paulastro

1 hour ago, Highburymark said:

From my inexpert calculations, Paul, the XWA 20mm will vignette slightly with the Baader T2 amici prism, but not by much. The prism has an aperture of 32/33mm and the APM 20mm has a field stop of 34.8mm (according to Don Pensack) despite an advertised 37mm, which should mean you’ll barely notice the difference. I stand to be corrected on this - but it’s amazing how few eyepieces vignette with the Baader T2 diagonals (I also have the standard Zeiss prism and BBHS mirror). However, it does mean you’ll need a 2”/T2 clicklock ep holder for 2” eyepieces to attach to the prism.
 

Many thanks Mark. Mark, where did you get the XWA 20mm from?   My two 2 inch eyepieces are the Celestron 30mm/70 Ultima Edge FF and the Baader Asheric 36mm/72, also the Baader Star Diagonals Manual I printed off some years ago has the clear aperture of the Baader T2 Astro Amici-Prism with BBHS coating as 31 mm clear aperture.

I do agree that Baader T2 prisms don't vignette very easily.  My Baader T2 body with 'extra large BBHS Prism by Zeiss-standard short optical length' (34mm clear aperture, 38.5mm optical length) doesn't vignette with either of my 2 inch eyepieces.

I must admit, your own and Stu's comments have moved me in the direction of the T2 amici-prism for which I thank you both.

PS I could swap out the 2inch T2 Clicklock and 2inch nosepiece from my other prism.

17 minutes ago, Space Hopper said:

All i can suggest is not to discount the APM version

https://www.apm-telescopes.net/en/apm-2-inch-erect-image-prism-with-fast-lock-and-ultra-broadband-coating

 

Is has a 46mm clear aperture meaning all your 2" eyepieces will do their thing and show NO vignetting.

And its a realistic price.

Many thanks.  Apologies if I seemed dismisive in any way re the APM, I didn't mean to be. 

Your club member may think a lot of it, but I've no way of knowing what criteria are important to him.  Also, I've no way of trying one out so if I ordered one I'd be buying blind.  If I bought one and tried it out I might think its great.  If I didnt or it wasnt as good as the zwO I have, would they be willing to take it back?  Not all suppliers are as helpful as FLO and others I have used. The 46mm clear aperture is good, but then my WO version is 40 and shows no vignetting, the expensive Baader is 44, but this is not the only important thing.  The Baader literature gives persuasive reasons for buying it. as the APM one does, even more so. The main thing  has going for it is that it has an excellent reputation,  their other prisms are certainly very good.  

Are there any reviews of the APM version pr other information.?  I didn't know it existed before you mentioned it.

1 hour ago, Highburymark said:

I have this one Paul - it’s superb. Only a tiny, almost imperceptible diffraction spike on very bright stars. Because they are difficult to make, there may be variations between different units, but I think the T2 Baader is the way to go if you want top quality without forking out for the very expensive 2”.

Many thanks Mark.  That's very useful, I'll take it into consideration.  It may come down to how important it is to increase the field in my 103 from 2.3 to up to 3.7 degrees! I'm saying thus on the basis I'm assuming there will be some vignetting if I use a T2 2 inch nosepiece and 2 inch eyepiece clamp because of the smaller clear aperture in the T2 version..  Have you tried yours with 2 inch eyepieces Mark? 

1 hour ago, Space Hopper said:

Hi, and yrs, that looks like the same one at a similar price to mine. I think its the same catalogue number too.

One difference, mine is a few years older and is 'pre' the fancy BBHS coatings.

I also have the big 2" mirror version WITH the BBHS coatings and it performs very well indeed.

Regarding the AMICI : i haven't used it really on high power planetary : i always use my standard prism which has a 2.6x gpc 'permanently residing in it for high power planetary. This has a 'quick coupler on it that attaches on to my binoviewer, a Baader Mk5.

