of about 2 mins max but tend to stick to the 30 sec to 90 second range so the question is how can people get 10 mins or so without something creeping into the sub?

Alan

[oldpink]

wind, cloud, streetlamps and LP tend to be my nemesis of taking long exposures
I guess it comes down to good conditions and accurate tracking / guiding

[Ags]

Long focal length narrows the FOV, reducing thge effect of the first four items on your list :-)

[ollypenrice]

Don't discard subs with satellites, meteors or aircraft. Take enough subs, use a good (I stress good) sigma reject routine, and they will all vanish. I find the routine in AstroArt 5 to be remarkably efficient for this.

Worst case scenario; an aircraft trail won't go away. Make one stack with the trail sub and another without it. Stretch them both in just the same way in Photoshop and paste the trail image on top of the no trail image. Run the eraser along the trail on the top layer to remove it. Flatten and continue streching the image.

More generally, always think about how to use most of the data you have. Don't throw out the baby with the bathwater.

Olly

[oldpink]

I tend to vet my shots then remove any obvious duds (shake / cloud) and stack the rest

[Alien 13]

As allways you peeps have come up trumps again on average i have been deleting around a quarter of my subs because of non tracking related issues its good to know there is another way i did figure that a longer FL would have less chance of a sattelite etc hitting the FOV but im stuck with wide field at the moment 330mm for the scope and less for the camera lenses.

Alan

[Andy Milner]

Oldpink: Do you use the ASI120MC you have as a guiding cam? Wondering if it will add too much weight added to the 9x50 finder if its possible to attach. Also keeping with the topic, wondering what subs will be like.

[oldpink]

that is my next project, I plan to buy the adapter to fit the ASI to my finder to keep weight to a min

[jambouk]

Re adaptors for asi zwo to 9x50 finder scope - Bernard at modern astronomy sells them; i've got one but not used it yet.

Jd

Sent from my iPhone using Tapatalk

[oldpink]

yeah thats the one I'm buying
but I'm afraid to purchase any more gear, I have enough cloud right now without inviting any more