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So here I am on a cold, grey, Thursday morning in the observatory. Watching clouds stream over a monochrome sun only pretending to be in H-alpha. The increase in clarity of the 174 over the 120 is as amazing as is the difference in image scale. The sun is covered in clear cells instead of pale pink, gelatinous blobs.
If
I had to guess I'd say the sun's image in the 174 is 1/4 of the size of
the 120. Though it ought to be about a half. The forecast is for a
little sun or sunny periods. So it's going to be one of those days! More
clouds than sunshine. Hours wasted in the hope of some decent images.
Hours wasted hoping to see a sharp limb to capture the large prom at 4
o'clock! Just after ten and the cloud is at about 98%. The lack of sun
makes it feel much colder in the observatory.
11.00
and I have had only teasing moments of partial clarity to capture a few
fuzzy "Snapshots" with SharpCap. Of course the sky is clear blue
overhead! I'll post better images if the sky ever does clear. Until
then, these are purely for comparison of image scale.Both images are 640x480 without any change in image size. It looks as if the 174 with 2x Barlow will match the 120 for image scale. See image right for 2x WO Barlow on the nose of the 174. Still 640x480 Mono8 settings. In fact the prom still looks slightly smaller with a 2x Barlow on the nose of the 174. Let's say 1/3 of the 120 image size without the Barlow. I hope I can capture a decent final image from all the videos by the end of today.
The speed of the 174 is astonishing at 640x480. Capturing 5000 frames in 12 seconds at just under 400fps. Of course, so many frames take longer to process. Not to mention the storage required. Now I can't get Registax to process 5000 frame videos! The processing screen instantly goes blank during alignment and never returns. Perhaps I had better make an effort to learn how to use AS!3.
An
interesting feature of these ZWO cameras is the 180 degree difference
in image orientation between the two, relative to the USB3 port.
Accidental or deliberate? I was just getting used to the 120. Remembering to invert the cable out after the lunch time, meridian flip. Now I haver to relearn the correct orientation for the 174. I forgot to invert the camera after lunch. These last two images are at 4 o'clock on the limb.
When the cloud finally cleared after 12.00 the seeing conditions became truly awful. I have paused at 13.00 for lunch and to warm up. It has reached 47F but feels ten degrees colder out there after four hours. On go the salopettes, after lunch, to join the down and fleece jackets.14:20 48F, clear but slightly milky skies now. Back to the fray. These last two images are taken with the 174MM Mono, processed in Registax from 50% of 3000 frames and recoloured in PhotoFiltre7. The 2x Barlow image has been heavily cropped and then enlarged again. To the detriment of the prom detail. The last image had only small amounts of the early wavelets and was cropped in Registax before saving. The black line was another, failed attempt to contain the Fill tool. The first signs of overlap into the prom are still visible.
Started packing up after 16.00 with the sun already below the trees. The crescent moon has been showing at dusk for the last two evenings but was far too low to capture.
Click on any image for an enlargement.
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