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Old 01-02-2014, 03:35 PM
aljo2345
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Am i wasting my time with an off-axis guider

On looking at all the amazing imaging and associated post on this forum, I was wondering whether i was waisting my time using an off axis guider for tracking purposes while taking pics; rather than using a guide scope. Does anyone use an off axis guider anymore? I understand that using a guide scope in conjunction with an auto guider is ultimatly easier an the back and neck. But with the effort, can eventually expect to get similar results guiding manually?

anyone??
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Old 01-02-2014, 04:29 PM
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Merlin66 (Ken)
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Reading the message my understanding is you want to guide manually with a Mk1 eyeball.
Using an off axis guider on longer focal lengths i.e. SCT's etc will give the best results - every time.

In the bad ol' days we used manual guiding all the time and with some success. The real problem is being able to magnify the guide star in a cross wire eyepiece such that you can see the corrections needed and click the controller to make them happen.
Our rule of thumb was we had to guide at x3 the focal length of the scope!! This usually meant adding a x3 barlow lens to the guide tube. You used to be able to buy a x3 barlow fitted in a diagonal especially for manual guiding. Lumicon used to sell them.

Having said all that, IMHO the way to go nowadays is with an off-axis guider and a small (QHY5) guide camera - much easier!!
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Old 01-02-2014, 04:39 PM
aljo2345
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ok Merlin66 i see, i have been using an LX90 8inch, with DSLR, guided manually with reticle (no barlow), I have a x2, would that be that insufficent? I understand that reticle eyepiece is 6mm.

Thanks Alex
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Old 01-02-2014, 04:51 PM
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Our cross wire eyepieces used to be around 10-12mm fl, so what you have sounds OK.
Keeping the guide star in the corner - half hidden by the wires was the technique used.....
This could/ would give 20 to 40 micron star images on hypered 2415 film.
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Old 01-02-2014, 05:07 PM
aljo2345
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Thanks, will have another go with the barlow this time.

best

Alex
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Old 01-02-2014, 06:59 PM
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I have been using an OAG for 4 or so years now and would never go back to flexure and out of round stars. Stick with the OAG. Even with wide field this is superior guiding.
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Old 01-02-2014, 07:08 PM
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Best way to manually guide is to defocus the guide star such that it's a small soft disk. An out of focus star is easier to center in the cross-hairs and you won't lose it behind the wire.
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Old 01-02-2014, 09:03 PM
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Quote:
Originally Posted by aljo2345 View Post
On looking at all the amazing imaging and associated post on this forum, I was wondering whether i was waisting my time using an off axis guider for tracking purposes while taking pics; rather than using a guide scope. Does anyone use an off axis guider anymore? I understand that using a guide scope in conjunction with an auto guider is ultimatly easier an the back and neck. But with the effort, can eventually expect to get similar results guiding manually?

anyone??
I missed the manual guiding bit. Hmmm been there and done that a long time ago. Why do you want to manual guide? Why not put a camera in the OAG and guide with PHD or similar programme? Even still the OAG guiding manually will be better than with a guide scope. Although the guide scope will have brighter stars.
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Old 02-02-2014, 11:01 AM
aljo2345
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Quote:
Originally Posted by Paul Haese View Post
I missed the manual guiding bit. Hmmm been there and done that a long time ago. Why do you want to manual guide? Why not put a camera in the OAG and guide with PHD or similar programme? Even still the OAG guiding manually will be better than with a guide scope. Although the guide scope will have brighter stars.

Hi Paul, thanks for your response! for me it is really an issue the cost and ease of set up. If i can avoid using additional equipment and get the results, as demonstrated in this forum, harder though it may be, i was thinking that might be the way to go. I do have an LPI which i am told can be used as a auto guider, average though it is and an Ebook I can use to run the software, though i have yet to try it. Wishing i had an observatory so i could set things up and not have to pull it all down at the end of each session.


