[nocturnal]

At the end I choose to buy a Smc k30 for 217€. I will have it in one week from Japan and we will see for the custom tax. Maybe nothing with luck and maybe around 70€ in more ...
It was so so hard to choose and I strongly hesitate with the k28f3.5 and the F28f2.8. But I really want to try the K30 and I think it will be possible to sell it without loose too much money to try the k28f3.5 or the F28f2.8.
I think the best choose was to found the A28f2 but it is rare and the only one I seen was at 400€ ...

I will post some photo here when I will receive the k30.
Thank you very very much again for your help.

That is a big price to pay for a SMC K30 lens plus custom fees. The PentaxUser website in the UK is a brilliant place to buy Pentex gear, all based on trust but it is fine. A member was selling the K30 lens a while ago for £135 plus no custom fees to the Eurozone. It is brilliant for picking up rare stuff and cheaper than Ebay (very much like this forum but here is mostly USA based).

I've the rare K35/f3.5 and even rarer K24/f3.5 I'll probably be selling shortly.

[JVi]

Vision and perception is definitely a variable thing. My job (career) centres on my ability to see things very well (one of my roles is to find things like a needle in a haystack). In performing this role I note variance in my colleagues aptitude (we call it observer bias). It is amazing the kinds of arguments that arise from this bias (I put these differences down to two things: inherent vision ability and learned/ cognitive processing of this input). Colour is simply a component of vision and we know this aspect of vision varies across the human race (e.g. colour blindness). In fact one of my colleagues is partially colour blind and when asked to find a certain orchid (red and green in colour), the person told me that he used differences in tone to find it (amazing skill / adaptation).

The purplish cast could be more evident because the other lenses exposed a little better (here I am trying to say that the f2 lenses seemed to grab the scene a little better from a light perspective). If I used some exposure compensation then I might get equivalence between the K28/3.5 and other lenses. This might lessen the purplish cast. Hmmm, food for thought.

I just recieved, less than an hour ago, a K 28 3.5 for $61USD, all in, off of EBay. It is clean, snappy and, well, I can't believe how good the images are, even wide open.
Thank you again for your commentary.

[chapolin]

I continue to see the photos here DSLR fun with 28mm: Club for any 28mm lens - Page 24 - PentaxForums.com and honestly I like a lot the F 28 f2.8 ...

[twilhelm]

That is a big price to pay for a SMC K30 lens plus custom fees. The PentaxUser website in the UK is a brilliant place to buy Pentex gear, all based on trust but it is fine. A member was selling the K30 lens a while ago for £135 plus no custom fees to the Eurozone. It is brilliant for picking up rare stuff and cheaper than Ebay (very much like this forum but here is mostly USA based).

I've the rare K35/f3.5 and even rarer K24/f3.5 I'll probably be selling shortly.

Is the K24 3.5 a rare lens? This is a genuine question, not being sarcastic. I picked one up from a camera shop a little over a year ago for $78 in pristine condition.

[nocturnal]

Is the K24 3.5 a rare lens? This is a genuine question, not being sarcastic. I picked one up from a camera shop a little over a year ago for $78 in pristine condition.

This one?

SMC Pentax 24mm F3.5 Reviews - K Prime Lenses - Pentax Lens Reviews & Lens Database

Very few reviews of it and others in forums thought it was rare and the f2.8 more common. Maybe you just hit a gem! I love it on a Pentax MX, looking through the viewfinder is great because of the view. It is a good lens, don't you think? Supposed to be excellent as a reversed macro lens maybe used with another lens, I might have tried this but can't remember.

[twilhelm]

This one?

SMC Pentax 24mm F3.5 Reviews - K Prime Lenses - Pentax Lens Reviews & Lens Database

Very few reviews of it and others in forums thought it was rare and the f2.8 more common. Maybe you just hit a gem! I love it on a Pentax MX, looking through the viewfinder is great because of the view. It is a good lens, don't you think? Supposed to be excellent as a reversed macro lens maybe used with another lens, I might have tried this but can't remember.

That’s the lens. I really like the lens a lot, on film and the K-1. Guess I’ll need to do a review soon!

[nocturnal]

Twilhelm, a review would be great as a long time since the last one and nobody has reviewed it with K1. I only used it once for astro landscapes using the astrotracer on the K-30, it did well with nice colours and the ISS appeared too just by coincidence one of a few times a year I drive up to the north Irish coast and a dark sky area.

