# Are Poor seeing conditions why this is happening? Is there anything I can do?

Started May 15, 2020 | Discussions thread
Re: Are Poor seeing conditions why this is happening? Is there anything I can do?

Trollmannx wrote:

Sounds like a pretty good night here!

The camera has 4.6 micron pixels.

With your telescope you are imaging at 0.6 arc sec per pixel. That is pretty demanding.

You already know it - but the general rule is to image at 1 - 2 arc sec per pixel. Most locations usually have 2 - 3 arc sec seeing (blurring during a time exposure). Mine is usually a bit worse than this - so your experience seems pretty spot on.

At my location stars are at times blurred by turbulence when using a measly 135 mm lens, and I have never realized the resolution limit of my 530 mm focal lenght astrograph. Always blurred stars here - atmospheric turbulence is the limiting factor (unless using ordinary lenses from wide to short telephoto).

Guess you will be imaging in the less demanding 400 - 800 mm focal lenght range when doing real work.

Hey Trollmannx

I'm currently googling the forumla to calculate image arc sec per pixel as I should learn how you calculated that.

I actually wasn't aware of that 1-2 rule, so I'm glad you mentioned it! I am deeply lacking of some of mathematic knowledge required to succeed in AP, though I'm just trying to learn everything as I encounter it. I'm currently learning about image to noise ratio and I learnt about arc secs/mins from a book a couple of years back which I should definitely re-read. So most areas have 2-3 arc seeing, meaning the that blur distortion spans across approximately 2-3 arc secs?

When you say "when using a measly 135mm lens", does that mean that the effects can be mitigated with a different focal length? I will of course need to google this as well as I don't yet entirely understand the importance of focal length further than its relation to useful magnification. That is to say, I don't yet know how it ties in with distortion from seeing conditions.

Thank you

Damian

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