Anyone have a clear grasp on the K3.3 crop function


Daronl

Link Posted 15/05/2021 - 21:33
CROP FUNCTION is referred to very sparsely on page 48 of the new K3.3 manual but does not explain what benefit it brings;
Smaller file size?
Faster buffering ?
Faster FPS ?

I COULD REALLY USE SOME WISDOM
Daronl

JohnX

Link Posted 16/05/2021 - 12:05
Looks like the answer to the first 2 of your 3 questions is 'Yes'!

Not sure about the 3rd.


https://www.youtube.com/watch?v=6Bqcz7Bu4gc
Last Edited by JohnX on 16/05/2021 - 12:11

JohnX

Link Posted 16/05/2021 - 12:17
Selecting the option shows a crop overlay in the OVF

The crop overlay (29) entirely covers all the AF points.


Last Edited by JohnX on 16/05/2021 - 12:18

womble

Link Posted 16/05/2021 - 20:31
JohnX wrote:
Selecting the option shows a crop overlay in the OVF

The crop overlay (29) entirely covers all the AF points.



But what is the point? What does the overlay represent? Why would you use it?
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

My website

JohnX

Link Posted 17/05/2021 - 11:52
TBH I don't know, but I'm thinking sports/moving objects.

womble

Link Posted 17/05/2021 - 13:01
I suspect that is one feature I'll never use!

K.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

My website

Waggy

Link Posted 18/05/2021 - 14:03
I believe that when shooting 4K video the camera only uses part of the sensor (so it applies about a 1.4x crop) so maybe that’s what the viewfinder overlay is for ?

(FYI- I’m doing lots of research on the new K3 iii, but I’m still on the fence on whether to invest……

I really want to stick with Pentax long term as I’ve now accumulated so many k mount lenses - but many of the reviews comment that you don’t really see a huge difference in autofocus performance using older SDM lenses, which is a shame )
Richard

womble

Link Posted 18/05/2021 - 14:38
Waggy wrote:
I really want to stick with Pentax long term as I’ve now accumulated so many k mount lenses - but many of the reviews comment that you don’t really see a huge difference in autofocus performance using older SDM lenses, which is a shame )

Because the fault lies with the lens SDM, not the camera body. Reviews using the newer lenses (or even the older screw drive ones) show a very marked improvement in performance. There is also a marked improvement in the use of manual lenses! It is a bit like fitting performance tyres to a moped's wheels, it doesn't really matter how good the tyres are if you only have a 49cc engine...
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

My website

Waggy

Link Posted 18/05/2021 - 15:32
Interesting that you say that there is also a marked improvement in the use of manual lenses - as for landscape I'm more than happy with my current K3 (mark 1) - and yes, it will make metering easier with my M series lenses.

But, for wildlife I use a 55-300mm (pre WR version) and DA* 300mm with 1.4x converter - and that's the area where the improved ISO and Autofocus of the K3 iii really appealed.
Richard

Daronl

Link Posted 20/05/2021 - 10:14
I think the crop function is not just about reduced file size but also provides a very nice built in focal length “extender”

So shooting with a DA* 300mm yesterday it became clear that whilst the normal crop factor associated with the APS sensor results in an equivalent image size of 450mm Focal length ( ie.300mm x 1.5 ) the crop Function on the K3.3 extends that by a further 30%.

So the 35mm equivalent focal length becomes 585mm using a 300 telephoto.

The image is also very good, certainly as good as a HD teleconverter.
Daronl
Last Edited by Daronl on 20/05/2021 - 10:16

RobL

Link Posted 21/05/2021 - 08:08
Daronl wrote:
I think the crop function is not just about reduced file size but also provides a very nice built in focal length “extender”

So shooting with a DA* 300mm yesterday it became clear that whilst the normal crop factor associated with the APS sensor results in an equivalent image size of 450mm Focal length ( ie.300mm x 1.5 ) the crop Function on the K3.3 extends that by a further 30%.

So the 35mm equivalent focal length becomes 585mm using a 300 telephoto.

The image is also very good, certainly as good as a HD teleconverter.

But doesn’t that just mean your are using a smaller area of the sensor which gives the same result as cropping in post processing? A teleconverter would use the whole sensor with a greater number of pixels.

LongTimeLurker

Link Posted 21/05/2021 - 12:39
RobL wrote:

But doesn’t that just mean your are using a smaller area of the sensor which gives the same result as cropping in post processing?

Yes, you are correct.

The focal length of a lens is a physical property of the lens and does not, and indeed cannot, change if the size of sensor the image circle is projected onto is changed.

As a practical example, I can take my Pentax 6x7 150mm lens and mount it on a 6x7 body, a so-called full frame body, an APS-C body or a micro four thirds body and the image circle is exactly the same. What does change with the change of body is the amount of the image circle captured by the media (film / digital sensor). An APS-C sensor is smaller than a 35mm full frame sensor and the smaller sensor will therefore capture less of the image circle, the same effect as cropping as you described, hence the term 'crop sensor' which is often used to describe a sensor smaller than a 35mm full frame sensor.

This discussion is not new by any means, but is sometimes worth (re)clarifying the effect of sensor sizes to help achieve understanding. Such an aim is not helped when publications (print and web) keep on with the suggestion that buying into a smaller format (sensor) means your lenses magically increase in focal length, and therefore give you greater image magnification for money spent compared with buying a 35mm full frame camera.
Nigel.

Getting older and grumpier. Taking longer to decide which lens to use today.

K5 with auto-everything lenses
A collection of manual primes to keep me in touch with the pleasures of doing it old-school.
Last Edited by LongTimeLurker on 21/05/2021 - 12:53

Horst

Link Posted 23/05/2021 - 08:51
Well, there is only one reason for a crop sensor, it makes it cheaper.
It has no advantage whatsoever except price. It does not increase the focal length of a lens.
If you have a full frame sensor and post process it to about 2/3 of its size, you have the same effect.
Say you have a 300mm lens and the aps sensor the makes it look like 450mm you have the amount of pixels your sensor gives you, Say 16MP or 23. If you have a full frame sensor and use a 450mm lens you have the 40 odd MP. A much better picture.
If it was.t so, you could reduce the size of the sensor to 1 Pixel and get a 16km or so lens, but not much of an image.
Regards, Horst
Last Edited by Horst on 23/05/2021 - 08:53

Lubbyman

Link Posted 23/05/2021 - 10:10
Horst wrote:
Well, there is only one reason for a crop sensor, it makes it cheaper.

Or to put it another way, there is only one reason for a full frame sensor rather than medium format, it makes it cheaper...

I think there's more to having different sizes of sensor than just price.

Steve

Horst

Link Posted 23/05/2021 - 10:26
Of course you are right, It possibly has to do with the size and weight, but technically, the smaller the sensor, the less expensive. the larger the sensor the better the quality,
Even if all the sensors no matter what size, had the same amount of pixels, the larger sensor still has a better picture quality. (lower noise better ISO rating ) assuming the where all manufactured to the same technical advances rating.
You get nothing for nothing,
Regards, Horst
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