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07-09-2015, 03:18 AM   #1
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How does a FF work in crop mode?

Just wonder if anyone can describe how they believe the FF will work in crop mode.

What will be visible in the view finder? The field of view will be much smaller so will it be like looking through a tunnel? And will the actual picture frame in the view finder be so small that it makes it harder to compose and focus?

How do the the focus points work? I assume the focus points are designed to cover as much area as possible on the FF sensor. Do some of these focus points fall outside of the usable area in crop mode?

May be there is something I'm missing.

07-09-2015, 03:44 AM   #2
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I think there won't be any fancy thing! crop mode means the camera itself will crop the photo for you! so you only miss the pixels outside APSC area.
You'll also see the cropped view in live view! but the viewfinder won't be changed.
07-09-2015, 04:13 AM   #3
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QuoteOriginally posted by Albermarle Quote
Just wonder if anyone can describe how they believe the FF will work in crop mode.

What will be visible in the view finder? The field of view will be much smaller so will it be like looking through a tunnel? And will the actual picture frame in the view finder be so small that it makes it harder to compose and focus?

How do the the focus points work? I assume the focus points are designed to cover as much area as possible on the FF sensor. Do some of these focus points fall outside of the usable area in crop mode?

May be there is something I'm missing.
Most of these details will be known when the camera is released.
My guess is that there will be some simple marking in the OVF showing the APS-C crop area, and with most APS-C lenses you will be able to see most/whole FF OVF area with some vignetting in the corners. But only the APS-C area will be captured. IMO it be a nice bonus to be able to see more in the OVF than is captured by the camera.

The APS-C crop coverage will be slightly less than half the area of the whole FF OVF area (if the FF OVF will show 100%)
07-09-2015, 04:27 AM   #4
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To get a good idea of how crop mode might work, it may be useful to look at how it works on a camera like the Nikon D810, which may resemble the Pentax camera. The D810 manual is downloadable from here:

Nikon | Download center | D810

Pages 74-77 relate for stills shooting. Note that crop mode options are also available for video.

07-09-2015, 04:48 AM   #5
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QuoteOriginally posted by Fogel70 Quote
My guess is that there will be some simple marking in the OVF showing the APS-C crop area,
What a basic solution that would be. I don't see how that would deal with all the different image circles of the DA lenses.
07-09-2015, 04:57 AM   #6
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Of course, no-one knows for sure, but I would expect it to work like this:

Yes the APS-C framing area will be displayed as a crop of the viewfinder, so you will be composing within a portion of the normal full frame view. While it is theoretically possible to optically magnify and mask the image so that the APS-C crop fills the same viewing angle, I doubt that this will be the case. More than likely, the APS-C crop will be indicated in the viewfinder either by corner markings permanently etched into the focusing screen, or via some kind of LCD/LED overlay which indicates the frame edges when needed. If the latter approach is taken, it could take the form of corner marks, lines or masks. So yes, you will likely be composing within a frame which is perceptually relatively small compared to the full frame view. How small it will be will depend on the viewfinder magnification. The largest current FF viewfinder (Canon 1D X) uses a magnification of 0.76x. If the FF Pentax mimics this, then you will get an APS-C view of 0.76x magnification. To put this into perspective, the K-3 is 0.95x, while the smallest size on a DSLR in recent times was 0.8x (Canon 1200D). So it is likely that the APS-C viewing area will be pretty 'pokey' to say the least, unless some kind of extra magnification is used. I would therefore expect composing and manually focusing to be somewhat compromised compared to an APS-C DSLR.

Personally I hope that a translucent dark mask is used to indicate the crop, so you can see elements outside of the frame, but at reduced contrast so you can still visualize the composition well enough.

Regarding focus points, I think it's likely that all of the points will fall within the APS-C crop anyway. It is possible that these will cover a larger area of the APS-C crop than in current APS-C models - we don't know yet.

In live view, I'm guessing that the cropped area will be magnified to fill the screen
07-09-2015, 05:03 AM   #7
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QuoteOriginally posted by Clavius Quote
What a basic solution that would be. I don't see how that would deal with all the different image circles of the DA lenses.
??

