Coating Lenses

[Ian Grant]

There is really no optical downside to coating, it wll not affect sharpness as someone implied above - although disassembling the lens to coat and reassembling slightly off obviously could.

I think it was Arax who stated on his site that Multi-coating some older lenses could actually be counter-productive, and that single coating was often a far better option. He no longer offers a coating service unfortunately.

Ian

 

[Nicholas Lindan]

Edmund optics sells lens elements that you can buy coated or uncoated, priced as follows for a 100mm fl/30mm dia/PCX:

$30.40 no coating
$33.20 MgF coating
$34.70 "Vis 0" 0.4% coating

Overlooking they are charging $30 for a $3 lens, coating seems to be around $2/surface.

An on-line discount eyeglass firm charges $6.95 for AR/no scratch coating, again around $2/surface.
Admittedly, a High Street optician will soak you for $80 for the same service.

Coating pricing is _very_ screwy.

 

[Paul Howell]

Being rather more realistic I remembered coming across someone who had his old lens coated (he may have done it himself) at an opticians lab, using the coating process used for spectacles (glasses).

Has anyone tried this. A lens like the Eurynar would be ideal as the elements aren't cemented, and they suffer badly from low contrast due to this.

Is there a tame optical technician on APUG ?

Ian[/QUOTE]


I had an old 135mm coated at a 1 hour lab 5 or 6 years ago, I had an antiglare and UV coating applied, cost $45, but only the front element was coated, on both sides, I think they dipped the lens, newer method uses a vacume chamber. It seems to work well enough, impoved contast. The Shop I used HandiLab here in Phoenix has gone under, I have an old 210mm lens that needs to recoated, but the last shop I asked said that they can only coat plastic lens, the manger said he would coat it at my risk. I havent had time to follow up.

 

[JPD]

... So ask any potential supplier if they are applying a hard coating and if so how they define "hard". ...

Good suggestion. I have emailed and asked them about the hardness of the coatings. I do, however, believe they are hard. It's not the late 1930's anymore.

 

[DaveOttawa]

Good suggestion. I have emailed and asked them about the hardness of the coatings. I do, however, believe they are hard. It's not the late 1930's anymore.

Well, I have received optics for a camera lens made & coated within the last year where the AR just wiped off. Hard coating was not specified on the drawings, for subsequent orders it was...
If you use a lab that coats eyeglasses it is a safe bet it will be hard coat though.

 

[j_landecker]

If only one of the exposed surfaces of a cemented group needs coating, can the painted edges and other surface be masked off, or does the whole thing need to be stripped down for the process?

 

[DaveOttawa]

If only one of the exposed surfaces of a cemented group needs coating, can the painted edges and other surface be masked off, or does the whole thing need to be stripped down for the process?

The answer is probably yes, you can coat the cemented group but it will depend on the lab, questions like: 1) how hot do they expect the part to get in the chamber 2) are they happy to put a part with unknown paint etc on in the chamber given that then there is a chance of offgassing contaminating the whole batch. In short its worth asking but there is a chance they will say no.

 

[JPD]

I got this answer from Longman: "Hi, Okay this is were it may come to a stop, the coatings are quite soft, mainly used for internal elements, hard coating we cannot perform and if we could would be more expensive."

Thanks DaveOttawa for the tip to ask them! It saves me/us both trouble and money.

I guess coating just the inner surfaces could be ok. The two negative elements and the inner surfaces of the front and rear elements. It would be cheaper, but still reduce the internal reflections a lot. Hmmm...

 

[Ian Grant]

There is another option, have the lens fully coated and then just fit a multi-coated filter so that the front element surface is protected.

At the moment I've put having my Eurynar coated on hold, it's a 150mm and in a larger Compur shutter than a 136mm or 150mm Tessar so it won't fit my Patent Etui.

Ian

 

[JPD]

There is another option, have the lens fully coated and then just fit a multi-coated filter so that the front element surface is protected.

At the moment I've put having my Eurynar coated on hold, it's a 150mm and in a larger Compur shutter than a 136mm or 150mm Tessar so it won't fit my Patent Etui.

Hm, I prefer to always use a light yellow filter anyway... Hmmm... I have time to think about it, because the coating will have to wait until after Christmas.

Ah, I read about your Patent Etui. What size is the hole for the shutter? It would be good to know, since I have planned to get a Patent Etui 9x12. I have five, I think, of the 6,5x9 version.

I've bought a 1915/16 Dogmar 6,3/135 and have taken test shots, but not developed the sheets yet. Too bad the Dogmar can't be dissassembeled compleatly for coating as the Eurynar.

 

[Ian Grant]

The 9x12 Patent Etui's take a Compur/Copal 1 shutter, the hole is the same for the Dial-set or Rim-set shutter.

Ian

 

[JPD]

The 9x12 Patent Etui's take a Compur/Copal 1 shutter, the hole is the same for the Dial-set or Rim-set shutter.

39mm? What did your Eurynar come with? A Compur 2, or a non standardized mount thread?

 

[Ian Grant]

The Eurynar's in an Ibsor shutter, which is almost identical to an early prontor press, I don't know the size and can't check at the moment as it's in the UK. However it's considerably larger than the Compur 1 and a non standard thread.

Ian

 

[DaveOttawa]

..It's not the late 1930's anymore.

Have you been checking the financial news - actually it IS the late 1930s

 

[sharpey]

Not sure if it's been mentioned, but Focal Point in Colorado does re-coating. Have sent an old lens off there for re-coating... Have heard good things.

 

[Ian Grant]

Lets us know the cost and how it turns out please.

Ian

 

[sharpey]

Will do... but am not sure how well I can judge quality... am a bit new at all this

 

[JLP]

If it looks like the lens element i got back from Focal point it will be as new. First class job for both polishing and coating.
Best to contact John Van Stelthen directly for pricing. http://www.focalpointlens.com/fp_intro.html

jan

 

[domaz]

This would be great for the 400mm P67 lens I saw on Ebay that went for $30 because the front coating was coming off. If only I had known at the time..

 

[sharpey]

Yup, I did just that. He gave me a ballpark... but needs to see the lens for an accurate quote... The lens probably isn't worth re-coating (Meopta Mirar out of a Flexaret IIa)... but the camera is part of the family, was my first TLR and used to belong to my wife's Grandpa back in Czech... so yeah...

 

[sharpey]

Wow... is all I can say... it cost me $90 US to do... but it came back top notch... Will definitely use Focalpoint again.. job well done at a decent price...

 

[JPD]

Just a link that could be of interest:

http://www.thinfilmcoating.com

 

[freygr]

An note, Magnesium Fluoride can be coated with the lens cold, be if you heat the lens to 300 degrees (I think F not C) the coating will be hard. All navy ships had an shop to recoat optics until the hard coatings made recoating unnecessary.