(UPDATE WITH IMAGES) Strange star shape through refractor??

[E_ri_k]

Hi all, I'm kinda freaking out a bit because something strange happened during an observing session last night with the TAK. I was out on Sunday night with no dramas. Went out last night and every star when in focus appears like a pinpoint, followed by a huge teardrop shape.

I didn't think of getting image of it at the time, but I'll try next chance I get. I don't know what it could be, I haven't bumped the scope at all or anything. It goes from its box to the mount and then back again.

I don't want to start adjusting its collimation or anything I'm not familiar with.

In the meantime, does anyone have any suggestions?

Erik

[ZeroID]

Dew on the lens ?

[E_ri_k]

No, there was no dew anywhere, or dust from what I could see.

[Akwestland]

Erik,

I am sorry that I cannot offer anything with your problem. However I would like to say hello as there are people out here that are on IIS. Reason being that I do not live far from you. Where do you do your observing from out of curiosity.

Anyway, G'Day.

Cheers,
Andrew & Kim.

[Exfso]

Erik, first of all do not touch the collimation on a Tak refractor, leave that up to Takahashi, no one else knows what to do with them. I can speak from experience on this matter. That is the content of another thread. My first toa130 had astigmatism and was sent back to the factory under warranty and they replaced the whole telescope. The star shapes on this were of a sort of triangular shape. It would be much easier to view an image of the star shapes to form an opinion.
Just briefly I managed to knock the collimation out of kilter when the scope clipped my roll off roof. At the advice of the Australian distributor I sent it to a mob in Sydney who he said were qualified to collimate my TOA130. They basically trashed it, and it had to go back to Japan to be rebuilt back to new specs. That company in Sydney has since ceased trading, which is not a surprise to me.
What I am saying is. if it is out of collimation, send it back to Takahashi, let no one else near it!!!

[E_ri_k]

Thanks for the advice Peter. Yes I was wondering if there was anyone in Australia able to work on it, but I'd rather send it back to Japan for safety's sake.

I will try get an photo of what I'm seeing when it clears up.
Erik

[E_ri_k]

Ok, so the problem persists, and the objective appears clean and no traces of dew.

Managed some quick shots between the cloud. One out of focus, and Two as close as I can get in focus. It is a bit tricky as the aberration is quite strong.

Hope someone can shed some light on this. Spoke to Calude from AEC and I'm liking at over 1K for shipping and collimation by Takahashi.....

Erik

[Hans Tucker]

Why not drop Fred at TNR a e-mail and show him these images. He might be able to assess the problem and provide some advice.

Personally, if it were me and it was confirmed a collimation problem and it was going back to Takahashi I would give trying to collimate the cell myself with the caveat that I remember what screws I turned, how much I turned them and in what order.

[E_ri_k]

Thanks. I'll email them and wait to hear what they say. I don't know what else it could be other than collimation.

Thinking back to when it happened, I do remember the dew shield sliding down because I didn't tighten the lock screws enough. It hit the collar which it rest on, but not very hard, and I didn't think anything of it, and I can't see how that could shift the lens cell???

Either way, I'm not really game to touch anything. There are Six adjustment screws from memory.

Erik

[Hans Tucker]

Pinched optics is another probability.

Interesting that Takahashi Mewlon owners will collimate their mirrors but refractor owners are scared to touch their optics given that both scopes have the same collimating screw push-pull pair arrangement.

[E_ri_k]

Any thought on how the optics may have become pinched? Not so much a fear of collimating it, just being cautious. I'm sure its straight forward, as with a Newtonian. Only I have read over and over again not to touch it, as other people have done so in the past and damaged their TAK refractors.

I have the TAK collimation scope which I use on my RC with ease, and the documentation clearly shows how to collimate a refractor, I would just need to have an adaptor made up so it can thread in to the refractor.

My only concern is, if I break something, it may end up more expensive to fix than if I don't....

Erik.

[ericwbenson]

Hi Erik,
That image is an absolute textbook case of coma, pretty bad too I might add, I have never seen it so clearly exemplified :(
Check out 'coma optical aberration' with google images. One (or both) of the lenses is decentered, that's really bad luck.

EB

[E_ri_k]

Hehe, well I'm glad I have a good example of it at least......Bad luck seams to have been affecting me quite often lately...Typical

Fred from TNR seams to think that something may have been loose to begin with and the subtle impact of the dew shield has caused something to shift.

On the bright side, perhaps this is a good discovery of a potential future issue?

