DAT

Nice work! I have managed 4 in a few limited [by the weather mainly] sessions over a month and I am super happy. The whole catalogue must be thrilling!

With regards to some of the collimation tools mentioned, if one has a 2" focuser and a good 2" to 1.25" reducer, does it matter whether one uses say a 1.25" or 2" laser or concentre?

Thank you, a nice selection of opinions and advice. I think given I have a Chesire, a concentre would perhaps be overkill although as someone has pointed out, it would be even better to try and see what works. Not sure about the laser either, as I have an 8" dob some seem to think this is not necessary, I think I would like to improve with what I have and then perhaps think about what would help to be more precise. I understand this is not strictly necessary but I enjoy the challenge of getting things just right (I have an 8" stellalyra f5.9 dob)

Hello there, I am still struggling with collimation but getting very close, I think...As soo as I can, I will take up someone's kind offer of an in person tutorial. For the time being, my cap and Chesire sight tube will certainly be good enough but was wandering whether someone could recommend a good laser that I can buy in the UK. I have been suggested everything from Glatter to Baader, Astrsystems and Ho-tech. All have pros and cons from price, to availability in the UK and so on. I am thinking of a laser to collimate in the dark and eventually to be more precise. Also, what do people think about a Concentre. Would that help for the secondary? I have posted on CN and had some advice already and as usual there is a wealth of information coming my way. Am interested in an SGL slant on the matter. I am in no rush to make a purchase as I have everything I need to get the job done now. Thanks in advance

There are some great pictures taken with a phone on this thread. I am wondering if anyone has had trouble with the size of their eyepieces? I have a reasonably priced celestron phone holder but it can only clip on to the stock eyepieces, which I no longer have. The eyepieces I "now" use are all too wide for it. When I did take pictures, sticking a timer on also helped as it gives the scope time to settle down in case you knock it when taking a picture, especially if you are not using a dob and the tripod is shaky. (I say "now" because I have had consistent cloud cover for feels like months )

I do not have much experience but the SL 30mm uff is the eyepiece I use the most (8" dob), not just a sky scanner. Everything looks good through it and sharp to the edge. I just have problems with the rubber eyecup which tends to slip off when I try and fold it up back up. I wear glasses and switch between having it down and folded up whilst pressing up against it.

Great insights on this thread, learning lots.

As a beginner it’s difficult to separate collimation issues from poor seeing. Scope is usually out a couple of hours before I start seeing, so do not think that is the issue. Do the eps need to acclimatise as well? The sky looked so clear the last two days I could not imagine the seeing conditions to be bad but I assume bad conditions are not always “visible. Will try and perform a start test again and see, last time I tried I would say it looked like a collimation issue as I got concentric rings but slightly off and very fuzzy. Thank you all for you help as always.

I think it must be more of a collimation issue otherwise I assume the picture would not be ok on the 30mm ep. At some point I will take up someone’s kind offer of help and get to the bottom of it. For the meantime I just have to keep trying and be patient

Thank you, have been meaning to come down for a while but work keeps getting in the way. Live in Wembley so would have to drive down, where would I park? will look it up on fb, thanks

Pretty sure it’s collimation + dew, wish it was though

Moon and Jupiter are not too bad , stars are all very blurry. EPS are all under 18mm (11,9,7). I messed up the secondary alignment previously , would like to think it is the cold but I have a feeling I am trying to blame the mirror for my ugly face. I just let the secondary clear up a bit inside and took the scope out again and same problem. I think it is a collimation issue

Hello, I am back with more problems. To those who have helped answer my questions in the past, particularly with regards to collimation, thank you. I cannot be sure if my scope (8” Stellalyra dob) is collimated but I have definitely made progress, at least in so far as understanding what is going on. I am currently getting quite frustrated as we have been blessed (in London) with clear nights , but my images are anything but clear , except on long focal length eps. I think I have fixed at least some of my collimation issues, crosshairs of Cheshire are centred on the doughnut as is the dot from the cap. I also no longer need an extension tube to focus 1.25”eps so hopefully the primary is no longer too far up the ota. I am wandering if the lack of clarity could be the cold weather, I leave my scope out for 2 hours before observing to acclimatise and tonight the secondary is totally obscured (frost/dew?). I would like to think it is the weather (if so, what can I do?) , but am very conscious that it could be something else I have done wrong (collimation issue). Thoughts and comments are much appreciated as usual

