Exact crop factor of K3 Sensor.


jules

Link Posted 06/02/2014 - 16:34
Anyone know, the exact crop factor of the 23.5mm x 15.6mm sensor in the K3, and no 1.5 won't do!
I need to know the exact value, my little brain won't wrap itself around that one today.
Got 1.53 in my head but that could be wrong of course...
Ta in advance...
Cheers Jules...
tri-elmar-fudd

Back in the room!
“The single most important component of a camera is the twelve inches behind it.”...Ansel Adams
www.exaggeratedperspectives.com

Algernon

Link Posted 06/02/2014 - 16:45
Is it just the aspect ratio you want or the exact mm size?

The aspect ratio is the pixel size of the RAW files.

6016w x 4000h = 3.008:2 or 1.504x

The spec. also mentions 16:9 which I presume is a crop.


EDIT: If you mean compared to 35mm FF it's
36/23.5 = 1.532 OR 24/15.6 = 1.538 based on height
which is probably more accurate because 35mm was
usually cropped on the length when printing.
--
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
Last Edited by Algernon on 06/02/2014 - 16:57

jamieallan

Link Posted 06/02/2014 - 18:25
I always thought the crop factor was calculated as the diagonal of a 36 X 24mm frame ie 43.2666mm approx divided by the diagonal of the particular sensor you are comparing (APS-C 23.7 X 15.7mm is 28.4285mm approx). If so the answer is :-

1.5264180559885595966299171925376

Hope that's exact enough
Jamie

Gamka

Link Posted 06/02/2014 - 19:02
jamieallan wrote:
I always thought the crop factor was calculated as the diagonal of a 36 X 24mm frame ie 43.2666mm approx divided by the diagonal of the particular sensor you are comparing (APS-C 23.7 X 15.7mm is 28.4285mm approx). If so the answer is :-

1.5264180559885595966299171925376

Hope that's exact enough

You need to check your maths:

1.521944700786210
Last Edited by Gamka on 06/02/2014 - 19:03

jules

Link Posted 06/02/2014 - 19:09
He He
I thought this would happen.
Anything official anywhere?
Cheers Jules...
tri-elmar-fudd

Back in the room!
“The single most important component of a camera is the twelve inches behind it.”...Ansel Adams
www.exaggeratedperspectives.com

jamieallan

Link Posted 06/02/2014 - 19:10

jules

Link Posted 06/02/2014 - 20:18

Resd that and that's what confused me...
Cheers Jules...
tri-elmar-fudd

Back in the room!
“The single most important component of a camera is the twelve inches behind it.”...Ansel Adams
www.exaggeratedperspectives.com

jamieallan

Link Posted 06/02/2014 - 21:28
Jules,
I think they use the diagonal measurement due to a throw back to the original TV Cathode Ray Tube days. As the original tube faces were circular the measurement of screen size was the diagonal of the largest 4:3 aspect rectangle that could be made from the tube face. It doesn't really make any sense these days but they've stuck with it. It would be far better to use the total area of the sensor in my view. The graphic in this I think is a far better illustration of sensor size

http://en.wikipedia.org/wiki/File:SensorSizes.svg
Jamie

McBrian

Link Posted 06/02/2014 - 22:20
Quote:
It doesn't really make any sense these days but they've stuck with it

Bit like the FF debate then
Cheers
Brian.
LBA is good for you, a Lens a day helps you work, rest and play.

K10D

Link Posted 06/02/2014 - 23:02
McBrian wrote:
Quote:
It doesn't really make any sense these days but they've stuck with it

Bit like the FF debate then

No debate. Some people have them some people don't.

Best regards
cameradextrous _ Motorcycles etc. link

sterretje

Link Posted 09/02/2014 - 10:38
I'm very curious as to why you like / need to know the exact crop factor
Pentax K10D + Vivitar 55/2.8 macro + Super Takumar 55/1.8 + SuperMultiCoated Takumar 85/1.8 + SuperMultiCoated Takumar 135/3.5 + SuperMultiCoated Takumar 200/4 + Super Takumar 300/4
Pentax K100D + DA18-55ALII + DA55-300
Pentax K5 + FA31Ltd + M50/1.7 + DFA100WR + M120/2.8 (+ DA18-55WR at occasion)
Last Edited by sterretje on 09/02/2014 - 10:40

SteveF

Link Posted 09/02/2014 - 11:48
sterretje wrote:
I'm very curious as to why you like / need to know the exact crop factor

Indeed, I would have thought that 1.5 is near enough for most purposes. Do tell.

jules

Link Posted 14/02/2014 - 09:08
I'm totally anal!

THEN NO ONES GIVEN ME A DEFINITIVE ANSWER EITHER WHICH IS DRIVING ME NUTS!

1.52?
Cheers Jules...
tri-elmar-fudd

Back in the room!
“The single most important component of a camera is the twelve inches behind it.”...Ansel Adams
www.exaggeratedperspectives.com

Gamka

Link Posted 14/02/2014 - 09:25
jules wrote:
I'm totally anal!

THEN NO ONES GIVEN ME A DEFINITIVE ANSWER EITHER WHICH IS DRIVING ME NUTS!

1.52?

How many decimal paces do you want?

jamieallen gave an answer - but with an incorrect calculation which I corrected. That is assuming the sizes of a 35mm frame at 36x24 and APS-C at 23.7x15.7 are exact and for example an APS-Cis not 23.7003x15.7002

Smeggypants

Link Posted 14/02/2014 - 09:39
jules wrote:
I'm totally anal!

Lucky for you so are Pentax

http://www.pentaxmedical.ca/en/education/procedure-room-videos.aspx
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283
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