Alex
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Old 02-02-2014, 11:11 AM
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Alex,
Caution,
The older LPI has no direct ST-4 port to allow you to connect to and control the mount.
You'll need an "adaptor" between the laptop and the mount - The Shoestring GPusb works well.
http://www.store.shoestringastronomy.com/gpusb.htm
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Old 02-02-2014, 01:19 PM
aljo2345
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Quote:
Originally Posted by Merlin66 View Post
Alex,
Caution,
The older LPI has no direct ST-4 port to allow you to connect to and control the mount.
You'll need an "adaptor" between the laptop and the mount - The Shoestring GPusb works well.
http://www.store.shoestringastronomy.com/gpusb.htm
Thanks for the warning! Does this adapter go between the PC and hand set?
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Old 02-02-2014, 01:32 PM
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Merlin66 (Ken)
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Hmmm
Which mount are you using??
There's usually an ST-4 guide port on the mount to accept the guide signals...the GPUSB would then go between the PC and the ST-4 port on the mount.
Your camera, connected to the PC and using say PHD2 guide software would generate the necessary guide signal.
HTH
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Old 02-02-2014, 02:27 PM
aljo2345
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Hi Ken, I am using a Meade LX90, fork mounted on wedge?
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Old 02-02-2014, 02:55 PM
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Bumma!
As far as I know there's no guide port on that scope to plug into!!
You need a small "module" - not sure of the number #909 ??? with the additional ports - unfortunately I believe they are no longer available.
Found this:
http://www.meade4m.com/index.php?/to...iding-problem/
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Old 02-02-2014, 04:45 PM
jamiep (Jamie)
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yep - but you can get these - the 909 APM clone ...

http://www.astrogene1000.com/product..._909_clone.htm

they'll allow an LX90 with a 497 handset to accept ST4 signals.
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Old 03-02-2014, 03:10 PM
aljo2345
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Cool thanks Jamie!
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Old 03-02-2014, 03:10 PM
aljo2345
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...and to you Ken!
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Old 03-02-2014, 03:25 PM
aljo2345
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LPI as auto-guider

Quote:
Originally Posted by Merlin66 View Post
Bumma!
As far as I know there's no guide port on that scope to plug into!!
You need a small "module" - not sure of the number #909 ??? with the additional ports - unfortunately I believe they are no longer available.
Found this:
http://www.meade4m.com/index.php?/to...iding-problem/

Found this, looks pretty straight forward with the existing LPI software:

LPI Auto-guider function, How to

For users familiar with the product, the LPI camera functions in a manner similar to the Meade Pictor 201XT CCD Autoguider.

An autoguider helps keep an object centered so that a 35mm camera can take long exposures of an image.
Note that you do not have to set the LPI camera for a long exposure using Exposure controls (2). Autoguiding is
used typically with telescope mounted in the equatorial mode, although it can also be used with LX200GPS
Telescope mounted in the alt/az mode.
To use the LPI camera as an autoguider, perform the following procedure. You will need an off-axis guider (see
the Meade General Catalog for more information) and the supplied serial cable that is appropriate for your
model telescope. You will also need to know the focal length of your telescope.
1. Attach the off-axis guider and your 35mm camera to your
telescope as described in that product’s instruction manual. Insert
and tighten the LPI imager into the eyepiece holder.
2. Go to the Object box and choose “Autoguide” from the list.
3. Attach one end of the serial cable to one of your PC’s comm ports and the
other end to the telescope’s RS-232 port.
4. Select the Comm port number from Comm Port box.
5. Click the Chk Scope button. If there is an error (cable, version, port, etc.), an error
message displays. Check to make sure your cable is properly attached, that you have the correct port
number selected and so forth. If the telescope connection is verified, you will receive a “passed” message.
6. In the Focal Length field, type in the focal length of your telescope.
7. Locate a star using your telescope’s alignment and Go To procedures. Focus and prepare the imager as
described earlier in this manual.
8. Draw a tracking box around the star.
9. Click the Start button.
10. When you click on the Start button, the program begins to calibrate. It then begins to autoguide your
telescope and displays X and Y error coordinates in the Status Display box (24).
11. Click the Abort button (the Start button renamed) when you are finished.
If you don’t move your telescope or rotate the guider assembly, you do not need to recalibrate. However, if you
wish to recalibrate, click on the Reset Cal button.
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