The reasons why i purchased the Amici were for terrestrial work with a smaller refractor, and also to help me on Lunar observations. I wanted to have a crack at 'the Lunar 100' and much prefer a correctly oriented image to aid identifications of craters etc.

I actually half considered the mega bucks Baader \Amici when they released it, but then some sense on my part kicked in. Nearly £600 on a diagonal is a bit crazy really.

I'm pleased with the 'cheaper' version though. One would assume the newer version with the posh coatings will perform even better.

The diffraction spike is only an issue on Venus really. And something really bright such as Sirius , Vega etc.

I don't think it will trouble you on the moon.

If you lived a bit closer to me, i'd happily lend it to you so you could try it out. 

The blue and white APM version is a good alternative though. I know a club member who uses one, and it performs very well.

 

Many thanks  that was very helpful.  I think in quality, the cheaper (smaller) one might be ok for me, but if I can't use it for sweeping with my 2 inch eyepieces (possible vignetting)  then that would  restrict the field with my 103 triplet to 2.3 degrees, instead of 3.0 or 3.7 degrees - I'll have to think about that as its half the price.

Whilst I agree that £600 is a lot for a prism/diagonal, it depends what you compare it with.  In our astronomy world some people will pay( and do) well over £600 for an eyepiece, £87  for anti vibration pads, £200 for counerweights and over £300 for some filters etc etc.

The reason I most want a better amici prism is that I have always resented having to put up with a mirror image view when using any ordinary diagram or prism.  It's not only annoying on the Moon and planets, but for any object or star field you look at you are not seeing reality, it's not what they really look like. Most people don't seem to be bothered by this, but if all telescopes had always given a right way round image and then someone had invented an optical system giving a mirror image people probably wouldn't put up with it!   (an inverted image is fine as it exists in reality, no upside down in the universe of course.)  Rant over 🤣.

Thanks for the APM prism heads up, but it may mot be as good as the Willuam Optics  2inch prism which I've used up to now. ( link in my first post in this thread)

Anyway, thanks again, I have somen thinking to do ☺️

2 hours ago, Space Hopper said:

Perhaps worth mentioning that it's quite difficult to make one of these diagonals well. Well enough, and consistently well enough for high power astro use.

You only need to look inside one to see the complexity of the thing.

Hence the sky high price of the Badder BBHS 2" Amici.

With the more budget models you often see a bright diffraction spike through very bright stars etc.

I have the 'cheaper' Baader version ; it performs ok, only giving the big diffraction spike on something really bright like Venus or Sirius etc.

On Lunar though, theres no issues.

Let us know which one you go far and how it performs on your C8 🙂

 

 

Space Hopper.  When you say the cheaper one  do you mean the one below.

https://www.firstlightoptics.com/diagonals/baader-t-2-90-baader-astro-amici-prism-with-bbhs-coating.html

I was thinking of buying it ( or even  possibly the expensive one!) to replace the William Optics one I have.  I've never really been troubled much by the diffraction spike, but I would expect one or both of the Baaders to have a better overall performance and be ok on powers of over x125 or so.  Of course the cheaper one probably has too small a prism to accommodate my Celestron Ultima Edgel FF 30/70 and Baader Aspheric 36/72 without vignetting.

Can you tell me how the cheaper one performs on Jupiter/ Saturn/Mars on higher powers 

IfI bought the expensive one, I'd use it all the time and sell my ordinary Baader prism #2456095 to recoup some money.

Thanks, Paul

3 hours ago, PatrickO said:

I'm looking for recommendations for a 90° erect image diagonal for lunar observation with my 8" SCT.

I've read that the Williams Optics one is good. Has anyone experience of it? Or of any others you would recommend or avoid.

Thanks, Patrick 

If you mean  the William Optics 2inch 90 deg one (listed on 365 Astronomy) at just over £200, Ive had one for some years.  I bought it used, then it wasn't available again until comparatively recently.

