F15Rules

2 hours ago, badhex said:

Thanks for this! Most illuminating so to speak. I am currently playing around with my Evostar 80ED which also has an aperture mask (I think 50mm, which would make it F12) built in to the end cap, so based in your reports perhaps I'll have a play with that too. 

I've also noticed @HollyHound has an FS60-CB up for sale, which would go nicely with a Q extender! If I were in the UK I would be sorely tempted by that 😅

Well, F12 would be a lovely focal length..about 10-12 years ago I had a Pentax Japan J80 F12 achromat..it was a truly wonderful scope, and gave me a view of the double double in Lyra which has only been matched my my FS128 and a D&G 128mm F15 achromat..a 2 metre long scope!!

The ED80 is a very nice scope, so at 50mm  F12 it should be a very interesting comparison!

Dave

Stopped down aperture experiment Part 2..

Part 1 looked at the first 3 targets on my list, now Part 2 looks at the remaining 3 targets:

- Epsilon Lyrae (double double), M57 Ring Nebula in Lyra,  M13 great globular cluster in Hercules.

- Epsilon Lyrae: the famous double double is a classic "celestial lollipop" often recommended for new observers as it's such a showpiece double star..each component of which is itself double. 

Keen eyed observers can, I believe, split each pair at c 60-70x magnification..I don't think I have ever managed the split at much under 80x, and nowadays I find  I need 90-10x to get a comfortable split🥴.. but it's a lovely system, with each pair at more or less right angles to the other, and all 4 components of similar brightness.

I do remember splitting epsilon with my Prinz 550 60mm F15 refractor at the age of 15..in those days I only had 0.965" eyepieces with narrow fields of view, but the two pairs were nevertheless stunning. And long focus fracs do throw up beautiful stellar images, with fine airy disks with usually a single diffraction ring on half decent nights..and so it proved with the FS128 stopped down to 50mm F20. Due to the poorish seeing, the sharpest image was seen at the 50mm aperture, although it clearly was a good deal dimmer than at 128mm. On a good night of seeing, the full aperture would definitely have been more pleasing, but tonight the F20 view was definitely the best.

M57 Ring Nebula in Lyra. Perhaps not surprisingly, this object can prove a bit disappointing at first look..it's quite faint in small to medium scopes like mine, and being below 9th magnitude. Moreover, it's not a big object, although I find it quite easy to locate: I usually use a low power wide angle eyepiece as a finder in the main scope as my 50mm Raci is only 9x magnification and so doesn't always show it.

This object gave the most "expected" view..ie the 50mm aperture view was the faintest, although it was obvious as a faint donut shape..I've always found that the Ring takes magnification well, surprisingly, despite it's faintness..higher power darkens the sky background, so increasing contrast. Moving to full aperture then, the donut shaped ring stood out well, even up to 200x, although little detail was visible, and I've never seen the central star..at c mag 13.5 it's beyond a 5" scope, certainly to my eyes!

Finally, M13, the Great Globular cluster in Hercules. A long time favourite target of mine, now fast sinking in the north west.

I looked firstly at full aperture to get my bearings so to speak..I know what to expect of this object..a small but quite bright nebulous disk at low power (50x or so), and in my Axiom LX 23mm at 82 deg fov it was a lovely sight, framed against a background of fainter stars..

What I love with M13 is that you can start at low power, and gradually move up through higher powers and see more detail at each step..beyond c100x the views become more detailed as more individual stars begin to resolve, beginning with mag c10, then increasing numbers of scintillating faint but distinct tiny points of light popping into view around mag 11-12 with each successive magnification. 

By 200x, the sky background is black, and many individual stars are resolved - this is the joy of refractors! - both with direct and averted vision. And the cluster grows in apparent size, giving a real 3D effect as the resolving stars seem to be in front of the unresolved main body of the cluster in the background.

