Ricochet

There is a second hand one showing as active on ABS: https://www.astrobuysell.com/uk/propview.php?view=149974 I use the Meade branded predecessor (same as the Bresser SA) to get my high power mono views from medium power eyepieces. That way there is only one "step" where you change from using the Telextender to not using it, whereas if you use it to try to gain intermediate powers between other eyepieces it will constantly be in and out of the focuser.

If these are for public use not your own then I think cheaper is better. If it has to be UWA then Nirvanas or whatever appears on the second hand market at a reasonable price. If you change your mind and want something better for your own use, perhaps push the boat out a bit and look at the Baader Morpheus range.

5-7mm is the range you need for Jupiter and Saturn with an 8" dob in my experience. Conditions will determine how much magnification you can use at each observing session. The moon appears to be approximately 0.5° in diameter and your telescope has a focal length of 1200mm so to get the minimum eyepiece focal length you can use you can use Fl(eyepiece) = 0.5° * 1200mm / AFoV(°) So if you want to buy Starguiders with 60° AFoV Fl(e) = 600 / 60 = 10mm Of course it is good to have a bit of space around the moon so you want a slightly longer focal length, meaning the 12mm Starguider would be a good choice.

If you're looking to widen the FoV I think you've made a good choice. I look forward to your thoughts on the Nirvana. Hopefully you get some clear nights soon.

What issues are you seeing with the X-cel LX? I had one and thought it was pretty good, part of me thinks I should have kept it. At slow focal ratios I don't know if you'll see any improvement in correction from any eyepiece so it would be down to the quality of the coatings and I would guess that only the BGO might be any better optically.

It won't. All the lenses/focal plane are up in the top section of the plastic barrel. If you screw a crosshair into the nosepiece it is out of focus. You would have to figure out how to affix a crosshair further up. I've had a pair of the 23mms for a while now. From memory they are nice optically, better corrected than the 25mm Starguider at faster focal ratios, but in my BVs I use the Starguiders because they give me full disk lunar and the nosepieces register more consistently. If you were planning on making a really lightweight setup the 23mm would be a good choice of eyepiece.

You can approximate it as Apparent field of view / magnification so AFoV * FLe / FLt And FLt = Apperture * FR 62° * 26 / 800 ~ 2° Assuming there is no vignetting from the baffle tube or focal reducer.

Good idea. ES recalled a whole batch of eyepieces recently because a lens or element had been installed the wrong way around. Perhaps something similar has happened here.

68° is about the angle that you can concentrate on without moving your eye. In addition the 82° and 68° eyepieces are different focal lengths so the TFoV will be about the same.

It really depends on what your budget is and what sort of targets you want to observe. If it was me I would probably be looking at the 20mm APM/Lunt HDC as my widest field option and either the 10mm Pentax XW or 12.5mm Baader Morpheus as my general purpose DSO eyepiece, adding shorter variations of the chosen line in the future. These are expensive and fairly bulky eyepieces so you may wish to go with something cheaper or lighter, depending on your preferences.

Also glass that doesn't fog up by the time you move onto your second target of the night.

Does the telescope have a little plate/sticker on it giving details such as the aperture and focal length? The first thing you will want is a 1.25" 90° star diagonal. Given the scope you have I probably wouldn't spend too much on it. Secondly, you will probably want a 32mm Plossl to max out the field of view. To work out what other eyepieces you should consider we really need the specifications of the exact telescope you've bought.

If you have poor quality eyepieces then a 3x telextender will slow the light cone more than the 2x version and so you might get better performance from the eyepieces. However, with good eyepieces it is unlikely to make any difference. I would also echo the previous advice that a 2x will probably be of more use to you. You may find that your binoculars do not have enough focuser travel to accommodate using telextenders. I don't think I can focus my spotting scope, which is essentially half a binocular, with my 2x telextender.

A manual scope is fine for visual use, but unsuitable for any sort of photography that requires an object to be tracked. Pay attention to the advice @Stu has already given you. You need to choose whether you are buying a visual or photographic set up (and if you choose photographic, your budget will have to be four figures so start with the book "Making Every Photon Count").