It is MUCH better than any other I've used over the years (and I've tried and owned quite a few others) and can be used on powers up to around x125 (which others I've tried have not been able to do) and still have a good image. It gives a nice image  with good contrast and is very well made. I would recommend it if it's still of the same quality.

The best one is generally acknowledged as being the Badder/Zeiss 2 inch 90 deg version  that costs around £600!  FLO lists it but currently out of stock.  

This is the one I have

https://www.365astronomy.com/William-Optics-90-degree-Erecting-Prism?path=113_152_358

Thanks Geoff.  I just launched the app and it prompted me to download the update.  Its all working  fine,  though no sun to try it out.   Good to be able to make the lens raise up without entering one of the modes 👍

48 minutes ago, mikeDnight said:

 It was a glorious day here yesterday, but come late afternoon the clouds rolled in. I phoned my mate Paul just for a chat and he told me it won't be clear over night.   As luck would have it however, it did clear sufficiently for me to have an hour and a half observing the Moon and so, because he was clouded out and because I'm a true friend, I sent him this: (I think he hates me!)

 

 

I spent my time playing with my ultra flat's and a Barlow,  as well as my amazing SvBony 3-8 Zoom. The following pic's are through the zoom using a hand held phone camera. The camera lens may not have been perfectly clean and there was an annoying thin cloud covering the sky that varied in thickness. All things considered however, I think it turned out not too bad.

I'm glad you had a session Mike, it was almost like seeing you in person - lucky me 😊.   Nice pics, I almost felt I was there!

I'd practice a bit though before you launch your channel on u-tube - unless it's a comedy channel 😅

Just checked and my firmware version is 2.3, and apparently I have the latest version.

2 hours ago, GasGiant said:

Seems there is an firmware update for the SStar, I dont think its on Android yet though.  Keep your eyes peeled 

 

 

Thanks for posting.  I'll check if it works on Android.  I've watched the video and from what I saw it seems all about having more control over the exposure in solar mode.  A shame, I was hoping for the mosaic feature.  Am I correct re the contents of the update??

19 minutes ago, Mr Spock said:

Not so. I regularly use my 12" on the moon with a 3.3mm eyepiece. That's x461 - and it is very sharp. With the C9.25 I used an 8mm eyepiece for x294 on the moon maybe half a dozen times in ten years of owning it.

It didn't have poor optics. The star test was perfect. With SCTs poor MTF is the problem, which is much worse on low contrast objects such as Jupiter's belts. This is why you hear many people say they prefer refractor views. It's also why SCTs are good at imaging as MTF can be corrected for in processing, assuming the optics are good quality.

This was using an 8 inch SC at up to x600, not a 12 inch Newt at up to x461.

.

2 minutes ago, Flame Nebula said:

Hi Paul, 

Indeed, as noted in my original post, there does seem to be a larger percentage of people on the CN site(which may or may not mean predominantly American based users) who reported sharp C9.25. But, then I see evidence from one user at least, who said their newt had no issues with the seeing on the same night the C9.25 gave mushy views. Logic seems to vanish then. Clearly, this could be one of those nightmare situations, where multiple factors are at play. So, a mushy view could be due to the OTA and/or seeing and/or collimation and/or thermals. 😬😬

 

Yes, you're right about the collimation issue.  Strange for SCs since they are about the easiest type of telescope to collimate in my view.  As you can imagine, with Peter Drew present, the SC I mentioned at Kelling all those years ago would have been spot on! 😊

2 hours ago, mikeDnight said:

Over 45 years Ive only once seen a SCT give a great view of Jupiter and that was an old orange 1980's C8. Other than that, and no matter what the aperture, I've found them to be consistently disappointing as regards planetary sharpness. Schmidt's original design was to be used as a camera and that's where they seem to shine, though how much of that is down to stacking and computer jiggery pokery I've no idea!  Maksutov's on the other hand, despite being similar in design other than the corrector plate, give very pleasing views, and once thermally stable, are probably as close to refractor like as it gets. So the issue with SCT's would appear to be down to the Schmidt corrector which is a thin mass produced lens made by sucking a optically flat plate onto a figured master plate. Once ground and polished it takes on the figure of the original. So the Schmidt plate is not an individually figured item, it's pot luck! 

