Deadlake

I went with the phenolic tube as you mention not wanting to get my hands frozen to the tube...

Thats really good to know. How about the Vernon scope diagonal or any others in the same ball park, e.g. APM 2 inch DiagonalPrism with Fast-Lock and Ultra Broadband Coating? edit: Vernon scope diagonal is £849 in 2" flavour, maybe not...

I have an APM LZOS 130 mm / F6 on order (an AP130GTX you can buy without waiting for your lottery ticket to come up 😃, the TSA120 is F7 and a 130 TOA is too slow to cool and too bulky). F6 due to being able to use it with a televue compressor for NV in case you where wondering why not go for the F9.2.

Has anyone used either the Baader BBHS or prism in a F6 APO scope?

Wednesday is looking good, hopefully it will hold. Martin

If the F stop of your EPs is not over 33 mm (from memory) you could get the T2 version rather then the 2” version, it’s half the price. Which one by the way > F7 the prism version?

You mean you end up with both.... 😃

If you get lucky with the chromatic shift it brings?

Or the Baader prism one? 😀😆

See if you can get from a UK importer, then you will not get hit with Brexit handling fees. TS does not charge UK tax, so ok on that front.

Indeed if you own a premium APO what else can you tweak. 😀😀😀

JetStream is the kind of Tak owner who Barlows up Vixen HR's on a TSA120. 😀 I'd hope 600x is enough for most planetary observations....

Indeed refractors are about being outside and setup in 15 minutes, most useable scope. No need to wait for acclimating or collimation overhead. It’s been pointed out before with the UK skies being able to use large apertures can be limited to a few nights a year.

Does any of a to c cover contrast, I think that’s more important to the human eye when looking at planets?

I have a Vixen SD103S scope. It’s been a delight to use, however the one thing I regret is not going for the SD115S version as that extra aperture would of brought the resolution of the scope within the usual maximum resolution of the UK skies and given extra reach on planetary viewing. The vixen scopes are lightweight like the Tak, which neglects the usual step up in weight with other manufacturers. The other item is that replacing the Vixen diagonal with a Baader prism and using Vixen HR EP’s has enabled really high resolution in the scope, x495 which I thought was the preserve of premium APO’s. The point being it’s all the visual train, that I would consider. Of course there are some Tak owners out there who like barlowing the Vixen HR’s as well as say it’s perfectly useable. Here is a good thread running at the moment on CN discussing quality of a lense verses aperture. https://www.cloudynights.com/topic/752583-does-aperture-outway-strehl-ratio/page-3#entry10846933 The answer is predictably optics quality can offset aperture within a certain difference, however as ever it’s a payoff between in this case a premium 4” will cost more then a good 5” which will show a similar view. Given the models you first linked to I’d go with aperture, I don’t think the weight increase will limit the use of the scope. Also doublets will cool down very quickly which always helps.

I forgot that part, but the scope this is for is F6, so makes even more sense to get the Baader BBHS now. However for a Tak 120 would the prism be the better choice?

Well I bought the prism without seeing the 2nd CN review favouring the BHSS. I might of bought the BHSS, however the chromatic shift with the prism might actually help out the doublet I use it in, by luck.

I have a full set of Vixen HR's due to JeremyS 😁, similar path being taken here...

I could see the value of a prism for your Tak doublets or bino-viewers, but I suspect for your APO the mirror is best. I was wondering if the prism came out best in the first CN review due to Baader improving the BHSS over time?

I have the Baader prism. Depending which review you read on CN the Baader BHSS or prism wins. From my understanding a prism diagonal actually introduces a small amount of chromatic shift. It cannot do any other as light entering a prism will disperse due to refraction. Ironically this trait can be used to correct some chromatic shift in other devices such as binoviewers. In real terms a prism cannot be as good as a pure mirror and will always be less efficient with light due to dispersion. The prism may have a beneficial affect on certain telescopes and introduce a chromatic shift on others. Would you need a good nights seeing to observe the chromatic shift or just different diagonals to try out? I'm planning on getting the 2" BHSS for a new APO scope, due to the faster cool down and the ability to use with EP field stops > 33 mm prism version I have. The cost difference between the Baader 2" prism/BBHS is not that much. I also know some dealers favour the BHSS for collimation of APO's. Martin

That did cross my mind. I have a 130 mm/F6 on order (600 mm focal length). I suspect it would able to go higher than x375 with a 1.6 HR however seems a little simplistic expecting it to work.

Indeed UK decided to not clear tax thru central clearing system (deals with different tax rates in EU) so now we have to pay handling fee if a company will still supply to UK. Just show companies will no longer trade if uneconomical, such as adding friction to trade... Maybe the answer is to have a warehouse in N.I., now the UK has been partitioned and N.I. is in the EU for trade purposes then as long as all good went thru there it would be less complicated, same tax regime?

This Saturday looks good as well

Smoother, I wonder if it's contrast related? I bought the other HR's EP's for use in a lower focal length scope, however to be honest to use on the moon and doubles I suspect a 2.5. mm and 4 mm TOE would suffice. Using the 1.6 mm HR on the moon was amazing because I didn't think the SD103S could support that magnification.

Just thought I'd update this. Since last October I've managed to get hold all of the HR series and replace the Vixen supplied diagonal with a Baader prism. Last Thursday and Saturday night the moon took over the night sky, so took a look thru the Vixen HR's from 1.6 to 3.4 mm and the TOE 4 mm the following notes: 1) Amazed at the detail the HR's managed to render when used with a Vixen SD103S, a good but not top tier ED doublet. I spent some time drifting over the surface of the moon, however at the magnification really made use of electric mount. 2) Baader prism made a huge difference to the detail rendered. The only really difference between the HR and TOE lines I can draw is with the HR you can use a 1.6 mm EP and the TOE will go down to 2.5 mm. The views are a little different, the TOE is smoother to look at while the HR show everything, warts and all. I'll update this once I've got a chance to look thru a new scope I've got on order.