$spider veins create diffraction spikes$

$spider veins create diffraction spikes$

#Spider veins create diffraction spikes free#

Well I’m feeling that this may have beaten me. I’m guessing I loosen the top screw and tighten the bottom to pull the secondary down slightly ? So, how can I remedy this ? Sorry I’m a novice and this is all new to me. Looking at the vanes face on the two that are left and right on my pics seem slightly raised at the secondary holder and curved upwards a little bit, while the others are straighter. Looking at this again I think you could be right with your diagnoses. Thanks so much for taking the time to respond to this, I’ve been twisting and turning the spider vanes about the place for 2 days now without any success, these split diffraction spikes stubbornly remain the same ! (the horizontal spikes are slightly wider, and the vertical X starts to ever so slightly shift upward) The diffraction pattern it produces at focus:Īnd at a very sligth defocus (50 microns according to Maskulator, within the critical focus) The aperture: (Btw, the size of the obstruction shouldn't be a critical parameter here.) The vertical vanes are precisely vertical, while the 'horizontal' vanes connect the 3 (9) o'clock position of the aperture to the 3 (9) o'clock position of the obstruction. An aperture with an obstruction that is slightly shifted upwards and 4 spidervanes. Here's the simulation I mentioned before. I've already learnt a bit about collimation and star testing so I understand that bit thanks. This is brilliant, thank you ! Exactly the info I need to identify and then tackle the dodgy spider vane with some confidence.

$spider veins create diffraction spikes$

The defocused star should be symmetrical and look the same on inside and outside of focus. But check collimation of the secondary mirror afterwards anyway.Įasiest way to check collimation is to focus on a bright star, then rock focus in and out. If you tighten as before, this shouldn't throw collimation off. Then loosen the screw on the outside of the tube, twist the vane until the diffraction spike looks good, and tighten the screw again. At that point you can hold a finger near each vane at a time and identify them in the view.Įither of these methods should give you the position of the twisted vane. Eventually you will see the shadows of the vanes. Repeat with each vane until you find the culprit.įocus on a bright star (like Deneb in Cygnus), and gradually defocus. Wrap something around the suspected vane and image a star. Thanks in advance for any advice you can offer. Could a twisted spider vane be really difficult to spot and still cause this ? I’ve looked at the vanes and they look OK, if you squint and use a bit of imagination one of them might be just a tiny bit twisted looking, but I’m not really that confident tbh.

#Spider veins create diffraction spikes free#

If it is a wonky spider vane, is there a hassle free way to identify which vane and straighten it out ? I only ask because I made the mistake of fiddling with secondary mirror a while ago and it took me days to get things good again ! Having googled it and searched on here I am guessing the cause is most likely a twisted spider vane ? It is interesting that the split spike is prominent on one side of the stars only and also only appear to be on the left side of the image, just wondering if this means anything ?

$spider veins create diffraction spikes$

I’ve checked each frame and the split spikes are there, so it isn’t something to do with stacking. I was reasonably happy with this as a first attempt until I noticed split diffraction spikes on the brightest stars. I’m a newby just trying to learn about my telescope and imaging so apologies if this sounds daft.Īttached is my first ever image of Andromeda, it’s 9 frames stacked in DSS taken through a SW 130PDS.

$spider veins create diffraction spikes$