Off to Japan I guess :(
Erik

Erik

[Hans Tucker]

Throughout this thread you haven't said what Takahashi refractor this is. Is it a doublet or a triplet refractor. If one of the lens element has shifted I guess this could cause the so diagnosed coma. Either way the skilled Takahashi technicians will make it better. I had to send my FS-78 back to Japan for a bit of a clean and alignment after one of the collimation screws came out completely and was rattling around in the dew shield. I was scared it scratched the front element of the objective which is the fluorite element.

[E_ri_k]

Good point I should have mentioned! It's a TOA150 triplet.
Erik

[brian nordstrom]

:question: Looks like a baffle has slipped into the light cone slightly ? , seen this once before .
Worth a look into .

Brian.

[Kunama]

Eric, is this what it looks like straight through viewing, i.e.. without a diagonal?

[Exfso]

That looks exactly like my TOA130 when it got clipped by my roll off roof. It was knocked out of collimation. I would bet my left one that this is out of collimation. I can give you the Takashashi email contact who will send it to his engineers for their take on it.
Email me. exfso2@adam.com.au

[LewisM]

A TOA150 or 130 is NOT a telescope I would recommend collimating at home, considering the layout of the elements (NOTHING like a regular doublet or triplet). Send it to Tak. NO ONE ELSE. Peter gives VERY sound advice.

[E_ri_k]

Thanks Brian, I will have a look through the objective in some bright light.

Yes it is, same result with Two different diagonals, and straight through.....



Thanks, I'll email you :)

[E_ri_k]

Yes, that's my understanding also. I doubt think there is anything I can do myself. Certainly not if the objective elements may need to be taken out or if it needs opening up. I'd rather leave it to the experts.

Erik

[LewisM]

The spacing on the TOA elements is the difference. TOA is an Orthoscopic Triplet... and the elements are not conventional in their layout.

There was an internal schematic of the TOA's online, but now I cannot find it. Perhaps someone else can?

I certainly would not mess with a TOA. I HAVE recollimnated an FC doublet after someone BADLY recollimated it (I had even placed collimation marks on the periphery before I sold it, and when I got it back, they were out by around 40° in the cell!), and I have collimated a quadruplet (Vixen DED108SS). Easy enough (though time consuming). No expert, far from it, but a TOA... no thanks.

[Exfso]

Hans, I have actually been on the phone to Fred at TNR a couple of years ago and he gave me a rather comprehensive run down of the Tak TOA's and basically said that they were much different to collimate than the conventional APO triplets and he most definitely would not feel comfortable trying to talk anyone through collimating one. They use specialised equipment for their collimating which I believe is not available to the general public. It may even be something that Takahashi developed, but that is only supposition on my part.:thumbsup:

[Kunama]

My understanding is:
The TOA cell has 18 collimation screws on the front of it, 9 are for collimating the 'whole cell' in relation to the tube, another nine are for the alignment of the first element in relation to the second element.

If the whole cell collimation is out then the deeper recessed screw set can be used to collimate the whole triplet assembly. This can be done with the Tak collimation scope. However, if the issue is miscollimation between the front element and the second one, i.e. the less recessed 9 screws (3 cap screws for the 'pull' action and 6 grub screws for the 'push' action) one will need the specialised equipment not available here in Australia.

I guess the issue is to establish if the miscollimation relates to the whole cell and its relationship to the tube or an element within the cell being out of line.

That's my understanding from looking at my TOA and reading stuff ...... It is a lot different from the FS78/FS128 etc
Haven't seen this on any other cells.

Personally I would firstly check if all the screws actually have equal tension on them but firstly I would mark the screws and note if and how much any are loose by.

[E_ri_k]

Well all sets of screws are tight, and visually I can't see anything out of place when looking down through the tube.

Waiting to hear back from Takahashi, presumably during the week sometime.
Erik

[E_ri_k]

Just incase anyone is interested, the TOA 150 has been sent back to Japan, thanks to Claude at AEC. Been about 1 month now. Eagerly waiting to get it back.....

[sharpiel]

Any idea of total cost involved in the transporting and fixing Erik?

[DavidTrap]

Fingers crossed for a safe and speedy return.

Very glad my TOA-130 arrived from Perth in good nick - Bob packaged it up beautifully. Was relieved when a quick star test tonight revealed a beautiful concentric airy disc pattern.

DT

[E_ri_k]

Not exactly sure Les, but from Claud's estimate, roughly $500 for the collimation, $700 to clean the optics, and just under $1000 in shipping back and forth. Not cheap, but It will come back basically new I guess.


Glad to hear! What was the story with your TOA?

[DavidTrap]

I bought the recently advertised TOA - only had a brief chance to get it outside last night. Waiting on a few more bits to arrive from various corners of the globe. Then I'll have to see if it lives up to expectations on the imaging front!

DT

[sharpiel]

Well...here's hoping I never need to do the same with mine :eyepop: