focus or something else

[Anthony1979]

Just wondering if this is a focus problem or is there some other issue

the spikes on the star

Vega.TIF

[CloudMagnet]

I take it you are using a reflector? Its normal for bight stars like Vega to have that effect. Looking at the other stars, the focus seems OK.

[Cornelius Varley]

4 minutes ago, Anthony1979 said:

Just wondering if this is a focus problem or is there some other issue

the spikes on the star

Vega.TIF 136.27 MB · 2 downloads

Can you upload the image as a jpeg or png ? The tiff file is 136mb in size and tiff files cannot be displayed.

[RT65CB-SWL]

As per @CloudMagnet says.

They are called 'diffraction spikes'. 

[Anthony1979]

sorry

[RT65CB-SWL]

Wow! ...that's better. 

[Anthony1979]

If you look closer at the spikes they are not lined up...  Are they not suppose to be single straight lines

[MarkAR]

The spikes being uneven leads me to believe its colimation or coma with a little focus. I think the stars are worst in the top left corner but they all seem to have an outward halo/trail.

[Anthony1979]

So it something not good then

[MarkAR]

What scope is it ?

Are you using a coma corrector or field flattener ? If yes then your back spacing to the camera sensor may be off, looks like you're too close.

Colimation can be dialled out by tweaking the mirror adjustment screws.

All relatively easy fixes.

 

[Anthony1979]

Im using skywatcher 150 p and a nikon D3500 with no coma corrector 

[MarkAR]

You might need to invest in one of these or similar.

https://www.firstlightoptics.com/coma-correctors/skywatcher-coma-corrector.html

Worth contacting FLO about suitability.

Grabbed this from Altair, your image is showing the stars look like the back space is too short.

[Anthony1979]

3 minutes ago, MarkAR said:

You might need to invest in one of these or similar.

https://www.firstlightoptics.com/coma-correctors/skywatcher-coma-corrector.html

Worth contacting FLO about suitability.

Grabbed this from Altair, your image is showing the stars look like the back space is too short.

I dont no what you mean by back space is to short sorry 

[MarkAR]

Meant to say back focus distance, that is the distance between your camera sensor and a coma corrector/ field flattener.

As you do not have a coma corrector it is irrelevant at the moment, it's just that your stars are looking similar to the camera too close screen grab.

Most optical adjustment attachments like field flatteners and coma correctors have a standard 55mm back focus, this allows for 10 or 11mm thickness of the camera adapter plus the 44 or 45mm distance from camera front flange to sensor.

[Anthony1979]

So how would i fix this problem 

[MarkAR]

 I would say start with collimating the mirror and get a coma corrector.

https://www.firstlightoptics.com/other-collimation-tools/premium-cheshire-collimating-eyepiece.html

Link before for coma corrector.

 

[Anthony1979]

The collimation looks fine though