Question about using Live View, digital zoom, and planetary imaging

[Crunchmeister]

I haven't yet tried the planetary imaging mode of BYN for the obvious reasons that the main planets that I'd want to image aren't up in the window of time I have to image. But I've been thinking about this and thought I would ask.

I've been considering upgrading to a better solution than my Celestron NexImage 5 for planetary imaging, and then this idea dawned upon me. It's been ok, but not exactly great, and I'd love to get something better. But it dawned on me that I may already have what I need now that I'm using BYN.

Obviously, using a DSLR directly for planetary imaging isn't the best solution. But the way I understand it, rather than shooting MOV video with the camera's internal video engine (or whatever it's called), BYN / BYE uses the live view feature, capturing images and encoding them together in an AVI file. Is this correct? 

Assuming that's correct, is it possible to use the digital zoom on the camera to zoom in on planets and use BYN that way without requiring the use of a barlow lens to magnify the planets? And if so, how good are the results I could expect using this technique (assuming it can be done, of course)? 

Sorry if this has been covered already or if I'm just asking the obvious here. But if this is a viable way of doing it, I'm more than likely going to be using BYN and my D7000 as my planetary and lunar imaging camera and just ditch the NexImage 5, since I have a friend who really would like to buy it. 

[myrialejean]

The LCD on my D7100 is 640x480.  I'm not sure what resolution the live view image provided via the USB is but BYN doesn't give an image any bigger than 640x480 from what I recall.  The onboard video is from a 16:9 crop scaled down to 1920x1080.  I agree that neither approach is optimal.  The onboard video capture gives a higher resolution (handy if you don't own a 5x Barlow) but the downside is the compression, not to mention converting and cropping the video so that AS!2 etc will eat it without choking.

 

I'm tempted to move the the 'dark side' and get a modded Canon for astro  .

Although both Canon and Nikon do equally horrendous stuff to their 'raw' images in terms of astrophotography use, Canon still seems to have the edge.

(I'd also feel less guilty about having a Canon surgically adjusted  )

[s3igell]

In general, Digital Zoom for Images gives you little but "Fat Pixels".  You are not actually collecting Finer Details, only making the Details that you captured Bigger.

 

A FullHD Video recorded from a Multi-MegaPixel DSLR is the interpolation of 4000-5000 Horizontal Pixels on the Sensor to only 1920 Pixels in the Video, and a similar ratio for the Vertical dimension.  This means that the detail originally captured on each of 2.5-3.5 Pixels is blended into a single output Pixel - losing any detail contained in them.

 

EDIT:  There are very few DSLRs that offer an actual Crop Movie Mode where 1:1 Pixel Ratio is recorded - only the Canon T2i and 60D/60Da offered 640x480@60fps, and the T3i offered "3x Zoom Video" 1728x1152@30fps (then Canon dropped the Feature from their DSLRs).

 

However, at least for the Canon implementation of LiveView, the 5x Zoom output corresponds almost exactly to a 1:1 Crop of the Central Portion of the Sensor Image.  This means that the Output Video contains every bit of Detail which the DSLR Sensor could Capture.

[admin]

I have not been able to implement the digital zoom in BYN as of yet.

 

And I'm not even sure it produces a 1:1 pixel resolution like most Canon does.  If is does not digital zoom for Nikons will be useless for image quality in BYN.  Digital zoom is not schedule for the initial BYN release 1.0. 

 

Regards,

[s3igell]

Assuming the Nikon SDK does provide successful LiveView Zoom, even if not "very close to 1:1" most any reduction over the FullHD high downscaling ratio would be "better than nothing" while not "ideal".

 

In any case, it sounds like BYN Users will need to anticipate this Feature as part of a Future Release...

[Crunchmeister]

Ok, I figured it wouldn't be that easy. Nothing ever is. The idea is sound in theory, but seem like the technology isn't there yet (not on the BYN side, but on Nikon's). Looks like I have to get a 2" visual back and 2" 3x Barlow for planetary work or stick with my NexImage 5.

 

 

[s3igell]

It's not a "Technology Issue"...

 

The Pixels on a Sensor are solid Silicon (well, and many blends of embedded rare-earth minerals), which cannot Expand or Shrink themselves on the Sensor Chip.

 

To get higher Image Resolution, either the Image needs to Expand (Optical Zoom) or the Pixels need to Shrink (can't be done in real-time - that's why Planetary Cams have such smaller Pixels).

