Jump to content


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Newbie cannot see anything thru ASI ZWO 183MC

  • Please log in to reply
9 replies to this topic

#1 Risktk1r


    Lift Off

  • *****
  • topic starter
  • Posts: 4
  • Joined: 07 Jan 2022

Posted 08 August 2022 - 12:57 PM

At the risk of sounding stupid, I need to ask if there is a way to "see" what my ZWO camera sees in the daytime. I wanted to focus on a house or building so I can check the focus on the scope. I have a Svbony 503 70, Field flattener, back spacer, ZWO 183 on the end. Running off a Dell laptop. Have Sharpcap, ASI Suite, PHD, ASCOM etc. Also have a Svbony guide camera. My issue is I cannot see anything to enable me to use the focuser to get me in the neighborhood. I have opened Sharpcap, activated the cameras, but all I see is a white screen. I am a very inexperienced user of Sharpcap. I realize I might be doing this all wrong but I am a few months deep and I have made no progress at all. 

I am hoping some one here will take pity on me and point me in the right direction and give me a shove. Thanking all in advance for taking the time to read this. Regards, Mike

#2 vtornado


    Fly Me to the Moon

  • *****
  • Posts: 5,873
  • Joined: 22 Jan 2016
  • Loc: NE Illinois

Posted 08 August 2022 - 01:10 PM

I had the same problem on the moon a few nights ago.  Big white screen.

My problem was the default exposure and gain of sharp cap is way to bright.

Set gain to zero and reduce the exposure time.

#3 farmeraa


    Lift Off

  • -----
  • Posts: 10
  • Joined: 24 Nov 2021

Posted 08 August 2022 - 01:14 PM

There's a lot of folks with more experience than me on here, but as far as I'm concerned you're on the right track. A coarse focus in the daytime gave me a good starting point for a real focus at night.


With a similar setup, I downloaded ASI Studio from the ZWO website (sounds like you already have it), ran the first tool in there which is the video capture tool ASICap, connected it to my camera, set gain and exposure to auto, and was able to get a rough focus on a live view of the most distant treetops I could see from my backyard in the daytime. I'm sure you could use Sharpcap for this just as well.


Anyway once you've done that, you're close enough to focus for stars so that you can finish the job when it gets dark, using whatever software you plan to use going forward. With any medium-ish gain setting and an exposure time of a few seconds, you should at least see blobs for stars, and you can finish focusing easily from there.

  • scadvice likes this

#4 TelescopeGreg



  • -----
  • Posts: 4,562
  • Joined: 16 Jul 2018
  • Loc: Auburn, California, USA

Posted 08 August 2022 - 01:34 PM

Yeah, surprisingly hard to do.  I found it much easier to use the Moon as an initial imaging target, than trying to dim things down enough to use these super-sensitive cameras during the day.  Moon first, then slew to some bright stars and go from there.  Making a Bahtinov mask can help with that last step:  https://www.deepskyw...tinov-mask.html

#5 FrostByte



  • *****
  • Moderators
  • Posts: 2,785
  • Joined: 14 Sep 2018
  • Loc: Upper Peninsula of Michigan

Posted 08 August 2022 - 01:47 PM

I had the same problem when I upgraded my guidescope from a 30mm to 50mm - just a blank white screen regardless of settings. I ended up covering about half of the objective with a sheet of paper to cut down on the light coming in to the scope, which worked surprisingly well. Just try covering the objective with your hand while the camera is looping and see if you can get something to show on the screen.

#6 ColdyNitesNC



  • -----
  • Posts: 482
  • Joined: 24 Feb 2018
  • Loc: Nevada City, Ca

Posted 08 August 2022 - 02:01 PM

In SharpCap, lower your exposure setting all the way to zero and raise it gradually. Set a low gain setting.

#7 Flybob


    Explorer 1

  • -----
  • Posts: 81
  • Joined: 02 Jul 2021
  • Loc: Maryland

Posted 08 August 2022 - 02:02 PM

The gain and exposure time is way too high for daytime use.  You are doing the right thing, just at the wrong time.  Wait until almost dark then set the gain and exposure time very low.  You can use large steps to get to the transition from a white screen to a black screen, then slowly work to the middle. 

#8 scadvice



  • *****
  • Vendors
  • Posts: 2,717
  • Joined: 20 Feb 2018
  • Loc: Lodi, California

Posted 08 August 2022 - 02:29 PM

I agree with Farmeraa that using ASI Studio and selecting the first box which is called ASICap. Be sure your camera is on and plugged in the your PC first. Then it will show up under 'Camera' select it -> hit the circle icon to the right to connect it-> scroll down to 'Control ' and make sure the Exposure and  Gain  "auto" boxes are checked.  I don't use this app for imaging I use N.I.N.A. but this is quick and convenient for checking your system out like focus ect and setting up a OAG system as it is easy to switch back and forth between cameras to match their focuses.


If after this you still cannot get it to be seen or to focus you may not have your backfocus correct.


Posting a picture of your setup helps us to evaluate what's going on. Also knowing the Flatteners backfocus would help. 

Edited by scadvice, 08 August 2022 - 02:35 PM.

#9 Oort Cloud

Oort Cloud


  • -----
  • Posts: 2,912
  • Joined: 19 Nov 2020
  • Loc: New Jersey, USA

Posted 08 August 2022 - 03:59 PM

Gain 0, exposure in milliseconds for daytime testing. White means too much exposure, all pixels are saturated with light. Try .01s to start, it might still be white if your optics are fast. If it is, go even lower like .001s

Once the image is neither white nor black, then try to focus.

#10 taoslap


    Lift Off

  • -----
  • Posts: 18
  • Joined: 12 Jun 2022

Posted 08 August 2022 - 04:19 PM

There is an Auto Exposure check box in Sharpcap that does it for my asi224mc. Works great in daylight.

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Recent Topics

Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics