Piero

Looks like we will soon move into another hobby: "visual satellonomy"! How is tracking going to work though?!

In that eventuality satellites will also be long gone, so we, well, our future generations, will experience really dark skies! To remain with Rutger Hauer, it does not seem to me that the fellas in Salute of the Jugger (1989) were much interested in visual astronomy! 😂

I assume you did not take apart the VIP lens element from its cell, right? 🫣

Hi, The orientation of the VIP element cell is "up" (towards the eyepiece) where those two opposite circles are. See my first image. I would imagine you played with them to take the cell out from the 1.25" nosepiece. Louis' diagram above ( https://stargazerslounge.com/topic/413443-need-help-to-reassemble-baader-vip-barlow/?do=findComment&comment=4411253 ) is very clear. Also, in that diagram, #29 is a ring which I did not include in my post above. That ring allows one to screw a 2" filter right at the bottom of the 2"-to-1.25" reducer. It works as 2" to T2 adapter.

I think the future of visual astronomy will be lunar and bright planets observing, due to the increasing light pollution and number of satellites. As a society in general, I think we are heading to a "blade runner" landscape without replicants or flying cars (at least in the short / medium term). As we approach that, I also think that there is a good chance that we face some very brutal war setting us back to another middle age. It seems a cyclic pattern in history.. On a positive side, middle ages also means dark skies, although I suspect that visual astronomy won't be a priority then..

I took a couple of pictures of my VIP Barlow. Mine was heavily modified but the lens direction is the same of course. Lens facing the eyepiece: Lens facing the focuser: In its original configuration the VIP Barlow is as follows: - 1.25" to 2" reducer adapter - 2x 15mm T2 spacers - VIP element screwed onto a 1.25" nosepiece - the 1.25" nosepiece It's a great barlow. One of the very best.

@The60mmKid That's a truly lovely scope!

My almost 10 years old TV60 with 24 Pan:

It is not just "newtonians and correct springs". You also need to have good secondary support (spider and holder), focuser (e.g. the bearings support the drawtube differently at different angles) and primary mirror lateral support. Then, if the telescope is a truss one, it also depends on pole length / diameters and pole attachments. With a laser collimator it is quite easy to see whether collimation changes at different levels of altitude.

Only if you have excellent mechanics. I would suggest to collimate at 60 degree. If you are doing some "serious" planetary observation, you might want to collimate at an angle closer to the planet altitude. -- EDIT: Reason for the 60 degrees The primary mirror is supported at the back and laterally. When the telescope points to the zenith, it is 100% supported at the back. When it points to the horizon, it is 100 % supported laterally. Assuming the angle x is the telescope altitude (0=pointing at the horizon, 1/2 pi=90 degree or pointing at the zenith), you could model the back and lateral supports with the functions sine and cosine, respectively (see plot below). The two forces intersect at 1/4 pi, which is 45 degrees. Therefore, one could simply collimate at 45 degrees, as a balance point. Practically, it is pointless to observe at the horizon and just above it as the atmosphere is thicker and the views are more affected by the seeing. The vast majority of observations is done between 30 and 90 degrees, therefore, my suggestion to collimate at 60 degrees.

For an objective way to assess the effects of various degrees of miscollimation, I would suggest to get a copy of Suiter's book (https://www.firstlightoptics.com/books/star-testing-astronomical-telescopes-a-manual-for-optical-evaluation-and-adjustment-second-edition-book.html ). This can also be found in the second hand market. A mild miscollimation in the primary mirror introduces some degree of coma. A severe miscollimation can also introduce astigmatism. If the optics are diffraction limited (1/4 lambda - which is just to say "commercially acceptable"), you want to collimate your telescope better than that to avoid introducing a larger error. In other words, you don't want that your collimation worsens the views delivered by your optics. To do that you need good collimation tools (=robust and collimated themselves) and you need to use them properly. These tools have tolerances, so the key point is to do the best job as possible so that your optics are collimated up to the tolerance of your tool. Assuming that you have collimated your Newtonian as good as possible with your trusted tool, what is enough? Well, if you draw something technically, what scale of ruler is good enough? It depends on the image size you observe. The higher the magnification is, the larger the diffraction disc becomes, the more you are challenging your optics, the more you can see imperfections. Take a 10" dobson. Below 150x possibly any tool can correct well enough. You likely need a good tool for higher magnifications tough. Above possibly 400x, you might even want to use an autocollimator. Of course you can just use a cheap collimation tool for any magnification you want to reach, but that tool will not offer a reading which is precise enough and these imperfections can be detected at high magnifications. Regarding "obsessing about collimation", well.. this is a generic comment. It really depends case by case. Personally, I find that if the optics are not close to ambient temperature, the introduced error is visibly larger than a slight miscollimation. If the mirrors are not supported properly, the introduced error is even larger. Reading comments by members it seems to me that a large number of people simply accepts the mirror supports as they are, meaning without questioning whether these work well or not. In addition to this, it seems to me that very few people use a fan to cool down their optics, justifying this with terms like (it does not have any effect, again, maybe the questions should be - is this fan working okay? Was it installed properly?). Often, the most basic and cheapest collimation tools are also employed (oddly, as cases of Televue and other high end eyepieces are often used). Finally, the statement often reported is: 150-250x is the highest magnification due to UK seeing (the only culprit of the equation!). In agreement with Suiter, collimation is a factor in the stack. There are many other factors to take into account, some of which are out of control, whereas other can be controlled. Unfortunately what people tend to get really fussy about are eyepieces, whereas the rest seems mostly neglected in my opinion. Eyepieces are just another step in the stack. The best eyepieces deliver miserably if other steps in that stack do not perform satisfactory (and yes, I write this by experience). I hope this helps a bit.

