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Post by Deleted on May 29, 2020 12:00:21 GMT
Rasa 8, zwo 290. Clear skies but lot of moonlight so images were a bit ordinary. That was most images I have done in 90 minutes. All 10s x 18. Looking forward to having another go at these with dark skies. M64 M88 M90 M91 M98 M99 M100 and one from Centaurus...ngc 5128 with the scope pointing away from the moon rather than almost straight at it like the Virgo galaxies
and I need to clean the camera cheers Paul
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Post by Deleted on Jun 3, 2020 14:19:02 GMT
I like those. :-) What focal ratio is the rasa8? Thanks, Jim
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Post by Deleted on Jun 3, 2020 14:22:42 GMT
I looked it up! f/2.0
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Post by Deleted on Jun 4, 2020 3:11:18 GMT
Yep, that is right Jim.F/2......and welcome to the forum I have a few scopes,but I find the Rasa is great for galaxies and the Esprit 80 is good for nebulae and other big bright things. I keep trying with lx90 8",but never get the quality I am happy with. The images can be better than that . I am just waiting for the moon to get out of the way. What I like about the Rasa is that I need exposures of 10secs or 15 at the most. I stack and the image is autosaved on sharpcap at 3 minutes. Usually,I am happy with a stack of 5 or 6 and dont get much benefit out of another 10 stacks to make up the 3 minutes, but you know what it is like when you have an image. You think, "I will give it a bit longer to see if it improves ",but it usually doesnt. Last night I tried a 742 planetary filter on the imx 432 camera and the lx90 8" with the night owl FR. That system was f4. The images were terrible.
Clear nights are infrequent at the moment so I wont waste any more nights trying to shut out moonlight. I will just point the scope south. There is plenty to see there. cheers Paul
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Post by Deleted on Jun 8, 2020 12:28:20 GMT
Moon more out of the way tonight,but streetlights still a problem to the north. Cleaned the camera but that dark ring persists in all the 290 images. What is that? Rasa ,zwo 290, 10sec x 18 stack,stretch on sharpcap M98 M99 M100 m64 M88
Eta Carina neb ,esprit 80,zwo183, 30s x 6,stretch in sharpcap
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iannz
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home town/country: Tarurutangi, NZ
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Post by iannz on Jun 8, 2020 20:40:30 GMT
water mark? total guess on my part,aware of but not yet up to speed on..... presumably inside where no man sanely goes
how do you clean your sct and how far do you go? dismantle etc contemplating such for mine...... love the Etca image
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iannz
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home town/country: Tarurutangi, NZ
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Post by iannz on Jun 8, 2020 20:41:42 GMT
try different cam, same ota.....
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Post by Deleted on Jun 9, 2020 10:12:20 GMT
Thanks Ian,I think it is a cam problem. This was an image of the Leo Triplet from late April with the imx 432 and the Rasa.No mark. I have not been saving my images over the last 12 months . My best record is what I have been posting on this forum. When friends ask me for some images,I go to this forum as I have thrown all the recent images out. Might have to start saving again. cheers Paul
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Post by howie1 on Jun 9, 2020 12:25:36 GMT
Moon more out of the way tonight,but streetlights still a problem to the north. Cleaned the camera but that dark ring persists in all the 290 images. What is that? Rasa ,zwo 290, 10sec x 18 stack,stretch on sharpcap M98 M99 M100 m64 M88
