Focusing issue with filter

[Mohib]

I am using a Nikon Z6 with William Optics Z61 II and a Radian triad ultra quad band filter. I had a good imaging session with it one night. I focused on the moon and I found that the stars were pretty sharp.   However, during my second imaging session, my stars were a little bloated. Since, WO Z61 II comes with a Bahtinov mask I want to use it, but the problem is I can’t see any stars. Neither in live view nor in the live view mode of APT (which I think is the same). Can someone help me with tips on achieving a good focus with my current setup. Am I missing something? Should I first find a bright star, maybe Polaris, focus and then image my target? 

[Jamgood]

Point your scope at a really bright star before using the Bahtinov Mask. Fine tune and remove. 👍

[rickwayne]

That's what I usually resorted to. You can also use timed exposures rather than live view, it's a pain but if you're patient it can work. The spikes get fat and insensitive if you get too bright a star, but that sounds like a problem you wish you had at this point!

For timed exposures, bump the ISO up to something ridiculous (you can do this with LV too if you haven't already tried it. Don't worry, no one EVER forgets to dial the ISO back down. Or to remove the Bahtinov mask...

[Jm1973]

9 hours ago, rickwayne said:

That's what I usually resorted to. You can also use timed exposures rather than live view, it's a pain but if you're patient it can work. The spikes get fat and insensitive if you get too bright a star, but that sounds like a problem you wish you had at this point!

For timed exposures, bump the ISO up to something ridiculous (you can do this with LV too if you haven't already tried it. Don't worry, no one EVER forgets to dial the ISO back down. Or to remove the Bahtinov mask...

Like no-one ever forgets to switch back to RAW after plate-solving with JPEG. 🤣

[Mohib]

On 04/12/2020 at 00:02, rickwayne said:

That's what I usually resorted to. You can also use timed exposures rather than live view, it's a pain but if you're patient it can work. The spikes get fat and insensitive if you get too bright a star, but that sounds like a problem you wish you had at this point!

For timed exposures, bump the ISO up to something ridiculous (you can do this with LV too if you haven't already tried it. Don't worry, no one EVER forgets to dial the ISO back down. Or to remove the Bahtinov mask...

Thanks. I guess I’ll try to be patient. And maybe find a bright star. 

[davew]

As you've found, the filter is blocking off most of the light you need to focus in live view. What you can try and it MAY help with the Z cameras ( It does for nightscape use on a static tripod ) on the flip out screen is -

Assuming the camera is on and in manual then go to the right of the view finder where you'll find the DISP button.  Around that is the photo to video lever. Turn the video lever to video, turn up the ISO to Hi2.00, shutter speed to 1/25. With a camera lens you'd also set the FR wide open. If it helps go to the Menu and in the spanner section, turn up the monitor brightness.

Now you can just flip between photo and video and the photo settings aren't altered. This brightens up the live view but it still may not be good enough so then do what is suggested above.

Just something to try 😎

Dave.

Edited December 5, 2020 by davew