Open Mike: The Complete History of the Pentax Fast 50

 

[Withdrawn]

 

Notice that the comments are still posted. I'll leave those up.

I'll probably post a revised version of this, but I'll need some time. More soon!

Mike

Comments

[Rob de Loe]

Wonderful, thanks. Pentax was my first "real" 35mm camera. Pentax is what I initially used when I started adapting old 35mm lenses to a Sony A7. I still use Pentax 645 sometimes on my GFX outfit.

You are not wrong about those Takumars. The 28/3.5 and the 35/3.5 are little mechanical jewels. The 28/3.5 does not do well on high resolution digital sensors, but I kept around for a long time just to be able to handle it.

[John Krumm]

On my "not likely" Pentax wishlist is a new DSLR, very basic, full frame but smaller and especially lighter than the K1. Call it the KFA or something like that, meant to be used with the small classic lenses. They will probably come out with a new film slr before that.

After reading this article I had to go upstairs, find my Pentax 35 HD FA f2, put it on a K to Z adapter, and try it out again. Not the same, but it's ok. Image quality is good. The lens is not designed for easy manual focus, with a thin rubber strip to turn, but it works.

[William Lewis]

Nice article Mike that meshes well with what I've learned here and there in my recent infatuation with things Pentaxian.

I have a Super Takumar 50/1.4 that I picked up cheap because it was yellowed. That's easy to fix. Less easy was the fungus that had etched the elements around the aperture... That one's pretty much a paperweight.

I then picked up a SMC Pentax-A 50/1.7 - not quite as fast but a very sweet user friendly day to day lens on my one Pentax film body. Love it there.

On my APS-C K-3 though, I have the absolutely lovely SMC Pentax-FA 50mm F1.4 in crop mode for an effective 75mm lens. Would the HD version be better? Probably, but I can't imagine needing to find out since this lens is so excellent.

And that's Ricoh/Pentax's biggest problem: they make so many good things that they have a hard time getting their happy users to upgrade.

[Bob Johnston]

A most interesting article Mike. I understood that the yellowing was due to thorium being present in one of the elements. The thorium is actually radioactive, but not enough to be dangerous. So, is it thorium or is it the cement? Does anyone know for sure?

[Dan Khong]

Getting a cheap FF mirrorless digital camera to start with (I have the Canon EOS RP), hunting down the highly affordable CZJ, Russian copies, and Taks to fit has been like a trip to Toys"R"Us all over again. The Jupiter-9 ("glowy") lens is my current plaything.

Not forgetting - with the appropriate Leica M/SM-Canon adapters - more play time!

I've been out shooting more since then.

[Chris Stone]

Actually the Classic lens is multi coated, hence the use of "smc" (Super Multi Coated) in the lens name. The distinction between the Classic and the HD version is that the HD version has the new improved HD multi coating on the lens which gives improved performance.

On a side note, when the K lens series were first released smc was actually in capitals "SMC". This was subsequently changed to "smc" all lower case. So you know you have an early K lens from 1975 is the name shows SMC in capitals.

[Well, I don't know about that. I've shot with an awful lot of Pentax 50mm f/1.4s, and I've never seen "rainbow flare." And I don't pamper my lenses--I'll put the sun in the frame, just out of the frame, shoot streetlights at night, you name it. You might be right, though. --Mike]

[Kodachromeguy]

"It's a special challenge, shooting with a single-coated lens." Hmmm, I think my E. Leitz M lenses are single coated. So is the Xenotar on my Rolleiflex, at least one Super-Takumar, a Jupiter-8, a Summitar, and a Color Skopar on a Voigtlander BL. I just go take pictures with them (on film). Just always use hoods.

[Rod S.]

For the current pair of Planar-type 50mm f/1.4 lenses, the SMC or smc designation on the 'Classic' version indicates that the coating is the 'classic' seven-layer coating used by Pentax since its introduction in 1971, and the HD designation on the second version shows it has the newer HD coating introduced in 2012.

So, no, the SMC/smc version is not - or should not - be single-coated.

[Bill S.]

Thanks for the excellent post! I have read most of your archived posts at LuLa, but have been unable to share them with others.

I have read that leaving a lens in the sun to eliminate yellowing can result in heating of the lens that can cause lubricants to diffuse throughout the lens, possibly on the to optics. Have you heard leaving a lens in the sun for an extended period can cause problems?

