Recently Browsing 0 members
No registered users viewing this page.
I've never had any success with my C9.25 when trying to get DSO's. I've seen images other people have taken and they have good round stars. I can never get these.
I've tried collimating the best that I possibly can, and adding the Celestron f/6.3 focal reducer but I still can't get round stars. I could understand it if the stars at the edges had comma, but the stars near the centre are showing comma too.
I've changed my back focus both in and out to no real difference, I'm just wondering what I'm doing wrong?
I took the two attached images last night. One shows my out of focus star from the camera, and the other image shows an integration of 120 x30 sec subs of M63 Sunflower Galaxy. The camera is an ASI 1600mm Pro. These are both full frame, not cropped.
When I've plate solved the individual frames for M63 they give a focal length of 1483mm. 1480mm would be f6.3 on this scope, which the focal reducer is supposed to give indicating my back focus spacing is about correct.
One thing I have noticed is that on the focus star the rings are concentric and clean, but the small reflections inside the smaller ring are not central. Is this normal for an SCT? I'd have thought the central reflections would be centred too.
I've wondered if the star comma was down to guiding errors, but would a 30 sec sub-frame show this much error? Incidentally, my guiding last night was the best I've ever had and I don't think it was down the guiding. When I use my refractor (although shorter focal length) the stars are perfectly round with this mount - NEQ6.
A few years ago I removed the secondary mirror to remove a large dark mark from it which was obscuring my views (it was a fleck of black paint from the inside of the tube). When I removed the secondary, I accidentally rotated it when unscrewing. Would this make a difference? I know that the corrector plate shouldn't be rotated, and wondered is it was the same with the secondary? I've searched online but can't find an answer to that.
I love this scope, but hardly use it nowadays because of the image quality.
Hope someone can offer some helpful advise.
By Victor Boesen
Yesterday I managed to climb out of bed at a little past 3:30AM to get my small portable rig out to a small nearby park and setup to observe Jupiter, Saturn and Mars. I got the Skywatcher Evostar 72ED DS-Pro last summer so I was especially excited to see how it would perform on Mars because of its red wavelengths which many small fracs often have trouble with handling.
At first it was partly cloudy but I persisted and was out and setup on the field at around 4AM. The sky was already surprisingly bright here in Denmark but Jupiter was shining bright and Saturn faintly visible almost right besides Jupiter. Fortunately for me it wasn't too cold, but I was happy I brought some gloves anyways;)
This picture was taken at 5AM while I was observing Mars.
I remember from last year that my scope didn't perform great on Jupiter for some reason, and the view of the gas giant wasn't anything different this time either. Using my 4.7mm ES 82 degree eyepiece not much detail visible except the two main bands and its moons. I would later return to Jupiter after the scope had cooled down a little and the view was perhaps a little sharper.
Pointing the scope at Saturn, which I was very satisfied with last year, I was amazed of the detail the small scope managed to squeeze out. It doesn't compare to the view I had last year with my 10" dob under great conditions at 255X but I was able to easily spot surface banding on the planet itself, and the Cassini division was also surprisingly stable. I really enjoy the stable and consistent view through the small refractor! I observed Saturn for quite a while until I eventually set out to try to find Mars. At this point I couldn't even see Saturn with the naked eye but I was fortunate that Saturn and Mars were approximately the same elevation above the horizon.
After a few sweeps across where I though Mars would be I finally located the small red speckle, this time with my 6.7mm eyepiece so I had a larger FOV. Switching to the 4.7mm, though still very small, I was surprised that I could pick up a dark surface marking across the disk on the lower southern half of the disk. Furthermore, the southern polar cap was really pronounced and you couldn't miss it. I watched Mars drift through the FOV until about 30 minutes after sunrise where the contrast between the planet and the sky became too low and the dew started to set on the lens element.
Using my small refractor for observing the planets I have always wanted to magnify things a little bit more, and I think the telescope would have no problem doing so. A Nagler zoom 3-6mm has been on my wish-list for a couple of years now, but the upcoming planet season really makes me want to find one second hand
Here's a video I've made that covers what I've written above with some footage I tried capturing through the eyepiece:
I hope everyone on here is still doing well despite the current situation!
This is a re-processed set of 159 images taken from a few years ago. Each image was generated from a 3 minute video. It shows Europa passing across the face of Jupiter casting it's shadow across the northern hemisphere. Telescope: Skymax 150 Maksutov with a TeleVue 2x Barlow lens and a Baader fringe killer filter. Camera: Canon 550D in 640x480 crop mode. ISO Auto at 1/60s exposure. Processing: Quality filtering and centring done using Pipp, stacking and wavelets processing done using Registax 6.