Herb H

These were taken last week with the same setup (Svbony SV503, Canon EOS T6i) but on my Celestron AVX GoTo mount which is a bit beefier. Any questions will be welcome. Irvine is Bortle 6 so we have some major light pollution. I used an Optolong L-enh filter to cut down on the glare.

Svbony makes nice product (I have the SV503 ED 80) but you might want to check the collimation, it might have drifted a bit when it got nicely banged around a few times on mail delivery ... Here's how I did in the Celestron C70 (and my C90 as well) and it made a big difference in clarity :

I used a field flattener in mine, no point in not using one for astrophotography. It is the recommended 0.8x one by svbony. My setup is the SV503 80ED, Skywatcher Star Adventurer 2i or Celestron AVX mount, Canon EOS T6i (750D) camera ... Frames stacked with DSS, minimal image processing. Irvine Ca is around Bortle 6.

You lost me there ... What is "All's collimation aid" ?

Yes indeed, I checked again and the screws are push - pull, so you need to use all of them to adjust the mirror, slowly two at a time (the two neighboring ones). This time around I decided to remove that nice prism, so I would get a better un-distorted view through the scope. You can see now the alignment is pretty good. 🙂 It was not difficult at all, just a few minutes fiddling with the screws - two at a time.

I believe the collimation screws on the C70 follow the usual pattern, but I am not 100% sure. Three adjustment screws and 3 locking screws.

Thanks ! If you do the collimation on yours, let me know how it went ! It is very simple to check !

So the conclusion is ... If you have a little C70, do yourself a favor and peel that rubber off, take the rounded plastic back cover off, and check the collimation by looking through the prism. If things are not concentric, adjust with an M2 hex key by trial and error ... Voila you are done 🙂

(6) Normally such scopes can be fine tuned using an artificial star (a point source), by then examining the Airy pattern. I did it here as well as a check ... But to do this you need to put that rounded plastic back with the eyepiece back on, which then covers the adj. screws. Anyhow, now the Airy rings look pretty good, not perfect but nearly concentric ! (sorry no picture, they are faint and hard to photo). So, overall success with I'd say half an hour enjoyable work. I then went outside and pointed the C70 at a faraway building, and it looks pretty sharp. Very happy with what I achieved ! ( Note that I was quite skeptical at first, since I worried that would have to look a the Airy pattern to collimate. In the end it was not necessary). (7) Below you see a picture of my artificial star that I did NOT need for decent collimation. Only useful perhaps at the end, for a second check.

(3) Looking down the prism into the inside of the optical tube, revealed that the image there (of the primary and secondary mirrors) was far from concentric ! That in a sense was a good thing, as it immediately revealed that something was grossly misaligned (sorry no picture here). (4) I then proceeded to fiddle with the six adjustment screws. They are three pull and three push M2 screws it seems, their combined effect is to first move (align) the rear mirror, and then lock it securely into position. (5) I was pleasantly surprised that within a few minutes, just by looking nice and straight at that circular pattern inside the prism, I was able to get the whole picture nice and centered, and nicely concentric ! (note that in the pic below I have trouble getting focused with my phone).

Next : (2) the black rounded plastic back cover comes easily off with two M2 screws. After which you can see the true scope flat backplate, with a nice prism at the center, and six recessed adjustment screws (three pairs).

.... As a follow up to my previous post, I did finally find the time to take the C90 apart and attempt some collimation. Hopefully what I write below will be helpful to others ! Here are my thoughts : (1) It is actually very easy to peel that rubber covering off, and expose the back. It turns out it is only slightly glued on at the bottom, where there's a seam. I cut through the seam with a fresh blade, and then slid the cover off. You can then see the scope with the back plate exposed.

I bought one of these on Amazon a few months ago... Decent optical quality, image is kinda crisp at the lowest magnification. I later threaded a Canon EOS T6i camera on it (with the supplied 1.25" standard telescope eyepiece adapter, and a camera T-mount for Canon) and took some decent quality pictures, although the image appears to be sharper in the provided zoom eyepiece at lowest magnification. I tried using both a 36mm and a 20mm Celestron Ploessel eyepieces, and came to the conclusion that the (zoom) eyepiece that comes with the scope is just fine ! It is good quality and needs no improvement imo; nevertheless the scope is used best at the lower (25x) magnification where the image is definitely crisper. I also liked the supplied short tripod, it is simple, effective, stiff, light and sturdy. A larger tripod only adds to the wobble, this one for most applications is just right imo ! But, today I checked the collimation with an artificial star, mine is definitely out of collimation. With the artificial star the pattern as you focus in and out is far from concentric, in fact it's pretty bad, more like a distorted 8. Unfortunately the six collimation screws are hard to get to (have to peel off all that rubber in order to get to the back where the screws are located), plus that prism makes it harder. Overall a bit disappointed that the factory did not make a serious effort to collimate this thing properly. Mine is definitely not what it could have been. Incidentally, I also have a Celestron C90 Mak and that one is spot on in collimation ! Nice concentric rings.