Moving to 50mm aperture I had to manage my expectations, but in fact the image, although small and much fainter was sharp and clear. As I racked up to c 115x I still got the improved contrast, just to a much less degree..a small number of individual stars of c mag 9.5-10 did begin to resolve, but only with averted vision, and intermittently. I didn't see the Propeller in either mode tonight, although I have seen it at 127mm several times, albeit not clearly (more my ageing eyes than the scope, I think). But I really enjoyed the views at both apertures.

So, what conclusions did I draw from this one session?

1. IMHO, Daniel's reports are based on good observing experience. I was pleasantly surprised at what I saw in my one scope used at very different apertures.

2. I think that local sky conditions will affect how the lower (and higher) apertures work here in the UK. But I am sure that it's worth experimenting and great fun to do so ..almost like discovering a new scope within your scope!

3. In order purely of my own experience in this one session, this is the order in which I would place my 6 targets in order of observing satisfaction at the 50mm aperture:

 a) (best) - Epsilon Lyrae   b) Pleiades                c) Vega, d) Jupiter                                              e) M13 Globular, Hercules f)  Ring Nebula M57 Lyra.                   

4. Many of our younger friends on SGL (say under 45years) may very well have never looked through a long focal length refractor before..I know that many are intrigued, but put off by the thought of using and balancing a long scope tube, and whether their mount will be steady enough? Well, here is a great way to bypass those concerns..just making a simple mask of say 50-60mm from card etc..on a 100mm F7 scope this will give you at 60mm an almost F12 focal length - plenty sufficient for you to see how good stellar images especially can be at a long focal length..sure, the fov will be narrower, but for observing doubles etc and planets this won't matter at all. Just remember, aperture always rules on fainter objects, but on nights of poor seeing but good transparency you may just find that that " it's not worth going outside tonight" night might just become very worthwhile indeed!

I, for one, intend to make such a mask and do more of this kind of observing this winter..as suggested by Jeremy previously Polaris and Mizar will be on my next list.

Thanks for sticking with this and do share your experiences if you have a go..(maybe on the observing forum..Mods, please move this post if you feel it should be over there?).

Clear Skies,

Dave

1 hour ago, JeremyS said:

Interesting experiment, Dave. Looking forward to part 2

Maybe have a go at Polaris?
 

Yes, Jeremy, good idea..I was also thinking the Mizar system as well..😊

Dave

Rather belatedly, here are my Part 1 thoughts from my session on Friday night. Part 2 to follow😊

Equipment used:

FS128 scope on Tak EM2 driven equatorial mount.

Eyepieces: TMB/Burgess 5mm Planetary series, Morpheus 9mm, Pentax XL 10.5mm, Morpheus 17.5mm, Axiom LX 23mm. All used in 2" sleeve mode.

Also used, Baader Zoom barlow 2.25x.

Conditions: Seeing poor to fair..after days of very changeable weather, and more rain in a week than for 5 months, the atmosphere is very active and unsettled. Transparency was good, however, with the Milky Way showing well right overhead.

Aims of session: to test and compare my FS128 apo at full 128mm F8.1 aperture, and at 50mm F20 stopped down aperture. This was following a link posted by Jeremy S from CN claiming that small c50-60 mm apertures can, on the right objects and under the right conditions get much closer to larger aperture performance. Here's the link in question:

https://www.cloudynights.com/topic/633339-put-your-stars-on-a-diet/ Author Credit: this article was published by Daniel Mounsey, and makes fascinating and thought provoking reading.

The central "challenge" of Daniel's article is for us to not be so conditioned to observing the way we have always done that we can't or won't look seriously at other ways of observing and using our existing equipment.

In my own case, I confess it didn't really occur to me that it could be worthwhile using my 5" apo at 2" aperture..and indeed why would it? (Even though the scope's maker, Takahashi, had seen fit to supply the scope with a 2" aperture removable disk in the centre of the dew shield)..if I had ever thought anything about this feature, it was probably that it would/could only be useful for solar projection or some such thing that didn't interest me.

But reading Daniel's piece, and his detailed and well argued reasoning, I was intrigued enough to give it a go..

