John

Low cost laser collimators often need collimation themselves before you can rely on them which is why I prefer the cheshire eyepiece.

For the planets 150x - 250x is usually a useful range. Maybe 300x on the moon or Mars if the seeing is excellent and the scope properly cooled and collimated.

2 hours ago, F15Rules said:

Ref the Avatar, I've been advised that the "Ageing Rocker" guitar theme has been complained about by some 70s disco fans..😂

From one ageing rocker to another, hold your ground !!!!

18 minutes ago, Deadlake said:

I thought you where going to mention this:

https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-100-degree-series-2-inch-eyepieces.html

£954.50

i can get an entire range of APM epks for that....

 

That 3 inch 30mm is a monster !

Here is a link to a suitable replacement tripod:

https://www.firstlightoptics.com/tripods/sky-watcher-heavy-duty-tripod-for-sky-tee-heq5-eq5.html

I was thinking of the Nikon NAV HW's but with the EiC tele-extender you do get 2 focal lengths out of each one:

https://www.apm-telescopes.de/en/product.html?shopgate_redirect=1&mobile=false&info=2769

A bit wasted on me though, not using 17mm much.

The Docter 12.5mm are reputed to be a little better than the 13mm Ethos but I've just remembered that they have recently gone out of production:

https://www.astroshop.eu/eyepieces/docter-12-5mm-1-25l-2l-ultra-wa-eyepiece/p,22974

Like Gerry, I paid around half that for my Ethos 21 (used) but that was a few years back now.

I notice that the ES 92's are now £400+ eyepieces now as well.

The scope is the same as the Skywatcher Explorer EQ5. Helios is the brand name that the manufacturer used before they changed to Skywatcher and moved to the blue colour scheme.

The weakest link is the aluminum tripod which will barely hold the scope steady enough to look through it let alone image anything. I would suggest changing to a steel legged 1.75 inch or even better 2 inch tripod.

If both motors are present and functioning you can use a control box like this plus a power supply:

On eyepieces, 400x will seldom be any use in all honesty. Pick a set that give something like 50x - 80x - 150x - 220x (or something around those magnifications) and they will serve you well. The BST Starguiders are a good bet

https://www.firstlightoptics.com/bst-starguider-eyepieces.html

I don't image so I can't give more advice on that front. You will want to check and adjust the collimation of the scope so a cheshire eyepiece would be very useful:

https://www.firstlightoptics.com/other-collimation-tools/premium-cheshire-collimating-eyepiece.html

10 hours ago, Deadlake said:

Given the cost of TeleVue, which ones would you buy and which ones would you buy another brand as you don't use them enough?

I'm sorry - I missed this question.

17mm is my most underused focal length. I replaced the Ethos 17mm with an ES 17mm / 92 because of this and I've thought about letting my 17.3mm Delos go as well but I keep finding excuses to hang onto it, usually after I've read a report from someone else saying how much they like the eyepiece

I guess a 17.5mm Morpheus would fill the gap very adequately but, as I tend to move directly from 20-something mm eyepieces to 13mm / 14mm eyepieces the poor 17mm's get overlooked so the Morpheus would get similar treatment I expect.

Other than that, I think my current Tele Vue's are "keepers". Probably .......

There are a few out there that might be a touch better in certain focal lengths but they cost even more than the Ethos's do.

9 minutes ago, Basementboy said:

Interesting! I hadn't considered any Altairs. Looks like a higher end scope than the Sky-Watcher Evostars? 

 

The Altair is an ED doublet so will be in a different price bracket than the Evostar achromats which are what have been discussed so far. The level of false colour control of an ED doublet is a substantial step up from that of an achromat. Plus the Altair is better engineered and finished and has a much superior focuser. Skywatcher do an ED doublet version of the Evostar:

https://www.firstlightoptics.com/pro-series/skywatcher-evostar-100ed-ds-pro-outfit.html

The Altair version is very well priced for a 4 inch aperture ED doublet refractor.

29 minutes ago, theropod said:

Re the above: those rights are apparently superseded the rights of others to enjoy the night sky.

Global communications produces a lot more £'s / $'s revenue than enjoying the night sky does.

I'm not happy about it at all as an amateur astronomer of course but these are the realities that drive global decision making whether we like them or not, I'm afraid.

https://spacenews.com/spacex-submits-paperwork-for-30000-more-starlink-satellites/

The submissions for approval seem to go to the ITU which is part of the United Nations. From their webpage:

Sorry, I've rather lost track of this thread lately

Looks like you are getting so good advice though

The "nose droop" tendency gets gradually less as the scope is pointed upwards. When I'm observing an area around the zenith I don't need any counterweight even with my heaviest eyepiece. When observing something close to the horizon (ie: Sirius) I need both counterweights.

