What is the effect of lens haze on images?

Question

I'm considering buying an old manual focus prime lens for my DSLR. I've noticed that they're often listed very cheap if they're described as "slightly clouded" or "hazy". I would like to understand whether this is a problem I can work with, or if I should steer clear.

Secifically, my questions are:

• What are the effects of clouding or haze on the resulting images?
• What typically causes clouding or haze in a lens? (I know that mould is one possible cause but I'm pretty sure there are others.)
• Does it affect all images, or does it only manifest under certain conditions? (I.e. can you mitigate the effects with shooting technique?)
• Can the effects be fixed in post-processing?
• Is the effect of a hazy lens always bad? If not, are there examples where it has been used creatively to good effect?

If it makes a difference, I use an APS-C DSLR and I would be buying a ~50mm manual focus fast prime, for street photography and as a general walk-around lens. I'm a hobbyist and mostly want it as a first step into trying manual focus, but I do want to produce high quality images.

I'd appreciate it if answers would stay on topic and focus on answering the specific questions above about hazy lenses, rather than commenting on whether I should want to buy a manual focus lens or not.

Answer 1

I'm considering buying an old manual focus prime lens for my DSLR.

Be aware that you ( at best ) will lose not only autofocus but also auto metering ( you'll have to set exposure manually ).

Be careful as well as not all DSLRs can mount manual lenses properly.

I've noticed that they're often listed very cheap if they're described as "slightly clouded" or "hazy". I would like to understand whether this is a problem I can work with, or if I should steer clear.

There is a problem with this.

It's sign that mold ( fungus ) has started to develop on the interior of the lens. I would never buy such a lens. It's (in general) not fixable and it just gets worse. Mold can ( will ) eat at optical coatings and even such attempts at cleaning as I've seen over the years will not undo the damage.

In my experience patience will let you find good lenses without mold for similar prices ( maybe a tiny bit more ), but any lens with even the suspicion of mold is not worth having, IMO. From time to time you may find a lens you already own develops mold, and there are techniques to try and keep this manageable, but why buy into this problem ?

Secifically, my questions are:

What are the effects of clouding or haze on the resulting images ?

Varies depending on the extent of the mold. The problem is that once you have mold it's going to get worse.

What causes clouding or haze in a lens?

Mold ( fungus ). And it's very persistent. While I think of it, try and keep your own lenses stored with desiccant packs or similar to keep humidity down to avoid this issue.

Does it affect all images, or does it only manifest under certain conditions? (I.e. can you mitigate the effects with shooting technique?)

Varies depending on how bad it is and exactly where in the lens it is.

Can the effects be fixed in post-processing ?

Not really.

Is the effect of a hazy lens always bad ?

Yes.

If not, are there examples where it has been used creatively to good effect ?

I've seen people use smashed up lenses for "creative" effects. This is quite different from using something normally ( and something you paid for ) and expecting only to use it for "creative" effects.

If it makes a difference, I use an APS-C DSLR and I would be buying a ~50mm manual focus fast prime, for street photography and as a general walk-around lens. I'm a hobbyist and mostly want it as a first step into trying manual focus

but I do want to produce high quality images.

Well avoid cloudy lenses for a start !

But also note that a manual fast prime will not automatically get you high quality images ( no lens will ). All a fast prime gets you is a wide aperture. All manual focus gets you is a requirements to learn to focus accurately yourself. Note that it was common for film cameras to use a type of viewfinder called a split focus screen which helped get accurate manual focus. DSLRs do not normally have these and manual focus can be a pain without one. These days I manually focus using a mirrorless camera that has focus peaking and an EVF, which is better.

So ask yourself exactly what you expect an old manual prime to do for you and is that realistic.

Answer 2

Here is my new year contribution, happy new year 2017

What are the effects of clouding or haze on the resulting images?

depends on where and how much, front element is often imperceptible. the effects varies but generally result in a lower contrast and sharpness.

the problem is that once it starts, it will continue if not stoped and will etch the glass, which, eventually may render the lens useless.

What causes clouding or haze in a lens?

Mold, usually develops because of bad storage. Though sometimes sellers mistake mold for easier to fix problems.

Does it affect all images, or does it only manifest under certain conditions? (I.e. can you mitigate the effects with shooting technique?)

yes, but it is worse in direct sunlight, lens flare type of situation.

Can the effects be fixed in post-processing?

Depends on the amount, but generaly no.

Is the effect of a hazy lens always bad? If not, are there examples where it has been used creatively to good effect?

Yes, it create a softer image that can be quite nice if you like etheral organic images rather than uber sharp aseptic pictures.

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If you want to stop the mold from growing...

• expose it to direct sunlights for a couple of days, UV kills fungus like nothing else. else put under a suntan bed, or next to one of the superb 1970's radiocative lens like the takumar.

• if you are handy and daring, disassemble the lens. the old manual lenses have no electronics parts to worry about. you would learn about the lens design and by bleaching the elements, you'll get rid of the mold

• i heard of using heated copper pennies in an enclosed environment with the lens so copper vaors act as a fungicite, don't know much about it, but should be easy to implement.

i am sure there are other methods. i think i remenber a guy using anti-fungal cream....

These methods should kill all the mold, you have a pristine lens for a fraction of the price. obvioulsy if the fungus has grown enough to eat the glass, you will have a patern of etches, which can be ok.

Note that getting hazy lenses, is sometimes the only way to get superb inequaled old lenses, though i have a few from the 1930-40's that have zero sign of mold.

Good luck at playing being HCB, that's how you get good, kiss and take away zooms, AF, and meter.