If they are then its a case of adding one bit of equipment at a time (filter, then OAG) and repeating the test to see if the issue comes back again. Check focus and then take an exposure without any correctors, filters or OAG in place to see if the diffraction spikes are as they should be. Then re-do the collimation, and perform a star test (use a really bright star like Vega).
If this were me, I would remove all the correctors etc and go back to basics with collimation, having first checked the spider is centering the secondary in the OTA and that the spider vanes are at 90 degrees to each other and that they are flat and not twisted.
This to me could be that the secondary is off axis to the primary, secondary is rotated, which might cause interference with the light cone, or the spider is bent. Here we can see that the horizontal ones are angled in relation to the vertical ones. Normally when something gets in the path you either have additional spikes, or one set gets blurred, but they still remain at 90 degrees to each other. I've taken the OPs image, cropped and deasurated it, then inverted so it's easier to see. The one thing that is really confusing is the angle of the spikes. I'm no expert, but did spend a year trying to resolve an extra diffraction spike on my 200P a few years back. Only other thing that I can think of would be focuser tube protruding far inside ota and blocking some of the mirror.Ĭan you check how much is it sticking out inside tube when you are in focus? MPCC III should not stick on the other side of focuser tube like some longer coma correctors - like this one: You are using guide scope, so no OAG/ONAG - that is good, one less thing to worry about Is the camera square to to focuser: I did pay attention when fixing it in the focuser, but I only noticed these spikes after my imaging session so it could be possible that it shifted.ĭo you have a good coma corrector: to be honest I would not have a clue how the check that this is what I bought last september: Baader 2" Newtonian Coma Corrector MPCC Mark III - from f/3.5
#Cell phone diffraction spikes full
Is the camera square to to focuser? Do you have a good coma corrector?ĭid you try guiding the mount: the mount - EQ6R Pro - was tracking, but my guiding scope - ZWO ASI120MM - did not show any star in PHD2, as it was a 99% full moon, I thought this was the cause and as it were just "test-shots", I did not bother. The stars are distorted toward the right hand side. That may explain the unusual diffraction spikes. The stars are trailed bottom left to top right. Sorry, only got a 'phone ATM but will reply anyway in case you gave a clear night ahead. Or is it my collimation that is not ok I admit, I did not check it, as I collimated last week during the day and the whole setup has not been moved. One of the things I modified, I attached a cooling system to the DSLR, bringing it's weight from 480g to 1080g, could that be the problem I don't remember where, but I seem to have read somewhere that the Orion8 focuser could take up to 1300g. I'm using a Orion 8 Astrograph and a Canon 500D. I had all sorts of problems, like my ZWO ASI 120MM (mini) not being able to display any stars in PHD2, so I decided to go without guiding, and honestly, as my polar alignment was very good, I was happy with the results of my 1 minute shots.īut having taken a closer look at the subs, I noticed strange diffraction spikes of the bright stars (see attached example).
Despite the full moon and the humid weather I could not resist to take some exposures yesterday, merely to test a couple of things, not with the intention to get something decent.
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