Focus issues when tethering to MBPR?

[Chris Barrett]

Shortly after moving to the MacBook Pro Retina, when they first came out, I noticed that my focus accuracy while shooting tethered started to suffer.  I use 100% zooms on the laptop for checking critical focus.  We were shooting furniture in studio this week, so I took my 24" Eizo along for the ride.  Everything changed... it seemed that it took me longer to find critical focus and when I later viewed the images I knew to be a little out of focus on the laptop screen, they seemed perfectly sharp.

Is the extra resolution of the MBPR fooling us into thinking images are sharp when they really aren't?  Why would this be?

CB

[Christoph B.]

Perhaps it's the tethering software that isn't optimised for the high retina resolution?

Due to the high resolution the 100% view doesn't offer the same magnification on your laptop monitor as it would on a lower resolution.

So even though it may look sharp because the image appears smaller, the focus could be slightly off... So far I haven't found a way around it, changing the resolution scale changes nothing because the base resolution remains the same - and obviously programs like Lightroom or C1 rely on the base resolution and not the scaled resolution.

edit. the only solution that works or me is previewing the photos at 200%.

[ErikKaffehr]

Hi,

It sounds like a very good explanation.

Best regards
Erik

Perhaps it's the tethering software that isn't optimised for the high retina resolution?

Due to the high resolution the 100% view doesn't offer the same magnification on your laptop monitor as it would on a lower resolution.

So even though it may look sharp because the image appears smaller, the focus could be slightly off... So far I haven't found a way around it, changing the resolution scale changes nothing because the base resolution remains the same - and obviously programs like Lightroom or C1 rely on the base resolution and not the scaled resolution.

edit. the only solution that works or me is previewing the photos at 200%.

[Bart_van_der_Wolf]

Due to the high resolution the 100% view doesn't offer the same magnification on your laptop monitor as it would on a lower resolution.

Correct. The 13 inch MBPR with Retina display has a 227 DPI screen resolution, and the 15 inch version is at 220 DPI. That's close to the average human visual acuity at roughly 9.2 inches viewing distance. So to really see the details, you need to view from a closer distance than that, or zoom in, just to see the limiting resolution clearer. You won't see more detail as such, the limit is the display, but you do get to see it bigger/easier because you are able to more easily resolve the detail that is there.

Zooming in at more than 100% should help, assuming that the tethering software doesn't interpolate incorrectly.

Cheers,
Bart

[Chris Livsey]

Correct. The 13 inch MBPR with Retina display has a 227 DPI screen resolution, and the 15 inch version is at 220 DPI.
Cheers,
Bart

How does this compare with MFDBs with live view rear screens? I presume, always dangerous, using tethered will be easier to "see" due to physical size but does it improve accuracy?
I rarely use live view, not that kind of shooter, but am looking to update the laptop.

[Bart_van_der_Wolf]

How does this compare with MFDBs with live view rear screens? I presume, always dangerous, using tethered will be easier to "see" due to physical size but does it improve accuracy?
I rarely use live view, not that kind of shooter, but am looking to update the laptop.

Hi Chris,

Depends on the LCD specs of the back, and if the Raw data is really used for display or a (resampled?) JPEG conversion (including sharpening and contrast adjstments). In general the display resolution is relatively low, but even then it helps to use a loupe. More recent displays have better resolution.

For instance the IQ250 display is said to be 1.15 MP (maybe something like 1232x928 pixels, or do they count R+G+B seperately?) and measures 3.2 inches, so that would be pretty high resolution for RGB, but still a small display, so a loupe would be needed if one could not zoom in. I don't have such an LCD, but I guess that at 200% zoom one is approx. at the visual acuity limit at normal reading distance, so 400% would be really needed for critical inspection, all assuming that the software/JPEG version resembles the Raw capture potential.

Cheers,
Bart

[Paul2660]

As a user of the IQ series, 150, 160, and 260, the feedback on the back's LCD, at 100% view is excellent in regards to a focus check, i.e. zooming in to view an image after the shot is taken.

Live View on the CCD backs, well, can't really do much with that at least outdoors.  Enough has been written about that. 

Live View on the IQ150, excellent, at 100% view.  Using a DF+ and 75-150 and 80mm LS lenses, I found the feedback at 100% to be excellent.  As I am nearsighted, to really check the screen, means taking off the glasses, and getting close, but this is true for me with Nikon, Canon etc.  When using the IQ150 with the DF+ I felt very comfortable with the feedback and did not find many miss focus shots.  Of course with current Phase Live View, you don't get focus peaking which would be a nice feature.  Obviously you don't need a EVF to use it, as the 645z has it and it's quite a good implementation to me.

Tethering, I only tether to the Surface pro 2, or 3.  All outdoors, in the field.  The best tool I have found so far, (thanks to the work by Ken Doo and Don Libby).  With the Surface 2 zoomed to 100%, you easily get perfect feedback on the focus.  I am 100% confident, if I see good focus on the Surface 2 or 3 screen at 100%, the image will be fine on my larger NEC 30" screens. 

I have not tried my 15" macbook with retina but over the weekend will try it tethered to see and compare it to the Surface 2 feedback.

Capture Pilot, which is Phase One's app, for both the iPad and iPhone, definitely has an issue displaying an image at 100%, and allowing for critical focus.  I have noticed this issue and made comments to Phase for over 2 years, however they have never either cared to fix it, or can.  The answer I have always been given was the resolution of the retina screen on the iPad is too much for Capture Pilot to resolve.  What you get is just enough blur that you really  can't check critical focus on finer items, (trees, grasses, distant buildings etc) when zoomed to 100%.  The only iPad that really worked at 100%, was the first generation of the iPad mini without retina.  The answer I got back from Phase was that, it was just not possible to make Capture Pilot work with a retina iPad, mini or full size, again this was 1.5 years ago.  I have tried the app a few times since and the feedback at 100% is still the same, not enough to determine critical focus when zoomed to 100%.  This is unlike the view of an image when viewed at 100% on the Surface 2 or 3, which gives the appropriate amount of resolution.

Paul C

[Chris Livsey]

Hi Chris,

Depends on the LCD specs of the back, and if the Raw data is really used for display or a (resampled?) JPEG conversion (including sharpening and contrast adjstments). In general the display resolution is relatively low, but even then it helps to use a loupe. More recent displays have better resolution.

For instance the IQ250 display is said to be 1.15 MP (maybe something like 1232x928 pixels, or do they count R+G+B seperately?) and measures 3.2 inches, so that would be pretty high resolution for RGB, but still a small display, so a loupe would be needed if one could not zoom in. I don't have such an LCD, but I guess that at 200% zoom one is approx. at the visual acuity limit at normal reading distance, so 400% would be really needed for critical inspection, all assuming that the software/JPEG version resembles the Raw capture potential.

Cheers,
Bart

Yes, thanks, too many apples v oranges I suspect and users expectations vary. There must be a jpeg conversion of some sort for live view RAW is RAW but then so is the tether.

[vjbelle]

I travel with my MBP Retina and find the screen very unreliable for critical focusing.  That screen really has a tendency to five a false impression of an in-focus image.  When I get back to my studio I view images on my PA272W which, at 100% pixels, shows what really is in or out.  This is one of the reasons why I'm hesitant to purchase any of the 4K monitors....

Victor

[douglevy]

Dumb question - is focus masking in C1 related to screen resolution at all? Can't you just use that? I know it's not perfect, but...?

[Christoph B.]

Focus masking isn't related to screen resolution but it's just ugly and if you want to see details of the things that are in focus you'll have to turn it on an off all the time.
Pretty annoying imho.