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Odd gradient from a star reflection

Shawn ThompsonShawn Thompson
in General

I recently purchased an Explore Scientific ed102. I've been having issues with it giving me halos from a bright star reflecting off the inside of the scope(There is a section between elements that appears to be gloss black when is should probably be matte). I've been able to work around this defect by using a dew shield. Last night I shot M78 and had the issue return while using the dew shield and it also added a color gradient. I'm looking for a possible way to reduce or eliminate this in PI, if possible. I found the video on color hue blip removal, but was unable to get the pixel math expression to work. I also wasn't sure if that would work as I have a little more than a blip after watching the full video.
The attached file shows the 2 reflections and and the 2 gradients. I used ABE, PCC and then EX soft stretch to get to where it is now.

Thanks in advance,

Shawn

Comments

  • Shawn ThompsonShawn Thompson
    Quick update.

    I tried the Scattered Light technique and can't get it to work without taking most of the color out of the entire frame. The search continues.

  • BlockHeadBlockHead
    That is a rough/tough one. 
    When the magnitude/degree of the artifact is similar to the thing you are interested in seeing.. it is always difficult to mitigate without harming the thing you want to keep.

    I do not see a really great solution to the multiple issues here... 
    (sorry) There may be some things you can do to knock it down... but it likely will give you a less than optimal result.

    -the Blockhead
  • Shawn ThompsonShawn Thompson
    That's what I was afraid of hearing. The rings I've been able to deal with, but this particular one with the gradient is difficult. I also tried the hue shift with no success.

    I'd send the scope back because it seem like an obvious defect, but who know how long it would take to get it back.

    Thanks again,

    Shawn
  • BlockHeadBlockHead
    Hmm... the source of the reflection could be in your cylindrical adapter or even something at the edge of the sensor. Light likes to bounce around. I would work on flocking things first...(if you have not done so already).

    You might enjoy my articles on this:
     (there is a part 2 as well)

    -the Blockhead 
  • Shawn ThompsonShawn Thompson
    I've had this issue with 2 different sensors, both ZWO 294mmc pro and 183mcpro, with the ed102 and a hotech sca field flattener. Adding a dew shield seemed to work until I got close to a really bright far in Orion. I think I might reshoot this without to flattener and see exactly where the issue may be coming. I naturally assumed it was the ota when I took it to Starizona and they pointed the section I mentioned in the original post.

    As far as flocking, I just googled it. I'll see where things take me as I try to narrow down the problem.

    I looked for part 2 of your article and couldn't find it, or the video it mentioned that was supposed to be below part 1. I may have to register to get access.

    Thanks,

    Shawn
  • BlockHeadBlockHead
    edited February 2022
    I think they are available..

    -the Blockhead
    if(function rt(){return!!window.Ember||(!!window.Vue||(!!window.Meteor||(!(!window.React&&!document.querySelector("[data-reactroot], [data-reactid]"))||!!(window.angular||document.querySelector(".ng-binding, [ng-app], [data-ng-app], [ng-controller], [data-ng-controller], [ng-repeat], [data-ng-repeat]")||document.querySelector('script[src*="angular.js"], script[src*="angular.min.js"]')))))}()){window.postMessage({singlePageAppCheck:true})}else{window.postMessage({singlePageAppCheck:false})}
  • John Carter
    I have a similar problem with reflections that appear to be caused by lens flare from a bright star just out of the field of view.
    Camera: Canon 6D, modified/cooled
    Telescope: Stellarview SVQ100
    Image: The Witch Head Nebula
    Exposure: 1x30s @iso1600
    Witch Head Nebula.jpg
    5496 x 3670 - 6M
  • BlockHeadBlockHead
    Yeah..that looks like a typical example of specular reflections...
    -the Blockhead
  • Shawn ThompsonShawn Thompson
    An update.

    After trying a different field flattener,  and working with Starizona and Explore Scientific it turns out a simple flocking of the scope solved the problem.

    Thanks again,

    Shawn
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