Hi all I have just received a Meade LPI and did some initial experiments last night and I was a bit unsure if what I was seeing was what I had aimed at which was the Pilaides forgive if I got name wrong. Have included a series of images done in the Meade AutoStar Suite with the standard settings the first one is done with the cap on and it shows dots of colour and the second is what I thought was pointed at Pilaides could someone please check them out and give me some advice
The darker image looks like it is not on target. What were the image times? Is this a single image or a combined image?
From my experience with an LPI, the image with the cap on shows what you get when it is not in focus.
Frank
The first image is with the cap on I wanted to see if it was dark nothing showing and the second image is probable out of focus but I thought that there were things that shouldn't be there that's why I did a shot with the cap on the second image is about 300 seconds. I used autostar suite and I think it stacked the images automatically. I may have misunderstood your answer so if I have please let me know and I will clarify my answer
Last edited by supernova1965; 17-01-2010 at 07:25 PM.
Reason: clarification
The LPI is mainly designed for imaging the moon and bright planets. The best way to start would be to point it at Jupiter or the moon or a really bright star and ensure you can get focus. If the first image is with the cap on then you have captured the hot pixels and noise. The second image is similar to what I get when it is not focused on an object. Envisage has an autostretch function that amplifies the noise if it can't find a bright object in the field.
The LPI is mainly designed for imaging the moon and bright planets. The best way to start would be to point it at Jupiter or the moon or a really bright star and ensure you can get focus. If the first image is with the cap on then you have captured the hot pixels and noise. The second image is similar to what I get when it is not focused on an object. Envisage has an autostretch function that amplifies the noise if it can't find a bright object in the field.
Peter
Right I tried to get Jupiter but I don't have a guided scope and it seemed to move very quickly and I didn't seem to have time to get it focused so I don't think I will be able to image it until I get a guided scope maybe when the moon is back I will have better luck
You should have received a parfocal ring with the LPI, this goes around the base of one of your 1.25" eyepieces to adjust the focus point of the eyepiece close to what your LPI would be, (this is usually with the eye piece pulled out about half way). You then clamp the parfocal ring and you can change between eyepiece and LPI with no focus change.
I found it best with about a 12-15mm eyepice, the LPI is usually approximated at a 9mm eyepice for FOV.
So
1) Put parfocal ring around 1.25"nose of eyepiece
2) slide eyepiece into focuser only about 1/2 way
3) clamp parfocal ring to hold eyepiece at the 1/2way insertion distance
4) adjust focus on bright object ie moon
5) swap to LPI, inserting LPI all the way into focuser
6) adjust focus to bring LPI to focus
7) remove LPI
8) replace eyepiece with parfocal ring attached, but dont adjust focus
9) adjust eyepiece insertion distance in focuser to bring eyepiece to correct focus by varying the parfocal ring
10) clamp parfocal ring at set distance from step 9
11) swap back and forth between eyepiece and LPI
12) enjoy.
Right I tried to get Jupiter but I don't have a guided scope and it seemed to move very quickly and I didn't seem to have time to get it focused so I don't think I will be able to image it until I get a guided scope maybe when the moon is back I will have better luck
Jupiter is going to be moving at pretty much the same rate as all the stars so without a scope that is tracking the object you are trying to image you are going to end up just getting a blur or noise. What type of scope/mount are you using?
You should have received a parfocal ring with the LPI, this goes around the base of one of your 1.25" eyepieces to adjust the focus point of the eyepiece close to what your LPI would be, (this is usually with the eye piece pulled out about half way). You then clamp the parfocal ring and you can change between eyepiece and LPI with no focus change.
I found it best with about a 12-15mm eyepice, the LPI is usually approximated at a 9mm eyepice for FOV.
So
1) Put parfocal ring around 1.25"nose of eyepiece
2) slide eyepiece into focuser only about 1/2 way
3) clamp parfocal ring to hold eyepiece at the 1/2way insertion distance
4) adjust focus on bright object ie moon
5) swap to LPI, inserting LPI all the way into focuser
6) adjust focus to bring LPI to focus
7) remove LPI
8) replace eyepiece with parfocal ring attached, but dont adjust focus
9) adjust eyepiece insertion distance in focuser to bring eyepiece to correct focus by varying the parfocal ring
10) clamp parfocal ring at set distance from step 9
11) swap back and forth between eyepiece and LPI
12) enjoy.
