Refractor producing ghost reflections of bright star - Forums

My Takahashi TSA-120 is giving me the following issue. I only started seeing this in the last month. The scope is almost two years old, no drops, or shocks, travels in padded case from closet to patio and back.

After meridian flip:

This same pattern shows up in all filters (above are Lum), on two separate cameras (ASI294MM using Astrodon filters and ASI533MM using Chroma filters).

After calibration and alignment, it shows as two ghosts, one on either side of the star:

The above image is IC348 using ASI533MM, Chroma filters and 0.7x Tak reducer. I get the same thing using just the flattener:

It is obviously some kind of reflection from the telescope. There was an incident where a surprise rain shower came up and there was rain on the objective before I could get it covered. After drying, there were water spots, so I carefully cleaned the objective using Takahashi blue fluid cleaning kit. I do not see any obvious spots, or smears, and nothing shows up on flats. I flipped both sets of filters, no change. Maybe coincidental, but I don't find any of these "ghosts" in images prior to the rain shower.

Any suggestions on how I can locate/fix the reflection source? Or do I need to send the scope to LST for repair?

Thanks for any input!

CS - Larry

Also of note, I did a visual star test on the IC348 star and other bright stars with eyepiece, and it appears perfect. Defocus give concentric rings with no deformation. This leads me to believe it is not a collimation issue.

Did you shine a flashlight down the OTA and look for dew residue on the rear objective? Found this on a used esprit I purchased recently. I don't blame the seller, you'd never see it unless you were specifically looking for it. A friend had the same thing on his scope.

Thanks for the response. I have shined a red flashlight from the objective end and not seen anything. Do you suggest shining it from the focuser end?

If there was residue on the rear objective, how could I remove it. I don't believe the objective lens cell can be removed, at least I have not been able to budge it, and I would be afraid to upset the collimation.

Was your friend able to resolve the issue?

Thanks!

CS - Larry

Ok, I dismantled everything from the focuser draw tube, and shined a bright flashlight from both ends, nothing of note on the objectives, just a few fine dust particles. There is a small (2-3mm) glob of something between objectives right along the rim, but that has been there since day 1. No reflections noted in OTA tube or draw tube when shining from objective and looking from focuser. This is really a mystery!!

Going out on a limb here… maybe I’m totally wrong, and if I am maybe I’ll learn something…

If the reflection or whatever it is is scope related, wouldn’t it stay in the same spot after flip?

You would think so, but the same thing happens with two different cameras and filter sets. Here's the same object with the ASI294MM and Astrodon filters:

Before flip

After flip

After star alignment and integration there is a ghost on both sides of the bright star:

After, stetching, LRGB processing and some noise reduction, you can see the two ghost smudges mostly contain the blue color of the bright star

To me the fact that the same thing happens with two different imaging trains indicates it must be the scope. After flip, the reflection has moved with the star and is about the same distance from the star, but 180 degrees on the other side of the star. Driving me crazy, about ready to send the scope back to Land, Sea, and Sky...

I was thinking maybe a terrestrial light source.

Yeah, that would seem logical, too. But there aren't any light sources that shine into my backyard. The only lights are two neighboring porch lights about 150+ yards away, but they are well shielded and only shine down on their porches, and almost always off by 10 PM. Both times I tried this target, the time span was about 6:30 PM to 3:00 AM. I wish that was the cause, but I don't see it. Also, I had another telescope imaging close to the same target (FSQ-85EDX) only about 10 feet away on the same patio, it does not show any extraneous reflections. Good guess, though!

Larry S:
Thanks for the response. I have shined a red flashlight from the objective end and not seen anything. Do you suggest shining it from the focuser end?

If there was residue on the rear objective, how could I remove it. I don't believe the objective lens cell can be removed, at least I have not been able to budge it, and I would be afraid to upset the collimation.

Was your friend able to resolve the issue?

Thanks!

CS - Larry

For us it was very easy to remove the lens cell, just three screws and a washer. I was a little scared to do it at first, but Kevin at Skywatcher gave me the the basic directions and assured me it would be fine. No need to recollimate. Took 30 minutes from start to finish, cleaning with some isopropyl. There's no doubt theres something SOMEWHERE on your lenses. You'll just have to find it. Looks like it's just a couple mm off dead center in one of your objectives.

Keep in mind, my situation may not be as simple as yours if it comes down to disassembly, but after talking to others, it's just maintenance we have to do every once in awhile to keep them in top shape, especially when they stay outside for extended periods of time.

Brian Puhl:
For us it was very easy to remove the lens cell, just three screws and a washer. I was a little scared to do it at first, but Kevin at Skywatcher gave me the the basic directions and assured me it would be fine. No need to recollimate. Took 30 minutes from start to finish, cleaning with some isopropyl. There's no doubt theres something SOMEWHERE on your lenses. You'll just have to find it. Looks like it's just a couple mm off dead center in one of your objectives.

Keep in mind, my situation may not be as simple as yours if it comes down to disassembly, but after talking to others, it's just maintenance we have to do every once in awhile to keep them in top shape, especially when they stay outside for extended periods of time.

