TeleVue objective cleaning

[NGC 1502]

My TeleVue Pronto objective was a bit grubby and in need of a clean. This included the rearmost lens surface, inaccessible without removing the lens cell.  Some folk worry about removing a TV refractor lens cell but it’s really no problem.

I don’t know if it matters, but I placed small stickers on the tube and adjacent lens cell to enable the cell to be replaced in the original orientation.

All TV refractor lens cells are secured to the tube with 3 hex head screws filled with a semi-hard substance. It’s not difficult to clean out the hex heads to enable removal with an allen key.  As I’d done this years ago, it was a 2 minute job to remove the screws and separate lens cell from the tube. Note- the lens cell complete with elements remain intact as a unit.

My preferred lens cleaner is Lens Bright as supplied by Specsaver opticians. Used with a clean micro fibre cloth I’ve found it works better than any other lens cleaner I’ve used. This includes 99% pure IPA.

Having used a bulb type puffer to remove any dust I carefully cleaned the rearmost and front optical surface.  A couple of tries left pristine optical surfaces.

I refitted the cell to tube with the 3 allen head screws. Before tightening, the cell can be adjusted for collimation. However I have previously found that if I pull the cell back onto the tube, then tighten the screws, collimation is spot on. Presumably that’s because everything was accurately and squarely constructed. So, a 2 minute job to replace the cell.

Last evening was unexpectedly clear at my location, so I set up the Pronto at dusk. First up was Jupiter as darkness fell. Nice and crisp at up to 120x, although 96x was even crisper. 150x and above was too much as I’ve always found with the Pronto.
My test object for collimation was Zeta Orionis- Alnitak, the easternmost belt star. At 120x split suspected, 150x split confirmed.  I tried my 2.5mm Vixen LV for 192x.  In the not great seeing split definitely observed in steady moments. I’d estimate the secondary star was seen about 30% of the time in steady moments, but a blur most of the time.

Castor. Using 150x, Castor A & B were 2 hard Airy disks with perfectly concentric first diffraction rings, beautiful sight😊

Now, I fully realise that my objective cleaning hardly improved the view. But it did satisfy my OCD with a pristine objective lens!

Ed.

Note- All allen heads on my Pronto accept Imperial allen keys. I don’t know if that applies to all TV refractors.

 

[RT65CB-SWL]

I use the Baader Optical Wonder fluid on my TeleVue Ranger objective element, though I have not gone and done the whole thing... just the outer surface. If I pluck up enough courage, I may consider it.

@NGC 1502 My Ranger also has US-imperial🇺🇸 screw-threads.

[F15Rules]

On 09/03/2024 at 09:21, NGC 1502 said:

My TeleVue Pronto objective was a bit grubby and in need of a clean. This included the rearmost lens surface, inaccessible without removing the lens cell.  Some folk worry about removing a TV refractor lens cell but it’s really no problem.

I don’t know if it matters, but I placed small stickers on the tube and adjacent lens cell to enable the cell to be replaced in the original orientation.

All TV refractor lens cells are secured to the tube with 3 hex head screws filled with a semi-hard substance. It’s not difficult to clean out the hex heads to enable removal with an allen key.  As I’d done this years ago, it was a 2 minute job to remove the screws and separate lens cell from the tube. Note- the lens cell complete with elements remain intact as a unit.

My preferred lens cleaner is Lens Bright as supplied by Specsaver opticians. Used with a clean micro fibre cloth I’ve found it works better than any other lens cleaner I’ve used. This includes 99% pure IPA.

Having used a bulb type puffer to remove any dust I carefully cleaned the rearmost and front optical surface.  A couple of tries left pristine optical surfaces.

I refitted the cell to tube with the 3 allen head screws. Before tightening, the cell can be adjusted for collimation. However I have previously found that if I pull the cell back onto the tube, then tighten the screws, collimation is spot on. Presumably that’s because everything was accurately and squarely constructed. So, a 2 minute job to replace the cell.

