which "black paint" to use on lens element?

kuuan · Expire: 2014-12-26

Got the 20mm f3.5 Pen-F Zuiko 'relatively' cheap because it had bubbles covering an internal lens element.
Fortunately it was easy to open and the bubbles could simply be wiped away. The bubbles were in the middle part of a lens element which has a grease like black paint around it's outer rim. I had the impression that this paint had a function and that part of it had kind of 'evaporated' causing the bubbles. I did not to wipe away all of it when cleaning off the 'bubbles'

The lens is very sensitive to strong light and photos often look as if there was a veil, e.g. jpeg out of cam

( the same after PPing and my better samples: http://forum.mflenses.com/g-zuiko-auto-w-20mm-f3-5-pen-f-halfframe-lens-t51076.html
others: http://www.flickr.com/photos/kuuan/sets/72157628125919493/ )

Now, could this be caused by the 'lack' of the black paint which is, was there e.g. to protect against internal reflections?
..or is it grease from the focus ring that causes trouble and must be cleaned off..
In case it has a function, what is it, and what's the paint / substance and can it be repaired?

thank you very much for any input,
best regards,
Andreas

visualopsins · Expire: 2025-04-11

RE: questions -- Yes! Probably no. And:

Edges of lens elements are often painted black to eliminate reflections from those edges which can cause loss of contrast, or 'veil'. Painting the edges of lens elements can improve performance in those lenses without it. Same reason inside of lens is often painted black, even flocked, with non-reflective material.

kuuan · Expire: 2014-12-26

visualopsins · Expire: 2025-04-11

Here's the technical explanation: http://www.edmundoptics.com/learning-and-support/technical/learning-center/application-notes/optics/edge-blackening/

Some people use magic marker with some success, but I think India Ink would be better, some type of opaque glass paint best -- just guessing here; the primary requirements imho are to adhere to glass, to be opaque, and to be non-reflective -- flat black rather than high gloss. Wink

Some paints will absorb more light. I didn't look, but Edmund might have a product, or micro-tools www.micro-tools.com/store/item_detail.aspx?ItemCode=15102-F

inombrable · Joined: 20 Mar 2012 Posts: 545 Location: Salamanca, Mexico

Hi kuuan,

Like visualopsins said, that effect on the lens surely is because of the lack of that paint, when i started cleaning my first lenses the black cover on the outer of the glass elements was dissolved and I ended up with photos like this.

Again like visualopsins said painting the edge of the glass will solve the problem, I use a permanent black marker and it has done the job every time with no problem (just be careful to paint only the edge!!!).

Good luck,

kuuan · Expire: 2014-12-26

thank you very visualopsins and inombrable for all your very helpful information!

paint should adhere to glass, be opaque and non reflective..sounds good
I just tried a cheap black "marker" as sold in stationary shops but unfortunately it did not fulfill the first requirement, rather than blackening the glass it took off some of the priory remaining paint ;(

it's a very big area the paint should cover, fortunately it is very much defined Smile

I will have to open the lens once again to try another paint. As mentioned dis/assembly of this lens, at least as much is needed for this job, is very easy and straightforward. If anyone is interested I shall take and post more photos of that.

kuuan · Expire: 2014-12-26

a second attempt with another, more expensive marker was much more successful, if not ideal but satisfactory.
I am very curious to see the difference of performance! ( just now there is tropical rain outside, hopefully later today )
and also still curious which paint would be best ( and just changed to title of the original post accordingly ) I would think acrylic paint resp. special air dry glass paint: http://www.ehow.com/video_4428575_painting-glass-choosing-glass-paints.html

#1 the name ring of a Pen-F lens has two holes, is very easy to take off. Total 4 rings come loose, be careful not to loose the ball doing the clicking aperture, for that one also could lift them up together as if they were one piece ( though every time again I am tempted to leave off the ball on purpose ) If taken off individually grooves determine their position for reassembly

#2 without these rings

#3 the front group screwed out

#4 turned around

s

#5 the front group screwed apart revealing the lens with the paint loss ( before repainting )

kuuan · Expire: 2014-12-26

peterqd · Expire: 2014-01-04

The contrast looks very much better to me Andreas. Not sure about the marker pen idea though, whenever I've tried using one to touch up paint chips it hasn't been as permanent as I'd like. You might get condensation inside the lens at some time. I'd go along with the Indian ink suggestion - Pelikan Scribtol is the most opaque and best quality I know, and once it's dried it's permanent. Most of the other inks for drawing pens these days are very thin and still water-soluble after drying.
http://www.pelikan-shop.co.uk/shop/Pulsar/en_GB_SHOP.ShopTwo.displayShop.89486./518--30-ml-17-black

pdccameras · Expire: 2014-08-11

+1 to Peter's suggestion of India Ink. It's good to have around. It works very well for filling in deeper lens scratches as well. I know it sounds weird, but it really works. Use a toothpick or similar to fill the scratch with the ink and then wipe off any excess. It will negate any contrast lowering flare which the scratch might have caused and have no discernable negative effect on IQ.

