Deadlake

1 hour ago, jetstream said:

What scope are you getting exactly?

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? 

13 minutes ago, John said:

Having checked the spec of the Baader T2 prism I use with my Tak, it appears that it is the BBHS version so I'll try it in the 130mm triplet sometime and see if I can notice any differences over the Astro Physics Maxbright that I use with that scope currently.

I probably need a night of exceptional seeing so that might take some time !

(Can't seem to get "seeing" of any kind lately )

Wednesday is looking good, hopefully it will hold.

Martin

13 minutes ago, John said:

I've been wondering about moving to a 2 inch Baader BBHS prism diagonal for my 130mm F/9.2 triplet but I'm doubtful that I will notice the difference for the additional £'s spent

 

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?

17 minutes ago, jetstream said:

When a lot of top refractor users talk about " this scope" has better color on Jupiter than "that scope" etc I think its down to the glasses used, f ratio etc and who knows what else. I do think a prism can also massage colours- but its a lot of money to gamble on.

By all means try the prism!

In my refractors the APO triplets like it- my one ED scope does not. This is not to say all ED doublets won't get along with it. Personally I'm not a gambler and I love known characteristics etc.

You mean you end up with both.... 😃

4 minutes ago, jetstream said:

Actually no! lol!😀

As much as I like this prism I cannot recommend it for doublet ED scopes- its too much money to gamble on it working with a particular ED scope. The Baader BBHS is "guaranteed" to work with any refractor IMHO.

If you get lucky with the chromatic shift it brings? 

2 minutes ago, jetstream said:

Excellent and don't forget one of these

https://www.teleskop-express.de/shop/product_info.php/info/p7951_Baader-2--BBHS-Sitall-Diagonal-Mirror-with-1-10-lambda-surface.html

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. 

12 minutes ago, jetstream said:

Can't really answer this but I will tell you a certainty- if I felt hindered in any way by this prism I would already have the BBHS... even on extremely faint objects the prism works well in the TSA120.Barnards Loop, California, Pleiades Bubble, Flaming Star etc etc no filter. Works well on galaxies too.

I want a BBHS for one reason- I have a weakness for owning good glass. And who knows-maybe I'll own a TEC 140 one day! and need another diag.

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

1 hour ago, Carl Au said:

Or use that scope most of the time either I imagine 

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....

27 minutes ago, johninderby said:

I think it’s the combination of all the factors including seeing and not so simple as just resolution or contrast. On some nights one may suit the seeing conditions better than another.

Is that why most own more than one scope. 🤔😁

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.

11 hours ago, vlaiv said:

I'm don't quite understand the comparison between two scopes, could you be more specific about that - in particular point about refractor being sharper but not having greater detail than in 8" dob and that it compensated for greater resolution of the dob by this sharpness.

I'm trying to imagine the scene - but failing. How can one thing be sharper while other has greater detail and greater resolution? This could be issue with terminology.

What exactly do you mean by:

a) sharpness

b) detail

c) resolution

You also mention that there was hint of razor thin Encke gap. What magnification was this at? As far as I know - Encke gap is only 325km and when Saturn is closest to the earth - that makes ~0.0559". Airy disk size of 120mm aperture is 2.14" or about x40 that of Encke gap when Saturn is closest to earth.

In above marble test, for anyone wanting to try this - it would be similar to trying to observe 16µm slit placed next to a 1cm marble at 60m distance.

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.

22 minutes ago, johninderby said:

Some usefull info.

https://agenaastro.com/articles/guides/diagonals/choosing-a-baader-diagonal.html

And this review

https://www.baader-planetarium.com/en/downloads/dl/file/id/160/product/1237/testreview_mirror_vs_dielectric_vs_prism_diagonal_comparison_w_paolini.pdf

And from the conclusions of the review.

”Quality prisms are prime candidates for the diagonal component in telescopes with focal ratios of f/7 or greater. Prism diagonals tested did not introduce any visually apparent chromatic aberration or spherical aberration in f/7 or f/8 telescopes and showed views just as brightly while notably higher in planetary contrast and notably lower in scatter on all celestial targets than similar high quality aluminum or dielectric mirrors. At f/6.25 chromatic aberration became apparent, but was inconsequential on all but the very brightest targets.”

 

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?

2 minutes ago, JeremyS said:

That’s not what I wanted to hear 🤣🤣🤣

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.

1 hour ago, jetstream said:

Thanks guys... now I want a Baader BBHS lol!

 

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

1 hour ago, JeremyS said:

Yes I’ve read loads  of reviews in Baader prism vs mirror. There do seem to be a few cases where ppl prefer the prism and maybe it’s in specific scopes with specific targets.

At least to me the balance was tipped towards the mirror which is why I bought it. But then there’s the nagging doubt about whether the prism might be better.

It’s this nagging doubt in many areas that leads to £££ being spent on scopes, eyepieces, mounts etc etc 🤣

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?

16 hours ago, JeremyS said:

Yes the BBHS is very nice. But I’ve not compared it to a prism. So it leaves me wondering 🤔. Expensive to try out tho 😊

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

On 25/01/2021 at 09:51, JTEC said:

Both seem to me to have the capacity to take your scope to unexpected levels and show what it can ‘really’ do - at least, on the Moon.  Barlowing them is interesting  : ) 

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.

56 minutes ago, Ags said:

If UK people are paying more it is exclusively because of how the UK is applying the rules. The money goes to to the UK government following the UKs interpretation of the rules.

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 

2 hours ago, JTEC said:

They’re fantastic aren’t they!  I have only the 4mm TOE and the 3.4mm HR and use them in a TEC 140 - don’t think the shorter ones would get much use.  I’ve tried to characterise the differences between them. I’d agree with your word ‘smoother’ for the TOE.  Perhaps paradoxically, the ‘smoothness’ doesn’t seem to entail any loss of available detail though. 

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.

I have a STL file to print a iPhone holder to mount puck adapter. This is to allow my phone to be held some distance from the mount so the phones compass etc will bot be interfered with by the metal of the mount. I can then use an alignment app to align with Polaris as a neighbours tree blocks direct line of site.

Moving the mount results on other trees getting in the way.

I uploaded the file to 3dprintuk however the puck adapter costs £2 to print but their minimum charge is £38. 

Is there any where else that allows for smaller 3D print runs?

Thanks

3 hours ago, DaveL59 said:

hmmm, seems there's potentially big costs to the suppliers if good are rejected back to them when the end-client doesn't want to pay the extra charges

Brexit: Retailers warn they could burn goods stuck in EU - BBC News

Rules of origin come into play too, just to make it even more fun.

This is a good question, e.g.

LZOS made in Russia imported into Germany and then resold, how that works under rules of origin I don't know.

Take FLO, buy from Baader in Germany, warehouse in UK, sell abroad. Will this be Percy Pig scenario?