What Nikon, Sony or Canon FF body makes cropping distinctions between various DX lenses?
07-09-2015, 05:03 AM - 1 Like   #8
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QuoteOriginally posted by Albermarle Quote
Just wonder if anyone can describe how they believe the FF will work in crop mode.
1. in crop mode, the viewfinder magnification does not change in the literal sense. However, viewfinder magnification are based on 50mm lenses compared to the naked eye. Not 50mm-equivalent lenses.

This is why with the same field of view and the same magnification, a full frame viewfinder looks much bigger.

However, if you use a crop lens, this advantage goes away and you are back at comparing literal viewfinder magnifications.

In the case of Nikon, a few examples:
- D810, crop factor corrected: 1.06x
- K3-II: 0.95x
- D7200: 0.94x
- D3300: 0.85x
- D810: 0.70x

Therefore, you see the cropped image in the viewfinder appears smaller than in even the worst entry level SLRs. To compensate, the Pentax FF would have to have a viewfinder almost as big as Pentax MX, i.e., more like 1.0x. Unlikely to happen as even the most expensive full frame cameras have no VF bigger than 0.76x, not anymore

So yes, the cropped viewfinder image is a bit like a view into a tunnel.

2. Nikon is able (in some of their full frame cameras) to shade / mask the area in crop mode which won't be captured. This helps with the composition. Alternatively, Nikon has red guides to highlight the cropping region. Useful as it supports a 1.2x crop mode too.

Both features are absent in Pentax viewfinders. It remains to be seen what Pentax does to highlight the cropping region. My guess is just an engraving on the matte screen.

3. The rear screen LV shows the cropped region in crop mode.

4. The AF module in APSC cameras is actually more or less the same as the one in full frame cameras. I.e., the AF points cover a relatively small area all within the cropped area. That's because the full frame mount and mirror and AF sub mirror don't allow to cover a larger portion of the full frame view.

It is more extreme actually with the 645Z which still has the same AF module, covering the innermost portion of its frame only.

5. With fast moving subjects like birds in flight, it is much easier to frame full frame even in crop mode. Because you can still track a subject when outside the frame.

6. In practice, you won't use the crop mode but crop in post processing. Based on subject detail inthe corners and vignetting which depends on aperture, zoom and distance. The standard DA-crop mode from Pentax won't do most DA lenses justice on a full frame camera.

07-09-2015, 05:25 AM   #9
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I wonder if Pentax has had time to develop a new (larger) AF module, or if they're just going to stick to a variant the K-3's AF. My guess is the latter, and as you pointed out, that would be rather convenient in crop mode. I do hope that they add some more markings to the viewfinder, however. Shading would be nice, though outlines would work just as well for me.

At the end of the day, though, we certainly haven't been waiting for the FF for this long to cut loose with crop lenses

QuoteOriginally posted by falconeye Quote
6. In practice, you won't use the crop mode but crop in post processing. Based on subject detail inthe corners and vignetting which depends on aperture, zoom and distance. The standard DA-crop mode from Pentax won't do most DA lenses justice on a full frame camera.
Yup, unless really put in a lot of effort. I just hope that the crop mode doesn't get forced upon us when a DA lens is mounted, or that it can be disabled at the very least.

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07-09-2015, 05:49 AM   #10
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QuoteOriginally posted by Adam Quote
I just hope that the crop mode doesn't get forced upon us when a DA lens is mounted, or that it can be disabled at the very least.
Me too, although I would be very surprised if not.
Pentax is pretty much using Nikon as a template in many things they do and the D750 must be their natural point of reference for their full frame project. The one to match and beat. The D750's crop mode is optional (like any other FF Nikon).
07-09-2015, 06:08 AM   #11
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QuoteOriginally posted by Adam Quote
I just hope that the crop mode doesn't get forced upon us when a DA lens is mounted, or that it can be disabled at the very least.
+1

I also hope that any crop mode would still allow judging what is outside the (cropped) frame, for the reasons others already mentioned.

QuoteOriginally posted by Adam Quote
I wonder if Pentax has had time to develop a new (larger) AF module, or if they're just going to stick to a variant the K-3's AF.
I wouldn't get my hopes up too high in terms of AF area coverage, because as Falk mentioned the FF mount and sub-mirror size present limitations.

