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02-12-2012, 04:40 PM   #61
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The Pentax lineup is missing the 28mm F/2.4 pancake. It could be made like the DA21mm F/3.2, using aspherical and/or low dispersion elements, combined with the smaller APS-C image circle, to be about the same size DA21mm. Or, perhaps Pentax is saving that one for the K-01, using the recessed rear element to make the external portion of the lens comparable to the DA40mm.

As for normal fast primes for APS-C, I can recommend the Sigma 30mm F/1.4 which is a great lens. Its just a little big. Its usable wide open, but I usually stop down to F/1.8 or F/2 and I get great results. I often use it as a night time street lens. I find that the corners are pretty acceptable at F/2, at infinity. For me the Pentax 31mm F/1.8 is priced too high.
- Sheldon

02-12-2012, 06:30 PM   #62
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QuoteOriginally posted by lytrytyr Quote
The problem with wide angle lenses is as much a question of the coverage angle as the register distance.
If you shorten the register distance for a given sensor format, you increase the coverage angle from the back of the lens.
It's a tradeoff, and doesn't lead to cheaper lenses.
Hadn't looked at it this way.
02-12-2012, 08:33 PM   #63
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QuoteOriginally posted by westmill Quote
Im well aware of the meaning of perspective distortion thank you very much !
In which case, you *do* understand why prints are relevant, then.
02-13-2012, 07:16 AM   #64
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Regardless of the technical reasons why wide-ish lenses large aperture lenses are hard to make I think you only need to look at the standard Pentax offerings from 30 yrs ago. The average Joe owned some combination of 28mm 2.8-3.5, 35mm 2.8-3.5, 50mm 1.7-2.0 and 135mm 3.5 lenses. If you want a cheap 28mm lens then you redesign the FA28f2.8. If you want a better 24 then you redesign the FA*24f2 but it will be at least $500 imo. I would love it but right now I'm waiting until I have money for a K28f2.

02-13-2012, 08:08 AM   #65
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QuoteOriginally posted by RKKS08 Quote
I miss such a lens for APS-C badly: a SMALL full metal manual focus 2.0/30 with acceptable IQ at 2.0 and very good IQ from 4-5.6 on FOR NOT MORE THAN €100 ($125) new. THIS would be the real equivalent to what Pentax offered during the film era. If not possible, I may accept a plasticy lens body, if the bajonet is made of metal.
Well, I've got myself a cheap Samsung NX100 + 30/2 combo (350€!), and this lens utterly ROCKS! Sharp wide open, and the whole thing is small!
Makes you wonder how the K5 + sigma 30/1.4 combo can be so huge!

I should do a showdown between the two combos, someday...
02-13-2012, 10:14 AM   #66
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QuoteOriginally posted by dlacouture Quote
Well, I've got myself a cheap Samsung NX100 + 30/2 combo (350!), and this lens utterly ROCKS! Sharp wide open, and the whole thing is small!
Makes you wonder how the K5 + sigma 30/1.4 combo can be so huge!

I should do a showdown between the two combos, someday...
Definitely because I want to buy the Samsung as a compact travel set.
02-13-2012, 11:50 AM   #67
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QuoteOriginally posted by Marc Sabatella Quote
In which case, you *do* understand why prints are relevant, then.
I understand prints can be used yes...... not that they are nesercary or rellivent NO.... loving the stars
Im more than happy with my understanding and I certainly dont want or need a lecture about it thanks !
02-13-2012, 12:25 PM   #68
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Besides portraiture, when is perspective distortion important enough to dictate lens choice? To me, getting what I want in the frame is paramount. Moving the camera is often not practical, and often not relevant unless the subject is a single object well within the frame. For landscape, camera position determines the subject as much as field of view does.

02-13-2012, 02:07 PM   #69
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50, 55 & 58mm lenses were considered standard on film. 50mm was usually the minimum for a standard lens. I'm firmly of the opinion that standard primes were made a bit longer than the diagonal of the sensor because they're more useful like that, not because 50mm was cheaper or easier than 43mm. The difference is not big, after all.

I like the 35mm FoV on digital considerably more than the 28mm, I find it far more flexible.

A DA* 35mm f/1.4 would be great though. Even if it was only 30mm, I'd still consider it, as it would be close enough.
02-13-2012, 02:13 PM   #70
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Lot's of cameras in film days shipped with a 58 as the normal (my first camera in fact shipped this way) it's a little long but not overly IMO (i shot wiht it a long time before getting a 28 back then)
and extra step or 2 back covers the difference for the most part

I agree a 28 pancake would be a nice addition ( I use my m28 a lot but an af pancake woul be a nice walkabout at what is the wide end of normal
02-13-2012, 02:21 PM   #71
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Ive just been checking out the 58mm Voightlander on photozone ! Its tested on full frame cannon 5d
Fantastic results overall. Only soft in the far corners. Used on APSC would take that away and make a great portrait lens.
Voigtlander Nokton 58mm f/1.4 SL II - Full Format Review / Test Report
02-13-2012, 05:21 PM   #72
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QuoteOriginally posted by Jonathan Mac Quote
50, 55 & 58mm lenses were considered standard on film. 50mm was usually the minimum for a standard lens. I'm firmly of the opinion that standard primes were made a bit longer than the diagonal of the sensor because they're more useful like that, not because 50mm was cheaper or easier than 43mm.
I have a nice pancake Chinon 45/2.8 and a big fat K50/1.2, both in PK-M mount. I have FF rangefinders with 45mm f/1.7 and f/1.8 lenses. I have never seen a 45/1.4 nor 45/1.2 for FF SLRs. I am very sure that fast 50-55-58mm lenses were made because they COULD be made, whilst 40-43-45mm lenses that fast weren't made because they COULDN'T be made, especially to clear an SLR mirrorbox, not and be commercially viable.

Back in film days, FF cameras were shipped with lenses ranging from 35-58mm. That's quite a 'normal' range. HF (half-frame, ~APS-C size) cameras shipped with lenses in the 24-40mm range (FOV equivalent to 35-60mm on FF), sometimes longer. But for non-SLRs, shorter optics predominated. And for FF SLRs, IIRC fast 58s predated fast 55s and 50s; fast 50s came to rule the field. That was the evolution: get shorter and faster.
02-13-2012, 06:04 PM   #73
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QuoteOriginally posted by kcobain1992 Quote
What do you mean by "normal"? I use a 50mm on my digital camera without any problem.
Normal is usually defined as the length of the diagonal of the film/sensor frame. That would make a 30mm normal for APS-C.

31, 33, 28 are close enough.
02-13-2012, 06:38 PM   #74
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QuoteOriginally posted by alohadave Quote
Normal is usually defined as the length of the diagonal of the film/sensor frame. That would make a 30mm normal for APS-C.
For nominal APS-C, the diagonal is 31.1mm. For my K20D sensor, it's 28.1mm. Whether an extra 2mm in either direction is significant or even noticeable, is questionable. Let the flame ware commence!
02-13-2012, 07:07 PM   #75
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QuoteOriginally posted by RioRico Quote
For nominal APS-C, the diagonal is 31.1mm. For my K20D sensor, it's 28.1mm. Whether an extra 2mm in either direction is significant or even noticeable, is questionable. Let the flame ware commence!
Well, if you look at full frame, the diagonal is 43.2mm, yet the normal lens has been 50 and 55 at various times.

It's a rule of thumb, not any physical law. I like how 28mm looks on APS-C, and I'd use that as a normal lens if I only had one lens to use.
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