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05-24-2013, 09:43 PM   #16
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QuoteOriginally posted by usmcxm35 Quote
But why are they still magical on Cropped FOV?
Because the field of view is not cropped. The sensor is cropped. The focal lengths provide the equivalent fields of view on 24mmx36mm to what the medium format lenses provide. You named the most important variable, though - FOV.

The person who started the thread is proposing that the combination of these particular field of view numbers and these depth of field numbers are what helps create the magic you see in the imagery, regardless of the sensor size.

I'm buying it. It is logical, and the math works to a high enough degree that I'm assuming it's probably not coincidence. Especially since focal lengths, as listed by the manufacturer, are not necessarily 100% accurate.

Way to go, Akarak! (in my opinion)

05-25-2013, 02:42 AM   #17
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QuoteOriginally posted by stevebrot Quote
Focal length is focal length...

Cropping is cropping...

DOF (at base) is determined by physical aperture, magnification, and viewing distance...

So, I would postulate the relationship of the Limiteds to Medium Format is that they are lenses with inadequate image circle to be used with 120 film...


Steve


(...good thing I don't drink or do drugs...this could have gotten out of control...)



Thank god you don't or else you woulda have distorted even more what i've said.I mean, where did you read about using the limiteds on medium format? ... did you even read my publication? because what you said makes no sense to the original post at all.

Maybe you should read it again, and if you come to the same conclusion i will review my post and reformulate.
05-25-2013, 02:44 AM   #18
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thank you for all your support, i believe this is a
"fearture" that makes pentax unique and it's really great that someone understands what i am trying to state here.


"Crop factor is simply the ratio of the diagonal lengths of two formats.

Remember Pythagoras'Theorem, for a rectangle the diagonal is the square root of the sum of the squared lengths of two adjacent sides.


For APS-C of 15.7mm x 23.7mm, is 15.7^2 + 23.7^2 = 808 and 808^0.5 = 28.4mm diagonal
For FF/35mm of 24mm x 36mm, is 24^2 + 36^2 = 1872 and 1872^0.5 = 43.3mm diagonal

For MF 645 ~ 56mmx42mm, is 56^2 + 42^2 = 3136 + 1764 = 4900 , and 4900 ^0.5 = 70 mm (645 cameras usualy come with 75mm fixed lens)
For MF 6x6 ~ 60mmx60mm, is 56^2 + 56^2 = 3136 + 3136 = 6272 , and 6272 ^0.5 = 79 mm (6x6 cameras usualy come with 80mm fixed lens)




Design215 Toolbox - Film Size Chart and Scale Comparison


If you can't get the square roots, you can use this online calculator
Square Root Calculator




some medium format images for you to compare with FA limited test shots.






05-25-2013, 02:52 AM   #19
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well, every serious photographer out there want's the best for his shots, and i tell you this.. as i try to make it out as a photographer with my old gear and stuff, whay i see around here for serious photography is medium format..

and if pentax can deliever the medium format composition on a 35mm negative, that is without doubt the most atracting fearture of pentax cameras to professional photographers.


the fact you can get a medium format look on a 35mm negative makes it's impossible to make billboards and stuff like you do with medium format, but it's not impossible to make photography for magazines, web related magazines, etc etc...

so before discarding all this hypothesis, maybe you should look into them, because again...

haev the "odd focal lenghts" renamed to "the medium format standard" if a really good thing for pentax and ourselves, pentaxians that have been fighting against stupid feartures of other manufactures that in the end of the day, will improve nothing in your photography.


this? this medium format on 35mm look? now this would make lots of people to buy the limited or eevn change to pentax

more friends


do the maths, and don't forget the Apertuer must also be converted.
the first times i used medium format i was shocked i couldn't get a faster lens than 2.8 as i like thin DOF, but when i found what that a f2.8 on medium format is a 1.4 equivalente on 35mm film, my life was great again..

05-25-2013, 07:11 AM   #20
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QuoteOriginally posted by Akarak Quote
the first times i used medium format i was shocked i couldn't get a faster lens than 2.8
SMC Pentax 67 / Takumar 6x7 105mm F2.4 Reviews - 67 Normal Primes - Pentax Lens Reviews & Lens Database

However, with medium format film,
it was difficult to keep the film flat enough
to be usable with any faster lenses.
05-25-2013, 09:48 AM - 1 Like   #21
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QuoteOriginally posted by fuent104 Quote
I find it interesting that you felt the need to make a post stating that you aren't interested in the topic.
Yeah, I can see how that seems a bit weird. It was just late-night mumble after an attempt to follow the conversation. No disrespect intended.

