What causes Haze in a Lens?

Question

What actually causes the Haze in old cameras ? recently I found a tlr Camera in my store room, it has little haze in it, Is it caused by lubricants in the internal mechanics or "inside the lens element" ? is it possible to remove it ?

Answer 1

The most common causes of internal haze in lenses can be divided into three main areas:

• Surface contaminants. Oil, grease, heavy dust, or even a thumbprint left by a careless technician.
• Fungus. This can usually be identified by the 'spiderweb' patterns.
• Balsam Separation. Pine balsam was once the primary material used to bond multiple lens elements together. Over time it tends to dry and the two lens elements begin to separate.

The first two can be dealt with fairly easily for anyone competent dis-assembling and re-assembling lenses.

The third is usually a fatal blow for most lenses because the time/effort to correct it is worth far more than most of the lenses that have the issue are worth.

Related:

What is the effect of lens haze on images?
What causes lens flare?

Is there a way to remove fungus without dismantling the lens?
Can fingerprints and smudges "ripen" if left on a lens for a long time?
Buying a lens with light haze?

Answer 2

On internal elements: Vaporized and condensed lubricants from aperture mechanisms, leaf shutters and other lens mechanics. Sometimes, other liquids that got inside and got trapped/washed stuff onto glass surfaces/left a residue (eg fleamarket lenses that got wet or suffered condensing moisture).

On external surfaces: Urban air pollution, tobacco or other smoke, residue from liquids.

Also, there are cases when it is NOT contamination but corrosion or fungus of the glass itself.

If it is mere contamination, it can usually be cleaned off with normal lens cleaning methods (be careful about the coatings on inner elements, unlike exterior coatings you can sometimes find coatings there that are far from scratch resistant!) - but this will obviously necessitate disassembling the lens to reach these inner surfaces, which can range between easy with some experience to nearly impossible depending on the lens construction.

On a fixed-lens medium format camera (TLR or folder), you often find one of the most easiest to service lens designs - 3 or 4 elements, sometimes grouped into modules that can be unscrewed from each side as one components. At the minimum, if you want to attempt this repair, get a lens opening tool (tweezers can be used instead sometimes, but they often do not get sufficiant purchase on retaining rings and are easy to let slip in a way that scratches glass parts), lint free(!) cleaning supplies and either isopropanol or sensor cleaner. Do not manhandle aperture or leaf shutter blades when they are exposed.