The seeing will visit you sooner or later. Just follow the golden rule "Don't you ever let a chance go by" (sound like a good name for a song ). Get out there every chance you can. The seeing may look like garbage but you never know you might just get that 5 minutes of absolute perfection appear out of nowhere one night and all the effort will feel worth it.
Besides it can't hang around over Dennis and Rob forever. Have a look at the results they are putting out and have a look at the results I'm putting out (none) and I only live a hundred clicks away. It can't all be seeing. I found out last night that part of my problem was my collimation has been just a tad out, and that has been enough to make most of my captures pretty much a write off.
Plus there are some (not me ) who just seem to have that extra something that tells them quietly without them even knowing it "This is what I need to do to get this shot right". Sorta like a green thumb. Mike, bird, DP, Dennis and Rob are good examples, but not the only ones. You and me, mate are going to have to work a bit harder. We just have green thumbs in other areas. Doesn't mean we can't learn though.
If it's a collimation issue then I'm really buggered, because to my eye the out of focus star tests look spot on. Nice round concentric circles with a pin-point airy disc at the very centre using the 10mm and 5mm eyepieces
Looks about the same as the diffraction patterns in my well collimated newt.
If it's out by a fraction, and that's what you say makes all the difference, I'm not sure I can tweak it any finer??? I simply can't see where I can improve it or make it better, with the skills I have??
It would be great to hear from someone who had their SCT very close to perfectly collimated and then took it that one extra (quantum leap) step and got it "bang on".
How did you achieve/gauge it? What difference did it make to your scope's performance?
i obviously can't comment on your collimation as i haven't looked thru your scope, but your description sounds spot on.
i put it down to seeing. canberra, hobart and adelaide sound like hell holes of seeing. I think hills in adelaide and hobart play havoc with the air and temperature drops in canberra sound atrocious. Launceston also has these large drops, but the presence of the oceans helps to moderate temps and conditions
This is only a gut feel, but if you compare the seeing i have got to birds, I feel I have had better runs of weather than bird. Both of us are controlling our temps. I would also say I have got better seeing than everywhere apart from brisbane. Then again, i am out most nights to report on what the seeing was like.
I am uploading 500 frames from the 26th april to the ftp area. (should be finished soon)
They have been quality sorted by ppmcentre, but if you have broadband, download the rar file. it is 80mbyte. If not, i can send them on cd. Then load them into registax and watch the program flick each image up. The purpose of this is to get a feel for great seeing. Then ask yourself, have any of your vids stayed steady like one. IF yes, we then have to work on collimation or processing.
Have a go at processing these bmps to see what you can get out of them.
On SCP, peter posted an image of jupiter that i was able to extract quite a bit more detail out of.
A few thoughts anyway. It is frustrating, but i have a horrible feeling canberra is not "seeing friendly"
Ok these two images were taken about an 3/4 hour apart and if anything the seeing was worse for the second one as I was shooting over the roof of my house.
The collimation still wasn't spot on but the small tweak I did made a surprising amount of difference. Capture settings should have been the same and I've kept the processing the same. Maybe I'm wrong that it was seeing improving that made the difference, but looking on the laptop screen while taking this shot was what decided for me to pack it in as it didn't seem to be getting any better seeing wise.
is the thread to the new ftp are, you will need a password from mike to post there, otherwise, guys that post there just give a link to it like i have.
This is a crucial read re collimation I believe with examples
There is a bit of a story involved (as there usually is with me )
But I'll shorten it
I've been getting a fair bit of heavy "blue around the limb" over the past couple of weeks and I thought it was coming from my barlow (but the blue was always on only one side ). I assumed I must have knocked a lens out of alignment in the barlow or something. So I switched from negative projection using the barlow to positive projection using an eyepiece. Still not good but better, so I accepted that and moved on thinking I would get myself a powermate after this Jupiter apparition. (I had taken the diagonal out of the equation which could have been affecting things as well)
Now in the mean time I'd been noticing that while Dennis and Robert were getting what to me looked like fantastic seeing, me living only 100km away was getting crud all the time. This made doing an effective star test on collimation all but useless. Normally I collimate with a 6mm eyepiece, but I just couldn't get the stars to stop flaring out one side and put it down to seeing.