Brian, thanks for the response. I can't find any screws at all near my objective. I took off the dew shield, there was a front cover ring on the end objective that I removed, but no screws. The manual even mentions the "pull screws".

I also read elsewhere that Tak changed the TSA-120 lens cell design and eliminated the collimation adjustment, and consequently the lens cell is no longer removeable. I guess I will need to call Land, Sea, & Sky to see what they say. Mine is a late 2021 model.

For what it's worth, this is what I saw. You could ONLY see it with a bright light shining at a specific angle. So very strange. It was an obs scope, so it had plenty of superficial indications of its time outside. It looks WAYYY worse than it was. I'm telling you, you only saw it if you were looking for it.
It doesn't sound line yours is as bad though. Certainly annoying unfortunately.

OK, thanks. I will try using a brighter light from different angles.

FWIW, I found this in the front of the TSA-120 manual:

So, I guess, it will be shipped back for service... Very disappointing, until this Fall, the scope was a solid performer.

Larry S:
OK, thanks. I will try using a brighter light from different angles.

FWIW, I found this in the front of the TSA-120 manual:

So, I guess, it will be shipped back for service... Very disappointing, until this Fall, the scope was a solid performer.

It also says for cleaning to contact your distributor before proceeding for the correct procedure...soooo which one is right?

Anyways good luck. I'm sure with a little patience you can find the source.

Thanks for pointing me here, Larry. First, as an AP scope owner for 35+ years, I would send anything to Tak for repairs if you feel they are warranted. Your warranty should not be waived for expedience.

Let me check for accuracy: with filters, you don't see the reflections without an FF or FR, correct?

Did the dew shield extender make any difference?

If not, is it possible that internal surfaces of the body of the FF/FR have developed a reflective surface on the inside? If we assume they do reflect, then rotating the camera/filters should show variation in the location and/or spacing of the reflections.

In the end, Tak has an autocollimator at their disposal that can map surface deformities and may help analyzing these results. A set of samples will guide them, e.g. rotated 0, 30, 45 and 60 degrees, with FF and FR in groups. Gathering the data may lead to your own determination of the cause. But correcting the error, leave that to the people who warrant their excellent products and trust they will help. Like an auto mechanic, give them all the data you can to guide them.

Sad you ran into this; I wish you well resolving it.

Randy,

Thanks for your interest and suggestions. I have not tried imaging without FF/FR, but visually, without either, I didn't notice anything like this with any of my eyepieces. I'm not sure that means anything. My eyes are not what they used to be.

But I may not have been clear that I have the same issue with both the flattener and reducer. There is just a slight difference in the distance from the bright star to the reflection.

There has not been a clear night since I got the dew shield extender. It looks like maybe New Years night might be clear. If the problem persists, I will be sending it to Tak.

Happy 2024!

Larry

And a happy 2024 to you!

The TSA-120 was sent to LSS in Houston, and now will be taking a round trip to Japan. 6+ months estimated turn-around. Not covered by warranty.

I would advise Tak TSA owners to avoid getting ANY liquid around the edge of the front lens cell. No cleaning solution and especially NO RAIN.

Hi Larry, only just found your post. I have exactly the same problem with my TOA150, with very bright stars I get a blue smudge to one side of the star before a meridian flip and exactly the same distance on the other side after. Very similar to your images. The lens does have a small mildew patch around a dust spec on the inside surface, slightly off centre. With some trepidation I plan to remove the lens cell (just 3 screws on the TOA) next week and clean the inside surface with acetone. Even if this isn't the cause, the mildew needs removing anyway before it does any damage. My scope is way out of warranty and I don't want to send it off and be without it for months. I'll let you know how it goes.
CS, Roger

Roger Gifkins:
Hi Larry, only just found your post. I have exactly the same problem with my TOA150

Good luck, Roger! The lens cell on the later model TSA-120 is not removable by end user. Also, LSS is unable to clean it, so I'm assuming there is something between lens elements, hence the trip to Japan. Talking to an LSS rep, it was related that moisture infiltration is a problem with the air-spaced triplets, but the TSA is more prone to it than TOA. I wish I had known before buying it. The estimated repair and shipping costs are roughly half what I paid for the scope initially (possibly more if lens elements need to be replaced). Moisture infiltration is not covered by warranty. I plan to sell it after repairs. Someone who would use it for visual observing would be well served by the TSA-120, and likely never expose it to a possible surprise rainstorm (sometimes a risk with automated astrophotography). I also have a Tak BabyQ petzval that went through all the same conditions (almost always used the scopes simultaneously) with no adverse effects.

Clear skies,

Larry

Larry S:
My Takahashi TSA-120 is giving me the following issue. I only started seeing this in the last month. The scope is almost two years old, no drops, or shocks, travels in padded case from closet to patio and back.

Hi, Larry S .

I have an FSQ 85 ED, and I noticed that I have a reflection at a brighter star in the center. I investigated and it is from the 1.01x flatener on the focuser. There is another problem, and if the filters are further apart, they are closer, as is the case with my Starlite filter wheel with unmounted Astrodon 36 mm filters.
After I removed the flatener, I have no more problems.
The correction on the corners is imperceptible. The camera is ASI 294 MM Pro.