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03-13-2018, 12:30 PM   #196
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QuoteOriginally posted by mecrox Quote
Some like Sigma or Tamron lenses, some don't. Some think Pentax can survive and prosper without third party support, some don't. Some like the big new FF reference lenses, some don't. Some can afford to spend $$$ on their kit, some can afford to spend only $. To me, it's all a pragmatic question of what works and what doesn't. So let's agree to differ and come back in 2020.
Well said. I wonder though if as small as Pentax is now whether they can satisfy all the different wants. They are a niche player and might get even more 'nichey'. Which means some may have to move to a different brand. While we all want Pentax to supply our needs and thus stay with the brand, I am concerned that they will need to make some hard decisions that will inevitably leave some users not satisfied.

03-14-2018, 06:58 AM - 7 Likes   #197
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Wow a lot of hullabullu about nothing on here. Pentax have a simple enough plan for their lens series. D(F)A zooms are covered at the top end with your standard range covering from 11 to 135 with f/2.8 in APS-C and 15 to 200 in FF again with f/2.8. They are reasonably expensive because f/2.8 glass costs money. So zooms covered (and they are the lens types the majority buy!)

Primes, you have 2 options, go Limited for the Pentax take on what it's engineers regard as an optic to create a pleasing image while staying true to their philosophy of smaller designs or take the DFA* line which do not have size or price constraints for high resolution bokeh while adding micro contrast that is sometimes lacking in the Sigma designs and AF lacking in the Zeiss stuff.

Those looking for an f/4 FF series will have to wait fairly patiently. Those waiting for fast super zooms will be better off investigating another system or search for a FA* 250-600 (one sold on the UK a couple of weeks ago for circa 5K GBP. Sigma or Zeiss fans? Investigate another system.

See nice and simple.
To go back on topic, a limited wider than the 31 would be cool say a 20/4 as would something in the 105 to 120 range with apertures of f/2.5 to f/3.2 for telephoto.

Usual caveats apply in that they probably won't test the best but subject isolation and 3D pop will be in abundance.

Last edited by robbiec; 03-14-2018 at 07:13 AM.
03-14-2018, 07:10 AM   #198
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QuoteOriginally posted by robbiec Quote
Wow a lot of hullabullu about nothing on here. Pentax have a simple enough plan for their lens series. D(F)A zooms are covered at the top end with your standard range covering from 11 to 135 with f/2.8 and 15 to 200 in FF again with f/2.8. They are reasonably expensive because f/2.8 glass costs money. So zooms covered (and they are the lens types the majority buy!)
Primes, you have 2 options, go Limited for the Pentax take on what it's engineers regard as an optic to create a pleasing image while staying through to their philosophy of smaller designs or take the DFA* line which do not have size or price constraints for high resolution bokeh
Those looking for an f/4 FF series will have to wait fairly patiently. Those waiting for fast super zooms will be better off investigating another system or search for a FA* 250-600 (one sold on the UK a couple of weeks ago for circa 5K GBP. Sigma or Zeiss fans? Investigate another system.
See nice and simple.
To go back on topic, a limited wider than the 31 would be cool say a 20/4 as would something in the 105 to 120 range with apertures of f/2.5 to f/3.2 for telephoto.
Clear, concise reasoning. Might we eventually see a FF catalog of * zooms and reference fl primes + a broader set of interesting Limiteds in the gaps?
03-14-2018, 08:14 AM   #199
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QuoteOriginally posted by monochrome Quote
Clear, concise reasoning. Might we eventually see a FF catalog of * zooms and reference fl primes + a broader set of interesting Limiteds in the gaps?
The next * zoom will probably be the 24-70/2.8 as the current one was really a gap filler. The 15-30/2.8 belongs in the lineup from what I have seen and heard from friends that have it, but it is not a * even if a lot closer to it than the 24-70.

We know about the current ref primes, 50/1.4 due soon, 85/1.4 probably next year and rumours of something like a 35/1.4 also on the design board which are the std 3 primes covered.

To throw something out there how about a 50/2.8 Macro Limited? , keep the current stellar optics, rebody in an alloy body, add HD, Aerobrite, DC and WR. A small, powerhouse of a lens that can go toe to toe with anything from any other optic manufacturer which would also reaffirm the Limited line as flagship designs by testing well to satisfy the Internet plebs


Last edited by robbiec; 03-14-2018 at 09:04 AM.
03-14-2018, 08:33 AM   #200
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QuoteOriginally posted by robbiec Quote
The next * zoom will probably be the 24-70/2.8 as the current one was really a gap filler. The 15-30/2.8 belongs in the lineup from what I have seen and heard from friends that have it but it is not a * even if a lot closer to it than the 24-70. We know about the current ref primes, 50/1.4 due soon, 85/1.4 probably next year and rumours of something like a 35/1.4 also on the design board which are the std 3 primes covered.

To throw something out there how about a 50/2.8 Macro Limited? , keep the current stellar optics, rebody in an alloy body, add HD, Aerobrite, DC and WR. A small, powerhouse of a lens that can go toe to toe with anything from any other optic manufacturer which would also reaffirm the Limited line as flagship designs by testing well to satisfy the Internet plebs
Given the FA50/2.8 Macro pedigree and that the DFA100 Macro is already a near-Limited, what’s not to like?!

IMO a Limited need not of necessity be an unusual fl, unless there is a specific design consideration e.g. the FA43 (for newer readers, 43mm is the diagonal of 24x36*, so the image circle efficiently covers the ‘sensor).**

* “The standard lens for a given format is usually taken to be the diagonal.”