 

So, you need to look at enhancing your Focal Length - adding a Barlow.

[gsedun]

Hi - a Canon user introduced me to BYN.  I watched him do a planetary movie and he was able to zoom in on the planet so that it was quite large on the screen.  He used my 20" Newtonian and the results were amazing.  I downloaded the BYN Free Trial and am able to connect and record a planetary AVI but I cannot find a way to only use the portion of the image right around the planet.  What am I missing?

 

Thanks

 

Garry 

[s3igell]

Looks like I have to get a 2" visual back and 2" 3x Barlow for planetary work

 

You will want a 2in Visual Back for your DSO and Lunar Imaging.  But won't need that for any of the Planets - they simply aren't big enough to be impacted by Vignetting.

 

You will benefit from a Barlow - whether 1.25in or 2in.  You'll want to invest in the best Glass that you can for your Barlow - ED Glass  and/or APO-quality.

 

You'll want a 3x Barlow, whether it's used with your D7000 or NexImage5, but anything more will definitely overpower both your Scope and the Seeing.  Even so, you'll only fill about 1/4 to 1/3rd of the NI5 Image or only a small image on the D7000.  This is why all those producing spectacular Planetary Images are using 14-16in SCTs.

[admin]

Hi Garry,

 

There are subtle differences between BYE and BYN.

 

The Canon SDK allows to increase live view zoom by 5x and 10x.  These options are offered in BYE.

 

The Nikon SDK does not allow that (as far as I know) so this feature is not implemented in BYN

 

Hope this helps,

 

Regards,

[myrialejean]

Perhaps we all need to start harassing Nikon until they put more features in their SDK 

Until there's something approaching 1:1 in Planetary it isn't particularly useful.

[s3igell]

At least Nikon provides decently Full Featured SDKs...  You could be stuck as a Sony/Minolta DSLR Owner...

 

Regarding the Nikon Planetary Imaging - you can always insert a Barlow into the Imaging Train.  Mars Jupiter and Saturn are all Bright Enough that even a 5x Barlow won't create an Image Too Slow for decent Recording... (Especially if you have a Large Dob...)

[myrialejean]

Yes, you can use a Barlow to scale up the image to cover the sensor, the problem is that the camera is then doing a rough and ready re-size of your nice 6000x4000 (D7100) data down to 640x480 for the live view image (possibly less in the BYN capture?).  If you capture video on the camera itself it's only scaled to 1980x1080 (D7100) but unhelpfully is compressed.  In a perfect world you want the full 1:1 live view image from camera (basically reeling off multiple shots with the shutter open and the mirror up) but USB bandwidth would be a big issue there even if the SDK did allow it.  The compromise is to be able to do it for a very small portion of the image - which Canon sort-of allow with the 5x zoom but Nikon don't.

[s3igell]

As the Happy Owner of 2x Canon DSLRs which CAN perform both BYE's 5x (and 10x) Zoom LiveView Planetary Video Capture and Canon's 640x480 1:1 Crop Movie Mode (unsupported by BYE), I can't directly equate what BYN provides as Planetary Video except that it should be the Resolution of the Rear LCD (1280x960 for your D7100).

Yes, I have described here and on other Forums the problems of In-Camera Downscaling (Interpolation) from the DSLR Sensor Full Resolution to FullHD 1920x1080 - a 2.5:1 or 3:1 or even 4:1 reduction further complicated by Debayering and then storage in an 8-bit Color format (possibly Lossy Compression too).  It does dilute the benefits of Video Stacking for Planetary Imaging, but one would still get some benefits from "Lucky Seeing".

The suggestion of using a 5x Barlow is based on the fact that such a Barlow would Optically Zoom the Image, spreading the Incoming Light across MORE PIXELS.  Thus, when the In-Camera Downscaling were performed, fewer of the Features represented in that Spread Image would be lost.  It's not a Perfect Solution, but rather Preferable to the un-Barlowed Alternative.

 

While Guylain has surely scoured the Nikon SDKs for hints that 5x Zoom LiveView might be supported, you Nikon Users need to keep looking at all the other Nikon DSLR Control Apps for any which purport to have cracked that Functionality.  Guylain has been known to track down "How To" from hints provided by other Software, and you might eventually get Parity with BYE on this Feature.