Tuesday night here in Melbourne was an opportunity to have another crack at tbe planetary trio. The seeing was fair, about 7/10 and transparency was good so here are two of the three. I'm working on a gif of Jupiter's rotation, so if it works, I'll post it later.
My usual setup on these: 8 inch f5 Newtonian, eyepice/barlow projection combination and Canon 550d using movie crop mode.
Good contrast and colour with Barlow producing decent enlargement whilst not diminishing image quality. Should be most pleased with these results using the DSLR. Well done.
Thanks Colin and Anth, yes the Canon works well with movie crop. I just wish I'd hung out for the 60d with it's variable view screen, makes it a lot more comfortable when framing shots.
Chris, movie crop mode is a feature available on a few Canon DSLR modles. I'm not sure if Nikon have this or equivalent on any of theirs. Basically, it uses the central part of the sensor in video mode, cropping it down to a 640 x 480 pixels thereby enlarging the image.
Despite the low resolution, taking thousands of video frames smooths out the result after stacking. These were the best 70% of about 8000 frames.
Someone correct me if I am wrong but I think that the crop mode on Canon does not compress the video. The "normal", uncropped video is compressed which affects the final outcome.
Chris, movie crop mode is a feature available on a few Canon DSLR modles. I'm not sure if Nikon have this or equivalent on any of theirs. Basically, it uses the central part of the sensor in video mode, cropping it down to a 640 x 480 pixels thereby enlarging the image.
Despite the low resolution, taking thousands of video frames smooths out the result after stacking. These were the best 70% of about 8000 frames.
Ah okay - so it's basically just an enlargement of the normal uncropped mode. Guess it would speed up the stacking process a bit, working with much smaller video / image files. Cool. My Nikon doesn't have that option - you can decrease the resolution but the frame is the same size.
Hmmm... for my first attempts this week I only shot about 3000 frames and used the best 500. Might try again with longer videos and more frames. Ta for that. I don't expect to get much more out of my little scope but it's worth trying.
That's right Chris, it's cropping the sensor down to a size of about 7mm or so, ending up similar to that of a web cam, that's why the image appears bigger in the view finder of the camera. The beauty of the Canon 550d/60d is it saves the cropped video as a native file to your internal memory card, no need for a computer.
You should be able to obtain a comparable result with your Nikon if you can find a software program ( maybe Sharpcap? ) that will capture video via the enlarged view of the planet on your camera's LCD viewfinder, ie Liveview. This is an alternate method for Canon DSLRs that don't have movie crop but like your Nikon, you will need to connect it to a computer to capture the video. Your frame rate will be limited to the video capture program you are using and the resolution will be calculated from the resolution of the camera's LCD. The end results are quite good though.
As long as you can magnify the image on your LCD using your camera's magnifying glass button, you should get a reasonable size image. Worth a try.
Another advantage of Canon's movie crop mode is that you can shoot at 60fps, which is an advantage on fast rotating planets like Jupiter, it can collect lots of frames in a short time span.
That's right Chris, it's cropping the sensor down to a size of about 7mm or so, ending up similar to that of a web cam, that's why the image appears bigger in the view finder of the camera. The beauty of the Canon 550d/60d is it saves the cropped video as a native file to your internal memory card, no need for a computer.
You should be able to obtain a comparable result with your Nikon if you can find a software program ( maybe Sharpcap? ) that will capture video via the enlarged view of the planet on your camera's LCD viewfinder, ie Liveview. This is an alternate method for Canon DSLRs that don't have movie crop but like your Nikon, you will need to connect it to a computer to capture the video. Your frame rate will be limited to the video capture program you are using and the resolution will be calculated from the resolution of the camera's LCD. The end results are quite good though.
As long as you can magnify the image on your LCD using your camera's magnifying glass button, you should get a reasonable size image. Worth a try.
Another advantage of Canon's movie crop mode is that you can shoot at 60fps, which is an advantage on fast rotating planets like Jupiter, it can collect lots of frames in a short time span.
At this early-beginner stage, I always record straight to the camera's SD card. I don't use a computer with the telescope yet, I don't have guiding. I just import the full size video into Registax, zoom right in whilst editing it, and crop the end result.
I can shoot at 60fps but that limits the shutter speed to a minimum of 1/60, which means double the ISO - which on this camera isn't a good thing! Using an ED80 and two Barlows for planets means I'm already stopped waaaay down. Think I'm getting a focal length of close to 5000mm or maybe just a bit under; with 80m aperture you know it's a tiny pinhole by the time it gets to the sensor. I think the attached from last night was shot at ISO 6400 which is the useable limit for this low-end DSLR.
(Such a crappy pic doesn't belong in the same thread as your amazing result... meh, it's an ED80, not designed for this stuff.)
Chris, you can only do the best you can with the equipment you have and I think you've done well there for a beginner.
I think you misunderstood me though, you don't need any extra optical magnification to try this video capture technique. You use the same setup as you have been using and the computer software just captures what you see on the Liveview of your camera's LCD screen. You don't have to alter exposures on the camera as the software has all you need to change exposure, gain and video capture settings. It's a bit like mirroring the screen of your mobile phone to the TV monitor, what you see is what you get.
I think I do know what you mean, but maybe you missed the part where I said I don't have a laptop anywhere near the telescope. It's just the telescope on a NEQ6. For DSOs I drift align then use a cheap intervalometer with subs under 2 mins. Very very basic rig. I get my data then take the whole thing inside and upload everything from the SD card.
Finally put this Jupiter gif together. Turned out to be a lot more difficult than I anticipated. Trying to match each frame so that colour, contrast and size are the same is quite difficult when each video grab I took varied in seeing conditions and field rotation. Oh well, it was just an experiment that I won't attempt again with the setup I have now.
Last edited by Mickoid; 03-06-2016 at 11:29 PM.
Reason: Add new picture
That's so cool! Seeing the gas giant spin gives it a whole new dimension. Worth the effort Mick, you should be happy the way you put this together and good detail in the sequence too I might add.
Thanks Klaus and Anth10 , glad you enjoyed it. The effort is worth it when you get a positive response from those that appreciate something a little different.
Thanks Russell, I think I've reached the limit with what my outfit can achieve on planetary images. The only variable whicb could improve my results would be excellent atmospheric stability and transparency. I must admit I have yet to photograph the planets on a night better than good seeing, so there is room to squeeze out a better result given the right conditions. We live in hope!