Last edited by dadipentak; 05-25-2013 at 09:55 AM.
05-25-2013, 05:52 PM   #22
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QuoteOriginally posted by lytrytyr Quote
SMC Pentax 67 / Takumar 6x7 105mm F2.4 Reviews - 67 Normal Primes - Pentax Lens Reviews & Lens Database

However, with medium format film,
it was difficult to keep the film flat enough
to be usable with any faster lenses.

thank you for this info, i didn't knew that, i hope everyone understands that even though it's f2.4, the depth of field would be about the same of a f1.2 on a fullframe camera....
05-25-2013, 07:00 PM   #23
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Could the comparison of FA Limited and Medium Format lenses have more to do with the engineering?...all mathematical comparisons aside, I believe the team of Pentax Japan lens designers of the late '90's and turn of the century created the color and IQ renditions of both the late model Pentax medium format lenses and the FA Limiteds. I still carry the 3 FA Limited lenses and also shot for a decade with the final two medium format lenses designed by pre Hoya Pentax Japan. Those guys somehow sought and created the undefinable "pixie dust" imaging that we all rave about nowadays. I think it's less a question of perspective and more a question of engineering...

05-25-2013, 07:30 PM   #24
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QuoteOriginally posted by Ron Boggs Quote
I think it's less a question of perspective and more a question of engineering...
If Akarak's theory is correct, I'd say it's equally about both.

I've never owned any of the pixie dust lenses. As such, I feel that the single most important property of a lens is its field of view. Perhaps my opinion will change if I get to shoot through pixie dust.
05-26-2013, 12:49 PM   #25
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It is not the focal lengths of the FA Limiteds that make them special. It is the optical design principles and the quality of workmanship.
05-26-2013, 12:57 PM   #26
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QuoteOriginally posted by rparmar Quote
It is not the focal lengths of the FA Limiteds that make them special. It is the optical design principles and the quality of workmanship.

but why do they go hand in hand with medium format compression, bokeh and composition?

you honestly believe it's a coincidence?
05-26-2013, 05:15 PM   #27
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QuoteOriginally posted by rparmar Quote
It is not the focal lengths of the FA Limiteds that make them special. It is the optical design principles and the quality of workmanship.
I believe it's all of the above. The quality of the workmanship is not apparent when you view the images. All that's left is the field of view and the optics. Clearly both of these things influence imagery shot through them.
05-27-2013, 06:27 PM   #28
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QuoteOriginally posted by Akarak Quote
but why do they go hand in hand with medium format compression, bokeh and composition?

you honestly believe it's a coincidence?
There is no coincidence. Pentax chose those focal lengths, perhaps to jibe with the MF lenses. (Though that's not what I have read.) Either way, this has nothing to do with the quality.

They could have made great 28mm and 50mm Limited lenses. They could have made great MF lenses in other lengths.

There is absolutely no causality here.
05-27-2013, 07:01 PM - 1 Like   #29
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QuoteOriginally posted by rparmar Quote
They could have made great 28mm and 50mm Limited lenses. They could have made great MF lenses in other lengths. There is absolutely no causality here.
Yes, they could have, but they chose not to. The fact that they chose "odd" focal lengths for their premium series of lenses would lead me to believe that the focal lengths were intentionally chosen to contribute to the uniqueness of each lens. That's part of what makes great design great design -complete control over every creative decision. Part of the design philosophy of the FA limited lenses was, necessarily, that the focal length would be one of the unique properties of each lens.
05-27-2013, 09:29 PM   #30
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QuoteOriginally posted by fuent104 Quote
Yes, they could have, but they chose not to. The fact that they chose "odd" focal lengths for their premium series of lenses would lead me to believe that the focal lengths were intentionally chosen to contribute to the uniqueness of each lens. That's part of what makes great design great design -complete control over every creative decision. Part of the design philosophy of the FA limited lenses was, necessarily, that the focal length would be one of the unique properties of each lens.
It was also a marketing ploy not to compete with other FA lenses in the same focal length and attract sales with the new and unique focal lengths. (Especially the FA43 and FA77)

Releasing an FA85/1.8LTD for example, would have competed with the FA*85/1.4 [IF].

Phil.
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