Jump to content

NLCbanner2024.jpg.2478be509670e60c2d6efd04834b8b47.jpg

dweller25

Members
 View Profile  See their activity

  • Posts

    6,202

  • Joined

  • Last visited

  • Days Won

    5

 Content Type 

Posts posted by dweller25

    What did we do wrong?

    in Getting Started With Observing

    Posted · Edited by dweller25

    It sounds like you have a good plan to first line the finder up with the eyepiece view in daylight, you will need to look at something at least 300mts away for the scope to come to focus.

    You may have an extension tube in the focuser that will need to be removed to achieve focus.

    The scope will need to be cooled down for at least an hour for best results.

    View on grass not hot concrete.

    Atmospheric seeing is poor at the moment so that will affect the quality of the views.

    Check and adjust collimation on a good night.

    Good luck 👍

    problems at med/high magnification

    in Getting Started With Observing

    Posted

    You have moved from a 130mm scope to a 200mm scope, in my experience the larger scope will be more affected by seeing conditions.

    The Jetstream is often over the UK and it will negatively affect the views in a telescope.

    Yesterday was quite windy and that definitely affects seeing.

    If you cannot get a high star to focus to a stable view then atmospheric stability is probably the issue and you just have to wait for better conditions.

    I have been in this position many times and just packed up !

    • Like 1

    problems at med/high magnification

    in Getting Started With Observing

    Posted

    39 minutes ago, DAT said:

    Thanks for all the responses. It’s obviously difficult for me to differentiate between bad collimation (although I am ruling this out), bad seeing and tube currents. However, I have had the same problem several times in a row and at the next opportunity I am going to try putting my scope further away from the house as I am wandering whether heat coming off the building could be affecting the  view. 

    And put the scope on grass not concrete as that holds heat

    • Thanks 1

    Why a Visual Observer should not try to take Photographs

    in Observing - Discussion

    Posted

    On 09/04/2024 at 17:18, MalcolmM said:

    OK, so this a mixture of imaging and observational, but I am a visual observer and I was intending to do a good visual session. That, and my approach to imaging would probably offend the real imagers! It's also a lesson on how not to do astronomy 🙂 Laurel and Hardy could have done a better job!

    A couple of days ago it was looking like it was going to be a clear moonless night. So under a blue clear afternoon sky, I thought I would do a double; try some imaging and visual at the same time. I generally take one picture a year. I do not do it seriously. So a rough polar alignment, an unmodified DSLR attached to the back of a scope, and fairly short subs does for me.

    For the first time in ages, I was able to prepare, so I put the scopes out at sixish to cool, and had time to get the rig ready to take some pictures. I attached my camera to the back of my FS60CB, did a test focus on some distant trees and locked it. I attached all the bits, charged the camera and USB battery pack (for the mount), didn't think I needed to adjust the polar alignment from the last time, dec should be fine, just a rough tweak in RA. I preprogrammed the intervalvometer for 40 shots of 40 seconds. I was ready. All I had to do was point and click! I had taken a picture of Markarian's Chain a couple of years ago, only 20 second subs and where you could see most of the galaxies, I thought I could double the exposure and get more detail and more galaxies. Generally 20 seconds gives no appreciable drift with the rough polar aligning. The Mewlon was also out and cooling. I was going to star hop to Markarian's Chain and see how much I could see. To this end I had created a crib sheet on my phone in order to help me star hop there, and provide a 'tour' of the area.

    I was ready! Or so I thought!

    I went out at 10ish thinking an hour or so should do it before coming back in and getting into bed before my partner fell asleep (she had her first day back at work after Easter the next day). First off, rough polar alignment. It was miles off, I couldn't see Polaris, all I could see was the wall of the house. Ah, the scope was too low to see over the house. I'll just move it a couple of feet. Move the tripod, that's better, now I can eyeball Polaris. Still way off though. Then I remembered I had sent the mount back for tightening up a bit of backlash and had had to adjust it way down to fit the packaging. So much for my preparation. However, no bother, a few turns on the dec screw and we're in business.

    So far so good. Now to adjust the focus. To do this, I point at a dim star, turn on the LCD on the back of the camera and zoom right in. I then simply try to minimise the size of the star in the LCD. This goes well, so now try to find Markarian's Chain. It is in a fairy blank part of the sky so even with the finder, in my light polluted skies, it can be a bit tricky. Finder? What finder? In all my preparations I had forgotten to attach the finder (normally the 60CB plus a 28mm Erfle has no need for a finder and it makes the scope even more portable than it already is). So back inside, rummaging around all the bits trying to find the finder, the correct screws, and the correct size allen key. Thankfully my partner is still reading, she's not asleep yet!

    Only by the grace of God did I not loose one of the screws down a drain. It dropped, it rolled, and it stopped 1cm short of ruining my evening totally. With the finder attached, it needed to be aligned now. "Bother", or words to that effect! Back inside, rummaging around for micro screwdriver, partner still reading (thank goodness), no she's not, she's fallen asleep, book in hand, light still on. Or she was untill I tripped into the coffee table! It's going well! So much for my preparation!

