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05-08-2007, 02:21 AM   #1
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My 4th 21 Limited..

Well..I am getting another 21mm Limited from Pentax. It seems that the 21 Limited doesn't like me at all...FF and BF issues have been endemic. Could have been a bad batch, but I hope this one works out as I really like that focal length and would use it in many applications if I felt confident in doing so. Until that happens I am using the Pentax 12-24.

05-08-2007, 02:36 AM   #2
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How do you estimate "FF and BF issues"?
AF is not perfect.
05-08-2007, 03:15 AM   #3
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I'm still on my first without issue on the K10d, though I did have slight (not a real world problem for me) FF on the K100d..

I am also curious how obvious was the FF/BF??
05-08-2007, 03:37 AM   #4
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???

QuoteOriginally posted by joele Quote
I'm still on my first without issue on the K10d, though I did have slight (not a real world problem for me) FF on the K100d..

I am also curious how obvious was the FF/BF??

You know Joel, what I am doing is kind of strange, yet essential to my achieving my final desired result. If the lens I am using cannot resolve perfectly what I am trying to accomplish, it cannot be used. I have "Never" had this problem before. Ever.

The circumstance is generally this. The position of the model might be for example leaning up against the "cyclo" i.e. solid rounded backdrop. I will be using a specific light that is very challenging for the AF sensor to identify, that being some hard pin light on the face to almost complete blackness on the neck, to light on the shoulder to the torso etc. I will focus on the "Eye" from a distance of lets say 2 meters. I will get an AF confirm and a second confirm to make sure it is in. I press the shutter, observe the image and where I focussed is out and where it is in focus is the torso..."NOT GOOD"..I mean "NOT GOOD". That happened twice and to rectify the problem, I had to USM at 1.0 pixels at 340 percent...

For landscapes and normal lighting conditions, it is fine. But this IS how I work. No ifs ands or buts. The 12-24 perfect the 16-45 perfect the 31, 40 and 70 perfect the 100 macro perfect. The "21" nada. If I manually focus, ignoring the AF confirm signal..It is OK.

Never had a problem with my lens of preference when with Canon, that being the 17-40L. So that is it in a nutshell. I told my guy at Pentax that if it can't be rectified I will have to stop using it..

Now how's that for an honest opinion coming from a sponsored Pentax photographer...

Ben

05-08-2007, 04:15 AM   #5
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QuoteOriginally posted by benjikan Quote
For landscapes and normal lighting conditions, it is fine. But this IS how I work. No ifs ands or buts.
So they could all be "bad" for those conditions? its just some of us haven't noticed it due to differeing requirements.. Pentax I assume are still working on the assumption that your just REALLY unlucky?
05-08-2007, 04:36 AM   #6
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Yeah..

QuoteOriginally posted by joele Quote
So they could all be "bad" for those conditions? its just some of us haven't noticed it due to differeing requirements.. Pentax I assume are still working on the assumption that your just REALLY unlucky?
I guess...I think they are a bit embarrassed.

So am I

Ben
05-08-2007, 04:42 AM   #7
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It is highly unlikely that I will buy a pancake including the one Benjikan mentions as an amateur with already enough lenses at hand. I simply cannot afford/justify buying them.
Still, I believe it is very honest of him to report this issue here. This makes the forum all the more valuable. A good message to all sponsored professionals!
05-08-2007, 05:44 AM   #8
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Photozone just posted the test of the DA 21mm: Pentax SMC-DA 21mm f/3.2 AL Limited - Photozone Review / Quick Test Report

It seems to be the worse of all the Limiteds (FA and DA), I wonder if it didn't have the back/front-focus problem... but I guess they test that before reviewing it (for example the test of the DA 50-20mm has been "delayed due to defect").


Their other Pentax lenses tests (including most of the Limiteds) are here: PhotoZone

05-08-2007, 05:44 AM   #9
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QuoteOriginally posted by benjikan Quote
Well..I am getting another 21mm Limited from Pentax. It seems that the 21 Limited doesn't like me at all...FF and BF issues have been endemic. Could have been a bad batch, but I hope this one works out as I really like that focal length and would use it in many applications if I felt confident in doing so. Until that happens I am using the Pentax 12-24.
I remember that last time you said your latest copy finally worked..
05-08-2007, 05:55 AM   #10
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Being an extreme amateur can I ask what is probably a foolish question.

