Stu

Nobody mentioned scope wars, boring or otherwise, this was a perfectly good post comparing thoughts on scopes the writer had experience of. Please don’t take this down a negative route. In answer to the 150ED mixed review question, I recall there were some packaging issues which led to review scopes being out of collimation. That was all rectified, not sure if any changes were made to the scope, I think it was mostly better packaging.

It normally does. I prefer the views through my 128mm vs the 100mm, providing the seeing is up to it. The SM125 is very light for its aperture so does counter some of the mount/weight/portability arguments, though to be fair it wasn’t on the OPs list 😉

With Baader AstroSolar film as a full aperture filter, you don’t need to worry at all about anything melting inside. If it was doing that, your eyeball would be melting too! I would likely go with the refractor as the apertures are very close and the unobstructed scope will likely do a little better. Could be wrong to, so try both!

I would respectfully disagree with your first quote above and agree with the second. No imagination needed to see the benefits of the optics to my eye. Not saying the 120ED is bad, it’s not, it’s just I enjoy looking through the 100 more and didn’t see a huge difference between the two in terms of what I could see. I prefer the 100 on planets. In terms of mag, the shortest eyepieces I have at the Vixen 2.4 HR Planetary and a 2 to 4mm Nagler Zoom. These give x308 and x370 respectively. I rarely use them and when I do it is on double stars and the seeing has to be excellent to make it worthwhile. I can’t see it performing well much higher than that. I’ve used x300 on Mars with my Vixen FL102S and it gave good results, although was comprehensively out performed by my 8” f8 dob on the same night.

Very true! Centring of the secondary is also trickier than with a traditional tensioned four vane spider. I actually quite like three vanes as each diffraction spike is less pronounced than with four vanes so is a little less intrusive. Still easy to centre the secondary as they are tensioned vanes still and can be thin.

Yes, in decent conditions you should be able to spot the kind of mottled effect across the surface which is granulation. In the larger spots you will see the darker centres called the umbra surrounded by the lighter penumbral areas. The other main thing to look for are faculae. These are seen nearer the limb where is is a little darker and appear as a network of bright wiggly lines. If you have a UHC or OIII filter you can try this as it can help enhance visibility of granulation and faculae.

Pretty sure they will be custom made by their owners, although some specialist builders may do stuff like that, not sure.

Yes, that’s about the size of it. Minimal secondary size (whilst ensuring sufficient illumination of the eyepiece) and nice thin vanes. Some people even use very fine wires instead of vanes to keep the diffraction to a minimum.

I would like to try a spec like that John. The scope I used had three curved vanes, presumably summing to the 180 degrees required to cancel diffraction. ‘Your’ design has two complete 360 turns so whilst it likely has more overall diffraction, I think the cancellation probably works better so you got excellent results.

I don’t think anyone sells them as standard now. OO used to, and Portaballs aren’t made anymore as far as I know. Protostar offer upgrade curved vanes: https://www.fpi-protostar.com/crvmnts.htm

As said, changing the mirror won’t change the diffraction spikes, they are an artefact of the secondary support vanes. Curved vanes need to go through at least 180 degrees in order to cancel out the diffraction and then it doesn’t get rid of it, it just smears it around the target so reduces contrast a little rather than having it concentrated in the spikes. I’ve used a couple of scopes (including a 8” Portaball with a Zambuto premium mirror in it) with curved vanes and wasn’t totally convinced by the benefits. Plenty of info on the web about it, including some here: http://www.astrosurf.com/viladrich/astro/instrument/sensitivity/spider-diffraction.htm

I assumed it was these features Nick was talking about Steve, although I may have misunderstood. I’ve not seen these filaments separated from the umbra like that before.

Lovely sketches Nick, not seen anything like that before. Might have a trawl through my solar book and see if they are mentioned. BTW I miss Cotterless45 😉

Oh no, he mentioned the T word! 😱😱😬😬 For complete transparency I own an FC-100DC, have owned 3 120EDs but have never owned a 150ED. I have owned a Vixen 150ED f9 which likely have similar views. To me, this is not all about the views, a lot of it is about useability. Let’s be clear, the 150ED will give significantly better views than the other two (assuming it’s not been damaged in transit!). If I had an observatory with it permanently mounted then I would leap at the chance of owning one. If however you need to setup and break down each time then for me it would get very limited use, as it would need a chunky mount and tripod to keep it stable. The 120EDs I owned were all nice scopes but for some reason I just didn’t click with them. To me, they don’t have the purity of the view through the Tak, and didn’t have enough of an advantage in terms of the views of planets and the DSOs I could observe from my home near London to make it worthwhile. Others would see it differently and I totally get that. So, for me in current circumstances I’ll stick with the little 4” beginning with a T. Disregarding image quality, it is one of the lightest 4” scopes around and is airline portable so can be taken anyway you go. It gives excellent Lunar, planetary, double star and white light solar views, and gives a credible effort on DSOs. Mine is my most used scope as it sits on a ScopeTech Zero mount and carbon fibre tripod ready to put out even for the shortest of sessions. It helps that I have a nice 5” version aswell when I want a bit more resolution and light grasp. In summary, it’s horses for courses. Tak optics obey the same laws of physics that everyone has to play by so a 6” Skywatcher beats a 4” Tak, but it’s about so much more than that as you can see.

Can you buy it from him??

Says made in Japan, so from what John says it is likely the same as a Vixen 102M anyway. Do you not get good results from it?

Do you mean the lack of colour, lack of markings or both? When were you observing it? Mars can be totally underwhelming to observe, or absolutely incredible when at opposition and at a good altitude. Sometimes it has global dust storms which blank out any detail even when it is close.

It’s very true that being a planetary observer involves fleeting glimpses of excellent views amongst hours of mediocrity! I also agree that many, even most modern scopes above 4” are capable of showing very good planetary views, the most important aspects are more likely to be seeing, and planetary altitude. My best Martian views were definitely through my 8” f8, whilst Jupiter is probably with the 5” apo.

Nice report SwiMatt. Sigma Orionis is actually a quadruple with a faint fourth component, well worth trying to pick out.

Jeremy is a proper ‘stronomer, unlike the rest of us mob (with a few notable exceptions!!) 🤣🤣

Pretty poor show. eBay?

😩😩 did you know that when you bought it? Pretty bad if not.

Oh no! Really sorry to see this Paul. Didn’t know you were taking the objective apart, did it need cleaning between the elements?

Yes, plenty of discussion around them. The idea is to get them ahead of the focus point as far as possible without vignetting to reduce the concentration of heat. They are reflection based filters so the thickness of glass is less relevant ie they don’t heat up as much as absorption ones. Ultimately they are there to take the strain off the etalon and other blocking filters and the bandpass on these filters is actually tighter than on the ERFs so I don’t believe they offer less protection. As you say though, everyone is responsible for their own safety and should make sure they are happy with their setup. I know of a number of people who use these in this way so am personally happy they are safe. I will use one (if I can get hold of one!) in my 60mm and see if I can reach focus with it. Personally I wouldn’t go up to 150mm with one, but would be ok with one in a 100mm I think.

I think I’ll forgive him one small mistake out of three, given his wonderful images 👍