[No, but that's really an area of the hobby I'm really quite far away from. It's been decades--more than one--since I shot old cameras seriously. If I were going to fix a lens this way I would use an LED full-spectrum or UV lamp of some sort. But I'm just not adjacent to this sort of thing, and not the guy to take advice from. There's a whole community of people online who are dedicated to adapting old lenses; I'd poke around until you find some of them and pay attention to what they say. --Mike]

[Sroyon]

I think Chris Stone is right, the SMC is also multicoated. See the comment here by Mistral75:

The smc FA 50mm f/1.4 Classic was the most interesting part of yesterday's live event. There were some interesting tidbits about the development of the lens

They explained that the original idea came from people who enjoyed the iridescent rainbow ghosting that occurred when framing the sun with old lenses like the Super-Takumar 55mm F1.8 on a K-1 with an adapter.

They knew that when the Super-Takumar was replaced by the Super-Multi-Coated Takumar, the inner frame of the lens barrel was redesigned to eliminate internal reflections.

They simulated the light reflection on the inner frame of the smc FA 50mm f/1.4 with and without a 'certain device' added between the Super-Takumar and the Super-Multi-Coated Takumar. The simulation confirmed the presence of a 'rainbow ring'.

They made a prototype and were able to reproduce the 'rainbow ring'.

They ran further simulations and discovered that by adjusting the shape and surface treatment of the inner frame of the lens barrel, they could control the intensity of the rainbow ring. (If the rainbow rings are too strong, they turn white.)

Also this Petapixel review shows comparisons, and concludes:

I honestly find the HD and Classic versions of the two lenses to deliver identical results in almost any situation. ... Indeed, the only real difference is when shooting both lenses towards bright light sources like the sun. ... The Classic exhibits stark and vivid rainbow circles which can be used to frame close-up subjects or add visual interest to the scene.

[Stelios]

You're almost making me buy Pentaxes...

[I'm almost making *myself* buy Pentaxes...must resist...must resist....

:-) --Mike]

[James Weekes]

Don’t resist. A simple K-mount or screw mount to Lmount adapter will put it on the front of your Sigma.

[Tony Gale]

“...if you shoot B&W film and develop and print it yourself, try the Pentax Classic (for normal shooting, not against the light) and note the shadows and the long-scale gradation.”

As a home-brew B&W shooter myself, I’ve come to absolutely love completely uncoated lenses. The three I rotate between the most are the Leitz Summar (the smallest 50/2 I’ve ever seen); a pre-war 50/1.5 Zeiss Sonnar; and a 105/3.5 National Optical Co Trinol, a weird 1940s English lens created by a spin-off from Taylor, Taylor & Hobson.

With a good lens hood, flare is rarely a problem (and, if anything, more predictable than a single-coated lens), but the tonality of the prints made with these lenses is just stunning, so I’m glad to see some of the Japanese lens manufacturers are making still making single-coated lenses to get close to that look.

Who’ll be the first niche/boutique company to make a totally uncoated lens though, eh?

[Stephen S.]

Reversing the yellowing of thoriated elements does not require UV light at all. Any light will do the trick; it's the photons that do the work. There is no reason to use UV bulbs and risk eye damage. It's a pervasive myth, easily disproven both theoretically, by understanding the mechanism behind the yellowing, and empirically, by camera technicians who spent several decades using tungsten light bulbs that output no UV, but have the same heat problems as sunlight, before they switched to fluorescent or LED bulbs with no heat and no UV.

[Tullio Emanuele]

Hi
What about the Pentax SMC 50mm f1.2 lens?

[Dave]

I'm going to agree with Chris Stone regarding the SMC coating on the Classic lens.

B&H says, "Through intentional fine-tuning of the lens design, this lens produces a unique visual effect known as rainbow flare when it captures an image at wide-open apertures and against strong backlight."

From Pentax Forums; "The second "new lens"—the SMC FA 50mm F1.4 Classic— keeps the original SMC coatings and is designed to enhance flare, . . ."

It's the fine-tuning that enables the rainbow effect, not any change in coating of the lens surfaces. I've never seen rainbow flare in my old Super-Takumar screw mount lenses -- well, not that I can remember. Just regular flare if mis-used.

From what I've seen in Youtube videos, the effect only happens at f/1.4. The video (down the page) at the B&H link you provided shows the flare effect, starting at smaller apertures. Only f/2.8 shows a little flare and only f/1.4 shows the rainbow colors. (Start at 3:16 in the video. [https://youtu.be/Zw1MZMEMjro?t=196])

The Classic lens does have the rounded aperture blades, which surprised me.

No matter the small mistakes, this post was an enjoyable read! :>)

[Cateto]

Actually I was going to save this article for reference, and I am very interested in reading an updated, corrected version of this text. So please do it, Mike, as I am not alone in this interest.

Thanks in advance!