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<blockquote data-quote="Dawg Pics" data-source="post: 828911" data-attributes="member: 26505">Looks like some kind of lens distortion.&nbsp; It is worse on the edges, which is what you expect in a wide angle lens. The spikes also change direction around the perimeter, which is also what you expect to see.&nbsp;&nbsp; Looks like your copy produces some spiking further into the image.&nbsp; It took me a couple minutes to locate a pattern that kind of looks similar to what you are getting.&nbsp; I am wondering if you have a bad copy of that lens. <img class="smilie smilie--emoji" loading="lazy" alt="🤔" title="Thinking face&nbsp; &nbsp; :thinking:" src="https://cdn.jsdelivr.net/joypixels/assets/6.6/png/unicode/64/1f914.png" data-shortname=":thinking:" />.&nbsp; If you point the lens directly at a bright star, do you get those diffraction looking spikes in the middle of the lens?&nbsp; I think the exagerated pattern on those very bright stars are just from the star being stretched out (coma) from being on the outer edge of the FOV.&nbsp; That is my best guess on what is going on here anyway.&nbsp; I make no guarantees regarding my amateur opinion about optics. <img class="smilie smilie--emoji" loading="lazy" alt="😉" title="Winking face&nbsp; &nbsp; :wink:" src="https://cdn.jsdelivr.net/joypixels/assets/6.6/png/unicode/64/1f609.png" data-shortname=":wink:" />Image below from&nbsp;&nbsp; <a href="https://www.lonelyspeck.com/a-practical-guide-to-lens-aberrations-and-the-lonely-speck-aberration-test/" target="_blank">https://www.lonelyspeck.com/a-practical-guide-to-lens-aberrations-and-the-lonely-speck-aberration-test/</a>[ATTACH=full]415113[/ATTACH]</blockquote>

[QUOTE="Dawg Pics, post: 828911, member: 26505"] Looks like some kind of lens distortion. It is worse on the edges, which is what you expect in a wide angle lens. The spikes also change direction around the perimeter, which is also what you expect to see. Looks like your copy produces some spiking further into the image. It took me a couple minutes to locate a pattern that kind of looks similar to what you are getting. I am wondering if you have a bad copy of that lens. 🤔. If you point the lens directly at a bright star, do you get those diffraction looking spikes in the middle of the lens? I think the exagerated pattern on those very bright stars are just from the star being stretched out (coma) from being on the outer edge of the FOV. That is my best guess on what is going on here anyway. I make no guarantees regarding my amateur opinion about optics. 😉 Image below from [URL]https://www.lonelyspeck.com/a-practical-guide-to-lens-aberrations-and-the-lonely-speck-aberration-test/[/URL] [ATTACH type="full" alt="IMG_1208.jpeg"]415113[/ATTACH] [/QUOTE]

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