Last edited by monochrome; 03-15-2018 at 06:58 AM.
03-14-2018, 09:05 AM   #201
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QuoteOriginally posted by monochrome Quote
Given the FA50/2.8 Macro pedigree and that the DFA100 Macro is already a near-Limited, what’s not to like?!

IMO a Limited need not of necessity be an unusual fl, unless there is a specific design consideration e.g. the FA43 (for newer readers, 43mm is the diagonal of 24x36, so the image circle efficiently covers the ‘sensor’).
Don't know where you got that reasoning - it's baloney all lens efficiently cover 35mm if that is what they're designed for.

The reason Pentax produced a 43mm lens for 35mm camera is 43mm provides an angle of view of 55 degrees the exact AoV of the Human eye

The Camera Versus the Human Eye

Which would also give us 28mm as the magical focal length for Pentax APS-C
using 2 X arctan ( frame \ 2*focal length)

Last edited by awaldram; 03-14-2018 at 09:16 AM.
03-14-2018, 10:12 AM - 1 Like   #202
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QuoteOriginally posted by awaldram Quote
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Don't know where you got that reasoning - it's baloney all lens efficiently cover 35mm if that is what they're designed for.

The reason Pentax produced a 43mm lens for 35mm camera is 43mm provides an angle of view of 55 degrees the exact AoV of the Human eye

The Camera Versus the Human Eye

Which would also give us 28mm as the magical focal length for Pentax APS-C
using 2 X arctan ( frame \ 2*focal length)
Well OK then.
03-14-2018, 05:55 PM   #203
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QuoteOriginally posted by awaldram Quote
[/COLOR]
Don't know where you got that reasoning - it's baloney all lens efficiently cover 35mm if that is what they're designed for.

The reason Pentax produced a 43mm lens for 35mm camera is 43mm provides an angle of view of 55 degrees the exact AoV of the Human eye

The Camera Versus the Human Eye

Which would also give us 28mm as the magical focal length for Pentax APS-C
using 2 X arctan ( frame \ 2*focal length)
Cone of visual attention is 55 Degrees. FOV is much wider but it is hard to identify things in your peripheral vision. The 55 degrees is also one eye not the overlapping cone of visual attention. Interesting link though, good find.

03-15-2018, 01:47 AM - 2 Likes   #204
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QuoteOriginally posted by SSGGeezer Quote
Cone of visual attention is 55 Degrees. FOV is much wider but it is hard to identify things in your peripheral vision. The 55 degrees is also one eye not the overlapping cone of visual attention. Interesting link though, good find.
hmm. how about 2 K-1 with FA 43 with overlapping cones?
03-15-2018, 05:04 AM   #205
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(OT warning) Much as I respect Roger Cicala's expertise, his explanation of the 55 degree cone of visual attention is clearly mistaken. If the "macula ... provides our ‘central vision’" its 6mm diameter combined with the eye's focal length of around 20mm would never produce a FOV of 55 degrees. "Central vision" in that sense is quite different from the cone of visual attention and much narrower. A better explanation is here:
"Although the eye's total field of view, central vision plus peripheral, can stretch to over a 160 degrees, the sharpest view of the eye is located in the foveal region located within the macula. But these regions only subtend fields of view of 0.5 to 2 degrees and 15 to 18 degrees respectively. The eye therefore must rotate off the facial plane to scan objects of interests with the fovea. The brain then integrates this higher-resolution information into a bigger picture called the cone of visual attention. This cone subtends approximately a 50-55 degree wide field of view, and is commonly referred to in photography as the eye's normal perspective."
03-15-2018, 05:42 AM   #206
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I thought the 43 came from the diagonal of 36mm (x 24mm) film.
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03-15-2018, 06:09 AM   #207
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QuoteOriginally posted by calsan Quote
I thought the 43 came from the diagonal of 36mm (x 24mm) film.
APPARENTLY you and I and John Riley (to cite just one reference) are incorrect. 43mm must be a coincidence. But you know how the internet is. These things take on a life of their own.

OTOH, I discussed efficient coverage of the sensor, so I was unclear.

Last edited by monochrome; 03-15-2018 at 10:07 AM.
03-15-2018, 06:19 AM   #208
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In that case Bojidar Dimitrov's Pentax K-Mount Page is also wrong :-):
"The focal length of this lens is exactly equal to the diagonal of the 35 mm film format, and this makes it the "perfect" "normal" lens. Its small size and low weight make it ideal for light travel and reporting."
03-15-2018, 06:51 AM - 1 Like   #209
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QuoteOriginally posted by Franc Quote
In that case Bojidar Dimitrov's Pentax K-Mount Page is also wrong :-):
"The focal length of this lens is exactly equal to the diagonal of the 35 mm film format, and this makes it the "perfect" "normal" lens. Its small size and low weight make it ideal for light travel and reporting."
In all fairness, I struck the clause to which I think the poster objected. By ‘efficiently’ I meant the the fl and the diameter of the image circle are equal, which is correct, but I assume the image circle of any FF lens is approximately 43mm. The statement was imperfect.

Let’s discuss Limiteds and how optics - both * lens designs and sublime, elegant Limited lenses - can restore the Pentax brand reputation as an optics company.
03-15-2018, 07:38 AM   #210
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I thought the main reason for the 40-ish mm focal lengths was just to make lenses that were as close to pancakes as possible. The registration distance for the K mount is 45mm and lenses that right around that focal length should be smallest. Clearly the 40 XSI is a demonstration of that fact, but it is only a f2.8 lens, but I don't know that there are many smaller 40-ish mm f1.9 lenses that have auto focus and also cover a full frame circle.
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