Eta Carina neb ,esprit 80,zwo183, 30s x 6,stretch in sharpcap That be a dust bunny Paul. You can figure out for sure if its still on your camera sensor by taking a shot, then rotating the camera 90 degrees and taking another shot. If it stays in the same position in the images (above and left of centre), then the dust bunny is still on the sensor protective lens. If the dust bunny moves to a different position in the image when you rotate the camera, then the dust is somewhere on the optics of the RASA. As a top hint where it may be ... They are kind of notorious for getting dust on the front corrector plate. When you attach the camera onto the front plate, you usually have the OTA pointing up a tad so it is easy to attach the camera. So any dust or debris on your hand or winter coat cuffs etc fall down onto the front corrector plate as you fiddle attaching the camera. So give that front plate a clean first. You can check if you fixed it by just seting up in the dark/night pointing out the window at pitch blackness and take some images. IE of clouds, horizon, rain, whatever just so its dark and so you can stretch the buggery out of the image which will show if the dust bunny has been cleaned ... or not. If not then in the day while inside your house peer down through the front plate attachment down into the primary mirror and see if you can see anything. Hopefully it isnt down on the primary. Good forum thread contining a link to another thread where there is a tool/formula way to work out how far the dust is from your sensor. The pixel size and f ratio are used to yield the mm away from the sensor and by finding some optic element that far away when the camera is placed in your scope .... bingo you've found the "thing" to clean. How to find where the dust mote is <----------- forum topic which is an interesting read .... and the actual calculator -----> link to the online calculatorCheers Howie
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Post by Dragon Man on Jun 9, 2020 15:27:43 GMT
Wow, you have been busy Paul! I like your results, nice detail and really sharp stars. I don't care about the dust bunny as it is quite a common thing with me too.
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Post by Deleted on Jun 10, 2020 0:04:17 GMT
Thanks Ken and Howie. The zwo 290 and the Rasa are a good team for galaxies.About the right FOV . The imx 432/Rasa FOV is just a bit too big and the galaxies come up a bit too small. So I would really like to sort the dust bunny. It really annoys me.
The larger stars are really bloated on the Rasa,and there appears to be nothing I can do about that. As long as the smaller ones are sharp ,I am usually satisfied cheers Paul
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Post by davy on Jun 10, 2020 3:37:13 GMT
Thanks Ken and Howie. The zwo 290 and the Rasa are a good team for galaxies.About the right FOV . The imx 432/Rasa FOV is just a bit too big and the galaxies come up a bit too small. So I would really like to sort the dust bunny. It really annoys me. The larger stars are really bloated on the Rasa,and there appears to be nothing I can do about that. As long as the smaller ones are sharp ,I am usually satisfied cheers Paul 2nd episode of stargazers lounge broadcast by nick does a tutorial on removing these and noise ect,, he has a book for sale in astronomy now for £11 shop.astronomynow.com/product/shooting-stars-2/
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Post by Deleted on Jun 10, 2020 10:47:53 GMT
The zwo 290 and the Rasa are a good team for galaxies. So, is the ZWO290 the fastest/most-light-sensitive camera to capture faint galaxies in a hurry?
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Post by Deleted on Jun 10, 2020 11:45:30 GMT
Jim ,I think the imx 432 is the most sensitive camera to capture faint galaxies but it has a 1" sensor and you need a scope with a FL of 800 or more to get the right fov. I cannot use gain at all with this camera on the rasa as it is a total whiteout. The zwo 290 mono is very sensitive as well and its sensor size in combo with the rasa fl of 400 gives about the right FOV for the galaxies.
I keep persisting with the lx90 8" sct,night owl FR and the imx 432 which has the right combo of FL with sensor size but the images are very ordinary . It is not a problem with the camera because it works well with the rasa. I have never been able to get decent images with the sct's and have wasted many a clear night trying. I have a 8" f/4 newt with a fl of 800 which I havent used for a couple of years. It is time to try the 432 with the newt. cheers Paul
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Post by Deleted on Jun 10, 2020 13:03:35 GMT
The zwo 290 mono is very sensitive as well and its sensor size in combo with the rasa fl of 400 gives about the right FOV for the galaxies. Thanks Paul. I might get one to try with my 120-300, f/2.8 camera lens. I'm a bit worried about possible bloated stars from non-astronomy optics with a camera that is probably sensitive to non-visual wavelengths. I suppose I should try it and see what happens!
Jim
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