Right I will have to get a parfocal ring from elsewhere as this was a second hand LPI and it is missing. I tried again tonight and found that I can not get it to focus down enough to bring jupiter into focus I run out of downward movement I have had the same problem with all of the web cams I have tried to adapt as well so I am starting to think it is something to do with my scope it is a Newtonian on a Dobsonian mount but there is about half of my mirror when averaged with coating loss which I hope to get recoated when I can afford it could this cause my inability to focus enough.
Jupiter is going to be moving at pretty much the same rate as all the stars so without a scope that is tracking the object you are trying to image you are going to end up just getting a blur or noise. What type of scope/mount are you using?
I have a Starfinder 10" Newtonian on a Dob mount. Is it possible that without tracking I will be able to have better luck with the moon or should I put away the LPI until I have a tracking scope. As I said in previous post the Mirror does have coating loss which I will get recoated when I can afford it. I bought the Scope second hand for only $56 so I am not complaining so am getting value for money even with the damage.
The LPI FOV is near enough to the FOV of a 6.4mm plossl. So practice viewing through an eyepiece that size to get an idea of what you will be looking for.
The parfocal distance is close to a Meade plossl eyepiece 1/4" further out than the LPI.
Practice with a land based object to learn about focus and exposure.
If your scope does not track then it will be almost impossible to image even the moon unless you are experienced in hand tracking. The FOV from that scope will be such that the object will take only a couple of seconds to pass through the FOV.
The below Stellarium shots show the relative FOV of some objects with your set up
1. part of pleides 2. Jupiter 3. part of the moon
Barry
Last edited by Barrykgerdes; 18-01-2010 at 07:56 AM.
You should be able to image the moon, jupiter, saturn, and venus with what you have. You will need to position the scope so the object drifts across the FOV of the LPI. You then stack the individual images you have captured. I started out this way and could get about 10 seconds total exposure before having to reposition the scope.
You should be able to image the moon, jupiter, saturn, and venus with what you have. You will need to position the scope so the object drifts across the FOV of the LPI. You then stack the individual images you have captured. I started out this way and could get about 10 seconds total exposure before having to reposition the scope.
Thanks all
Peter what do you think about my running out of focal range inwards before I get things in focus I can focus them fine with an EP but with the LPI I just run out of range.
I managed to achieve focus with my neximage and the GSO 10" dob without any issues so I expect you should be ok with the LPI. I have changed focuser since I got the LPI and have also shortened my OTA for DSLR work so can't check. The best way to check is to find something really big and bright like the moon so it is easy to get the scope in the right position and then keep it there with one hand moving the scope while you focus with the other. It is possible you won't be able to rack the focuser in far enough then you will need to consider what you can change to help. Options include:
Make the 2"-1 1/4" adaptor as low profile as you can - I machined the flange on mine down to get the DSI to focus with a filter wheel.
Move the primary mirror forward (longer colimation bolts)
Reduce the length of the optical tube - last resort.
You can also use a 2x barlow to solve the inward focus problem however this will double your magnification and make the object transit your FOV in half the time so not so good for a Dob mount.
Make the 2"-1 1/4" adaptor as low profile as you can - I machined the flange on mine down to get the DSI to focus with a filter wheel.
Move the primary mirror forward (longer colimation bolts)
Peter
Thanks Peter for your reply do you know of a tutorial for these two options I think I will have to try one of them as I tried to focus on a Street light and couldn't even get a focus on it.
I'm not sure about a tutorial but here is what I did with the 2"-1 1/4" adaptor to make it fit further into the focuser. This will give you an extra 10mm of inward travel. The longer colimation bolts involves swapping them for longer bolts and longer springs. This will allow you to move the mirror forward - probably another 10mm. You just change over one at a time.
Could someone let me know what this parfocal ring looks like as I found what appears to be some sort of ring in one of my drawers. Warren received the LPI from me. I actually never used it, it was still in its original box. Attached is an image of this ring, it was in a baby plastic bag with another adapter, which I am sure is meant for the cabling that went with the LPI.
