Clarkey

Yes, agreed. However, there are fungal spores everywhere so surface removal is a bit of a thankless task. With regards to the UV, yes, fluorite glass does allow some transmission into the UV shorter wavelengths. I believe the Esprit uses BK7 glass as the non-ED elements. This has very poor transmission below 300nm. Yes, it does depend on thickness - thicker glass moves the wavelengths, and the exact glass properties will vary. In general, for biological disinfection 254nm is the target wavelength to damage DNA / RNA. At this wavelength the transmission is near zero. Given that many fungal spores are very resistant to UV the benefit of a UV light will be negligible.

To save anyone some money who might be thinking of the UVC idea. I might be wrong, but to my knowledge UVC will not pass through glass. (This is why you do not get sunburn sitting in the car). Anything within a glass lens cell will not be affected. FWIW, if you manage to get the atmosphere dry enough using a desiccant, this will probably finish off most things that are likely to grow in the lens cell.

I'm now in a dilemma. Should I be happy that the weather across the rest of the UK is just as pants as it is here, so what I'm putting up with is not that bad. Or should I just be more depressed.😭 The trouble I have is once we get out of winter, there is not enough darkness for imaging. I will keep praying for a long cold spell in the spring. Now where did I put those golf clubs.....

Looking through the guidelog, I would agree with @900SL that changing the cable would be a good starting point. Initially the guide commands were working OK, but for some reason just stopped. This suggests a mechanical or electrical issue rather than software or drivers. Did you try slewing from the PC to see if the mount was responding from any other software? On a separate point, you might want to increase your guiding exposure slightly. At 1s you are likely to be 'chasing the seeing'. Probably 2 - 3 seconds would be better.

Yes you will be. The centre of the RA axis will be pointed at the pole regardless of the mount tilt. If the mount being perfectly level was critical, we would be taking levels to our mounts to get them perfect. The measured RA / DEC might be wrong (hence the goto issue), but the axis will be correct.

Which bit don't you agree with? It is correct that you only need to be approximately level. If you are correctly polar aligned, it should not matter. The only issue with not being level is a single star alignment will lead to inaccurate go-to's. 3 star alignment should remove the problem and give accurate goto's. Tracking should not be affected as you will be on the same rotational axis.

I'm not sure if I am imagining it, but this year seems to have been awful for clear skies - at least since the summer. In August I eventually got round to building my imaging observatory with two pillars and mounts. One for wide field and the other for smaller objects. However, since then I have not managed a single imaging session. I got half a night in about 3 weeks ago, but the seeing was so poor I literally binned the data. Also, I had a serious condensation problem on one of the scopes. I set up my gear this evening as the forecast was promising, but no sooner had I started a sequence it clouded over completely. So due to being this far north and the weather, I have not got a decent imaging session since early May. I think the most annoying part is that there are plenty of others regularly churning out images in other parts of the UK, often not that far away. My concern is that with global warming as it is, this may become the norm. Despite the observatory (and the £3k spent on it), I am seriously considering selling up and taking up golf. (Expensive, frustrating and achieves very little - sound familiar?) At least with golf you can play when it is cloudy. What makes things even worse is the forecast here is regularly a total work of fiction. Often the forecast is for completely clear skies and it is overcast and raining. Perhaps worse is the opposite. Lousy forecast and wake up to clear skies and a frost. Ok. Rant over. Didn't make me feel any better either.

Mine does sometimes and in the same place - obviously a sensor issue. It is OK with dithering and bias though.

I think you could at least double that figure for here. I have managed one imaging session since the end of the summer and the seeing was so bad I binned (literally) all the data. I estimate I get about 2-3 days per month that are useable for imaging, plus a few more that might be OK for visual. I am beginning to feel the observatory was not a good investment of time and money........ By the time I had finished, my PC would be out of date and FITS files would be a thing of the past. 🤣

I don't think you will be disappointed. I was debating the Esprit 100 when the SM90 came out and I got it at the initial reduced price of £1300 so it was a bit of a no brainer to me. My only worry with the Esprit is there are quite a few stories relating to pinched optics in cold weather. There is obviously an issue with the lens cell which can be a problem. I'm not sure how common the problem is though.

The focuser on mine is very good. Most of my other imaging scopes I have changed for Baader Steeltrack but not this one. Nice and smooth R&P with a good rotator and virtually zero backlash. The imaging circle for the SM90 is quoted as being up to APS-C, so ok with an IMX571. I have not tried mine with it - it is set up with the mono kit, but I have no reason to doubt it would be OK. I have had quite a few scopes and this was certainly the best out of the box. I have not needed to modify or adjust anything. Honestly cannot fault it.