I have bought a couple of items from Bresser through eBay and was worried about duties/tax. They confirmed this does not get added and indeed they were not. I would email to check just to be sure. I cannot say anything about warranty which is a a valid point someone else pointed out

Thanks, will have a look tonight and post some pictures. I have messed up with the mirrors so I have a feeling the primary may not be where it should - learning how to collimate the hard way….

That is the problem I had, I was having to pull out the 1.25” pieces too. I got round it by putting the 2” extension in and then putting the 1.25” adapter into the extension, then the 1.25” eyepieces .

Gso dob

Hello again I am back with another slight issue. I have posted previously about problems with collimating my Stellalyra 8" dob, (f 5.9). Yesterday I was out on a rare clear night and noticed that, to achieve focus, I either had to pull out every eyepiece or leave the extension tube in that came with the scope. This did not bother me as I had clear images, I even managed to put a 5mm in to see Jupiter ( although the image was not perfect). This was the case with a 7mm, 9mm, 18mm and a 2" 30mm. Is this normal or have I moved something around to much? Mirrors are almost in the right pace but not quite, I would say they are aligned though as like I said, images were super clear with 7mm eyepiece down...

Well done, first sessions are pretty exciting.

It but would be interesting to see how a tv panoptic (35 & 41mm) or Pentax (40mm) performs. I have managed to get a great view of the double cluster with the SL 30mm uff and an even better view of each cluster separately with a TV delite 18mm, I wouldn't want to loose much quality by increasing the TFOV

Somewhere else I asked the question about what was the lowest mag ep that could be used in an 8" dob and as expected replies were quite different. Some people suggested respecting the 6mm exit pupil "rule", especially if the observer is of a "certain age". On an f/6 that meant using a 35-36mm, no lower. This would avoid washed out backgrounds and unwanted reflections. Others said you could get away with a 40mm depending on the target (e.g. Pleiades), and that the problems expected would not be too noticeable. I really enjoy my Stellalyra 30mm uff but it cannot frame the Pleiades that well, a fair chunk is missing. I would be curious as to what it looked like in a 40mm from where I am (heavy light polluted area). In my previous scope (130p f/5), the Pleaides was stunning through an es 68 24mm (x27).

Excuse my ignorance but what do you mean by a=b? I understand how the secondary is moving and how the outside screws need to be loosened or tightened as the secondary holder gets moved up or down the tube by turning the central screw screw cw or ccw. I think I have achieved this (it is better than it looks in the photo :)):

I must be close, I have measured as precisely as possible with a ruler (looking through a cap) and positioned the secondary further down the tube. It must have all been looking aligned to me because I think I confused the reflection of the primary with the outline of the secondary and tilt was way off too so it all “looked “ ok to me. I think this is better:

Glad you said that about turning the screw clockwise, did not make sense…. I thought something was up because I assumed the screws should not protrude that much, there is clearly something I am missing because through the focuser the secondary does look aligned to me, I am not seeing this. I am coming your way when I can!

Hello everyone, I think I am getting somewhere. After reviewing all the information passed on and reading 3 guides quite a few times I have tried to do the following: 1) Align the secondary under the focuser until it is centred , 2) adjust the tilt until I see a nice circle and 3), get the dot from the collimation tools centred on the doughnut of the primary I am confused as one guide said that turning the central screw of the secondary holder clockwise made the secondary mirror move down the ota. I found the opposite. I think what I see through the chesire and the cap looks good, I can see the three mirror clips and the dot is in the centre. What worries me is that I felt I had to adjust the secondary holder lots so that the outside screws have ended quite far out . I moved it a fair bit out of the tube until I felt is was directly under the focuser. Please someone have a look at the pictures and tell me what you think. I would perform a start test but can only see Jupiter and the moon right now. Scope is outside acclimatising just in case. My wobbly hands do not take good pictures and the dot is more centred than appears, I promise