[BigMackCam]

Quite right Sir

On an unrelated note, you have the identical kitchen work surfaces and paint colour as my kitchen... unless you've been sneaking in when I'm not at home

Apologies to the OP - I'll cease and desist now

[pschlute]

On an unrelated note, you have the identical kitchen work surfaces and paint colour as my kitchen... unless you've been sneaking in when I'm not at home

..... guilty....including drinking your champagne

[Wheatfield]

I have a couple of lenses that are made of unobtainium.

[Not a Number]

"The stuff that dreams are made of"

You Tube

You Tube

[sergeremy]

I see what you did there

'A cute' mistake indeed, dare I say.

[sergeremy]

Quite right Sir

Peter, you are losing all the bubbles there, without the pleasure of seeing them sensuously slithering up the glass wall...

[MikeMcE]

Or no elements needed for coffee


Hang up and DRIVE!

[BigMackCam]

Or no elements needed for coffee

I hope you're gonna wipe that thing down before drinking coffee from it, Mike

[MikeMcE]

I hope you're gonna wipe that thing down before drinking coffee from it, Mike

Nah, more flavor!


Hang up and DRIVE!

[mikesbike]

But what about the actual bodies of the lenese?
I'm looking specifically at the HD PENTAX-DA 55-300mmF4.5-6.3ED PLM WR RE.

The lens bodies of any brand for APS-C cameras with the zoom range of 55-300mm will be made of plastic. This above Pentax model is one of the newest, which incorporates the PLM technology for faster autofocus (AF). The RE stands for Retracting, as the lens barrel can be drawn in for extra compactness during carrying. But you have to be using a fairly later model of Pentax camera for this lens to function properly. The previous model, the HD DA 55-300mm f/4-5.8 WR is still available, which still depends on the camera's screw-driven AF. Nothing wrong with this, as some costly Pentax lenses still use this technology.

[Wheatfield]

Or no elements needed for coffee


Hang up and DRIVE!

I knew Canon lenses were good for something.

[i_trax]

Or no elements needed for coffee


Hang up and DRIVE!

Mine is STABILIZED , good for milkshakes.
Oh, and you misplaced your hood?

[Digitalis]

Often cheap polymer thermoplastics,in other cases advanced carbon composites and semi-crystalline Polycarbonates and in other cases Metals such as Aluminium, Brass and Magnesium alloys. Lens barrels are seldom made of a singular material, they are frequently a mixed combination of materials.

All lens elements are glass.

Optical glass which is a silicon dioxide based amorphous solid*, is easily manufactured, formed and polished. However its optical properties and physical properties can be modified through the addition of various metal oxides and non-metals such as: Boron, Lead**, Copper, Cobalt, Tantalum, Cadmium**, Phosphorus**, Calcium, Vanadium, Magnesium, Sulfur and Arsenic**. These elements are added in trace amounts to alter mechanical properties as well as optical refractive index (and also to change colour transmittance of the lens itself). Older lenses can have radioactive elements such as, Thorium (mildly radioactive) Strontium (very radioactive) Lanthanum isotopes (strongly radioactive), as these elements decay radioactively the energy given off causes the lens element to eventually turn Yellow / Deep amber - The precise manner in which this yellowing occurs is a matter of ongoing debate: One hypothesis suggests it is the formation of colour centers created through highly energetic radioactive decay within the structure of the glass itself that cause the discoloration; another hypothesis is that the micrometer thin metallic coatings on the surface of the lens element ( there can be up to 13 different coatings of various metallic compositions on a single lens element) are affected by the radioactive decay and are (reversibly) transformed into an altered chemical state by it.

Mine is STABILIZED , good for milkshakes.

Wouldn't having a gyroscopically stabilized container suppress any external force and lead to a disappointing milkshake?

in fond memory (or is that mammary ?) of Marie Antoinette

If those glasses were made these days they would look VERY different.

Except the ones that aren't For example, the hybrid aspherical elements in various models, including the DA15...

These are at least partially made of glass with a polycartbonate aspheric element bonded to it. I'd imagine it would be quite a nuisance to get the refractive indexes of the materials to match.


*Natural glass does exist, any natural process where high temperatures and a suitable silicate material is present can produce glass, lightning strikes on the beach (Fulgerites) Volcanic glass ( Obsidian). Also naturally grown crystals can be used for lenses, though they have pretty abysmal optical transmittance compared to synthetically lab grown ones.

** Thankfully the inclusion of these elements has been greatly reduced over the decades since RoHS and similar environmental safety and waste management measures have been put in place.

[Alex645]

Most of the consumer grade lenses are plastic and glass some having metal mounts.
Most of the limited and pro grade DA* lenses are metal and glass.
A good majority of both are weather resistant.

And the weather resistant and all weather rated lenses have silicon rubber gaskets or rings.

[stephen_G]

It was not, I'm afraid - if you look closely, the word did not have the accented 'e' - which I admit could have been a grave mistake,

With these digressions, I bet the OP is really glad he asked !

The digressions are very entertainng, glad I asked the question!

---------- Post added 12-01-21 at 03:50 AM ----------

I see what you did there



Indeed. It's almost as if there's some sort of competition that requires six posts a day before an entry can be claimed... for a lens that, I'm pretty certain, contains no plastic elements

Competition?

---------- Post added 12-01-21 at 03:54 AM ----------

The lens bodies of any brand for APS-C cameras with the zoom range of 55-300mm will be made of plastic. This above Pentax model is one of the newest, which incorporates the PLM technology for faster autofocus (AF). The RE stands for Retracting, as the lens barrel can be drawn in for extra compactness during carrying. But you have to be using a fairly later model of Pentax camera for this lens to function properly. The previous model, the HD DA 55-300mm f/4-5.8 WR is still available, which still depends on the camera's screw-driven AF. Nothing wrong with this, as some costly Pentax lenses still use this technology.

Thanks for clarifying Mike.