[bclaff]

Probably not of general interest but perhaps for some.
There are quite a few optical prescriptions entered into the PhotonsToPhotos Optical Bench which is an interactive ray tracer.
Those that closely correspond to production lenses are on a separate page called the Optical Bench Hub.
You'll find quite a few Pentax brand lenses listed under Ricoh. (Many from Known and Unknown Pentax lens designers and their lenses )
I'm always interested in finding more relevant patents to enter (and brand).
If you're curious about the basics of optics you may find the Optics Primer an interesting read as well.

[lytrytyr]

A brief moment of excitement when I saw "Pentax 21 mm f/2.8".
Could this be the new D FA 21 Limited?
But it was just a mislabeled 110 format 20-40 mm zoom.

[RobA_Oz]

A brief moment of excitement when I saw "Pentax 21 mm f/2.8".
Could this be the new D FA 21 Limited?
But it was just a mislabeled 110 format 20-40 mm zoom.

Did you work out what the Pentax 26mm f4.1 was?

Nice find, bclaff.

The FA*28-70 looks to have some additional elements behind the assembly – a teleconverter perhaps, but why?

[bclaff]

A brief moment of excitement when I saw "Pentax 21 mm f/2.8".
Could this be the new D FA 21 Limited?
But it was just a mislabeled 110 format 20-40 mm zoom.

I don't see "Pentax 21 mm f/2.8" in my list. Can you provide a Link?
I do see these:

Attached Images

 

[bclaff]

Did you work out what the Pentax 26mm f4.1 was?

That is not a production lens simply an example from a patent.

The FA*28-70 looks to have some additional elements behind the assembly – a teleconverter perhaps, but why?

The production figure for that lens is for the telephoto end.
Try using the scenario buttons to get to scenario#3
You should see:

[RobA_Oz]

That is not a production lens simply an example from a patent.



The production figure for that lens is for the telephoto end.
Try using the scenario buttons to get to scenario#3
You should see:

OK, thanks. I can see that I didn’t try enough of the scenarios.

[AstroDave]

Nice information.

It would be very convenient in your Optics Primer to be able to navigate between pages (or at least on to your intended next page) without having to go back to the first page.

[lytrytyr]

I don't see "Pentax 21 mm f/2.8" in my list. Can you provide a Link?

It was in the "Choose a lens" dropdown for the "Optical Bench",
about a third of the way down.

The address-bar link is too generic to be of any help.

[bclaff]

Nice information.

It would be very convenient in your Optics Primer to be able to navigate between pages (or at least on to your intended next page) without having to go back to the first page.

Did you miss the Next Article link?

[bclaff]

It was in the "Choose a lens" dropdown for the "Optical Bench",
about a third of the way down.

The address-bar link is too generic to be of any help.

OK. Found it. For future reference: note the Link button.
It brings up a URL that will return to the page. The highlighted part is the patent ID and example.
Looks like a copy/paste error in the title. I'll fix that.

[AstroDave]

Did you miss the Next Article link?

Clearly, I did! Mea culpa.

I still think it would be nice to have that at the bottom/end of each article as well, since that's where you wind up as you are reading it, especially if you have scrolled down aways and don't have the top of the page on screen, so you don't have to scroll back up!

[lytrytyr]

For future reference: note the Link button.
It brings up a URL that will return to the page.

Ah, I wondered what that was for.

The highlighted part is the patent ID and example.
Looks like a copy/paste error in the title. I'll fix that.

Did you copy the "Pentax 21 mm f/2.8" title from a recent Ricoh patent?

Inquiring minds want to know!

[bclaff]

Did you copy the "Pentax 21 mm f/2.8" title from a recent Ricoh patent?
Inquiring minds want to know!

No. That simply indicates a 21mm f/2.8 patent filed by Pentax. But it's not one that corresponds to a production lens.

[lytrytyr]

Is the filed patent recent enough that it could be the (hopefully) forthcoming D FA 21 Limited?
They may not be totally ready to call it a production lens yet.

[bclaff]

Is the filed patent recent enough that it could be the (hopefully) forthcoming D FA 21 Limited?
They may not be totally ready to call it a production lens yet.

I try to stay away from speculating based on patent applications. Most do not come to fruition.