How to Recover A Damaged Projector Lens

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Introduction

I had a bit of a mis-adventure with one of my projectors. I have acquired an Epson PU2010, high-brightness (10,000 lumens) laser projector recently. Since these projectors don’t come with a lens, and Epson was out of stock of the lens option that fit my throw ratio, I had to resort to getting a used lens.

I found one on eBay that seemed to be in great shape, and relatively cheap so I pressed on the Buy It Now button. When the lens arrived, it looked in pretty good shape minus a few minor scratched. However, I didn’t investigate it using a high-power flashlight which usually reveals every scratch and dust particle. I simply installed it on the projector and I pressed start.

Well, about 30mins into my projector setup, I decided to take some contrast measurements. I was eager to do this because this is the first projector in Epson’s line-up that has 1″ LCD panels as opposed to the smaller 0.7″ and 0.6″ ones included in the lower-end models. I wasn’t sure if this would result in a contrast increase – as that all depends on the rest of the optics.

Well, good news: the Epson PU2010 measures around 2500:1 native on/off, up from around 1700:1 for the 0.7″ panel, without Epson putting major filtering in place.

Major Misadventure

So I go to measure ANSI. Mmm, 200:1. That’s below average for an Epson. Then I remember that the lens might be dusty. So in the heat of the moment, pun intended, I open a lens cleaner and jump up to wipe the lens. No sooner I do that, I realise this might not have been such a great idea… 10,000 lumens, small lens… unless that lens is pure glass with no coating on it, this could end badly.

Well, as soon as I have this thought, the lens coating, which I didn’t even realise was there, started bubbling up along the small scratches. I look at the projection and it now looks like I have smeared vaseline on the lens with streaking all across the screen. I turn the projector off, but it’s way too late: this lens is ruined.

I detach the lens, to have a closer look. Well, it looks as if the front of the lens is melting off. Now I’m thinking… shoot, I need to see if I can remove the lens coating, but what with? Next stupid idea: oh, the cream cleaner I use for the glass cook-top. That doesn’t scratch glass, so surely it will be fine for this.

Well, the lens coating came off alright, but with it came a million tiny scratches as well. Surely, it’d be fine for putting pans on it to cook eggs, but to project out of this mess?

You need to understand, I have had countless projectors, and I would obviously NEVER do such a thing to any of my home theatre projectors with fixed lenses. But I do have a defence. Epson states – as I found out later – at the end of their user guide for these high-powered laser projectors, that you should not touch the lens for any purpose while the projector is on, or until the lens has cooled down after shutoff.

As I learnt the hard way, with a high-powered laser projectors, the lens coating can become heat sensitive / soft and touching it with a cold wipe WILL damage it.

Now to add insult to injury, I rubbed the coating off with something that can buff glass, and is said not to scratch it, but clearly it did or made the existing scratches much worse by removing the coating. Either way, the lens was totally unusable. Or was it?

PS. I wish I had a picture of what that lens looked like once I was “finished with it”. But in my shame, the last thing I was thinking of was recording evidence of my idiotic actions – what literally NOT to do – since I should know better.

Recovering the Lens

Well, I did order another lens that was literally brand new – old dealer stock but never used. Epson was still out of stock.

But I thought, surely I could recover the lens somehow – minus coating – while I wait for my new lens. After all, the delicate glass on expensive watches can be polished to remove scratches and they use PolyWatch do it.

So off I went to order some PolyWatch to see if it could work its magic. A few days later, it arrived and I went to work on the lens:

1. I put a dot of PolyWatch on the lens and started buffing it with the included white polishing cloth.
2. I did another round with a bit more PolyWatch.
3. I wiped it with a newly washed soft cotton kitchen towel to remove any of the remaining grime and the PolyWatch (don’t use paper or anything else for this purpose).

I kid you not, within 5mins, the PolyWatch removed all the remaining lens coating, and all surface scratches from the lens. The lens looked perfect under a flashlight.

Moment of Truth

I installed the lens back onto the projector to check. Did it work? To my surprise, the projected image was now much much clearer. While the lens coating was off, and likely reduced my contrast a bit, the image didn’t have any streaking and was back to being razor sharp, probably back to around 95% of what it was previously.

I will wait for the new lens with the proper coating to run further tests, and maybe compare this recovered lens to it. But for now, the projector is back up and running for day to day tasks, even if not critical viewing.

Projection Lens Handling and Cleaning Guidelines

Since I demonstrated what NOT to do with a projection lens, I thought it wise to include some general projection lens handling guidelines as well.

1. Never touch a projection lens with your fingers / skin. As your skin has oils on it, these will contaminate the lens. Any oil on the lens can create concentrated heat on the surface causing damage over time – especially true as we have just learnt for high-powered projectors (anything over 3000 lumens)
2. A little dust will not hurt the image, so unless there is excessive dust or gunk build-up, just resist the urge to touch the lens, period. Leave it be.
3. Your first port of call should be to blow the dust off with a dust blower such as this. If you want to use a high-powered dust blower, make sure to use one that has a filter so it doesn’t cause even more of a mess A dust blower without a filter could deposit even more dirt on your lens, than it already has or chuck debris against it causing streaks or damage. One example of one with a filter is this one.
4. If you really need to remove dust from the lens, it is best to do it with a brush specifically designed for precision optical lenses, such as this or this. While a brush may still leave a bit of dust on the lens, this is ok, you do not need it to be squeaky clean, less is more here.
5. If there is still a good amount of dust or residue on the lens, then you can use a lens cloth (called a lint free microfibre cloth) specifically designed for (coated) lenses – such as the ones that came with your glasses if you have them. Otherwise, you can buy a lens kit from here that has these lens cloths. However, I DO NOT recommend you use the included tissue paper for lenses. That is just a really bad idea. You can very easily scratch your lens with that if there is ANY small crease in that paper. Just throw it away or use it for your phone, not your projector.
6. If there is any very hard-to remove residue, you can use a fraction of a drop of original formulation Dawn dishwashing liquid on a cotton swab to remove it, then use a very soft freshly washed and dampened cotton kitchen towel to remove the Dawn and wipe the lens. You may need to do this quite a few times to remove the Dawn by using fresh water – rinsing the kitchen towel. Then use a dry cotton cloth to wipe moisture off. You can then use the lens cloth to tidy things up if needed. Btw, I recommend Dawn as it has no additives that would leave a residue once wiped.

Now we can add a 7th rule which is this:

7. Never handle a projection lens while the projector is running or the projection lens is still hot – warm. Allow the lens the cool to room temperature before handling. This is especially important if you are using a microfibre cloth as the cloth itself can actually melt onto the lens from the heat. Then you really need to use the PolyWatch trick to recover your lens – but if it had an expensive coating on it, it won’t be 100% again.

Closing Thoughts

The lens coating on that Epson lens was likely Magnesium Fluoride from the colour of reflection, or it could have been a multi-layered coating of that and other materials. These lens coatings are used to stop the light from diffracting as it hits lens / air transitions and to stop the light reflecting backwards into the light path by allowing the lens to pass most of the light through. This helps both brightness and contrast.

I am kind of impressed that Epson includes this sort of coating on even their cheapest professional lenses (around $500), and was certainly unexpected, along with how delicate this coating becomes under the heat of so many lumens firing through it.

But I thought to share my misadventure in the hope that it will help you recover your projector lens, should it, or its coating, seemingly have been scratched beyond repair. Maybe not to 100%, but enough that you can get back to watching your favourite shows.