I got it ridiculously cheap as I spotted it in a job lot of duff lenses by an antiques dealer on ebay who didn't list it and didn't know what they were selling. I love the styling and build of the K range.

[KC0PET]

That’s the lens. I really like the lens a lot, on film and the K-1. Guess I’ll need to do a review soon!

I have one of those also and keep meaning to post a review. I usually try to get organized and cover my bases before I post a review. I wouldn't call it a rare lens, from watching pentax 24mm ebay listings it seems there are usually several listed at any given time, I didn't have much trouble finding a good price on one when I pursued it. I don't have the K 28 f/3.5 but I have the K 35 f/3.5 and the 24 is not quite as sharp and I rate it somewhat below the 35 in general, but the K 24 is a very nice lens and I enjoy shooting with it, and I like the 24mm focal length on APS-C.

[monochrome]

Is the K24 3.5 a rare lens? This is a genuine question, not being sarcastic. I picked one up from a camera shop a little over a year ago for $78 in pristine condition.

KCOPET describes (below) the relative scarcity of K24/3.5 well, I think. It has been uncommon to see one for a long time. Lately many formerly hard-to-find manual lenses have appeared on eBay listed by sellers in Japan. This commonly happens when the Yen is weak. Also, as is noted in other collectibles such as Kimono and related textiles, Japanese are ageing and selling their lifelong collections of many things that their children don’t want. We in the west are a ready market for such as these.

K24/3.5 was only manufactured from 1975 - 1977 as it is a former Takumar m42 lens with a bayonet K-mount conversion. It was replaced by the K24/2.8, a more compact lens, at the time the M lenses were introduced. Your good fortune is not uncommon in retail shops. EBay prices are often not a value because sellers are informed about values,

I have one of those also and keep meaning to post a review. I usually try to get organized and cover my bases before I post a review. I wouldn't call it a rare lens, from watching pentax 24mm ebay listings it seems there are usually several listed at any given time, I didn't have much trouble finding a good price on one when I pursued it. I don't have the K 28 f/3.5 but I have the K 35 f/3.5 and the 24 is not quite as sharp and I rate it somewhat below the 35 in general, but the K 24 is a very nice lens and I enjoy shooting with it, and I like the 24mm focal length on APS-C.

Well the K35/3.5 is a pretty special lens as they go

[cyberjunkie]

I would rate both the pentax 28mm f3.5's, and the kiron/vivitar 28mm f2's, as good 28's. In .

The pentaxes will be more consistent lenses, much sharper wide.

The "K" 28mm f3.5 is relatively overpriced, it has acquired a particular cachet and when it comes up for auction it regularly bids over £100 (here in UK). The "M" 28mm f3.5 is much better value (£30-50 typically) and really most of the time there is little difference in results.
The kiron can also be found as a vivitar (28mm f2's with 22xxxx serials). BUT, whether vivitar or kiron watch out for ones with gummed up iris's - a common problem. There are also komine made vivitar 28mm f2's (28xxxx serials) these can be equally recommended actually, a vivitar 28mm f1.9 (tokina - 37xxx serials,

You summed up the situation very well..
I agree with pretty much everything.
I add just a few info.

The Vivitar 2/28mm is a good lens in both versions. Some say the Komine is better, some prefer the Kiron. Neither of them is cheap. It's a good thing you remembered the Petri 2/28 (also available as Cosina), cause it's easier to find at a decent price.
I add two optics to your list:
Soligor C/D P 2/28mm (Tokina, serial starting with 1)
Chinon Multi-Coated 2.8/28mm (Tomioka or Cosina, green lettering, elliptic reference mark)
The former was never made in PK mount, the only compatible option is the M42. It is fast, very well made, and has good IQ. Not cheap, though.
The latter is very cheap, relatively well made, and has good sharpness at landscape distances. Close up it gives swirly bokeh wide open, showing that it's not optimized for short conjugates.
The main difference between faster (f/2) and slower (f/3.5) lenses is mainly about ease of focusing in low light and close up background separation.
Sharpness is not related to the max aperture. The two SMC Pentax (f/2 and f/3.5) are quite similar stopped down, or used for landscape. I believe the very expensive f/2 has an edge at close distance, because of its design.
In the end the choice of the right objective depends on what kind of use is planned, and of course to personal taste. If bokeh is of no concern and low light photography is not your thing, a relatively cheap lens won't show its low cost in the final image.
After experimenting with countless vintage lenses I realized that most lenses are quite good, and even the weaker ones can do well after some PP.