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About MarkS

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    Melbourne, Australia

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  1. The ASA10N/3"Wynne does not vignette noticeably with a KAF8300 size sensor. I see no vignetting with a similar set-up, but I use 36mm filters. The adapter is 42mm i.d. When checking for ray path obstructions remember that the rays are converging. I suspect the filters may be too small. Mark
  2. Hi Nick, You have opened a thorny subject! Newtonian type astrographs are very difficult to collimate AND achieve coplanarity on the image plane and the sensor plane. All collimation tutorials that I've seen achieve collimation of the central ray, which is generally fine for observing, but the problem is that there are any number of configurations that will give central ray collimation, BUT ONLY ONE that results in coplanarity of image and sensor planes. The faster the optics the more critical the problem is because the focus depth becomes extremely shallow. In your case it is about as critical as it gets! I have checked this by obtaining "perfect" axial collimation on my ASA10N for a range of secondary axial positions encompassing several millimetres. Many of these alignments yield disastrously misshapen stars in the image corners when using a 16200 class camera with an image diagonal of about 34mm. The ASA method does get to the correct distance, but I would recommend that you ensure you get the same positioning with the mirror turned 90degrees in BOTH directions. I found this tedious but doable. Note that when both the setting and the axial collimation are correct the image seen looking down the focuser barrel with Cat's Eye or similar tools will not exhibit concentricity. Again, the faster the optics, the more pronounced the effect is. I am assuming here that the ASA8H behaves similarly to the ASA10N. Hope this helps. Mark
  3. MarkS

    NGC 6744

    Thanks for the comment, Michael. Much appreciated. Mark
  4. Hi Michael, I think what you are referring to is the "confirm each exposure" check box, which you will find in the Autopoint screen in the "Basic Pointingfile Settings" area. Cheers, Mark
  5. MarkS

    NGC 6744

    The southern galaxy NGC6744 lies about 30Mly away in Pavo. It is thought to be quite similar to our Milky Way, but is around twice the diameter at 200kly. It also has an associated dwarf not unlike the Magellanic Clouds. This LRGB image was shot over 3 nights using a custom Officina RiDK 300, Moravian G4-9000, and DDM85A. Processed in Pixinsight and Photoshop.
  6. Hi Andrzej I like this one! Great detail and colour intensity. Mark
  7. Why do you want to run AF with these filters? I have never tried to do this, but your problem is perhaps that there is not enough signal in SII and OIII bands of many stars. The usual procedure if your filters are not parfocal is to set focus very accurately (AF or manual) on L or R as a reference and then determine the focus offsets for the other filters. This can be done with careful AF or manual focusing on a suitable star field. There is provision in Sequence to record the offsets, which are then applied automatically to to the focus setting for each subframe. Hope this helps. Mark
  8. '3560 image stars and 2860 plate stars' look way too many. Try limiting the magnitude ranges for plate solving to reduce these numbers. Refer to Sequence 200 Manual: 2.Settings Plate Solve. Mark
  9. I hesitate to ask the obvious question, but here goes anyway: Was the the sky clear? Deneb is pretty bright, but if there is high cloud you may not get enough stars for synch. What does the Sequence panel say about the Synch failure? How many stars were found and how many catalog stars were there? Mark
  10. Robert, Impossible to tell. But the easiest thing to do is try another cable or two before anything else! Mark
  11. USB 3 cables are not better than USB 2 cables in a USB 2 system - which the DDM 85 is. You are better off with the highest quality USB 2 cables you can find. USB 3 cables have separate wires for USB 3 and USB 2 connections. Mark
  12. Colin, Your experience with the OSC camera is potentially very useful to others. I hope you are going to report back when you've completed a real life run! Mark
  13. Dave, Your Exposure file and .trg are line for line identical to any of mine, with one exception which I think is immaterial, viz: I do not bother to name my trg files except when saving them, so the name fields are null. I cannot see that making any difference whatever. I guess the conclusion I would draw from this is that there may be something buried deep in the Sequence.ini file (to be found in Program Data). If you can post it, I'm happy to do a line for line check..... Mark
  14. Dave, Have you ticked the ' Dont use Readout Modes ' box? If not, do it and see what happens..... Mark
  15. Dave, Why do you have MaximDL doing the image saving? It may be irrelevant, but that IS a difference from what works for me. I have Sequence doing the saving - how to is in the Sequence 200 documentation. That way MaximDL is out of proceedings,except for its exposure and filter wheel drivers. Just a thought! Mark
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