Mm.. I think DIY makes sense if you want a medium/large dobson (e.g. > 12") or you want a custom solution. It's an amazing experience though. I'd recommend a copy of "the Dobsonian telescope" by Kriege. "The portable Newtonian telescope" by Highe is also excellent but in my opinion it's more advanced and this can put one off. If you are interested, here's the album showing the building of my 16" f4 dobson: https://photos.app.goo.gl/DAZ8CqeRtJGe83jF8 .

Well, both my 12" and 16" home made dobsons have the focuser to the West when the telescope points to the South (north emisphere). The primary reason is pulling instead of pushing when tracking manually. The second reason is that I slightly prefer this configuration. My dominant eye is left and it is slightly closer to the telescope when aiming with the Rigel or telrad. My 8" f6 solid tube dobson has the focuser installed to the left like most of commercial dobsons. It's usable just fine although I prefer the other way around. 12" and 16" dobs: 8" f6 dob (focuser and eyepiece sold years ago..)

That's a good question. It took me a bit to answer the OP's question, because the whole selection of 5 eyepieces somehow depends on the telescope. The eyepiece set I mentioned cannot be used with my TV60, so that telescope would go. As you noticed, the paracorr2 has an impact too. I'm not sure whether I would use an f4 dobson with a set of <= 50 deg AFOV eyepieces because a coma corrector is not available. Therefore that fast telescope would go too. The two remaining telescopes I have are a 12" f6 dob and the 4" tak f7.4. With these telescopes I very much like the minimal set: 30mm APM UFF, Docter, Zeiss Zoom 25.1-6.7mm and Baader VIP Barlow. The OP said barlows are not allowed though (ouch)! Mm.. I could go for the 30mm APM UFF and the 4 short focal lengths of Pentax XW. However, the limit of 5 eyepieces does not play well as a medium power is left out.. therefore, between the two telescopes the refractor would go. With only the dobson left, I could just use the 30mm APM UFF, docter, Zeiss zoom and skip the Barlow. A completely different approach could be to use 24 Pan, 13-7-5-3.5mm Nagler T6 and keep all telescopes apart from the f4 one or accept views "full of comets". Planetary observing would be a bit sacrificed with this set though.. Somehow all this reasoning shows that if one has more telescopes, more eyepieces are likely needed too.

- N22T4 - docter - APM XWA 9, 7, 4.77mm I assume the paracorr2 does not count as an eyepiece, despite the fact that Barlows are not allowed here.

I recently received a kineoptics HC-2 focuser (https://www.kineoptics.com/HC-2.html) shipped from the US to replace the Antares helical focuser currently fitted on my 12" f6 dob (aka Phoenix). This new focuser should allow me to use non-parfocal eyepieces more efficiently - my plan is to use my 30mm APM UFF and Zeiss zoom +/- VIP in addition to my small set of 24Pan and 3 naglers T6. I will soon receive an aluminium plate so that I can create a custom base for this new focuser (to shorten the story, I cannot change the UTA plywood panel and the new focuser mounting holes kind of overlap with the current drawtube hole on the plywood panel so I need to make a custom base). I also received a couple of metal bars to update the counterweight system so that this will be neater and a bit more flexible. These bars are removable and will be attached to the mirror cell directly. They will also compensate for the extra weight of the 2" eyepieces I intend to use. After fitting the new focuser, I will need to cut the truss poles, slightly decreasing the height of the telescope.

For me, it depends on the telescope and its focal length. - 8" dob, I like f6 - 12" dob, I like f5-6 - 16" dob, I like around f4. These f-ratios allow one to observe without a ladder. Regarding refractors, I like sub f7.5 EDs, but these can be pricey.

I use a 2" Howie Glatter (650nm) with 1mm aperture stop attachment and collimate both focuser and primary, also matching the 1/4" white triangle mark on the primary against the concentric rings projected by the laser onto the attachment surface. The tublug is used sometimes, when I am tired. Other times, I use a 2" Catseye telecat for both focuser and primary alignments. This tool is also used for positioning the secondary correctly. This is easy for me as I don't value the theory of "benefitting" from an excessively small central obstruction at all.

Oh dear.. It's easier to think in terms of "how many cases do you have?"

Well, I'm probably the black sheep here but I much prefer modern designs with more eye relief and wider fov for all targets TBH. For observing more details, I use a telescope with larger aperture. I used to have a few Vixen HRs and they were excellent, although, as said above, 42 deg afov feels too restrictive to my eye.

A few parts in my telescopes have stainless steel in contact with aluminium and they are completely fine. I used A4 (mostly otherwise A2) stainless steel and 6082 alloy aluminium. All sold here in the UK. I agree with Keith's comment above.

You can apply films to the roof and windows to reject most of the heat coming from the Sun, so that the conservatory is at acceptable temperature in the summer. It can be a DIY job. They also reject nearly all UV light. E.g.: https://www.abodewindowfilms.co.uk/product/coolkote-conservatory-roof-window-film/

Thanks I chose mine with central column because it enables one to observe standing or sitting using a normal chair. It has never let me down.

For a while I had both 2" Baader BBHS mirror and prism diagonals. They were used with my 4" tak f7.4. None of them showed more details than the other, but the prism showed some chromatic aberration on that telescope and so I let it go. The prism also seemed to take a considerable longer time to cool down.

Uni 19 + AOK Ayo 2. Oh.. and a Tak FC100-FT with a Zeiss zoom + VIP barlow on top of it!