Mike, I can understand you saying this , to some degree,  as your experiences are  in the Lancashire/Yorkshire area - which have generally rather poor seeing - even when compared to most other parts of Britain. 

Add to this that most SCs in use are 8inches or more in aperture and the fact that SCs have suffered from varying quality control issues at various times, and what you say is understandable.

However, in places where the seeing is consisteantly much better than in the UK (parts of the USA etc),  the SCs have a much better reputation - including for planetary.  Peter Drew, who used his 8inch SC from his property in Tenerife over many years, told me many times how he was frequently able to get excellent results on the planets using magnifications between x400 and x600. This would be almost impossible in the UK.

Though I agree in the UK an SC would not be many peoples first choice as a mainly visual planetary telescope - I don't think it deserves its sometimes poor reputation.

My best view of Mars was many years ago through a 16 inch Meade 16 inch SC at Kelling Heath.  The view as dawn broke over the heath was outstanding.  This particular SCs  had been taken to Kelling from The Astronomy Centre by Peter .Drew and some other members.

1 hour ago, Flame Nebula said:

Hi Paul, 

How do you rate the Askar refractors to other brands, like SW, Tak? 

Well, all of these makes produce some great scopes, and I've enjoyed owning and using samples of all of them over the years.  

The most important thing to me is clearly the optics have to be of a good standard, and after that it's if the scope I'm considering buying has other features that may be particularly useful for the purpose I have in mind for it 

Many four inch refractors have good optics.  I went for the Askar because it had a few features that swung it for me such as two finder feet, a handle you can fit accessories to easily, binoviwer friendly   calibrated rotating focuser which is a rack and pinion etc etc.  Other observers will have their own priorities.  

Personally, I don't feel any make of scope is better than all of the others in all aspects, it's a matter personal preference.  We are very lucky in that there are many good quality manufacturers out there.  Certainly many more than there were fifty years ago!

1 hour ago, Nicola Fletcher said:

That would be amazing.  I would probably choose another top scope if I was able to travel with something bigger. Problem is, there’s a risk with a bigger scope that you might have to check it in. I don’t know if I could cope with the stress of that. If my 4” was airline portable that would be ideal - but I just don’t think it is.  There is zero hassle associated with the 3” that splits in two and goes in my camera bag with my camera and can be mounted on a photo tripod. It also weighs practically nothing. My ears always prick up though when I hear of people bringing bigger scopes on trips away!

Yes  I'm lucky Nicola in that the Askar triplet has a removeable four inch section  of tube which brings it down to 21.5 inches long, and if that's not enough the focusser unscrews which brings it down to 15 inches. Just a shame I'm not going anywhere at the moment. 😊

1 minute ago, JeremyS said:

Ah, you mean a TSA 120 or TOA 130, Paul.

🤔

I've had a TSA120 Jeremy.  It wasn't too bad. 😊

I agree with you Nicola.  But if I was lucky enough to be able to go to the S hemisphere I'd take  something smaller than I use at home  perhaps my four inch triplet or 130PDS.

1 hour ago, Flame Nebula said:

I think this scope is winning the keepers competition, so far. 

Not necessarily, users of other makes and apertures of scope just don't feel the need to go on about them all the time. 

Personally, I'd prefer to have something with more aperture that was more useful for deep sky as well as planets and double stars 😊.

You're welcome.  I think you get a great deal for your money, and FLO have knocked the price down from £999 to £949? But I guess you know this 😊.

It's not likely, but if you live within a reasonable distance of BD22 I'd be happy for you to pop along with your binoviewing gear to actually try it out if you're considering buying one.  It's always so much a gamble buying something if you haven't had the chance to try it out.