Well last night I gave it another go but I used the laptop and ToUcam with positive eyepiece projection instead of negative projection with the barlow. Spica looked like a mass of jelly in an earthquake, but I tried to see something. Nah, useless. Then I swung over to Beta Centaurus and noticed something. Even though it was jumping around all over the place I could definately identify flaring to one side (this was all done defocused). So I started to try to adjust the flaring out. It only took a couple of minor tweaks on one screw and the flaring seemed to centralize around the defocused star. Focusing on the star I could only make out minor differences. When I slewed back to Jupiter I noticed a considerable difference.
In the three images, the first darker sample is as bright as I could go with gain and gamma without the blue being unprocessoutable, so to speak. It was taken on the 27th of April. The second image is from the start of the night last night. I had collimated between the 27th and last night but obviously not well enough. The third image is from when I slewed back to Jupiter and noticed a difference from earlier in the night so I used the remaining "blue limb" and the flaring on one of the moons to guide me in a final small tweak.
It may not be the proper way to do it and is as rough as guts, but it sure as hell made me happier than the results I've been getting over the past few weeks.
Negative projection and postivie projection are just different ways of increasing the FL and there for the magnification of your imaging system.
The 4 main types of imaging. Afocal; Yep we've all been there and moved on quickly Prime focus; wacking the camera/toucam without their lenses, in where the eyepiece is supposed to go. Negative projection; using a 2x telecoverter with a camera or a barlow with a webcam. This effectively increases the focal length of your telescope by the multiplication factor of the converter/barlow, which I'm sure you already knew.
Positive eyepiece projection is a bit different. You place an eyepiece in a tube (I use a meade variable Tele-extender) and then attach your webcam to the other end of the tube. The tube then usually screws onto the scope. What happens then is that you get the normal view through the eyepiece but it is projected onto the toucam chip. To get a handle on the idea, get a torch and hold it about a foot from the wall. The wall represents the chip and the lense of the torch the lens of the eyepiece. Now move backwards. The image ie the circle of light gets bigger. The same thing happens by mounting the toucam away from the eyepiece. And the further away you get the chip the larger the image. With my variable extender and a 2000mm natural FL of my scope, if I get the toucam chip about 145 mm away from the eyepiece, this will give me an effective focal length of 12 500mm when using a 20mm eyepiece. With a 15mm eyepiece; 17 333mm FL, 5mm eyepiece; 56 000mm and with a 1mm eyepiece a whooping 288 000mm, as if that will ever be useful But effective FL of 5 000 mm to 10 000mm are definately useful to me.
If you can get hold of the book Astrophotography for the Amatuer by Michael Covington, he explains it really well.
[quote=matt]
Positive/negative.... I do not understand that at all.
But I'm definitely going to try and tweak my collimation using the webcam.
quote]
firstly paul, it makes sense what you are saying. Chris go collimates on the moons of jupiter to make sure he can get the sharpest image. Mind you, his seeing conditions are fantastic and obviously the c11 is easier to collimate whilst tracking a moon of jupiter than my dob with a dob driver.
secondly, i have heard guys say, do not collimate with the toucam and i was believing this, but, the blue limb issue is something i have noticed too.
If i am to view thru the eyepiece, then collimate to that, but if i am to image, then collimate to the toucam seems to make sense to me!!
Dave if you or I were imaging through a refractor I would have said it was chromatic aberation. But SCT and Newts shouldn't suffer from that. So my thinking was that if I was getting blue on a limb it either had to be in my barlow or something was acting as a diffraction crystal. The only thing I could think of was a miscollimation. I dont know if I was right , but the blue limb is largely gone now.
Matt if you are interested I have an excel spread sheet that I made up that does all the calculations for you.
![[1ponders]'s Avatar](../vbiis/customavatars/avatar45_9.gif){kind=avatar}
![[1ponders] is offline](/vbiis/images/statusicon/user_offline.gif)
). Get out there every chance you can. The seeing may look like garbage but you never know you might just get that 5 minutes of absolute perfection appear out of nowhere one night and all the effort will feel worth it.
Have a look at the results they are putting out and have a look at the results I'm putting out (none) and I only live a hundred clicks away. It can't all be seeing. I found out last night that part of my problem was my collimation has been just a tad out, and that has been enough to make most of my captures pretty much a write off.
) who just seem to have that extra something that tells them quietly without them even knowing it "This is what I need to do to get this shot right". Sorta like a green thumb. Mike, bird, DP, Dennis and Rob are good examples, but not the only ones. You and me, mate are going to have to work a bit harder. We just have green thumbs in other areas. Doesn't mean we can't learn though.
We must stick together.
..& console each other in rough times! >
<
But effective FL of 5 000 mm to 10 000mm are definately useful to me. 
