How many Frames for lunar pic?

[Astroblagger]

Hello i tried lunar imaging with a webcam for the first time using sharpcap the other night, i then ran the AVIs through registax, they are ok, but looking for afew tips, How many frames should i ideally be looking to get? i tried 200-300 is that enough? also what settings should i be using. I just had the settings on auto, but do you have to keep them the same as if putting them in a mosiac they will be different shades? Not sure how people get these very crisp close in images of craters? Any advice would be appreciated.

[brianb]

1. Never use auto for anything!

2. You need to get the focus right. I know it's not easy ... but your sample images suggest that focus is your major issue at present.

3. Number of frames - put this down to experience. The higher the gain the more frames you need to stack to keep noise reasonable. The worse the seeing the more frames you need to shoot to get an acceptable number of sharp frames ... for closeups I often shoot 2000 frame AVIs and stack 400 frames (20%) but in bad seeing I might shoot 3000 frames & stack only 15%. Smaller scale images with the gain turned down, 100 out of 400 is enough for my camera.

[Astroblagger]

Cheers for the advice brian, would a bahtinov mask do the job if i turned the scope to a bright star, focussed then back to the moon. Also what would be the best program to use for building a mosaic?

[brianb]

would a bahtinov mask do the job if i turned the scope to a bright star, focussed then back to the moon.

Probably, but I do without. The moon is very easy to focus on especially compared with Jupiter or Mars.

Also what would be the best program to use for building a mosaic?

I find Microsoft Composite Image Editor usually does a very good job, it's dead easy to use and you can't grumble ablout the price (£0.00p).

[TheThing]

The Microsoft program is often called ICE if you're Googling it.

As Brian says, focus is key. Also, which cam are you using? If you have the oppotunity try single shot's rather than AVIs. I think Craterlet lets you do this. For the moon, it's often all you need.

[Astroblagger]

Single shots with which camera? a dslr or the webcam?

[TheThing]

Either. I use a webcam as I have no DSLR.

[WayBig]

1. Never use auto for anything!

2. You need to get the focus right. I know it's not easy ... but your sample images suggest that focus is your major issue at present.

3. Number of frames - put this down to experience. The higher the gain the more frames you need to stack to keep noise reasonable. The worse the seeing the more frames you need to shoot to get an acceptable number of sharp frames ... for closeups I often shoot 2000 frame AVIs and stack 400 frames (20%) but in bad seeing I might shoot 3000 frames & stack only 15%. Smaller scale images with the gain turned down, 100 out of 400 is enough for my camera.

How do you decide which 15% to stack - do you review them all one by one and delete the ones that arent up to scratch?

[brianb]

How do you decide which 15% to stack

I don't, Avistack does ... just set the slider ...

[Astroblagger]

Out of interest what size eyepiece roughly would a webcam imager be equivilant too? For ease of focusing?

[brianb]

what size eyepiece roughly would a webcam imager be equivilant too? For ease of focusing?

The field of view of a "standard" webcam is about the same as an ordinary 6mm eyepiece (Plossl type, not extra wide field). In my experience a 6mm EP is not focusable sufficiently for visual work with an f/10 or slower scope but a webcam can be focused at up to about f/30 when the seeing is reasonable. The webcam reacts faster than the eye does at low light levels.