P.

kuuan · Expire: 2014-12-26

ah, Indian ink is just 'plain ink' as used in fountain pens and thus easily available, right?
and ink used for Chinese calligraphy should be just as fine too, right? because that I should be able to find very easily here in Saigon.

thank you very much Peter and pdccamera for you suggestions and hints, great to know that it even can be used to fill scratches, great to know!

note on the lens performance:
yes Peter I also believe that the performance has improved.
All my 3 Pen-F wide angels have problems with light coming in from the front, with light often strongly 'bleeding' into objects in front of it. I hope these words describe what I want to say. I don't know and would love to know the technical term for that.

I think that this is even true for my undamaged Pen-F wide angle lens and that this limits their use somewhat. I like them still, they give me the impression of 'brilliance in detail', to describe it somehow. That together with that 'light bleeding', in this case even the 'haze' of the still unrepaired 20mm, 'can' benefit certain images:

thank's again and best regards,
andreas

pdccameras · Expire: 2014-08-11

kuuan · Expire: 2014-12-26

thank you very much once again Paul!
so first I shall try local / Chinese ink as sold for calligraphy

thank's for the hint using a lens shade. I am much aware of it being much recommended for the reasons you state. Because of the bulk they add and even more so because imo a lens shade makes a camera, on the street, look more 'important', 'serious' even 'threatening' I rather strongly dislike them and plea guilty of hardly ever using one. I bought a lens shade specially for my Pen-F lenses, the cheapest, plastic foldable kind whose shape can be changed to fit wide to tele lens and which is the type I like best. Sometimes I use it but not that day. Some metal one's I had bought because they are so cool Wink

never make it to the street. I often use my hand to shade but if I remember right I did not for this shot.

and the staircase is not jepg out of the camera but already had been edited incl. boosting contrast.
jpeg out of the camera looks like this:

another go at editing

best greetings, and regards,
andreas

peterqd · Expire: 2014-01-04

kds315* · Expire: 2021-03-09

Quite some helpful ideas I got from this discussion, thanks for sharing!

hoanpham · Expire: 2015-01-18

I grew up with dipping pens, and still have a complete set of caligraphy dipping pens with some very old black ink. The ink I have might be permanent, but not completely non-reflective. Never tried on glass, never tried to see if ink is permanent. I think they are. Many of my pens have a black coating that is not washable, but the ink might react on metal surface only.

What I know about quality of the chinese ink (in saigon) might be vary alot. The good quality ink in wet bottle won't develop bad smell after a week or two, while bad quality ink will have some kind of bacteria and smell badly after a while. In case you paint the glass element or inner metal parts with the bad type, you may introduce rare fungus at the later time.

I haven't use any ink that is non water based. Quality ink I had looks like small crystal/stone alike, not the man-made shape tiny sylinders. Crystal type dissolved completely and can be very thick, while the other type leaves some rest compound that make fine dipping pen useless.

Ink can be found in black, semi glossy or more like matt but not 100% non-reflective. My other fav color is dark fiolet with some magenta.

I use destilled water, air tight small container.

And my ink supply is very short for the moment...

kuuan · Expire: 2014-12-26

kuuan · Expire: 2014-12-26

my_photography · Expire: 2016-12-25

Interesting discussion going on here.

I doubt that Chinese Ink is permanent. As far as I remember, it can easily be washed with water. Therefore, I don't think it is the best choice for coloring the edge of your lens.

kuuan · Expire: 2014-12-26

thank's

the suggestions from the other forum in order of occurrence:

visualopsins · Expire: 2025-04-11

kuuan · Expire: 2014-12-26

thank you for very much visualopsins for the clarification of what exactly Indian Ink was and the importance of the waterproof binder.

( I am sure you are right, the correct ink should be available in Saigon, I am also sure that a branded 'model' flat black paint could be found too. It's just that this is my last few days in town and most likely I won't take the time to look for it anymore )