I highly expect Pentax to introduce a new AF module with the FF module, if they are serious about pitching it as a high-end model to professionals at a higher price point "than what Pentaxians are used to". I personally wouldn't need higher AF performance, but if Ricoh plans to charge a premium price for the FF model, it needs to deliver the goods where it counts.
07-09-2015, 09:16 AM   #12
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QuoteOriginally posted by Clavius Quote
What a basic solution that would be. I don't see how that would deal with all the different image circles of the DA lenses.
Good point. Maybe they'll include engraved viewfinder crop marks at 1.1, 1.2, 1.3, 1.4, and 1.5 to cover most of the bases. Maybe also 1.6 so people migrating from Canon can feel at home. And why not throw in crop marks for a 4x crop for the extreme birders?
12-24-2015, 08:23 AM   #13
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Okay, I'm confused about FF and APS-C crop mode. Even more so than before with Full Frame by PENTAX | RICOH IMAGING.

When I stick my Pentax DA* 55mm f/1.4 onto my Pentax K-5ii body, I get a 82.5mm 35mm equivalent view.

Now, when I go to stick the same lens on the upcoming Pentax full frame in FF mode, do I have a 55mm view or something else?

Same lens, same full frame camera, but in APS-C mode, am I getting the 82.5mm 35mm equivalent view again?

A very merry Christmas to all, especially those who can help declutter my mind here for this situation.
12-24-2015, 08:38 AM   #14
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That's why this "equivalent" nonsense is rather confusing than helpful.

The lens has a focal length, and that's it; regardless of which camera it's used with, and even if it is or not put on a camera. It simply doesn't matter, focal length is a pure optical property of the lens. Which is quite obvious, since the glass elements don't change

The camera-dependent factor is the frame size, be it 35mm (FF), APS-C or something else. The frame size, together with the lens' focal length, gives you the angle of view which is what you're interested on. There's a simple formula of deriving the angle of view from the focal length and frame size, but a simple visual evaluation is usually fine.

Now, what is the difference from having an APS-C frame on an APS-C camera, or a same-sized APS-C frame on a FF camera? Yep, none. It's as if you replaced the FF sensor with an APS-C one. So you will get the same angle of view.

The same thing if you crop the FF frame to APS-C size, in post.
12-24-2015, 09:17 AM   #15
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QuoteOriginally posted by comprock Quote
When I stick my Pentax DA* 55mm f/1.4 onto my Pentax K-5ii body, I get a 82.5mm 35mm equivalent view.
Correct.

QuoteOriginally posted by comprock Quote
Now, when I go to stick the same lens on the upcoming Pentax full frame in FF mode, do I have a 55mm view or something else?
Yes, you will have a "55mm 35mm equivalent view", because you are using a 55mm lens on a 35mm format camera.

QuoteOriginally posted by comprock Quote
Same lens, same full frame camera, but in APS-C mode, am I getting the 82.5mm 35mm equivalent view again?
Yes, exactly, as cropping an FF sensor to APS-C dimensions is the same as using an APS-C sensor.

QuoteOriginally posted by Kunzite Quote
That's why this "equivalent" nonsense is rather confusing than helpful.
The actual nonsense is to refer to equivalent parameters as "nonsense".

QuoteOriginally posted by Kunzite Quote
The lens has a focal length, and that's it; regardless of which camera it's used with, and even if it is or not put on a camera. It simply doesn't matter, focal length is a pure optical property of the lens.
Sure, but comprock never ever suggested that the lens' actual focal length would change.

He very carefully and correctly always spoke of a "35mm equivalent" focal length, not an actual focal length. Why are you criticising an error that was never made?

QuoteOriginally posted by Kunzite Quote
The frame size, together with the lens' focal length, gives you the angle of view which is what you're interested on.
Correct, but any angle of view can be expressed as a focal length when assuming a particular format size.

We could be talking about a "40 degree (horizontal) angle of view" but referring to "50mm on FF" or "50mm FF-equivalent" is much more meaningful to most people as they can visualise the framing of a 50mm lens on a full-frame camera, but have little idea what "40 degree (horizontal) angle of view" actually means / looks like.

I believe that associating an angle of view with a lens (as opposed to a focal length) would be more helpful -- as for instance a ~43mm FF lens and an ~28mm APS-C lens would both be referred to as 53.4 (diagonal) angle of view lenses, highlighting the fact that both lenses fulfill the same role on their respective formats -- but this is not the approach the vast majority of photographers grew up. Hence, expressing the angle of view with respect to a known format size, is useful.

Last edited by Class A; 12-24-2015 at 09:39 AM.
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