Rikenon 20mm?

[ramon_castro]

does this lens exist? any comment, thanks

[steve_levine]

"ROKINON" was an aftermarket brand of lenses , made in various mounts. (I have a 24 & a 135 in Olympus OM mount for example). Stopped down a few stops these were acceptably sharp for my uses. I shot many color slides with these along side my Olympus Zuiko lenses, and I never noticed any huge quality differences.

[dj_soroka]

Don't know anything about a Rikenon 20 mm.

 

Rikenon or Rokinon ??

 

I was pleasantly surprised by the excellent performance of a Rokinon 7-element teleconvertor (that I inherited) with my 180 mm f/2.8 ED Ais lens.

 

This was long after swearing off teleconvertors for anything except 300 mm and longer lenses.

[sid_reilly]

Of course Rikenon was trademark for Ricoh's own SLR lenses. Checked with a friend who still uses a Ricoh XR-something and he doesn't recall any Rikenon shorter than 28mm.

 

Most Ricoh's can use K-Mount lenses (except for the Ricoh XR-P and XR-M which used modified R-K K-mount's), and Pentax made two K-mounts in this range: a 20mm f4 SMC-Pentax M and then a 20mm f2.8 SMC-Pentax A.

[sid_reilly]

Should have written most LATER X-series and K-series Ricoh's can use K-mounts (earlier Ricoh's use thread mount lenses).

[sid_reilly]

Out of curiousity, kept looking into this. Butkus.org hints through pictures that ultra-wide-angle Rikenon's shorter than the 28mm were made. See his Ricoh on-line catalogs, in his two photos of later Rikenon lenses there are three that seem to look like ultra-wide-angle's or fisheye's.

 

There was a 21mm f3.8 Rikenon made in thread mount (not K-mount) found on a few sites, then a fisheye 16mm f2.8 XR Rikenon R-K-mount lens is now listed, expensively, at Kevin Cameras.

 

So no definitive answer, but there may just possibly be a 21mm, not 20mm, Rikenon in K-mount or R-K mount.

[david_m]

I own a 21mm Rikenon lens. It is M42 screw mount.

[frank_yang]

Ricoh made few wide angels in K mount. I have a rare 16mm f2.8 Rikenon fisheye made by Ricoh in K mount, and its a vary interesting lens as you have to twist the front element off to change filters. Its located between front and rear elements. Coating is a vary deep purple tone and its about as good a fisheye as I can ask for. The color, contrast, sharpness is much better than what you might think compare to Nikon or Canon's equivalent. I like my Ricoh 16mm fisheye better as its colors are cooler compare to my Nikon's which is bias toward the warmer tones.

 

Ricoh also made other wide angles in K mount. Besides the 16mm fisheye it aslo have a 18mm wide angel, next is 24mm f2.8 and then the 28mm f2.8. The 18mm and 24mm never made it to the later version of all Ricoh lenses that have the P chip in them so its vary desirable since its not commonly found, and if you can find it on ebay it will cost you a pretty penny. Ricoh lenses are vary underated, but you'll not be dissapointed if you get a couple and try it out like I did.

[al_parker1]

Subject: Response to Rikenon 20mm?

 

Yes it does exist and I have one! The 20mm F3.5 Rikenon sports a Pentax Screw-Mount. It's quite sharp and can be used on any Pentax Screw-Mount or K-Mount camera (adapter required). It is also RADIO-ACTIVE! The rare-earth glass used in the design sends my geiger counter off the scale!!! Quite a conversation piece!

[al_parker1]

Correction! It is a 21mm Rikenon. I got it out of the camera closet last night and realized that it was indeed 21mm! It's also still radioactive!

[jean_jacques_granas1]

Hello Al,

 

I realise this may be a question you have no answer to, but what sort of 'radioactivity' are we talking about here? Is it potentially harmful? Do you have to keep the lens in a lead-lined container? Do you glow at night? :-)

 

Jean-Jacques

[al_parker1]

The radiation from the rare earth elements used in the 21mm Rikenon and several notorious Pentax lenses is said to be relatively harmless but it�s best to keep the lenses away from constant, close body contact. Telescope and microscope eyepieces made from these materials could cause cataracts. It is thought that as time goes by some actually become more radioactive. See: http://medfmt.8k.com/mf/radioactive.html

 

Walking through an airport radiation detector with one of these lenses might create a little excitement for the bored security personnel!

[pekka_maki]

Hello,

 

I just like to ask (if you still read this discussion) does anybody know if the lens XR Rikenon 1:1.7 25 or 28 mm exist? I have Rikenon 1.7 50 mm (diameter 52 mm) and now need the same lens design but in smaller size. In other words the same lens with all dimension scaled half from original.

[frank_yang]

Hi Pekka

 

Ricoh has made 55mm f2.2, 50mm f2, 50mm f1.7, 50mm f1.5 and 55mm f1.2, they all have 52mm filter thread except the 55mm f1.2. None of them can be consider compact 50's like the Nikon 50mm f1.8 AIS or Series E's but their performance can not be faulted, hard to screw up a 50-55mm lens design anyway.

 

If you want a compact lens in K-mount that share 52mm filter thread, Ricoh in the mid 90's before they pull out of the US film camera market have made a 45mm f2.8 Pancake compact and 28mm f3.5 Asphperical Pancake. Both are rare and does not show up on ebay often and if they do the price is out of this world.

 

Chinon made a 45mm f2.8 pancake in K mount (Rare). Pentax SMC 40mm f2.8 common found, Cosinon 40mm f2.5 yes f2.5 K mount pancake and Vivitar 40mm f2.5 (made by Cosina) pancake. All four are compact but use 49mm filter threads. Only the Pentax can be found easily in the used market. If you ever see all four lenses, you think they come from the same factory but small difference does exit like the Chinon focal lenth of 45mm instead of 40mm and Cosina lens speed of f2.5 which I did check with my camera meter that it does give slight exposure difference compare to f2.8 lens. K-mount is fun to get into as the variety lenses option available to one is hard to beat and come pretty close to being a universal mount compared to the original Pentax M42 screw mount.

 

Hope this helps

[rick_mason]

<p>Ricoh also made a XR Rikenon 16mm fisheye lens f2.8, I've got it. Its great. K mount.</p>