Deadlake

Not which ladder to buy 😀, parrcor options or effect of obstruction... 😆.

Using an NV EP is not so sensitive to a mirror acclimating. By the way whereas the refractor guys like to discuss which brand is best don't the Dob owners like to discuss which mirror is best, i.e. I've got a Lockwood Optics mirror???😄 Same as having a light green telescope.....

A 9.25" mirror versus a 24" one, which one will cool down fastest??? Not that you need that so much for DSO's... 😀

But Gerry what are going to see more with your 24" Dob monster or a C9.25 with a NV eyepiece? 😀 I know which one will show more and is more movable and maybe costs less....

I use dark sky meter on iOS, however do not know how comparable it is with the Unihedron.

Given the endless cloudy nights over the winter how many people spent time plotting new gear when otherwise they would be looking up? But yes, I've bought quite a lot due to forward planning then not going to use it. At the same time I have over spent my planned budget: Initially went with a scope tech zero mount for light weight use, however now prefer the Vixen SXP2 GEM mount I have now for ease of use. Original attempted to use a Vixen SLV 2.5 mm EP for looking at moon/planets, now have a full set of Vixen HR's and TOE 4mm. I did think that a Vixen 103SD would suffice, now have a 130 mm LZOS on order. There is a trend here...

Have you got a light meter or using your iPhone to measure. Has @GavStar got one?

I'm might go over sooner, have some stuff for the tip at Milford. I think we have 3 car parks within 5 minutes of each over so will do a drive by.

How do we know what the temperatures where when the photos where taken? I'm trying to work out how you are correlating the image shown to low temperature. For example why not collimation is an issue? I know what dealer who collimated all the scopes he gets in that have been through QC and that applies from Far East to premium manufactures.

Where is you starting point, West End Village? Thursley common is around 5 mins more travel time than Ranmoor and the SQM is just under 21, plus the car park you can walk straight out onto a field. Its 5 minutes off the A3. I'll see how dark its really is.

Close in time to travel and distance are obviously not the same. I think there is a location which is south of the A3 around Haslemere, looking a the light pollution maps. Near Bignor, the roads are slow out there as noted. I'll keep digging, we after 21.3 SQM or is 21 SQM enough?

The "juant' as you call it is why I was thinking of sites off the A3, as the its pretty quick to get away from London. As soon as you get on the road to Petworth the roads are not as fast.

Collate sites and maybe ground truth, e.g. iPhone app?

If you following the map down you need to get to south of Chiddingfold to get to over 21 SQM, which would will give new targets to see. Not tried Hankley common, but planning on looking at south of Haslemere as the SQM gets to around 21.3 and its 30 minutes from where I live. Hankley is a little closer to me, so maybe a good idea to give it a go as well.

The above temperature ranges are the manufacture specs…

Nice pictures Gavin as always. Surprised you have not got one of these yet at 140 mm over 100 mm. 😀

Takahashi are ok to -25 oC, APM LZOS lower and TEC and AP being oil based, I think around -20 oC from memory. I'd expect most scopes to work for AP usage to work at -10 oC given it will be left out over night for image capture on those clear winter nights (well not this year😀)

The TOA-130 takes an age to cool down for maybe some of the best views, excellent colour correction. And it's super heavy, so you would not be carrying that across a farm in case of a slip up... 😀 This thread comes down to are you prepared to pay a premium for a 10% performance delta or need high magnification. Actually as noted the premium APO's can provide a larger magnification, but at the same time cannot overcome aperture for limiting magnitude of whats viewable. All have trade offs.

How much does the weight different between the SW120ED and TSA120 (which is the lightest 120mm APO I can think off) make a difference to which one to use? One thing about either the of the Japanese brands Takahashi or Vixen is there are lighter than other brands.

I'd be interested to know how guiding worked for belt and harmonic drive mounts, they have a larger periodic error and so need a different approach, presume thats need to be guided???? Automatic meridian flip is also assume have it on my SXP2 mount as well.

I'm surprised that Takahashi have not entered this area as the FSQ range given its speed is well suited for NV and Mewlons as well where a long focal length is required.

If these scope where as fast as F6 I'd give them a look, shame they are not. A reducer does not work for my use case. I do look forward to the reviews for the Triplets as I suspect they will start to get close to the premium makes. Also the difference between FPL55 and FPL53, if figuring the FPL55 maybe we will see that, interesting...

My question would be can you build an observatory? I think the GSO 10" is under rated, particularly the new version where the focusers and body are not linked. If you have a Tak collimation scope then the main complaint about this scope goes away.

GSO optics are pretty good really. Particularly for the price. ASA (who are extreme quality) tested the bigger GSO RC’s and confirmed as much. The mirrors are quartz which makes for very low expansion so cool down is very minimal unlike the Pyrex mirror of a Celestron. The GSO coating is also very good and very uniform. Its near 100% from 4-700nm and then tails off a bit. The mirror coatings are a hard dielectric coating. I would assume aluminium but I don’t actually know. From whatI’ve been told the GSO mirrors are better then the EdgeHD, you might need to go up market to get a better Astrograph, maybe a planewave, however same time you want lower weight. The corrector on the SCT still need cleaning , just because it’s sealed does not mean no maintenance. Only plus I can see is weight saving.

Markus has posted an update here: https://www.cloudynights.com/topic/758189-new-apm-zoom-eyepiece-77mm-154mm-75°-constant-fov/?p=11034801 However in another part the price for the astro version is now €395. In the US I guess an extra 20% on top that and more for the UK as well due to Brexit, but maybe just another 4% tariffs.