    Back to finding Markarian's chain. I'm using my phone crib sheet and the finder to try and work from Vindemiatrix. Upside down and left to right, you just gotta love star hopping. I get to a blank bit of sky in the finder that I think might be close and I'm sure to recognise some of the star shapes from the crib sheet. A quick 10 second exposure and ... nothing. Not one star! Lens cap definitely off, intervalvometer definitely set for 40 seconds (and I interrupt it after 10). Try again a couple of times before remembering Einstein's famous quote and start to think what else might be wrong. Eventually I remembered the 'bulb' setting on the camera. So much for my prearation! A 1/1000 second exposure might just be a little to quick.

    A lot of fiddling later and I was pointing at the right place. I think! My crib sheet seems to bear no resemblace to what I'm seeing. Very little is visible with a 10 second shot. So I give it 40 seconds and wow ... enormous star trails. Is the mount on? Has the polar alignment shifted? Everything looked OK. Maybe 40 seconds was just too much; I had never taken such long exposures before. I'm getting fed up (as you, the reader, probably is too!) so I go back to 20 second subs and just let it go. I want to do some visual observing.

    I start at Denebola and hop across to M65 and M66. It's at this point I remember I usually have the 60CB dual mounted with the Mewlon and use it, with a 28mm Erfle as a finder. So much easier than straight through viewing and dealing with upside down as well as left to right! But the 60CB is taking pictures! Call me vain, but I will not alter the beautiful lines of the Mewlon, so it's down on hands and knees and squinting through the otherwise excellent finder - I'm too tired to raise the tripod and besides, a bit of Mewlon worship is no bad thing 🙂 M65 and M66 are easy in the Mewlon. I can see the different shapes, M65 being thinner and M66 possibly looks a little lumpy. I can also, with averted vision, just occasionally see a smudge where NGC3628 sits between the 2 stars of the upright of a 'T' asterism. I can even sense the plane of the galaxy is perpendicular to the upright, so it's a definite sighting. I can see all three in the same FOV and in the moments when I can see NGC3628, it's a very immersive view.

    I then roughly point the scope half way between Theta Leonis and Regulus and look for 52 Leonis. From there it's an easy hop down to M95, 96 and 105. I can fit M95 and M96 into the same FOV, but need to pan to see M105. All are just appearing as misty orbs, no structure.

    A quick look at M81 and M82 as they are easy and I'm getting cold and I'm concious I'm going to awaken my partner when I go in. A very obvious difference in shape between the two and a lumpy appearnce to M82. These two fit in the same FOV (32mm 85 degree Masuyama) and there is something humbling about seeing multiple galaxies in the same FOV and ponder on the sheer scale of what you are looking at. I never did get to Markarian's Chain.

    The imaging is still going but I cut it short as it's now one in the morning! My one hour has turned into three. Pack everything away, bring it inside, knock the door rims with the tripods, wake my partner, fill a hot water bottle, go to bed wondering how the images will look. Can't sleep so get up to look at the images on a laptop. They're awfull. Big star trails. Something's badly wrong. A total wash out. Back to bed and thinking what might be wrong. I come to the conclusion that there must be some setting in the handset that is wrong. Lunar rather than sidereal tracking, though I didn't think there was such a dramatic difference.

    The next day I went through all the menu options on the handset. Turned out that the tracking speed can be set to be loads too fast or too slow. I can't think why you might want this option, but it's there. Again, so much for my preparation!

    I need to try again some night. I want to know if rough alignment will allow me to take 40 second subs. But, in reality, the attempted imaging just got in the way of a good night's observing 🙂

    If you've got this far, thanks for reading!
    Malcolm

    I was thinking about getting back into imaging until I read this 😱

    • Haha 2

    Buying/ Selling

    in The Astro Lounge

    Posted

    There was a 250mm Mewlon for sale on AstroBuySell for quite some time for a VERY low price.

    It was eventually bought but it was a scam and the buyer lost all his money.

    If a deal is too good to be true - it usually is !

    Never do a high value bank transfer without seeing the item in person.

    SGL has a sales section which I have used quite a bit and never had an issue but the usual take care rules still apply.

     

    • Like 2

    First light with C8 Edge HD

    in Imaging - Discussion

    Posted · Edited by dweller25

    That doughnut image does not really confirm good collimation as it is too far from focus.

    Ideally you should perform final collimation at perfect focus, on a high star and at x300 plus power - you should be able to see a perfect airy disk if seeing allows…..

     

    IMG_0644.thumb.jpeg.11ba938365780d0f7a4bd490ea9091a7.jpeg

    • Like 2

    Orion Optics VX10 vs VX10L dobsonian

    in Discussions - Scopes / Whole setups

    Posted · Edited by dweller25

    If you have collimated before then you will not find the f/4.8 tricky to collimate, although the f/6.3 would have more latitude.

    But even if you have not collimated before it’s a learnable process 👍

    The f/6.3 is more suited to planetary as it has a smaller secondary obstruction, but it’s a long telescope.

    Both are good 🙂

    • Thanks 1

    Refractor Choice.

    in Discussions - Scopes / Whole setups

    Posted

    16 hours ago, bosun21 said:

    The OP jonbossley is a visual observer as per his first light report. He returned the scope due to image shift at high magnification. This apparently can be rectified by adjustment screws on the focuser, although this shouldn't need to be done with a new scope.

    Sorry, you did say you were considering the 140mm and my response was for the 120mm !

    • Like 1
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.