dweller25

Whilst the primary mirror does not move during focusing, it is attached to a movable plate that can be used to adjust it’s collimation from the rear. What you adjust depends on what moves out of alignment. If you are lucky then only the secondary will need tweaking, but if the primary support plate moves then it gets more complicated - I believe you have to adjust the primary and then the secondary multiple times until collimation is correct. Some users have reported that due to the compromised F/12 design these GSO Cassegrains do not work at full aperture.

@Stu1smartcookie Have you seen this thread on CN ? https://www.cloudynights.com/topic/624303-new-at-6-and-8-classical-cassegrain/

Awesome 😀👍

Here is what I did……

@A McEwan I’m going to throw in a curved ball here….. Rather than going smaller go larger…. The Mewlon 180c will be a great match for the Vixen GP but will capture more light and have better resolution then the FC100. I have been VERY surprised by just how good the M180c is and I am definitely a refractor guy 🙂

As above plus the secondary appears to be slightly tilted too in the East, West direction, BUT that could be camera placement.

+1 for the 150mm Dobsonian, it’s a very capable scope and will perform well on your chosen targets…… https://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-150p-dobsonian.html It’s over budget brand new but Astronomers need patience so perhaps just keep saving ? ……. Or buy second hand ?

My back was starting to complain using the Tak straight through finder so I have added a Skywatcher 8x50 RACI - this scope is MUCH more comfortable to use now 😀

Best of luck 👍

Briiliant 👍

I used a 6.5kg, 102mm F/8 refractor on my Vixen GP with a Vixen AL110 tripod for visual and it was fine, so your 6.5 kg, 115mm F/7.7 should be fine too 🙂 Nice scope 👍

I’m not sure there is any difference between old and new Skywatcher 150ED units - apart from the delivery boxes which have been beefed up. If you are buying a used ED150 it would be very wise to star test it before purchase. Every new unit is now pre-checked and tuned - if required - as part of the purchase price. So you can buy new with confidence. They do represent excellent value for money in the 6” refractor arena 👍

Hello @Stardaze If you plan to do a lot of high power observing then a motor driven Equatorial mount makes for a very relaxed viewing session. As already said the Vixen GP or the Chinese clone Skywatcher EQ5 would make a good choice for the 4” Refractor. If you do mostly low power work, then an alt-az setup with wide angle eyepieces would work very well.

Very nice, quality setup👍

The best planetary eyepiece is ………… A Binoviewer 🙂 Although not everyone gets on with them

Walls and floors can be cold and damp, hanging the OTA from the roof is the driest option possible - optics will last much longer - I stored a newt for 23 years like this and it faired well.

The OO 6” F/8 is a very capable scope and gives truly apochromatic views with a known optical performance. At £628 it would give the same performance as a 120mm APO triplet costing much more. A Chinese 6” F/8 MAY be very close optically for less money BUT the optical quality does vary. Whatever you get, If you store the OTA supported from the garage roof the optics will be fine.

We don’t get many good and clear nights in the UK, so when one comes along I want to know I have the very best optics to take advantage of it. So I spend a bit more money to get the scope that suits my needs.

Good idea, but, the cooling air will travel straight from the front of the DK primary baffle to the front of the OTA having little effect on the mirror. it would work if I drilled holes in the backplate - but I’m not that brave 🤷🏻

It blows air down the tube, but after 4 months the mirror is still very clean. If I do start to see dust build up I will put a filter behind the fan, or perhaps put the whole OTA in a large plastic box and circulate filtered air through it…….. I definitely do not want to drill holes through the rear of the OTA 😱

Great image @neil phillips 👍 Here is what I use to cool my Dall Kirkham down, I just rest it on the front of the horizontal OTA for an hour.

The EQ5 is good for up to 1000mm focal length refractors and visual use 👍

Wow, that middle image is astonishingly good given the sky conditions 😱

Saw 45 Cap close to Jupiter on Saturday evening - It looked like a 5th Moon 🙂

wow - three options of the best value for money/performance/weight telescope you can get. Of the three I would choose the Bresser because……. 1. It has big altitude bearings. 2. It has a rack and pinion focuser. 3. It’s white 😂 You will need to add a rear fan but they are less than £10 The optics in all three scopes will be similar. Good luck with your choice 👍