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SMC Pentax 1:3.5 15mm on it's first walkabout.
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PostPosted: Thu Apr 19, 2012 5:27 pm    Post subject: SMC Pentax 1:3.5 15mm on it's first walkabout. Reply with quote

This half brother of the Distagon 3.5/15 arrived today. I got a good deal on this Pentax as the Distagon's are really unaffordable for me for now.
My copy is well used as can be seen by the paint loss, but the glass is pristine. Very well built compact little bomb of metal and an enormous piece of glass up front.

After having trouble with the adapter I bought with it, it now sits on my 5D MkII as if it belongs there. For those interested I use a Kipon adapter. It is the only one I have found that has the lens sit on the camera as it should. Most adapters put the lens on a 40 degree angle but then you can see the sun hood in the frame. I did have to operate on the lens and get rid of the plastic fin and the aperture lever.

Anyway here are some pics I took just now. It is not an easy lens to work with.

All pics straight from the camera. All at 5.6, 400 ISO, various shutter times. I forgot to set the camera to high quality and RAW after taking some lowers JPG's for the web yesterday.














PostPosted: Thu Apr 19, 2012 5:44 pm    Post subject: Reply with quote

Congratulations, it's a full title brother, it is even possible that Zeiss provided the glasses already manufactured to Pentax,
in which case only the assembling and the barrel would be different.


PostPosted: Thu Apr 19, 2012 5:54 pm    Post subject: Reply with quote

It looks really soft on the edges, was it wide open?


PostPosted: Thu Apr 19, 2012 5:58 pm    Post subject: Reply with quote

I'm guessing that's field curvature?


PostPosted: Thu Apr 19, 2012 6:10 pm    Post subject: Reply with quote

Orio wrote:
Congratulations, it's a full title brother, it is even possible that Zeiss provided the glasses already manufactured to Pentax,
in which case only the assembling and the barrel would be different.


OK, I didn't know that. I knew it was Herr Glatzel's recipe. The barrel is different then the Distagon. It works (focus and aperture) the other way around. A bit annoying if you're used to Contax, but hey, who's complaining ?

Quote:
It looks really soft on the edges, was it wide open?


No, all pics 5.6. I does look soft. I have to try some more with other apertures.


PostPosted: Thu Apr 19, 2012 6:13 pm    Post subject: Reply with quote

propellor wrote:

OK, I didn't know that.


It's only my speculation, since it was a very difficult lens to produce, requiring top quality glass, so it seems credible to me
that Zeiss could provide the glass pieces already manufactured as part of the agreement with Pentax.


PostPosted: Thu Apr 19, 2012 6:15 pm    Post subject: Reply with quote

The softness varies between frames, for instance, the Leidseplein shot is better on the edges than the one with the guy in the white shirt looking at his phone on the right hand side, strange.


PostPosted: Thu Apr 19, 2012 6:36 pm    Post subject: Reply with quote

estrange indeed. I made a series just now in all apertures ;


3.5, iso 1000

5.6, iso 1000

8, iso 1000

11, iso 1000

16, iso 1000

22, iso 1000

Wide open it is definitely soft. It gets much better after f8.


PostPosted: Thu Apr 19, 2012 6:53 pm    Post subject: Reply with quote

2 more. First f5.6, iso 1000. Second f8, iso 1000.

Focus is on the middle lens


f5.6, iso 1000

f8, iso 1000.


PostPosted: Thu Apr 19, 2012 6:53 pm    Post subject: Reply with quote

Remember that it's a 15mm spherical lens. There are no aspherical elements.
Some corner loss (read: spherical aberration) in a spherical lens of 15mm is unavoidable.
On the plus side, you have the great feeling of classical spherical lenses made with rare earth glasses.
It surely looks different from polymeric aspherical surfaces of contemporary super wides - especially in the contrast.
The quality loss, however, should be confined to the extreme corners, such as in this example of mine:

whole:


corner:


Of course, the geometrical distortion at the corners is unavoidable (and much inferior to that of other comparable lenses of it's time)
The Distagon 3.5/15 is best used at f/11 on full frame, which is the diffraction limit.
On APS-C, it can be used at any aperture, because the center is very sharp from wide open.


PostPosted: Thu Apr 19, 2012 7:00 pm    Post subject: Reply with quote

It does indeed get much better stopped down.

BTW, I know exactly where your flat is, nice part of town to live!

I miss living in Amsterdam Sad


PostPosted: Thu Apr 19, 2012 7:32 pm    Post subject: Reply with quote

Thanks Orio, i was starting to wonder if I bought a lemon. But I just have to get used to it a bit more and get to know it's limits.

@ Ian....., Not too difficult if you know your way around A'dam a little. Smile

why did you leave and where do you live now?


PostPosted: Thu Apr 19, 2012 8:00 pm    Post subject: Reply with quote

Sure, you're in a well-known spot. Wink

I had to come home due to family commitments, sadly. I live in NW England. A few of my friends are on holiday in Amsterdam this week, sadly I couldn't afford to join them.