Last evening was unexpectedly clear at my location, so I set up the Pronto at dusk. First up was Jupiter as darkness fell. Nice and crisp at up to 120x, although 96x was even crisper. 150x and above was too much as I’ve always found with the Pronto.
My test object for collimation was Zeta Orionis- Alnitak, the easternmost belt star. At 120x split suspected, 150x split confirmed.  I tried my 2.5mm Vixen LV for 192x.  In the not great seeing split definitely observed in steady moments. I’d estimate the secondary star was seen about 30% of the time in steady moments, but a blur most of the time.

Castor. Using 150x, Castor A & B were 2 hard Airy disks with perfectly concentric first diffraction rings, beautiful sight😊

Now, I fully realise that my objective cleaning hardly improved the view. But it did satisfy my OCD with a pristine objective lens!

Ed.

Note- All allen heads on my Pronto accept Imperial allen keys. I don’t know if that applies to all TV refractors.

 

Some photos please, Ed?? 😊

Dave

[Moonlit Night]

I recently cleaned my Tele Vue 102 using the bulb blower and Baader wonderfluid and a brand new micropore cloth method (absolutely no lense pens) I didn’t need to remove the objective and quite frankly find the prospect terrifying. However that doesn’t sound too bad so if I am ever in that position (whisper it, fungus) then perhaps I will give it a try. 

Edited March 10 by Moonlit Night

[Moonlit Night]

On 09/03/2024 at 09:21, NGC 1502 said:

 

Note- All allen heads on my Pronto accept Imperial allen keys. I don’t know if that applies to all TV refractors.

 

I would think so, I found obtaining the right ones a bit of a pain. Same is true with Tele Vue mounts in my experience. I love my HD4, best mount I ever owned, although I did mod it with a AMD clamp which I prefer as a mounting option.

Edited March 10 by Moonlit Night

[NGC 1502]

12 hours ago, F15Rules said:

Some photos please, Ed?? 😊

Dave

Ok Dave, I’ll try soon😊

[NGC 1502]

11 hours ago, Moonlit Night said:

I would think so, I found obtaining the right ones a bit of a pain. Same is true with Tele Vue mounts in my experience. I love my HD4, best mount I ever owned, although I did mod it with a AMD clamp which I prefer as a mounting option.

Indeed, you won’t find Imperial allen keys in most High Street locations.  But an online search or dedicated tool shop should bring success.

[NGC 1502]

11 hours ago, Moonlit Night said:

I recently cleaned my Tele Vue 102 using the bulb blower and Baader wonderfluid and a brand new micropore cloth method (absolutely no lense pens) I didn’t need to remove the objective and quite frankly find the prospect terrifying. However that doesn’t sound too bad so if I am ever in that position (whisper it, fungus) then perhaps I will give it a try. 

TV 102……I have the S&T magazine review of that model…..sounds like a great traditional scope……enjoy😊

[NGC 1502]

16 hours ago, NGC 1502 said:

Ok Dave, I’ll try soon😊

Pictures added😊

Some explanations-  Close up shows 1 of 3 Allen head screws to secure lens cell to tube. Removing all 3 allows lens cell to be removed. When replacing, the cell can be tipped in any direction for collimation.  DIY dovetail has 2 pegs and a “dimple” to locate onto mount. “Dimple” allows securing screw to engage more positively. Therefore the dovetail only fits in one position but does so VERY securely.  All eyepieces are a similar weight with the use of the TV bronze adapter shown with the 11t6 Nagler, so no balance issues.  Safety line between diagonal and focuser. Pristine objective satisfies my OCD😊  Alt-Az mount is TeleOptics mini Giro on wooden surveyor’s tripod. Mount lives just inside my back door to south facing garden…..

…….questions welcome…….

Ed.

[RT65CB-SWL]

I like the 'safety line' [image #1 & #5] to stop the star diagonal and any attached accessory falling out and getting damaged when it hits the ground. 

Don't sell the rights  ...or let a father and son [ie Al & Dave] see it! 

Edited March 11 by RT65CB-SWL

[NGC 1502]

55 minutes ago, RT65CB-SWL said:

Don't sell the rights  ...or let a father and son [ie Al & Dave] see it! 

World Patents Pending.  Imitators WILL be prosecuted😁