I didn't have that much time, so I selected several targets, with the aim of comparing the 5" and 2" views through the same scope, with the same eyepieces, and trying to assess and describe the key differences and similarities that I saw.

Targets ( in the order I observed them):

Jupiter, Pleiades, Vega, Epsilon Lyrae (double double), M57 Ring Nebula in Lyra,  M13 great globular cluster in Hercules.

Jupiter:

At 128mm F8 - very bright at low power (too bright), 45 x and 60x. Very sharp. Two main equatorial belts seen and of a darkish brown colour. At higher power ( 99x and 115x), larger, fainter disk but few additional details seen as seeing was not cooperating. The main two belts did just hint at some structure, but the atmosphere would hold still long enough for this to be satisfying. The 4 main moons were clearly shown as tiny disks at all powers. I tried the TMB Burgess 5mm for 208x but just far too much for the conditions and a wobbly mess.

At 50mm F20. At the same powers as per full aperture, the disk was noticeably fainter, but more comfortable to look at as there was less sheer brightness. The same two bands were visible, but paler in tone. The satellites were fainter, but pin sharp - not seen so much as disks but tight stellar points..more than once I felt I saw a single diffraction ring around a couple of the points. At the medium powers the view did become more "woolly"..but apart from the different brightness level, I could see as much (or as little) detail on Jupiter as I could at full aperture.

Pleiades: I felt that this object was the one where on this night the views were most similar..at 45x at F8 (82deg Axiom 23mm LX) I could almost get the whole asterism in the fov, at both apertures..but what really surprised me was how similar the two views were, despite the 5" to 2" difference in aperture! Sure, the 2" view was clearly fainter, but the stellar images were pin sharp, and easier to fine focus (due to the long F20 focal length adding depth of focus?). The little asterism of 6 main stars leading off in a line was visible with direct vision at both apertures, and 2 of the 3 fainter stars close to this line were visible with averted vision at 2" as well! No sign of nebulosity at either aperture, but the cluster was still quite low down at this point.

Vega: a beautiful star at any power or aperture, this was a joy at both apertures..and I could see Vega's faint (optical double?) 10th mag companion star at c 5 o'clock position with both apertures..direct every time at 5" and with averted vision and some direct glimpses at 2". No false colour at all, just a lovely pure white point.

To be continued, with conclusions..🙂

Dave

1 hour ago, Stephenstargazer said:

I do think the variation between different manufacturers 'Vixen' rails and clamps is getting worse, and dont even start me on incompatible finder brackets.

I agree..the vast majority of "Vixen" aftermarket accessories like dovetails etc have nothing whatever to do with Vixen..they are Chinese knock offs, often to incorrect tolerances and inferior design/build quality. If you want a true Vixen product you need to buy it from añ authorised Vixen stockist..

Dave

Hi Alan,

SO sorry when I heard about this calamity..as a previous delighted owner and user of two of these fantastic scopes I can feel your pain and loss at such an awful incident.

Thank goodness your insurer is doing the right thing Alan..and I know the temptation is to rush out for another scope, but I really hope it proves possible for you to source another Vixen apo..they are superb scopes, right up there with Takahashi IMHO. If they had offered a 5" Apo I would have happily gone for one instead of the Tak 5" I was lucky enough to see on sale almost 6 years ago.

Do let us see your replacement scope once it's all sorted out..👍

Best wishes,

Dave 

I had an interesting hour outside last night..

Picking up on Jeremy's link to the (excellent and fascinating) CN thread where a member was extolling the virtue of small aperture objectives, and how he "masked" down his FS128 to just 50mm by removing the centre section of the dew shield, I decided to have a try myself. 

I'll write that up this evening all being well, but for now suffice it to say that it was quite an eye opening experience!

Here's a couple of shots of "Trinity" at full 128mm aperture and also masked down to 50mm😊.

Dave

On 30/09/2022 at 12:49, JeremyS said:

Congratulations Malcolm. A fine scope if ever there was one.

