Cleaning the Tak 😬

[Stu]

I hate doing this job, as I’m always very nervous of causing damage to my favourite scope. The FC100DC is my workhorse really, used for white light solar, lunar, planetary, doubles and a bit of widefield DSO observing too. It travels around with me wherever I can fit it in, and so the objective does pick up a fair amount of muck.

I think this is only the second or third time I’ve done it, and I did the usual of vacuuming around the edge of the objective to clear any grit, liberal use of a bulb blower, gentle brush around to clear any remaining dust, more vacuuming and blowing before going with the Baader Wonderfluid. I soak the cloth well and make sure I dampen the whole surface well before attempting to shift any muck.

Anyway, the job is done now. It is not pristine by any means, and there is definitely some stuff between the two lens elements. Next time I think I might send it to Mr Reid for some more intense attention and a proper service.

I’m not too precious about the scope, I use it a lot and take good care of it, but I guess you have to accept a degree of wear and tear as a result. It has shown me some amazing views, including last night on the Moon and Mars, so it is still going strong. Actually observing Mars at high power was what prompted me to clean it as I was seeing some flaring as Mars passed across the view, and assumed this might be caused by the grubby objective. We will see next time out!

[Franklin]

Looks like a proper job to me👍.

[Roy Challen]

That first pic looks like the reflection of a beautiful starlit sky😀

[markse68]

first pic looks like you’ve been using it as an ash tray Stu! Or maybe for serving peanuts. Wow that was dirty. I’m a bit worried about the primary of my 150p - at first glance it looks pretty reflecty but shine a light and it is dusted with tiny spots. Cleaning doesn’t help so i think it must be oxidising through the coating. It is 30+ years old though

Mark

Edited January 3, 2023 by markse68

[ollypenrice]

According to some sources it is best to clean reflectors reasonably often because pollen can be chemically aggressive. Some insist that you shouldn't squirt the wonder fluid onto the lens but only put it on the cloth. I tend to think that dissolving is the gentlest of treatments so I do squirt the lens but I don't leave it for long and keep it pointing downwards -ish. A dabbing action with cotton wool means there is no need to move any grit relative to the surface. In the end, lens coatings are not like soft aluminium mirrors so I clean mine fairly often (2 or 3 times a year.)

Olly

[Stu]

31 minutes ago, Roy Challen said:

That first pic looks like the reflection of a beautiful starlit sky😀

🤣🤣 I see a few nebulae in there too!! 😬🤣

[Stu]

27 minutes ago, markse68 said:

first pic looks like you’ve been using it as an ash tray Stu! Or maybe for serving peanuts. Wow that was dirty. I’m a bit worried about the primary of my 150p - at first glance it looks pretty reflecty but shine a light and it is dusted with tiny spots. Cleaning doesn’t help so i think it must be oxidising through the coating. It is 30+ years old though

Mark

I know! It was pretty grubby wasn’t it? 😬

There are still a few noticeable bits between the elements but they will have to wait a proper service. Might try to do it a little more frequently in future.

[RobertI]

3 hours ago, Stu said:

It is not pristine by any means, and there is definitely some stuff between the two lens elements

I'm afraid it's ruined Stu, if you want to give it to me I might be able to find a use for it. 🤭 Seriously though, good job, a clean lens is a thing of beauty.

[Highburymark]

I was surprised when I owned a DC that the gap between the lenses is not fully sealed off to the outside world. Maybe this is common knowledge (?) - but If I used a blower around the edge, I could make the few dust particles between the doublet lenses move around, and eventually succeeded in making them disappear. No guarantees using this technique - guess it could also make matters worse, but it worked for me.

[Stu]

58 minutes ago, Highburymark said:

I was surprised when I owned a DC that the gap between the lenses is not fully sealed off to the outside world. Maybe this is common knowledge (?) - but If I used a blower around the edge, I could make the few dust particles between the doublet lenses move around, and eventually succeeded in making them disappear. No guarantees using this technique - guess it could also make matters worse, but it worked for me.

Thanks Mark. It makes sense I guess given that some muck has got in between the elements. I’ll give that a go 👍

[wesdon1]

My goodness @Stu !! That looks like the speedometer on my off road motorbike after a day of racing around my mates farm on it!!?? haha! Joking aside, what I really struggle with, is how in God's good name does dirt and grit find it's way IN BETWEEN two tightly fitted Objectives!!?? HOW!!?? Incredible!! 

