Is a Bahtinov masks good for planetary imaging?

[WilliamAstro]

So I used a bahtinov mask for imaging Jupiter and Mars and from this forum post on Cloudy Nights someone said basically that bahtinov masks aren't good enough for that as they are for low resolution imaging, I was advised to tweak the focus from time to time and observe any changes in detail until I get the best result. I used a bahtinov mask and Sharpcap to calculate the symmetry of lines from the star. I was told from my Jupiter image taken with my 5 inch Mak that it is significantly over-sharpened.

Any thoughts and opinions?

I'm not giving the person any slander from what they said it's just that I need more research on what they're talking about.

Cheers

William

 

[newbie alert]

I've too read that you need to use the moon's as the thing to focus on.. I'm not that convinced that chasing the air turbulence is the thing to do either...

I have used a mask to focus on a near to Jupiter and that worked out well so I'd use what's best for you and come to your own conclusions

At the end of the day it's your image, so you sharpen as you wish to your eye... Ive seen plenty of oversharpened Jupiter's, I'd say yours is quite nice to my eye, nice job

[ONIKKINEN]

I dont trust bahtinov masks, even for DSO imaging. My star sizes decreased noticeably after switching to statistics (HFR) and visual based focusing. I think just visually looking at a dim star is better than a bahtinov mask for focus! But some folks like them, so user error and differences in the masks could play a part too.

I am no planetary imaging veteran and only dipped my toes a couple of times to attempting Jupiter imaging with a DSLR (in raw video mode). Focusing was a real pain in the backside with having to look at the small screen on my 550D, but i found that visually focusing on the Galilean moons and a shadow transit of Ganymede was what were the easiest. The shadow of Ganymede disappeared if out of focus slightly and appeared as a sharp and quite obvious dark disk on Jupiter when in good focus.

[Clarkey]

6 minutes ago, ONIKKINEN said:

I dont trust bahtinov masks, even for DSO imaging. My star sizes decreased noticeably after switching to statistics (HFR) and visual based focusing.

I am happy to use a bahtinov mask if necessary, but statistical measurement is easier as I am always connected to a screen. I generally get the same result either way.

[neil phillips]

8 hours ago, WilliamAstro said:

So I used a bahtinov mask for imaging Jupiter and Mars and from this forum post on Cloudy Nights someone said basically that bahtinov masks aren't good enough for that as they are for low resolution imaging, I was advised to tweak the focus from time to time and observe any changes in detail until I get the best result. I used a bahtinov mask and Sharpcap to calculate the symmetry of lines from the star. I was told from my Jupiter image taken with my 5 inch Mak that it is significantly over-sharpened.

Any thoughts and opinions?

I'm not giving the person any slander from what they said it's just that I need more research on what they're talking about.

Cheers

William

 

I wouldn't trust them either. At very high resolutions under good seeing. I Sit there moving the focuser tiny amounts. And it can make a huge difference between slightly soft and razor sharp. I doubt a mask could be that accurate. Eyes and a small movement of the focuser looking at the edge of the planet, and the fine detail coming through. Shows you when your focusing is getting tighter. So for rough focusing i am sure they are great. But micro focusing on fine planetary detail. Not for me.

Btw ive seen far worse over sharpened images. Doesn't look too bad to me. your real problem is going to be the small scope size unfortunately. But we all start somewhere. If you really find you want more, in time its off to the for sales section. 5 inch maks are great though. And your image is good too.  I use even 70mm cheap refractors to good use. So its not all about light buckets. But ultimately it is still the limiting factor. My legs and back know this the last few days

[CraigT82]

That’s a great image for the scope size, nice work. 
I don’t use a bhat or any kind of aid for focusing. Just do it by eye and looking at the screen whilst going back and forth through the focus point. It’s difficult when seeing is poor as the planetary detail you’re looking for on the screen is hard to see. When seeing is good it’s much easier. 

[Elp]

I find it's better to have the planet over exposed so it's a bright dot, focus until it's sharp then reduce the exposure time to see the surface detail then make a few fine adjustments.