Got haze? Send it to me

[EdSawyer]

Renato - thanks for sharing the details. Indeed, the rear group of the Pentac seems to be pressed into the mount. I have 3 of them (and have had more) and all are built this way. It seems like they were cemented together, and then the mount was press-formed around them somehow? Not sure. You could remove them but as you mentioned it would end up sacrificing the rear mount/group barrel.

I think Steven's concern is the profile of the lens could change with this sort of polishing, e.g. the optical characteristics of it could end up worse - it's hard to say how much of an effect there might be. It will be interesting to see before/after shots taken with it, if you had a chance to take some before polishing.

thanks again for sharing the info!

-Ed

[RSalles]

Ed,

I made a couple of pics with film, came bad IMO due to the flare. As soon as the lens is ready I'll be glad to post some pics, as what I'm seeing just on the GG made a huge difference before-after. It will take some time to finish the lens, take the shots and scan, but I'll do as time permits,

Cheers,

Renato

[RSalles]

Just to update the thread, I was waiting for some stuff to arrive from abroad to complete the work, and I'm preparing an photo expo in Europe with all the framing/mounting made by me and labo work, plus my ordinary job, so, not all that time I would have to proceed to further cleaning.

That sad, I have arrived yesterday at the point where the cleaning is considered done, with very little haze remaining in the outer perimeter of both front and rear optical elements, barely visible, BTW.
I have some pics I made at the moment when the cleaning was finished, the second hand hanging the glass is from my wife who helped me in those,

Front element:



Back:



Front + back mounted:



There's an album with Google with more pics for whom can be interested, showing also the glass view against a strong light source, here's the link:
https://goo.gl/photos/ZKJdWHAVKNWzACsD9

I'm planning in the next week-end or ASAP to take some photos with the lens, scan and upload to the forum,

Cheers,

Renato

[Peter De Smidt]

Interesting stuff, Renato. That's for posting it.

[EdSawyer]

Looks really good! Will be interesting to see results from images shot with it before and after.

[RSalles]

Looks really good! Will be interesting to see results from images shot with it before and after.

Ed, I will as soon as the rain let me goes outdoors,

Cheers,

Renato

[RSalles]

As promised and as weather permits, some pics before/after:

Before:

f11:


f8:


Wide open - 2.9


Also WO:


More following the lens after have been cleaned,

[RSalles]

I have just 1 pic so far to show the lens rendering after cleaning, the weather is very heavy around here all the week, with some stretch windows of sunlight:

This picture is exactly as it came from the scanning procedure, I scan my negs with a full frame camera.

f4 - I tried to make a pic or two with the lens at 2.9, but as I have it mounted on my Sinar with the Sinar Copal shutter, the shutter goes only to 1/60, so wide open will certainly blow the highlights heavily. The problem could have been solved with a ND filter, but I don't have one big enough.



Another picture with some "auto levels", no sharpening:


The idea was to provoque some sparks and haze, if any, that's why I have pointed the camera to a very light reflective subject, trying to stress the glass surface and the lack of coating, flooding it with light - the picture was taken near a window - and make it cry

As the weather permits I'll try to make a portrait from my daughter or my wife, to show how the results comes in a real scenario. But with this series I think you can have an idea of the hole process the lens have traveled and how better it is when viewed side by side before/after,

Cheers,

Renato

[B.S.Kumar]

Hi Renato,

I think a more controlled series of photos would be ideal, perhaps if you have space to leave a set in place for the before and after shots. But if not, a static scene looking outside a window would also be good.

On a more technical note, what actually causes haze? Sometimes I see it as a ring around the lenses, other times the center of the lens. More often than not, the haze affects only the rear or front group, not both the groups. Why is this so?

Kumar

[RSalles]

Hi Kumar,

I agree, a more controlled shot series with before/after would be the best, but I hadn't the idea at that time that I could clean the haze in this lens, so severe was it.

About haze, I saw 2 types so far: micro scratches and "oxidation" of the optical element. I'm not sure if I can name it oxidation btw, but it seems, as it appears as an effect of environmental process, as the glass face exposed suffers the most. You can add to this moisture, fumes, humidity, pollution, etc. As I'm not a glass scientist in any way this is only a supposition I do. It can affect both sides, as in this lens, front and back glass optics. As the weather comes better I'll make more "normal" shots, promise,

Cheers,

Renato