Not a real one I'm afraid. Just another incomer. I have been in Penrith for 20 years, but I don't think you are Cumbrian for at least 3 generations😂

I use the 1600mm pro with unmounted 31mm filters - so marginally bigger but probably only a mm or two. According to 'Astronomy Tools' the minimum filter size would be around 26mm. So in theory 1.25 inch should be Ok. If you were interested I'm sure you could ask the question on SGL, there are a few with the SM90. Or check with FLO.

Not to mention all the other kit required for a dual rig.... I speak from experience!

I can recommend Stella Mira 90mm triplet. Slightly wider FOV but good quality and excellent for imaging. A significant step up over the ED80. Alternatively, as you already have a good mount, you could keep the ED80 and get something with a slightly longer FL for galaxies etc? Maybe a 100 - 115mm triplet?

It did originally but it jammed the roof opening so I modified it. I had planned the design but for a number of reasons I had to make a number of modifications, this being one of them. Hindsight is a wonderful thing. Good point. I had to do a modification to a pier extension which is all held by the central bolt. So yes, it might have moved.

Due to my own idiocy, I managed to jam my HEQ5 against the door of my recently finished observatory. Seeing my guiding going to pot, I went and unjammed it after a few minutes, but the tracking now seems worse that it was previously. What I am wondering is, what have I damaged? Normally when adjusting the backlash, the motor whines, but in this case the mount was clicking. This makes me thing the gears were 'jumping'. If this is the case, I suspect I am likely to need a new worm and gear wheel in one or both axis. I was wondering two things; Firstly, has anyone done anything similar and what damage was done? Secondly, if I do need new gear wheels, where is the best place to source them? On another point - if you ever build an observatory make sure it has spring loaded doors.☹️

I would re-iterate what @Phillyo is saying about second hand. Most astro kit advertised is well looked after and you will get much more for your money. For the mount in particular I would suggest something better than the EQM-35 such as the HEQ5. The mount is by far the most important part of the set up and if you get a poor one, you will struggle from day one. Also, if you buy second hand you will lose very little if you re-sell later.

I'll add this image as it is the first image I have managed since the beginning of the summer. Unfortunately, I built myself an imaging observatory in September - so it has been cloudy ever since. Apologies to anyone in the North West UK..... This is a cluster of star clusters. This includes M103, the Fuzzy Butterfly Cluster (NGC654), the Lawnmower Cluster (NGC663), the Yin-Yang Cluster (NGC659) and IC166. Taken with a StellaMira 90mm Triplet with the 0.8 flattener reducer in LRGB using a 1600MM PRO. Processing was kept to a minimum with gradient removal, a slight stretch, levels adjustment and a bit of additional vibrance. All done in APP and Affinity.

I have a pretty basic laptop Lenovo S340 (pentium gold), and I have used it for deep-sky and planetary imaging without issue - including a dual rig. As long as it has a suitably sized SSD and USB 3 ports it should be fine. It does not need a lot of processor power. I expanded the RAM but as long as you have 8Gb or more it should be fine. If you want to use it for image processing, then obviously that is a different matter entirely. My current rigs use the Mele Quieter 2 mini PC's, which use Celeron processors. I have not tried then for planetary imaging, but I suspect they would be OK as they have extra SSD storage.

My method is relatively simple and works for me. I have a Reego collimator which I use to collimate the secondary mirror. (You can use a collimation cap or Cheshire but the LED in the Reego does make it a bit easier. However - do not buy the Reego for the RC8 as they are ridiculously expensive for what they are). I then get the primary correct using a star test. If you want to check the distance for the correct FL you can use a Ronchi grating, but I have never felt the need. It is loosely based on this method: A Procedure for Collimating Ritchey-Chrétien and Other Cassegrain Telescopes (deepskyinstruments.com) I can get away with the simple secondary collimation as there is no evidence of tilt in the mirror / focuser interface. If you have tilt here, it is more difficult. In this case you could use the method David suggests - he kindly sent me a copy too. It is certainly a thorough method, but I would not be dismantling my scope without the need to.

Welcome to SGL. If you are looking to get into imaging, you don't want to be going any lighter than the AVX in my opinion. Probably a pretty good match with the ED80. By the time you have added the camera and other kit you will be close to 2/3 of the quoted capacity which is a good rule of thumb. Looking at the selection you have, it is a pretty good range for FL and types - although with the others the Astromaster is probably a bit redundant. But as you say, there is little resale value.

Don't sweat it. It's not as hard as it is hyped up to be.

Normally yes. I have the Stella Mira version with the 48 and 42mm reducers and the measurement is from the back of that.

The spacing is normally from the back of the flattener excluding the actual thread - so you will need about 37.5mm of spacers.