My first EEVA - M51

[M40]

Here it is, my first effort at EEVA and the grin factor is still there. All I have done is lighten it a bit in ms photo's. 15 x 20 seconds using a lodestar x2, 85mm refractor and starlight live. I am going to have limited opportunities in the near future as we are building up for a move but there was no way I was going to miss at least one clear night. 

I am puzzled over one thing though, I expected the image to get clearer with the more pictures taken but that proved not to be the case as all that happened was the image got blockier, is that normal or is it user error?

[Mike JW]

I think the shot is very good when you consider the size of the scope. What do you mean by 'blockier'?. The tracking may be drifting and that could give you stars that are not round. I get around this by using shorter subs.

Mike

[M40]

Thanks Mike, by blockier I mean more pixelated. The picture just seemed to overwrite itself and get less definition. I guess it's down to playing with settings etc and more experience with the settings and what to expect. Overall though, exceptionally well pleased and looking forward to the next time 

[Martin Meredith]

Excellent result! Much better than my first effort...

The blockiness might be due the Lodestar's large pixels combining with a short focal length, resulting in undersampling. What was the FL of your refractor? I have a 77mm f6 refractor and sometimes see blockiness on nights where the seeing is good.

As for the blockiness appearing to increase with each new sub, it might be simply that the SNR improves and the blockiness becomes more evident?

Martin

[M40]

I think you have hit the nail right on the head there, I put the telescope and the lodestar info in the CCD suitability checker and straight away it flew over to the under sampling side of things. The telescope is a Stella Mira 85mm, f/6.6, 560mm focal length. I have future thoughts on getting a zwo asi385, that seems to work very well in the calculator but that's in the future. Now I understand what under sampling is at least I can work with it. Many thanks