Could anyone please give advice on any safe objective lens cleaning products such as (Pursol) that would not degrade or affect the multi layer anti reflective coatings of the Istar TCR lens?
Hi,
It is very disappointing that nobody has answered your question after all this time.
They do say that; "fools rush in where angels fear to tread."
So I will foolishly offer some generalized advice on lens cleaning for other readers to mull over.
Firstly, it should be understood that even a dirty lens still performs well.
Far better to leave the lens dirty than use a poor technique for cleaning.
The visible difference through the eyepiece is likely to be too slight to notice.
The real problem is the hopefully long life of most refractors.
Every cleaning is a potential disaster waiting to happen.
The cumulative effect of umpteen cleanings eventually adds up over a century or more.
Storing a refractor horizontally is probably best if you have no case.
Better than standing it on its nose to minimize the storage footprint.
Nor pointing upwards to collect stray micrometeorites and house dust.
Fortunately the triangular form of the TCR does not easily lend itself to rolling.
I was present when a fine antique refractor was placed on a sideboard.
As soon as the owner turned his back the OTA rolled straight off and onto the tiled floor!
The objective was cracked right across and became worthless in that moment of inattention.
Leaving dovetails, finders and tube rings on a tubular OTA is a useful safety measure against such unwanted rolling.
For exposed storage I would recommend you find a suitable plastic lens cap.
Hopefully there is somewhere to fit one on the back of the objective cell.
Soft plastic lids come in many different sizes from food storage containers amongst many other sources.
Plastic is best because it doesn't damage lens glass, coatings or paint if you should miss the target.
Do not let anything touch nor rest against the glass itself!
Primary lens cleaning: Only if absolutely necessary!
Remove all jewellery.
Wash your hands and dry them carefully on a clean, dry, well laundered, cotton towel. Not tissue nor paper towel!
Start with a lens blower rubber bulb to puff away any surface dust.
Keep the plastic blowing tip well away from the lens to avoid scratching the surface.
Now move onto a large, soft, clean, camel hair, lens brush to
very gently sweep the surface of remaining loose dust.
Repeat with the lens blower at intervals to lift away any loosened dust from the brushing.
Don't ever run the bristles through your greasy fingers or you'll leave a residue of grease on the brush!
And where are you going to use that greasy brush? On your nice, clean lens?
Some might suggest air canisters to blow off dust but these might have enough pressure to blow dust between the elements.
Never use any form of compressor because the pressurized air will almost certainly be contaminated with oil.
Nor is a compressor remotely necessary.
Last resort cleaning of fingermarks or water stains:
Buy some good quality camera lens wipes from a camera shop along with some good quality lens cleaning fluid.
This will contain alcohol but use no other substitute for cleaning.
Nor drink any of the fluid before starting work!
Use NO other form of tissue on a lens surface or mirror. Not ever!
Most common tissue will contain filler and most kinds are very dusty and
very abrasive.
Try wiping your spectacles on tissue regularly and they'll soon begin to cloud over.
Now wash your hands again and dry them carefully on a clean, dry, cotton towel.
Not tissue because it will contain abrasive dust.
Check you haven't forgotten to remove your jewellery!
Open a fresh sachet and fold the slightly moist, fresh, virgin lens wipe to about the size of your thumb.
Now apply a little of your specialist coated lens cleaner to make it slightly more damp. NOT dripping wet!
Now draw the moist wipe
very gently across the lens surface without applying the least pressure.
Only the weight of the moist tissue must be allowed to touch the lens surface.
NO fingers! NO fingernails. NO rings. NO bracelets! NO tools. NO abrasives. NO rubbing!
Some suggest breathing on lenses to apply a cleaning mist prior to a good scrub with a micro-fiber cloth.
Yet most humans, dogs and cats have fat droplets in their breath. Not an ideal lens cleaner in the long term?
It's up to the user and potential abuser of the lens.
Since I cannot monitor the reader for their false assumptions, clumsiness, lack of foresight nor any missteps, nor even simple impatience I accept absolutely no responsibility for the advice offered.
NEVER dismantle any objective for cleaning unless you are an experienced expert and have the skill to ignore my conservative advice.
I always welcome constructive criticism of my advice and opinions regarding telescopes and optics.
Anyone who thinks my methods can be improved on, or reworded for better understanding, is completely free to do so.
Your valuable contribution will be added to the sum of my own collection of knowledge. [Or lack of.]
