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Hi Ray
Part of the problem is that the image is from my handheld phone so it doesn’t grab the whole picture. Getting it all aligned was a bit tricky. Yes straightness of lines is what you are looking for. I’ve also been advised to look for any ‘clocking’ of the image as you move from outside to inside of focus or vice verse. If the orientation of the lines change at all that probably indicates astigmatism.
The different parts of the image are the secondary which had a reflection of the ronchi grating and light source. You can also see the spider gains. I think it would be more centered if I used a beamsplitter. My impression is that the light source and grating need to be extremely close. This is the first time I’ve used this test so I’m learning too. However I’ve had very experienced people confirm the test shows a finished mirror.
Rod
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