How to best focus on the Moon? - Forums

Topic starter

Jan 8, 2023

I have never managed to get a really satisfying focus when taking images of the moon, as seiing disturbs the focus.

Obviously most tools that help to focus on stars don't help on a moon surface like Bathinov masks, or autofocus routines from Nina or AisAir, including contrast driven routines like the NINA beta version or sharpcap.

Of course I tried to focus on stars and then just use that on the moon, which makes sense from theory being both infinitely far away from an optics standpoint. But I always had the feeling that I could get more focus by focussing on the moon and that the edges needed a different focus point than the craters.

So, which best practices and recommendations on how to get the best focus set on the moon would you have?

Engaging

andrea tasselli

Frequent contributor

Jan 8, 2023

If you do fine-focus on the stars and then switch to the Moon the latter isn't going in perfect focus and vice-versa. There isn't a trick per-se but it is easier to get a sharp focus on the Moon's edge and then switch to a crater.

Arny

Topic starter

Jan 8, 2023

andrea tasselli:
If you do fine-focus on the stars and then switch to the Moon the latter isn't going in perfect focus and vice-versa. There isn't a trick per-se but it is easier to get a sharp focus on the Moon's edge and then switch to a crater.

thanks for confirming, that star ocus unequal moon focus :-)

is there any good software support to focus that you have used successfully?

andrea tasselli

Frequent contributor

Jan 8, 2023

No that I know of. Your eyes should be your guide.

Wouter D'hoye

Jan 8, 2023

The best way for me is to focus on subtle detail in crater walls. Like terasses, ridges etc. When they constantly pop in and out of focus due to seeing then you are in focus. The worse the seeing appears during focusing the closer you are.

One thing that make’s focusing considerably easier is an electronic focus motor. This will r’duce the shake you introduce when touching the focuser.

CS

Wouter

Concise

Michael Kohl

Jan 8, 2023

The focus should " popping ", as it was already written above. If that doesn't happen, the seeing is too bad for shooting anyway.
A 1/10 micro focuser is also helpful.

CS
Micha

Andy Wray

Jan 8, 2023 · Edited: Jan 8, 2023

The moon should be one of the easiest things to focus on ... I tend to do it manually. Also, it is so bright that you can use really short exposures on it (maybe 1/10th of a second through a narrowband filter or even 160th second with no filter at all). Here's a simple moon capture at 0.12 secs exposure.

Moon Feb 10th 2022

Well Written Helpful Concise

Arny

Topic starter

Jan 8, 2023

Andy Wray:
The moon should be one of the easiest things to focus on ... I tend to do it manually. Also, it is so bright that you can use really short exposures on it (maybe 1/10th of a second through a narrowband filter or even 160th second with no filter at all). Here's a simple moon capture at 0.12 secs exposure.

Moon Feb 10th 2022

that is good advice - never thought of that - ambarrassing :-)

BTW: great "snap shot" - how much of the cristal clear sharpness magic is driven by the Ha filter?

Arny

Topic starter

Jan 8, 2023

Wouter D'hoye:
The best way for me is to focus on subtle detail in crater walls. Like terasses, ridges etc. When they constantly pop in and out of focus due to seeing then you are in focus. The worse the seeing appears during focusing the closer you are.

One thing that make’s focusing considerably easier is an electronic focus motor. This will r’duce the shake you introduce when touching the focuser.

CS

Wouter

great idea - thank you!
Never thought of using the popping to my advantage

PS: I did get a motor focus to at eliminate the wobble of my hand touching the scope ...