I think a lot of us have learned to collimate reasonably well using online guides like the one linked above. My collimation equipment is as follows: The red FLO cheshire/sight tube for the secondary A 2x barlow and laser for the primary A short cheshire with the crosshairs removed for checking the primary after 2.

Magnification can be calculated by dividing the focal length of the telescope by the focal length of the eyepiece. The maximum magnification that you can use with a telescope is determined by the aperture of the telescope. Since both the f5 and f8 150p have the same aperture they can utilise the same magnification, you will just need different eyepieces to get there. What the f8 version will give you is a smaller secondary mirror, which means less diffraction and so slightly better (sharper) planetary performance. However, the 200p will probably have even better performance due to having a larger primary mirror.

For visual use of a Newtonian scope I prefer a dobsonian mount over an equatorial mount and so would choose the Skyliner 200p. If you do want a tripod mounted scope an f5 150p on an AZ4 mount will probably work better than a 150pl.

That looks like it is set up with only the 1.25" adaptor in place and so should be able to focus with an eyepiece. What happens when you point it at a star and move the focuser the entire length of travel? Do you see a doughnut of light getting smaller towards one end of focuser travel but never focusing or do you see nothing at all? If you don't see anything perhaps it is because the finder is not aligned and you are not pointing at any bright stars. Try in the daytime on the furthest terrestrial object you can see. As terrestrial objects are closer you will need the focuser position to be further out than at night but if you can get it to focus at least you can get the finder aligned before testing at night.

Take a photo of your focuser set up with any eyepiece etc that you are trying to use and post it here. Skywatcher scopes come with both 1.25" and 2" extension tubes in the focuser when you only use one at a time. Many new owners are caught out by this.

I used some spare flocking on the left half of some old safety glasses. It's a lot easier to take on and off than a patch and more comfortable. Perhaps a more expensive patch would perform better than the £1 eBay special though.

You're halving the brightness so it is like dividing your aperture by 1.4, so with your 200p it would be like using a 140mm scope. On planets it doesn't matter but on DSOs I've always thought a single eyepiece gives a better view.

How many telescopes were the authors of this old advice expecting their readers to be able to buy? These days lots of people own multiple scopes, but when scopes were relatively more expensive was it the norm that people would only own a single telescope? Perhaps we should split the question into two: What is the minimum aperture that a telescope has to be to for it to gain regular usage when you have larger options? What is the minimum aperture that you would choose if you could only own one telescope? I suspect that these answers would not be the same.

Is this on a new telescope or second hand? If it is new just send/take it back and get it replaced. In fact even second hand you could ask for your money back as the chance of it breaking the first time you use it is very slim (assuming this is what happened). If you really do have to fix it then look at it from the other end to the one shown in your photos. It looks to me like you've still got the 2" eyepiece clamp attached. If you've removed the grubscrew locking it to the thread then it will unscrew and this might free the "hex" section of the drawtube. Once you've got that off the plastic ring at the top of the focuser can also be removed. Also, have a look for any small screws on the inside of the drawtube. From memory I think there is an obvious small screw at the bottom of the drawtube that prevents it from being drawn too far up the focuser, so there is probably one at the top end too.

I think that a 15mm would probably be a reasonable choice.

If you live in a town light pollution will probably mean a 7mm exit pupil leaves you with a bright sky background and so a 5mm "limit" is more appropriate. If your scope has a 1.25" only focuser then a 32mm Plossl still makes sense as a finder eyepiece as it is the cheapest way of maximising the field of view the telescope can give. I see you've just taken the 18mm suggestion straight from the first post but I don't really like the focal lengths suggested for an f5 scope. To me there's an obvious gap which I guess is filled by barlowing the 25mm to get a 12.5mm. However, I don't like using barlows to get intermediate steps. Better to have the low/medium powers and then just use the barlow to get your high powers I think. So between your 9 and 25mm you could buy both ~12.5 and 18mm eyepieces but if you're going to skip one I'd skip the 18 (in my set the equivalent of the 18 is skipped). Additionally, the general suggestion for upgrade eyepieces is the Starguider line and at f5 the 12mm is good while the 18mm is not.