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SteveP

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About SteveP

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  1. Chris Thanks for the clarification on dark flats. I now understand why you are calibrating with both flats and 'dark flats'. Unfortunately, that wouldn't explain why the image is being over calibrated Steve
  2. Now I'm confused! Chris - When you refer to 'dark flats', do you mean 'dark subtracted flats' ie you have taken a flat and from it deducted a dark to remove any dark current? This is what I had assumed you had done. If that is the case than deducting (strictly speaking dividing by) a flat and also a dark flat will result in over calibration Rob on the other hand uses the phrase 'flat dark' and I don't then disagree with anything he then says about using a flat dark. Can youjust clear up this point? Steve
  3. One simple way to check whether it is field rotation is to take a set of individual subs at different exposure times eg 1 min, 2 mins, 3 mins and see whether the trailing gets progressively worse Steve
  4. Chris I think you may have misunderstood something. A dark flat is not the same as a bias frame. A bias frame merely captures noise which is fixed and independent of exposure time. The reason why dark flats are used is to remove the bias component from a flat. In practice, they are not used very often. Also, you may need bias frames only if the darks have to be scaled. What software are you using to calibrate the images? THere may be something unusual in the way it sequences the processing Having your dewshield on the scope shouldn't impact on the quality of your flats. If the star trailing is independent of exposure time then you may need to look elsewhere. Something may well be moving in your imaging train. I'd start be checking all the connections especially any which have a compression fitting Steve
  5. I'm puzzled as to why you are applying both flats and dark flats. If you really are doing that then the flat is being applied twice which is why you appear to have an over calibrated image. My advice would be to re-process the image by calibrating with just flats and darks if the darks are at a similar temp to your lights. You also seem to have some field rotation as shown by the 'circular' star trailing towards the corners. Field curvature problems would typically give rise to radial star trailing HTH Steve
  6. Andy As others have said, SX's Star2000 uses one chip for both imaging and guiding. That approach is however no longer used. Have a look on the SX site for the appropriate software. I also see that you're using Maxim. I think Maxim can use Star2000 with the appropriate drivers. If you search on Star2000 on Maxim's Help, i'm sure you'll find something to set you in the right direction Steve
  7. Starjumper Which version of Maxim are you using? If it's a recent 5.XX, there is a useful recommended process workflow in the Help. Search for 'Recommended Processing Sequence' From memory, you can use the Stack command to do the Debayering and colour conversion to create the R, G, B images HTH Steve
  8. Alan Unfortunately it depends on the mount itself! Some store the PEC information whilst others have to have it replayed every time. I've no idea whether the CGEM does or doesn't. The best source of mount specific info is often the manual. Which PEC software have you used? If it's PemPro, have a look on the PemPro support site. Ray Gralak who wrote PemPro is always available and offers excellent advice Steve
  9. Harry Contact Brian Brooks at astroparts.co.uk He's made a few adapters for me for assembling CCDs, filter wheels, etc and he has always been reliable. His prices are reasonable given the custom nature of these things Steve
  10. Hi Paul I can't help you specifically with PHD but here's what I do using Maxim to both guide my mount and acquire the images 1. Link all the various bits together (mount, imaging camera, guide camera, focuser etc ) including having the guide camera connected to the mount's ST4 autoguiding port and the various connections made to the laptop 2 Polar align the mount. I use PemPro and try to get it to within 3-4 arcmins of the pole 3 Align the mount for accurate GoTo's - I happen to use Maxim's version of plate solving for this in conjunction with TheSky6 using the Sync command. Effectively it's a 3 star alignment but I tend to use 6-8 reference points 4 GoTo the object I intend to image 5 Start the autoguiding process within Maxim, ie find a guidestar, and then calibrate the mount. This important stage tells Maxim how to correct the mount as the signals from the guide camera are received. I expect there to be something very similar in PHD 6 Once the mount has been calibrated, start autoguiding on the guidestar and wait for it to stabilise 7 Start imaging I suspect that one area you'll need to look at in particular are the detailed PHD settings, eg aggresiveness or whatever PHD might call it, which is how you fine tune the software to your particular set-up. There are some examples on SGL of what others have used successfully in PHD. You might want to have a look at them I hope that this gives you some ideas about how I do it which you can read across to PHD Steve
  11. Paul What you've described is the process for aligning your scope for GoTo purposes. When autoguiding, this is still required in that it helps to find targets that much easier. However in addition, you also need to 'polar align' your mount as well, ie align the mount so that it is parallel with the earth's polar axis. There are several ways to do this including manual drift alignment or software controlled using a CCD or webcam. If you have a search on here, you'll find lots of advice on the different approaches for polar alignment. I'm not familiar with PHD so can't comment on whether it incorporates any polar alignment routines itself. HTH Steve
  12. Rob Does the H18 have a shutter? The reason I ask is that I recall somebody on another forum - it may have been CN or Yahoo - was describing a similar problem and that there was a build up of frost on the protective glass behind the shutter which left a residue as it defrosted. It could be a similar issue Steve
  13. Rob I suggest your problem lies with the master flat itself. If you look carefully, the flat contains a galaxy-like artefact at the bottom-middle which accords with a similar artefact on the light. After applying the flat, this artefact disappears in the calibrated frame as you'd expect. However, those weird raindrop type artefacts around the edge of the flat have just been reversed on the calibrated frame which suggests to me that these artefacts aren't a permanebt feature in the optical train. Have a look at all of the individual flats and see if there is anything strange on any of them Steve
  14. Welcome to SGL I'm a little confused by what you have shown in the photograph. I recognise ADM's Vixen style dovetail but I'm not sure about the other piece. Have you photographed the base of the scope's mounting rings? If so, both mounting rings are attached perpendicular to the dovetail. With both rings installed and bolted tightly through the dovetail, you should find that the stability improves. Unfortunately, this design of dovetail doesn't provide much of a platform on which to attach the mounting rings. What scope are you mounting and onto which mount? HTH Steve
  15. Ian It's good to hear of somebody thinking about the future use for their equipment. If you are serious about wanting to get into astophotography, then investing in the best mount you can afford is the way forward. An EQ6 Pro would be an excellent platform and you have to spend considerably more to improve on its capabilities. Whether you need GoTo is an important consideration. Without doubt you will need some way to target your imaging subjects. There are two ways to do this. Firstly, and easiest, via the mount's own GoTo facility. As you've realised, you'll pay extra for this with the EQ6. Secondly, by using EQAscom (sometimes known as EQMod) which is freeware and excellent! It's used widely with HEQ5 and EQ6 mounts. However, it would be best used in conjunction with planetarium software (some of which is freeware) and needs a small adapter and a couple of cables. It might cost you £70-80 for the extra bits. It also needs a laptop! So far as a scope is concerned, you'd do well to heed the advice above HTH Steve
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