Shutter speeds for lunar stills imaging

astronebulee

Hi
I'd like to take some images if the moon with my Canon 600D dslr whilst connected to my asiair pro, what are the shitter speeds I woukd need to type into the exposure length on my asiair pro screen a rough range would be good as you obviously can't ripe in 1/250 or such.

w7ay

astronebulee what are the shitter speeds I woukd need to type into the exposure length

I assume you mean shutter speeds?

Recall that at Full Moon, the center of the Moon receives the same amount of light from the Sun as the noonday Earth does. So the old "1/ASA, f/16 rule," that we used before exposure meters became common in cameras, holds. Does not work during a lunar eclipse of course.

The only difference between full Moon and noonday Earth is the Albedo of the Moon vs Earth (which depends on whether you are on a beach vs a football field, anyway). They are within a factor of about 2 of one another (Moon's albedo is lower), so just give the Full Moon one extra f-stop compared to noonday Earth.

When it is Full moon, just start with the settings you would use when you take pictures down your street at Noon when it is sunny, and increase the exposure by one f-stop.

The best is to just look at the histogram and max ADU of a preview image and tune so there are no pixel saturates. If you use up the maximum of the histogram without it saturating, you can recover everything during post processing.

Chen

johnpd

Exposure would depend on the ISO and Focal Ratio settings. I found an image of a first quarter Moon using a Nikon D7500 camera. It was set at a shutter speed of 1/250, f/6.5, ISO 100 and it was a decent exposure. Probably ISO 100 would be best and then depending on your f/#, adjust the exposure accordingly.

JohnD

astronebulee

Thank you guys, I understand the shutter speeds needed but how to input them into my asiair pro as it died t let you select 1/??? Only 0.???? What is the equivalent for an asiair pro. So for example when I take my buss frames for deep sky I choose the fastest which is 1/4000 which ic 0.000032 on the asiair pro.

johnpd

I do not use a DSLR so I don't not know what the ASIAIR presents in the settings for them. Unfortunately ASIAIR documentation is rather sparse in this area and may others. If ASIAIR still uses the standard seconds, milliseconds, microseconds, then I can guess what they might be.
For 1/4000 DSLR setting, it would be .25ms. For a 1/250 setting it would be 4ms. You can calculate the rest.
Then there is the ISO setting. I guess that would be set in the camera although it could be related to Gain.

What does the ASIAIR show for Gain. Is there a slider or does it show actual DLSR ISO numbers?
If it just has a slider, what is the range of the slider? You could probably estimate what you would need to set it at depending on the ISO settings for your camera.

EDIT: I found a screen print of what the ASIAIR displays for ISO. It is on the "Main Camera Settings" screen and it does show the actual ISO settings in a drop down list. It replaces the Gain setting values. So those are the two things to set: ISO on the "Main Camera Settings" screen and then the appropriate milliseconds or seconds value for the exposure.

JohnD

astronebulee

Thank you John, I think it's a trial and error thing for me to have a go at when imaging the Moon with my dslr. I know 1/4000 is 0.000032 so will work back wards from there for 1/250. I agree the documentation is very sparse. You correctly pointed out that the gain is replaced by the dslr iso setting.