It’s probably bad form to link to another Forum, but if you have not read the first post in this thread, you should (and I suspect you’ll read the whole thread). It’s not specifically about this scope, but summarises by high quality small scopes can be so attractive.

https://www.cloudynights.com/topic/633339-put-your-stars-on-a-diet/

Also have a look at what this guy does: https://www.fzu.cz/~kupco/astro/equipment/FOA60.html

 

Great link, Jeremy, thanks👍.

Very thought provoking and a great read (which I will read in full later this evening)..at 50mm aperture my FS128 would be over F20..😱😁..

..but if I made a 69.3mm mask, it would be an exactly F15 apochromat..👏😎.

As the saying goes, F15RULES!

Watch this space!😂

Dave

I had no response to general inquiries to Altair Astro some years ago and haven't bothered since.

I suspect some of these companies are very small, and  born out of their hobby, so perhaps not business savvy?

Nothing wrong with that, perhaps, but their slowness to reply to enquiries, could, for all they know, lead to them not picking up good future business..

By contrast, I sent an email question to FLO earlier this week..I got a reply from Grant the same day.

Enough said.

Dave

3 minutes ago, Chaz2b said:

I’ve now opened my eyes and it’s SV04047, so a 2004 model and the 47 th made that year. Still don’t know what the SV represents.

And if anyone mentions a connection with SVbony again……..!

chaz

Maybe "Serial Value" or similar??🤔

Dave

35 minutes ago, JeremyS said:

These details about Tak mysteries like serial numbers are more grist for the mill of Tak ownership 👍🏻
Perhaps we should discuss the intricacies of Taks colour scheme changes next: battleship grey, green, baby blue 😊

🤦🤦🤦🤦🤦🥴😭

24 minutes ago, Chaz2b said:

Well, you've just created a conundrum for me, having googled about tak serial numbers and how they're generated, mine doesn't fit the sequence! Apparently the first two had a letter and a number which indicated the reigning sovereign and year, but who/what is SV?

Chaz

Odd. Do you have a photo of the SV details you mentioned?

9 hours ago, JeremyS said:

I’ve got FOMO 🥲

Oh dear, Jeremy..

Perhaps we should revert to the subject of ATHR*** to ease your troubled mind??😋😂

Dave

*** ATHR  - All Things Handle Related

3 hours ago, Chaz2b said:

Wow! Lock ‘n load!

I haven't got round to figuring out the date of manufacture, but I can give my serial number, sv0:047 if that gives a clue. 
 

The serial number is shown on the stamped blue plate with silver script on the top right of the focuser, see photo..

On my scope, shown above, the stamped 5 digit number shows the year of manufacture (first two characters "99" ie 1999), and the number scope that scope was, of that  type, made in that year (008). So, my scope was number 99008 , ie the eighth FS128 scope made in 1999.

HTH,

Dave

1 hour ago, Chaz2b said:

Doesn’t your best deserve the best? Bagged this from Harrisons, £133 all in.

Fitted in seconds! I said..seconds!!

lovely bit of engineering. Takahashi MEF3.

chaz

Lovely addition to a lovely old FS78 👍..looks like yours is a 1994 build, Chaz?

I installed one a couple of years ago on my 1999 FS128, great bit of kit. You got a bargain, I paid more than that used!🤦😊

Dave

3 minutes ago, Space Hopper said:

I'm impressed the AZ100 can handle it with no counterweight.

Although the FS128 is quite a large scope, it's relatively light at just 7.5kg (16.5 pounds), and c 9kg with finder, 2" diagonal etc, so it's much easier to handle (sorry Jeremy) than you might think.

Mine is on a Tak EM2 equatorial mount ( think Vixen GPDX size) with a sturdy solid wood tripod, and properly balanced is a delight to use, and settles within 1-2 seconds. The AZ100 will therefore handle it with ease👍.

Dave

10 minutes ago, Alan White said:

Congratulation on a fine scope, nice aperture and focal length.
Looks super on the AZ100.
Enjoy.

