Pitch Black Skies

Hi all, Another proud owner of a 130P-DS! Yes that is a swimming hat on the end of it 🤣, and yes we are getting torrential rain but you already know that isn't why it's there. I am delighted to be a part of this thread. I have read every single post from page 1-142 and learned am absolute ton and have seen some beautiful and talented astrophotography. A huge well done to Russe on starting a mammoth thread and an almost cult following. I'll be hoping to leave my mark too, contributing and learning from you guys. Clear Skies 👍

See this thread.

It's £679 on FLO but when I add it to the basket it drops to £565. If I was to buy it I would then be hit with hefty customs charges. Since Brexit it is just too expensive to buy anything from the UK. It's cheaper to have stuff shipped from the EU now.

That is a snapshot from the FLO website. Although the prices are lower, customs fees need to be also taken into account. In fact it is actually working out more expensive for me now to buy from FLO than it is from astroshop.eu or teleskop-express. A pity really, because I have always dealt with FLO.

Welcome to SGL!

I've just come across this on a website so actually all are right. It could take a bit of trial and error between 8-11mm. Anybody want to lend some spacers? 😆

I have this one already ordered from a few days ago. If it seems okay I will keep it, but if not I will order the ones you mentioned and definitely do a comparison. I suppose what works for one might not work for all though. Thank you again for sharing your knowledge and experience.

Right 🤣 So on the latest figures we have: 52.16mm On that old graph it was: 52.60mm You use: 53mm which I agree is very close to the above figures. But now Jamgood has thrown a spanner into the works with TS recommendation at 55mm 🤣 It would be interesting to see an image with same camera set at 53mm and then 55mm.

Yes! Exactly what I was trying to do. Where are you getting 0.16mm from? Thanks so much for sharing those pictures btw 👍

I'm having trouble with the graph hyperlink. This is what I was trying to insert. Page 55 Second last post.

Cool, where are you getting that from? Also, it doesn't marry up with the graph you shared before. Going by the above figures, F=650mm, working distance =52.16mm

Thanks, I've amended that hyperlink now. Are they easy to source? I'll have at look on FLO and Teleskop-express. Edit: I didn't receive any spacing or paperwork with mine, the Skywatcher Aplanatic from FLO. I found this and this. They should work yeah? @Jamgood Are you getting results with just this?

On an older post you attached a graph showing the working space for the GPU, which concluded to be 52.5mm for the fl of 650mm on the 130P-DS. Can you reference where you got that graph, and how did you get the spacing right with an aps-c sensor? The distance to my sensor (Canon 800D) is 44mm and if I use this recommended adapter, it bumps that working distance up to 55mm. Which going by the graph, 55mm would be required for a fl of 850mm.

There is an interesting thread that highlights removing the primary clips will only introduce more diffraction spikes from the primary mirror edge, and that the shadows from the primary mirror clips are in fact blocking some of those diffraction spikes.

A little systematic investigation of a topic nevers hurts 🙂 Yes, although I think Josh will agree the findings have been worth it. Clear skies

Thanks, it's great that you had an opportunity to try a variety of CC's with it. Makes it a lot easier for people like me to decide. The GPU/Aplanatic it is, and I think the pictures above have really sealed the deal.

Awesome, I can clearly see the primary mirror clips interference, not so much the Pacman affect though. There seems to be more nebulosity in the first, but I can also see vignetting. Is that down to total exposure time or post processing?

I see, so the secondary just about covers the sensor, and then if the primary is moved up it's resulting in less reflected light on a just about covered sensor. We need to make every photon count 🧐 Is that implying the GSO isn't as close a second as I thought you were saying? The reason I ask is, the 715mm or so doesn't seem to make a huge difference in the fov calculator.

Oops, got mixed up. Where I wrote 'GSO' I meant 'SW 0.9x'. Too late to edit now. You've lost me there. Indeed, still a great little scope FWIW.

Oh right, I get you now. So I would need to cut it a little bit with the GPU, and more with the GSO as the GSO decreases the fl thus protrudes the focuser tube a little deeper into the OTA. Would moving the primary up not be a better option with longer collimation screws? Will cutting the focuser tube have any negative affect if switching to visual, i.e, will it be long enough to reach back focus? I suppose the extension tube could be used to compensate for the reduced back focus maybe?

I believe the Sky-Watcher 0.9x Coma Corrector is supposedly modified for the P-DS range. But if I mount that CC in my 130P-DS, I am going to have to hacksaw the end of my focuser tube to achieve good results? 🤔 Surely that can't be right.. Increasing the fl isn't ideal either with the GSO CC, I would have gotten the 150P-DS in that case, with an increase in light gathering too. The shorter fl and lighter weight is what drew me to the 130. The GPU might be best choice it seems. It's stated to be optimised for F4 though. It's not so straight forward, glad there is forums like this to get some advice.

Thank you, Is the GPU the same as the Sky-Watcher f4 Aplanatic Coma Corrector?

Would the Baader have been a better choice? I'm trying to decide on a CC for my 130P-DS too. I use a Canon EOS 800D.

Just to remember guys, a very similar challenge took place last year. Actually I think it was in 2019, before the very first lockdown. It's absolutely mind-blowing what can be seen these days with an amateur telescope. Imagine the possibilities when the James Webb is finally launched!

Great picture! I've noticed 6 diffraction spikes in your stars. Have you upgraded the spider?