I've seen this or something very similar before in an old book on ATM. Whilst the diffraction spikes appear smaller or even appear gone the energy is simply spread out over a wider area impacting on contrast.
Whether a loss of contrast bothers you depends on what you're looking at as does the appearance or not of a bright spike. The only way to eliminate the diffraction caused by the spider vanes is to not have any whether they be straight, curved or otherwise masked and that's not possible with a standard Newtonian design.
The proof will be in the pudding so to say. I will be interested in the results of your experiments Bojan. Where did the design come from? Or how did you come up with the design?
I’ve seen that before. The way this works is by having curved edges, where the radius of the curve is the same as the semidiameter (ie radius) of the primary mirror. The result being light diffracted will contribute a circular diffraction pattern concentric with that of the mirror, and if done right, no spikes.
The basic principle is that a curved edge in the light path produces a circular diffraction pattern, which must reduce to a circle at the focus. Whereas a straight edge (conventional vanes) produces a straight spike.
The snag with that beastie however is the hideous obstruction incurred. By all means try it, though I suspect the end result will be worse, not better, than without it.
There is a better solution - a curved vane spider - which achieves same without the obstruction penalty.
Though I know you are well aware of the ultimate solution ...
I don't understand why people buy SCTs, having owned one. I think the C11 also has a big obstruction problem, among others. Now a refractor would not have those issues, but of course the cost factors become considerable, but that is the price of high resolution without spikes. The middle ground might be a small secondary Mak-Newt, better resolution and no spikes. It is a shame the market is neglecting Mak-Newts.
I have a 5" APO refractor. I like that telescope very much. For the money I paid for that telescope I could had bought a 12" RC telescope, then I get a f/8 or with reducer f/6.3 system. The field or image circle about 55 mm. Something you can not use today, maybe in future with medium format sensors. My 5" telescope too have a big image circle, maybe 55 mm, but only 910 mm focallength and a slow f/7.
If I buy a new telescope in future it will be either a 6" APO refractor or a 10" RC telescope. But I live in a city with high light pollution so I use my not so heavy Star Adventurer and camera lenses more, that equipment I easy can take with me out to darker places.
Small telescope without spikes or big telescope with spikes. I think Mak-Newt normally have a limited image circle and can get uggly reflections in the correction lens.
I'm not made of money and I always buy used equipment.
I used a six inch Meade for years where the secondary mirror sat on a glass disk and the had magical properties to correct the image.
I wonder say one stuck in a disk off glass and hang the seconary as with the meade...and if you do need a corrector plate where do you get that sort of glass..but I do wonder the effect on the image...I expect there are folk doing it if I look...theres always someone doing something like you think of doing☺
Alex
I did not think more about this but looking at posts all over about the idea ...someone said just add a long dew tube ... did he mean just get out there or does a dew tube reduce spikes?
Alex
If you did put in a glass disk of high quality and with a dew tube the internal reflection in the glass window would be reduced you could think.
There must be high quality glass so I wonder.
Alex
If you did put in a glass disk of high quality ... Alex
Alex you're quite right that would eliminate the spikes of course but a disk of plane parallel optical glass to quarter-wavelength wavefront error is not cheap in the size needed for a reflector. Strain, bubbles, ripples, curvature and wedge (non-parallelism) just to name a few defects in plate glass that just don’t work well in a scope.
I did see one 8" newtonian made this way once, in the mid 1980's - the owner asked me to look at it, unsure if it was a schmidt-newtonian or just a newtonian with flat disk (it was the latter, and the glass was uncoated). Optically the scope was OK and it looked like a DIY affair made by someone competent with a machine-shop, though I have no idea who made it.
Tried this weekend from Mt Pleasant visually on 10"Newt at Sirius B- it works, but it did not help to detect B-component... at the end, I glimpsed it but only when jetsteeam calmed down for couple of minutes around 22:00..