PostPosted: Thu Apr 19, 2012 8:13 pm    Post subject: Reply with quote

Well, Orio brought it up before me but I still have to ask whether it's the spherical or aspherical element version?
What brand is that friction arm?


PostPosted: Fri Apr 20, 2012 1:14 am    Post subject: Reply with quote

Himself wrote:
Well, Orio brought it up before me but I still have to ask whether it's the spherical or aspherical element version?
What brand is that friction arm?


Sorin, correct, now that you write about it, I recall that Pentax made also a variation of the lens with an aspherical element,
but discontinued it soon due to the stellar costs.

Propellor, a look at the f/8 MTF shows that drastic corner falloff is in the nature of the lens.



However, it is so marginal that even on full frame, the central edge of the longer side is only slightly affected
(because the edge of the image circle falls out of the sensor frame for it's most part):



PostPosted: Fri Apr 20, 2012 5:23 am    Post subject: comparisons Reply with quote

I did some close range comparisons of ultrawides including this K15/3.5 as well as the purported aspherical version here:

http://www.pentaxforums.com/forums/pentax-slr-lens-discussion/146188-comparison-8-ultrawide-lenses.html

Not sure about the extreme corners but borders were reasonable. Better than here. But perhaps at longer distances it degrades. I have seen this effect actually, now that I think about it.


PostPosted: Fri Apr 20, 2012 7:08 am    Post subject: Reply with quote

Congrats.

Personally, this lens was and still is one of the most difficult to use, especially when I don't have dslr FF bodies. My is Takumar Asph version, used several times a year in the last 30 years. Very good at center, good with crop sensors, corner performance is not as good with film and need to be aware in every shot.


PostPosted: Fri Apr 20, 2012 9:07 am    Post subject: Reply with quote

I really like this lens: it's beautiful and (from the tests I saw here and elsewhere) performs great.

The corner softness is a really minor issue, for me.
If I had that money to spend in a lens, I'd buy one right now: congrats.


PostPosted: Fri Apr 20, 2012 2:43 pm    Post subject: Reply with quote

Himself wrote:
Well, Orio brought it up before me but I still have to ask whether it's the spherical or aspherical element version?
What brand is that friction arm?


It is the later version, the spherical.
The arm came with the small dolly. I think it is Chinese. You can find them on ebay. Maybe they are called Magic Arm...

@Orio, thanks for the chart. I understand better the characteristics of this lens now. It will take some more flying hours with it to fully understand it strengths and it's shortcomings.

If I get something spectacular I will post.


PostPosted: Fri Apr 20, 2012 4:44 pm    Post subject: Reply with quote

Orio wrote:
Himself wrote:
Well, Orio brought it up before me but I still have to ask whether it's the spherical or aspherical element version?
What brand is that friction arm?


Sorin, correct, now that you write about it, I recall that Pentax made also a variation of the lens with an aspherical element,
but discontinued it soon due to the stellar costs.



Rumors say they made only 400 copies.


PostPosted: Fri Apr 20, 2012 4:51 pm    Post subject: Reply with quote

Himself wrote:

Rumors say they made only 400 copies.


Well, the total number of Distagon 3.5/15 (spherical) is less than 2000, so hardly surprising.
It was not an everyday lens. It still isn't. Rolling Eyes


PostPosted: Fri Apr 20, 2012 4:59 pm    Post subject: Reply with quote

Those are unbelievably low numbers. That does explain prices for the Distagon. Any idea how many SMC Pentaxes were made? (The spherical of course)


PostPosted: Sat Apr 21, 2012 5:45 pm    Post subject: Reply with quote

Well my fear of it being a lemon is completely gone.
Maybe I will keep this lens glued to my camera forever..... Rolling Eyes

Here are some more pics. What I find incredible is the versatility of this lens. Architecture, streetscapes (haven't been to the "land" yet) and even people. It looks like you can shoot everything with this lens.

I shot some moving pictures on the carnival and will edit this asap. That shows the incredible correction of the lens. As you pan the lens the buildings and stalls do not warp as the camera moves past them. An effect you often see with ENG (Electronic Nes Gathering) camera's.

Next shots are all between F8 and F11. The corner sharpness has indeed improved dramatically Orio, thanks. I tend to shoot in low F's but this lens needs a bit higher F-stop.
Oh, and no PP whatsoever.


Apple's patented stairs in the new Apple Store in Amsterdam

Apple's patented stairs in the new Apple Store in Amsterdam 2

guestimated focus. About 1,5 meters

Sun straight into the lens and still the boy and girl have contrast

The coat on the right is now pretty sharp. Shot from the hip

Love those flares

Inside an elevator at the Puma store

Red pants are all the rage now in Amsterdam




Some carnival shots on the Dam square





Verdict: I love this lens. Very Happy


PostPosted: Sat Apr 21, 2012 5:52 pm    Post subject: Reply with quote

Great series, looks much, much better stopped down, I think you found how to use it, congrats!


PostPosted: Mon Apr 23, 2012 10:32 am    Post subject: Reply with quote

Yeah thanks, I am happy now. I am starting to get the feel for it.