Noise in Frame & Focus (Live View)

[jsguitar]

Using BYN.  In Frame & Focus, I only get noise.  Seems to be light related as I can see objects in the light.  Anyone else have this problem? Tried multiple camera settings.  Stars look focused through eye piece.

Equipment:  Nikon d7500 mounted on a Celestron SCT 8 AVX mount.  

[astroman133]

You should also reduce the Shutter value to say, 1 second, then see if adjusting the ISO has any effect.

You can easily test how to lighten and darken the LiveView images during the day with a lens on the camera, while sitting at the kitchen table. 

From looking at the manual for the D7500 I can see that it has a setting for "Exposure preview". This may need to be enabled to allow the shutter and ISO to adjust the LiveView image brightness.

[admin]

It's not a problem, that is what LV is. Keep in mind that LV is only a few milliseconds worth of data so there is very little light actually being capture at once.  

You have ISO set to 1600, it may be able to tame it down a bit with a lower ISO. Yours is on the high side of noisy though, that is a lot of noise in that sample you provided.

[astroman133]

First, since your post is about BYN, it should be in the BYN forum, not the General forum. The BYN forum is the place where Nikon owners go to search for solutions to issues and to ask for help.

Both the ISO and Shutter settings are used to adjust the brightness of the LiveView image, which is only a few milliseconds in duration. When the image's brightness is increased, noise also becomes more visible. Have you tried lowering the ISO and/or Shutter values? You should be able to darken the image to get to a point where you can see stars but the noise is not overpowering

You may also be way out of focus. When you remove the eyepiece and diagonal and install a camera, the length of the light path is changed, so you need to re-focus. With the small FOV of the SCT, and if you are using the internal focuser, it can be a challenge to get close enough to critical focus to even see a bright star. Your best bet may be to get close to focus on a distant terrestrial object during the day, using your camera with the same setup as you will use for nighttime imaging. It should be at least a mile away, or as far as you can get it. Then don't change the setup or focus while switching to nighttime imaging, until you have a bright star, like Vega, or the moon in the field-of-view.

[jsguitar]

admin, I have tried lower ISO.  400 for example. That amount of noise I provided is what I see no matter the ISO setting.  So all of the settings would be with the camera and not the software?

[jsguitar]

astroman133, Sorry for being in the wrong forum.  I have lowered both ISO and changed the shutter speed.  If I go to fast on the shutter the noise disappears but all I have is a black screen.  Makes sense on what you said about the focus changes from eye piece to camera.  Hard to focus telescope through live view when all I see is the noise.  The moon is out now so I'll try focusing on that in live view.  

[jsguitar]

Thanks.  I have reduced the shutter speed to 1 second and other settings.  It does start going away as I do that.  I still don't see any stars, even the bright ones, as it is just a dark screen at a certain shutter speed.  I have sat in my den in the dark with the lens on the camera and the camera hooked up to BYN trying different settings.  Should I get the same reaction with the lens as I would with the camera hooked to the telescope?

[astroman133]

Yes. If you pick an ISO, say 400, and start shortening the exposure, the LiveView image on the camera's LCD display should get noticeably darker.

What you report as a dark screen with no stars could be due to 1 of 2 things...The camera is so out of focus that the star's disk is larger than the field-of-view and the image appears uniform. The second could be due to the fact that even if you are in focus, there may not be any bright stars in the field.

To determine of you are close to focus, you can look through the camera's viewfinder, while the camera is mounted on the telescope. This will especially work with the moon.

To determine if you actually have bright stars in the FOV, just take a 4 second Snap picture at ISO 400.

[jsguitar]

Will do.  Thank you.

[admin]

maybe this will help.

 

[jsguitar]

Thank you admin.  I'll give a try.

[jsguitar]

astroman133, Just wanted to let you know that putting the shutter value at 1 second and then adjusting the ISO per you suggestion worked.  At shutter speed 1 sec and ISO of 1600 I was able to get live view.  Now that I can get LV I'll be able to adjust focusing using the  bahtinov mask and adjust ISO and shutter speed to allow more light, etc.  Thanks much for the help.

[astroman133]

You may still need to take Snap images on the Frame and Focus screen to see the spikes created by the mask. I would suggest using FWHM or HFD with LiveView to get close to critical focus and then add the mask to do any final adjustments with Snap images.

[jsguitar]

Thanks.  I will look into the FWHM or HFD with LiveView.  3 days of rain starting tonight though so it will be awhile.  Give me a chance to youtube this.

[gwzap]

On 8/30/2020 at 10:44 AM, astroman133 said:

Yes. If you pick an ISO, say 400, and start shortening the exposure, the LiveView image on the camera's LCD display should get noticeably darker.

What you report as a dark screen with no stars could be due to 1 of 2 things...The camera is so out of focus that the star's disk is larger than the field-of-view and the image appears uniform. The second could be due to the fact that even if you are in focus, there may not be any bright stars in the field.

To determine of you are close to focus, you can look through the camera's viewfinder, while the camera is mounted on the telescope. This will especially work with the moon.

To determine if you actually have bright stars in the FOV, just take a 4 second Snap picture at ISO 400.

Hello, I used my Nikon D7500 for the first time with BYNikon.  However, in live view, I could change the shutter and iso settings, but nothing changed the live view as it does for my Canon 600d with BYEOS.  I could see when I was focusing, but live view would not dim as I moved my ISO to 100, and shutter speed to 1/8000 and the sun was stayed just as bright.  I eventually gave up which was ok at that point as clouds moved in.  

[astroman133]

I believe that with a Nikon and BYN you need to pause LiveView change your ISO and/or shutter and then resume LiveView to see any brightness changes.

I found it difficult to use the sun as a focus target. It was easier to focus with a bright star before the sun rose.

Also, in the future, please create a new thread rather than ask an unrelated question at the end of an old thread. Thanks/.

[astroman133]

Also, I would not try to adjust focus while looking at the sun. Try a different target. Either a bright star, or the inside of your kitchen to see how brightness changes with changes to ISO and shutter duration.

[admin]

SdDev focus metric works pretty well focusing on a bright object like the moon. should/may work on the sun as well.