Thats why the length of chain approach works quite well - the lower the scope is pointing, the more chain is off the ground and vice versa. It's not the neatest solution though.

2 minutes ago, Deadlake said:

True. Here they (all the EP's I'm looking at now given the price rises) are on a 130/F6:

No other pro's and cons between the 20 and 30 mm? 

The higher magnification will show DSO's better if you have some LP to contend with. Thats why I don't use my Nagler 31 very often compared with my Ethos 21.

The scope will handle a lot higher than 156x of course !

3 hours ago, Deadlake said:

APM prices are going up 5-15% from the start of March. The 20 mm will be going up the most. Delivery times will be a little slower as different courier who can navigate the border (handling, charges etc) is being used.

Thinking of getting:

1. APM 30mm Ultra Flat Field Eyepiece 70°
2. APM 20mm 100 Degree AFOV Eyepiece

Need to sort out a 25 mm now.
 

Why a 25mm ?

The 20 / 100 will show practically as much sky as the 30mm / 70. Personally I'm not sure that you need even both of those, let alone squeezing a 25mm in between them.

I've simulated the true fields below for my 12 inch F/5.3 dob. The 30 / 70 eyepiece is in red, the 20 / 100 in yellow:

I think the main purpose of these charts and diagrams is to fuel discussion on forums

If we ever get a clear, dark night again, I'll have a go with my Vixen ED102SS F/6.5. With the 31mm Nagler I get a 3.8 degree true field with that scope.

I have the feeling that I might have glimpsed part of this nebula in the past but it's been a long time ......

Good luck Gerry

It would be interesting to know if something like the TSA 102 could properly split the close pair of the Tegmine (Zeta Cancri) triple star. My data shows the separation at 1.1 arc seconds which is a touch tighter than the Dawes limit for 102mm aperture of 1.14 arc seconds.

33 minutes ago, Deadlake said:

If you stuck NV on your DOB I t would be like having a 50”, how much would one of those cost?

One of our members does use NV with his 20 inch dob under dark skies:

https://stargazerslounge.com/topic/369957-supernova-snat2021j-in-ngc4414-mag132/?tab=comments#comment-4018381

17 minutes ago, starboy71 said:

Thanks John it makes sense now,so i`m ok with just that one 2 inch ep you think? i was worried i`d have to get a whole `range `of `em to match my 1.25`s....phew!!!

I think so. A 30mm 2 inch eyepiece is a good focal length for wide field observing with an 8 inch dobsonian.

38 minutes ago, mikeDnight said:

I was just seeing who was paying attention. ☺  Takahashi's claim, not mine!  

Roger Vine thinks fluorite is good but he is a little more modest about it than Takahashi !:

http://www.scopeviews.co.uk/Fluorite.htm

My favourite bit from that is:

"....In truth the optical materials that make up the lens in your telescope (or binoculars or camera) are just one part of several factors which affect the lens’ performance. The design, figure and assembly of the lens all count too...."

25 minutes ago, Deadlake said:

Looking at the cost of Televue based EPs, I could own half of some of the EP collections on CN and have spare cash for a NV monocular and see so much more, the richest of richest field telescopes. Being late to the party has benefits...

Agreed. Tele Vue eyepieces are expensive. No escaping that. I bought all but two of mine used otherwise I would not be able to afford the ones I have. 

Luckily there are some excellent and less expensive options available these days

I use a DIY counterweight on the bottom section of my dob because many of my eyepieces are heavy. My tube is aluminum so I use a magnetized kitchen knife rack and a couple of old iron weights for this purpose. If you have a steel tube you can put magnets directly onto the tube. Wrap them in something to stop them scratching the tube.

My eyepieces go up to 1175g in weight.

285g might be OK using the tension handles on each side of the altitude axis. As the tube drops (ie: to observe things lower in the sky) the tendency for the nose of the scope to drop increases.

Edit: I'll just add that the only benefit you get from 2 inch eyepieces is the larger field of view. They don't deliver better performance than 1.25" eyepieces. Most folks have one or two 2 inch eyepieces for low power / wide field observing and then 1.25" eyepieces in the medium to shorter focal lengths.

So why did Takahashi drop the TSA102 model ?

Apart from Canon Optron are there any other manufacturers of objectives that use CaF₂ ?

Shocking though it is, this is rather old news. The FCC granted Space-X permission to launch over 12,000 satellites back in 2018. The condition with that permission was that they were all up there in operation by 2024.