Why do you need to use the 21mm Prime if the 12-24mm and the 16 - 45mm Zooms work perfectly?
As you stated, Benjikan, your preferred lens with the canon was a 17-40mm.

Is a prime lens that much noticeably better, or is it a case of because a 21mm prime exists?

I sincerely hope this doesn't come across as having a go at you - I am genuinely interested as why you would need the 21mm prime when the two zooms work for your needs; as you stated.
05-08-2007, 06:26 AM   #11
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QuoteOriginally posted by Falcons Quote
Being an extreme amateur can I ask what is probably a foolish question.

Why do you need to use the 21mm Prime if the 12-24mm and the 16 - 45mm Zooms work perfectly?
As you stated, Benjikan, your preferred lens with the canon was a 17-40mm.

Is a prime lens that much noticeably better, or is it a case of because a 21mm prime exists?

I sincerely hope this doesn't come across as having a go at you - I am genuinely interested as why you would need the 21mm prime when the two zooms work for your needs; as you stated.
Okay, let me, being an extremely extreme amateur, to answer this question ;-)

Prime is prime, zoom is zoom. Prime is for highest possible image quality, zoom is for convenience and flexibility, in short.

You may ask what image quality difference(s)? There are actually a lot of them, see:- RiceHigh's Subjective Ratings on Pentax Lenses on Pentax DSLRs
05-08-2007, 06:29 AM   #12
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No offence ricehigh, but your subjective testings don't interest me. would still love to see a photo though.
05-08-2007, 07:17 AM   #13
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Well...

QuoteOriginally posted by RiceHigh Quote
I remember that last time you said your latest copy finally worked..

...I was wrong!

Ben
05-08-2007, 07:21 AM   #14
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Great Question

QuoteOriginally posted by Falcons Quote
Being an extreme amateur can I ask what is probably a foolish question.

Why do you need to use the 21mm Prime if the 12-24mm and the 16 - 45mm Zooms work perfectly?
As you stated, Benjikan, your preferred lens with the canon was a 17-40mm.

Is a prime lens that much noticeably better, or is it a case of because a 21mm prime exists?

I sincerely hope this doesn't come across as having a go at you - I am genuinely interested as why you would need the 21mm prime when the two zooms work for your needs; as you stated.
To tell you the truth, I was under the impression that the 21L would be much better than a zoom. It is also lighter on the body. It seems that I was wrong in this specific case, as so far the 12-24 is sharper. However, the 31, 40 and 70 are absolutely brilliant. I find it very convenient using zoom lenses for many reasons. I can reframe artistically as well as rest in the same position while shooting, experimenting with different cropping possibilities as well as function in a very tight spot, especially with extreme wide angle lenses.

Ben
05-08-2007, 10:14 AM   #15
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Zooms are pretty sharp these days....

QuoteOriginally posted by benjikan Quote
To tell you the truth, I was under the impression that the 21L would be much better than a zoom. It is also lighter on the body. It seems that I was wrong in this specific case, as so far the 12-24 is sharper. However, the 31, 40 and 70 are absolutely brilliant. I find it very convenient using zoom lenses for many reasons. I can reframe artistically as well as rest in the same position while shooting, experimenting with different cropping possibilities as well as function in a very tight spot, especially with extreme wide angle lenses.

Ben
I tested a bunch of DA* and FA* primes and zooms and the biggest surprise was that the zooms were just as sharp as the primes most of the time. The primes however have better contrast and therefore look sharper (subjectively) at a distance and with fewer aspheric elements generally have nicer bokeh and (being fixed focal) less CA. But after PP there is nothing in it. As a result I decided not to buy the 21 as I am sooooo happy with the 12-24 which is my favourite lens!

However the 16-45 and the 12-24 were so close to the 21 and 40 pancakes I was really taken aback - especially by the 12-24 which you would expect to have much more severe issues at 12mm, but actually has LESS linear distortion than the 21 from 14-24mm.

But the pancakes are not as good as the FA LTDs especially the 43, which is simply stellar. One problem is they seem to have a curved focus plane which really cocks up off-centre focus points. The only way I could get the 21 to focus well off-centre was to do it manually. Perhaps that is the only solution and is a limitation of the pancake format?

Pentax - bring back the 24mm F2.0 - that was one amazing lens!!!
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