[Ratlet]

I had a flashback with that first pic.  Looked like the rig in my student flat in Edinburgh.  4 lads in there and not a hoover between us.  Just kidding cracking, job cleaning it.  Can't blame you for letting it develop.  I'd be bricking it having to clean it.

Good job on the cleaning.  

Edited January 5, 2023 by Ratlet

[Highburymark]

1 hour ago, wesdon1 said:

My goodness @Stu !! That looks like the speedometer on my off road motorbike after a day of racing around my mates farm on it!!?? haha! Joking aside, what I really struggle with, is how in God's good name does dirt and grit find it's way IN BETWEEN two tightly fitted Objectives!!?? HOW!!?? Incredible!! 

I can only presume that the gap between the doublet lenses is not fully sealed off to aid with temperature control? Glass expands and contracts in changing temperatures, so perhaps a small opening helps glass keep its shape? 

[Sunshine]

I'm curious about why you removed the lens cell to clean, is there not a risk of misalignment when reinstalling? 

[Stu]

6 hours ago, Sunshine said:

I'm curious about why you removed the lens cell to clean, is there not a risk of misalignment when reinstalling? 

Because the back had some dust on it too which I couldn’t get to otherwise. Strangely, I’ve never been able to remove the cell before, but this time it unscrewed very easily. The lens elements are held in the cell, which just unscrews and screws back in again so there is no risk of misalignment.

[F15Rules]

Great job, Stu..👍

I was immediately reminded of a few years ago, when I acquired a Vixen ED103s apo whose owner had died some while previously..the scope had sat unused and uncovered in a dusty shed for some time, and so was filthy..

I took a punt on it and spent an hour or so giving it a good, gentle clean with Baader Wonder Fluid and polishing with Renaissance Wax..it came up very nicely, and she is now happily settled with Steve aka  @Saganite

👍

Edited January 5, 2023 by F15Rules
Photos added

[jock1958]

Nice job @Stu Ive done my FC-100DL the once since I bought it in 2018 and it’s probably due another going over.
Hadn’t thought about removing the lens cell to do it though, I just unscrewed the dew shield for access.  

Does the lens cell just unscrew?

[Sunshine]

This is contagious, now I want to clean my lens but it’s pretty clean so I’ll resist temptation.

Edited January 5, 2023 by Sunshine

[Sunshine]

53 minutes ago, F15Rules said:

Great job, Stu..👍

I was immediately reminded of a few years ago, when I acquired a Vixen ED103s apo whose owner had died some while previously..the scope had sat unused and uncovered in a dusty shed for some time, and so was filthy..

I took a punt on it and spent an hour or so giving it a good, gentle clean with Baader Wonder Fluid and polishing with Renaissance Wax..it came up very nicely, and she now happily with Steve @Saganite..

Dave

 

I love how you chose your telescope to match your kettle! it looks great on the countertop!.

Edited January 5, 2023 by Sunshine

[JeremyS]

Polishing with Renaissance wax is indeed one of the world’s under recognised  pleasures, Dave 👍🏻

Edited January 5, 2023 by JeremyS

[F15Rules]

10 minutes ago, JeremyS said:

Polishing with Renaissance wax is indeed one of the world’s under recognised  pleasures, Dave 👍🏻

Indeed, Jeremy..I could wax lyrical about waxing with Renaissance Wax all day!😂

[JeremyS]

12 minutes ago, F15Rules said:

Indeed, Jeremy..I could wax lyrical about waxing with Renaissance Wax all day!😂

Slippery slope, Dave, slippery slope.

[Stu]

34 minutes ago, Sunshine said:

This is contagious, now I want to clean my lens but it’s pretty clean so I’ll resist temptation.

Personally I do it as infrequently as I can, only when needed.

[Stu]

58 minutes ago, jock1958 said:

Does the lens cell just unscrew?

It did this time, yes. Every previous effort I’ve made has been unsuccessful, it just seemed stuck fast so I’ve no idea what freed it finally.

[F15Rules]

15 minutes ago, Stu said:

It did this time, yes. Every previous effort I’ve made has been unsuccessful, it just seemed stuck fast so I’ve no idea what freed it finally.

It may just have been tight Stu, and the recent up and down temperature extremes may have loosened it off?

Alternatively, (and I've no idea if this is the case in your scope), my FS128 dewshield threads on and off (very fine thread, so care is needed not to cross the threads), but the objective cell has a tiny grub screw on the side of the main ota tube which needs to be unscrewed before the lens cell itself can be unthreaded from the main ota🤔 .

Just a thought..

Dave