49 minutes ago, Space Hopper said:

So how does it perform visually with the binoviewers Paul ?

Assuming it can focus natively minus the tube extension........but do you then have sufficient 'out' focus travel if you want to crank the power up a bit ?

Or do you have to refit the extension again for that ?

Just wondering, as I use a Baader bino, and you need a focusing range of 65-70 mm to view natively at one end and then using a 2.6x multiplier (gpc) at the other.

I can comfortably do that with my own scope, and there's not that many refractors that will allow this as a rule of thumb, usually something imaging optimised with a lot of in focus.......

Space Hopper.

My binoviewer is a Baader Maxbright v1 and I was using x2 24mm Orthos. At infinity the graduated tube was at 40mm, leaving 60mm infocus left and 40mm out focus left.  I was using a T2 Baader/Zeiss BBHS Prism with a 2inch Baader clicklock at the eyepiece end and a 2 inch nosepiece at the scope end.

I've mentioned all this because of course it will be different if any of these are different in your setup.   

If you mean you want to put the power up you can just use shorter focal length eyepieces or your multiplier.  I've not used a multiplier and don't know it's affect on the focus position,   it may not have any?

I really don't think you'd have any problems, after all the graduated focus gives you 100mm to play with, and there are many other ways you can change the focus point - eg the light path through various diagonals and prisms.

Remember also, there is 100mm extra infocus as the 4inch section of tube has been removed.  I  can't imagine many other refractors being so binocular friendly.

I hope this is of some use, but feel free if there is anything else I can do to help.  You probably know most if not all of what I've said as you already use a binoviewer, you may know a lot more - in which case I apologise.

Yes, I agree with you Mark.  I particularly like the two finder feet and being able to attach other items on the handle and dovetail.  Its very compatable with adapting it to Starsense use which is one of the reasons that attracted me to it.  There are many other features I could mention, and not only the price!  😊.

18 minutes ago, Stu said:

My like was for the second picture 🤣

Looks like a really well though out scope Paul, great optics and flexibility too. Out of interest, how much does it weigh, with rings?

Planning any trips abroad? Could be good!!👍 

According to the spec it's 5.5Kg Stu.  Sounds about right, before I read the spec I thought it was 12.6lbs.

I've been thinking of a trip abroad sometime, but health wise following a heart procedure in Dec I'd have to talk to the medics. 😊. And get a new passport 😀.

I've had my Askar since last year. As some folks will know, it has a four inch section of tube which can be unscrewed.  This is to facilitate inserting reducers and field flatteners for astrophotography.  Its also for using binoviwers without having to use barlows  or other means to bring them to focus.

I'd never done this until this afternoon, as I didn't think it a good idea to have to take out a section of tube and reassemble it outside in the dark if I wished to use it with and without a binoviwer during the same session. Anyway, up to now I had only used my binoviewer for planetary and lunar observing.

It hadn't dawned on me before today, that this problem could be solved by taking out the section of tube permanently and just bring it back into monovision by just using a couple of two inch extention tubes after I have finished binoviwewing!  

I removed the tube section, and, of course, it all worked very well.. A shame it took so long for the penny to drop 😂.

Another advantage in removing the tube section is that with a two inch prism on board it is now only 21 inches long with the dew shield retracted.  If necessary for travel purposes the focuser could also be removed and this would reduce the length to a mere 15 inches long.

Can't wait now to get some low power binoviewing time 🙂.

Sorry I'm in one of the pics, my wife refused to be the model!

I'm very happy with the S50.  I think to throw £4k at the Celestron now would be a huge gamble.   I'll stick with what I've got - certainly until Seestar Mk 11 is unveiled.  If Seestar can market the S50 for £500, just think what  we might get for eight or even twice the price 🤗.

Thanks for all the info Steve, it's very useful.