Advise on how to capture the Lunar occultation of Mars?

[Kon]

I think this topic might be relevant to others so it might be a better place than the usual advise section. It is a one off event for a while so i want to get it right, if I can.  With the Moon occultation of Mars, what is the best way to capture it at high resolution next to the limp of the moon? Using any camera will probably overexpose the moon. Do you record a movie of the event and set gain to Mars and then shoot the moon at less gain to make a composite, I don't like doing that, or do you get the gain relative to the moon and brighten up Mars later postprocessing? Or do you use the planetary camera to take stills and stack them? Or am I thinking it completely wrong? I assume with the 8" Dob, I am probably better off without the barlow?

Thanks for any help, Kostas

Edited December 6, 2022 by Kon

[Nik271]

I also don't like fiddling with composites, so planning to use my DSLR and 1500mm focal length Mak, this way the moon fills the height of the sensor and there will be room for Mars on the long side.

Blown up highlights cannot be recovered, so I'm going to expose for the Moon and hope Mars can be brightened up. At 1500mm Mars will be quite small anyway. 

I'm going to shoot stills for better resolution and hope seeing is not too bad so I can pick a decent one. Stacking a video will mean some kind of composite since Moon Mars angular separation will change in the span of even a minute.

At least the weather forecast is promising!  

[Kon]

9 minutes ago, Nik271 said:

I also don't like fiddling with composites, so planning to use my DSLR and 1500mm focal length Mak, this way the moon fills the height of the sensor and there will be room for Mars on the long side.

Blown up highlights cannot be recovered, so I'm going to expose for the Moon and hope Mars can be brightened up. At 1500mm Mars will be quite small anyway. 

I'm going to shoot stills for better resolution and hope seeing is not too bad so I can pick a decent one. Stacking a video will mean some kind of composite since Moon Mars angular separation will change in the span of even a minute.

At least the weather forecast is promising!  

I am in two minds here. Likewise, I go for the DSLR but I quite fancy a more close up . As it is opposition tomorrow night, my plan is to test my planetary camera on the moon to not be over exposed and then capture a few frames of Mars and see if I can get something decent under the same settings. I agree that I will be limited on the frames I can stack, thus being in two minds 😬. At least the weather is looking good.

[Nik271]

I was just checking the surface brightness of Moon and Mars and it looks we are in luck: they are almost the same per unit area. It seems they both shine at  about 4-th magnitude per square arcsecond. So hopefully both will be exposed almost equally next to each other.

[Kon]

13 minutes ago, Nik271 said:

I was just checking the surface brightness of Moon and Mars and it looks we are in luck: they are almost the same per unit area. It seems they both shine at  about 4-th magnitude per square arcsecond. So hopefully both will be exposed almost equally next to each other.

Thanks Nik. Sounds that it may work. Where did you get these interesting information?

[Nik271]

FIrst I tried searching the internet but surface brightness of Mars was hard to find. Then I realised it's all simple maths: Moon has about 100 times the angular diameter of Mars this opposition. So it has 10000 larger angular area.  It is also 10 magnitudes brighter, -12 as opposed to -2 for Mars. 10 magnitudes is precisely 100 squared larger total brightness. Since the Moon angular area is also 100^2 times larger than Mars it follow that they should be more or less the same surface brightness😀

6 minutes ago, Kon said:

Thanks Nik. Sounds that it may work. Where did you get these interesting information?

 

[Kon]

2 minutes ago, Nik271 said:

FIrst I tried searching the internet but surface brightness of Mars was hard to find. Then I realised it's all simple maths: Moon has about 100 times the angular diameter of Mars this opposition. So it has 10000 larger angular area.  It is also 10 magnitudes brighter, -12 as opposed to -2 for Mars. 10 magnitudes is precisely 100 squared larger total brightness. Since the Moon angular area is also 100^2 times larger than Mars it follow that they should be more or less the same surface brightness😀

 

Thanks, it makes sense.