Live View On D7100

[myrialejean]

Hi,

 

I used Beta 02h today for a bit of white light solar imaging with my D7100.

All was fine imaging-wise but focusing was a major headache.  In the end I resorted to using the camera's LCD screen instead.

 

The problem was that (unless I've missed something ) there doesn't seem to be any means of altering the shutter or ISO in the actual live view (frame and focus or planetary).  With stars this isn't an issue but with the Sun it makes it near-impossible (in my case anyway) to focus as you can't really see any detail such as sun spots.

 

On the camera itself you have to switch to video mode for the shutter speed to affect the live view display but it does allow you to dial down the expose enough to be able to focus.  However, as I've found out before, if the D7100's live view switch is left in video mode BYN shows completely blank (black) live view.

 

I obviously turned off the 'Maximum Sensitivity' option.  This allowed me to override the ISO and shutter but had no effect on the live view image.  This is much the same as on the camera itself when LV is in 'camera' mode rather than 'video'.  Also managed to completely lock up BYN a couple of times when changing the ISO with LV active (an API issue I suspect).

 

On the subject of video, it would be nice if the BYN planetary capture could do more than 640x424 (unless I've missed another setting  ).  The D7100 itself captures video quite nicely at 1920x1080 giving loads of scope for cropping.  What would be good for planetary would be to be able to capture a stream of frames with the mirror locked up perhaps cropped from the full 6000x4000 res - wishful thinking I suspect  .

 

Apart from these minor grumbles however it's an excellent product and i'm looking forward to purchasing the final version.

 

Rich Bamford.

[admin]

The problem was that (unless I've missed something ) there doesn't seem to be any means of altering the shutter or ISO in the actual live view (frame and focus or planetary).  With stars this isn't an issue but with the Sun it makes it near-impossible (in my case anyway) to focus as you can't really see any detail such as sun spots.

 

The Nikon SDK does NOT allow any changes while in live view.  You have to pause live view, make the changes, and resume live view.  This is a Nikon limitation that Canon does not have.

 

Hope this helps,

[myrialejean]

Hi Guylain,

 

After some further investigation I have found that you are indeed absolutely correct in that you have to pause live view in order to make changes to the exposure in frame and focus .

The one caveat to this is that on the D7100 it only works (in mine anyway) if the live view switch is set to 'video'.

With the switch left in the usual 'still' position the camera seems to ignore BYN and attempts to auto-expose.

This seems to replicate what happens on the D7100 anyway - I.e. you only see the actual expose in the LCD when in 'video' mode.

Ignore what I said previously about BYN not working with the camera in video mode, can't replicate that at all any more 

 

I suspect that the SDK doesn't have an option to force the D7100 into video mode but at least I now know what to do.

 

Rich.

[admin]

Thanks for reporting back with additional information Rich.

 

Regards,

[s3igell]

It seems that Nikon D7100 has a few "Oddities" with its LiveView - detailed on Review sites such as DPREVIEW.

 

In general, BYE/BYN Frame&Focus and Planetary modes are at the mercy of the LiveView data made available by the various DSLRs' SDKs.

This is almost always a redirected stream of the Image originally destined for the DSLR Rear LCD, and that dictates both the Size and ultimately the Resolution of the available LiveView Captured Image.  As the standard LiveView Image will have been designed for the DSLR User to see a LCD representation of the full Frame about to be recorded, and that Image Data (6000x4000 in D7100) needs to be "Reduced" to fit the smaller 640x480 LCD (640x424 size is likely due to lower area dedicated to Shooting Data Display).  Worse, that "Reduction" is performed by Interpolation which "mashes" the detail of a 9x9 pixel square of the DSLR Sensor into a single Pixel - destroying much of the Fine Detail which we (as Planetary Imagers) would want.  All this happens before the output is made available for the SDK to redirect to BYE/BYN.  Lucky for us, each DSLR implements a couple of Zoom LiveView modes where the Camera's Firmware "knows" that a smaller portion of the overall Sensor will be displayed onto the LCD and therefore "cheats" by avoiding the Interpolation process and simply stats with a Crop selection that might even be output as a 1:1 direct Pixel output (unfortunately not likely in the case of the D7100 where 6000 reduced to 640 is an odd 9.375:1 ratio).

[WJShaheen]

On 1/18/2015 at 2:38 AM, myrialejean said:

Hi Guylain,

 

After some further investigation I have found that you are indeed absolutely correct in that you have to pause live view in order to make changes to the exposure in frame and focus .

The one caveat to this is that on the D7100 it only works (in mine anyway) if the live view switch is set to 'video'.

With the switch left in the usual 'still' position the camera seems to ignore BYN and attempts to auto-expose.

This seems to replicate what happens on the D7100 anyway - I.e. you only see the actual expose in the LCD when in 'video' mode.

Ignore what I said previously about BYN not working with the camera in video mode, can't replicate that at all any more 

 

I suspect that the SDK doesn't have an option to force the D7100 into video mode but at least I now know what to do.

 

Rich.

Have been having the same issue with my D7500. Found the Lv button needs to be in camera mode, not video. 

(I have been wrestling with this for several days and only found this after reading your post.)

Bill in Gold Canyon,  AZ