I might have similar news tomorrow if all goes well.

🤔🤔🍿🍿😎😎😁😁!!

Well the FS128 has a VERY happy new owner👍..

More details on the Scopes/Whole setups forum..😊

Dave

1 hour ago, josefk said:

You'll especially enjoy this read now even if you've seen it before. i know i would! http://www.scopeviews.co.uk/TakFS128.htm

Yep, that's a good review, written by Roger Vine, who owned his FS128 for 2 or 3 years then sold it, and bitterly regretted it later..he also rated the smaller FS102 4" sibling of the 128 very highly.

Dave

SO chuffed for you John..

I predict you will not sell this scope..

Looking at your pics, no further words needed from me apart from CONGRATULATIONS 👏🎉!!

Dave

2 hours ago, JeremyS said:

Dave, when you add the 2-inch barrel extenders to the Ethos, the undercuts become irrelevant 😊

Jeremy, I'm sure I could handle the weight, but I couldn't afford the barrel extenders..

Dave

5 minutes ago, Dave scutt said:

Nice postman brought a few items thanks to   @HollyHound.

Can't wait to go home and try them out.

If only they didn't have undercuts I'd have bought them (cost no object!😂🤣)

Dave

On 21/10/2022 at 15:19, HollyHound said:

Few bits arrived today…

Clicklock 2” to 1.25” Adaptor - Got fed up swapping, so now DZ, M180 and FOA60 can all accept 1.25” eyepieces easily again 

Baader ND Filter

ES 24mm 68 - My FC-76DCU has been reverted to 1.25” eyepieces only (keeping it simple) and so this is the new “widefield” eyepiece… I sold my Pan24 last year and long wait for another and Erfle no longer available. As reviews of this one are good, it should be perfect for the role, and slightly better eye relief… it’s also about the same weight as all my 1.25” XWs, so will make scope balancing a non issue 🤞

The ES24 68 is a cracking eyepiece Gary. I've not used a Panoptic 24mm but I know they are revered on the forums. I think you will like the ES 24, very comfortable, well built and delivers nice widefield views.

I bought mine about 8 years or more back when Bresser.de did occasional silly deals on eyepieces..I think to get more units out into the field and build awareness of their products (this was before Telescope House was taken over)..I paid £59 shipped from Germany for mine!😱😎.

Of course, true to form (then..I've learned my lesson since!), I sold it and bought a Vixen LVW 22mm (fabulous eyepiece).

Enjoy yours, and let us have your thoughts post first light?

Dave

1 hour ago, dweller25 said:

Maybe - but it’s less than the price of a new Tak 4” F/8 Fluorite doublet.

Just for clarity - it’s not mine.

I don't disagree, David, but to be paying his asking price, I'd be wanting the original parts that it would have been sold with, including the 7x50mm finder, which appears to have been offered separately, along with the illuminator which Jeremy has got his handles, sorry, hands on..😁.

I think the original (and excellent) clamshell tube ring is included though, and there seems to be an electric focusing unit as well?

I think I'd want to do a physical check on the scope before committing to buy at that price, given his comments about bodywork touch ups and "fair condition". But if all of that checks out ok, you and I both know what a wonderful refractor the FS128 is 👍.

Dave

7 hours ago, MalcolmM said:

I've been trying to avoid this thread but the pull was too much I think the 128 is just too big and heavy for me but I was absolutely fascinated by the Twin Views. Spent half an hour researching them and must have seen the same reviews as @F15Rules; ghosting, only so so on the views but mechanically excellent. Small clear aperture too? Anyway, much as I'd love a pair, just because they are Tak and rare and interesting, I managed to resist. I value my relationship too much

Malcolm 

I felt just the same. The Twin Views look great, but at the end of the day it's the views that count, and for that price you could almost get a pair of new Maxbright MKII's.

At the moment I'm happy with my trusty older Revelation binoviewers, they work well in the Tak👍.

Dave