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rikyuu

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About rikyuu

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  1. oh how I wish I didn't put that little red line on the graph. It was just meant to be an indication. Really, I was just going to post the scan of the Skywatcher OIII characteristics as they aren't available on the net and I bought one, so I had the little paper thingy with a graph on it so thouhgt it might be useful to someone looking at these filters. After scanning it, I though it might be useful to newbies to add a little extra info so spent some time adding the graphs together for the other bits I have. Nothing scientific, I don't have a spectothingy or a QE calculator I'm afraid. I just did it in my lunch break and I found it a useful visualisaiton. Someone please delete my graph and post before I get calls from NASA!!
  2. Thanks for the feedback Merlin. I should have more specifically said 300d filter removed, rather than modified. I keep calling it modified as I modified it, but the standard convention is to call it filter removed. Just a little background into the 'filter removed' estimation I made: There's precious little information on this that I can find, most are fitted with the baader filter which cuts off cleanly at 700nm as you say. I just wanted to provide an indication of the continuation of the response of the camera into the IR region with the filter removed and estimated that as the red peak is so narrow compared to the blue and green responses, coupled with the standard filter which cuts off around 550nm sloping down to 700nm which roughly corresponds to the unmodified red response, that without the standard filter, the red response would continue broadly into the IR band up to 700nm, but maybe not as flat as I have shown in the gross estimation. In the absence of more accurate info, it's just an estimation of this. I've also presumed it still has some significant response in IR due to the need of a sharp IR cut filter at 700nm. I was considering the value of putting this line on there due to the lack of info, but thought it would still be a useful indication.
  3. had another look around, the only thing I could find was an adapter ring on Ebay which converts from 36mm to 49mm, but was over £40 incl delivery and might not work anyway. I think I can make something. I have the metal ring from a 2" filter, I reckon if I cut a 2" disc out of something thin to fit into this, which has a 36mm hole in it, then I can mount the 36mm IR pass filter into this. I have a small piece of Teflon sheet which (in the absence of anything else) might be the right thickness and easily cut. I guess even cardboard might do it, at least just to experiment. I don't know what images I will get with an IR pass filter, but it's just an attempt at something different.
  4. hi, I thought I'd combine the information I have on the characteristics of the 300d, Sky Watcher OIII filter and Astronomik CLS filter into one graph and include the light spectrum and main emission lines for information. I hope this is useful to someone. Cheers
  5. ps, I meant imaging with the scope of course, not just imaging the scope, which wouldn't be as interesting, although at least it would be possible, as imaging with the scope is not, due to cloud of course.
  6. hi, I've had an IR pass filter knocking around for a few years and thought it could be useful for a bit of experimentation with imaging the scope. However, it appears to have a 36mm thread and I can't find any suitable adapters. Does anyone know of any adapter that will convert it to 1.25", 2", SCT or 42mm so I can use it with the scope? Cheers
  7. in Feb 08 I bought a 10" dob and looked at Saturn. I thought it would make a good photo and snapped it afocally with a compact cam. It looked quite nice. Then I thought I want to photo nebulas and galaxies too. So I had to get a GOTO mount with 8" SCT coupled to a modified DSLR with a CLS filter, autoguided with a C80ED with a Mintron camera, all connected to a laptop along with dew heaters, timers, battery packs, mounting brackets, rings etc etc. That's how it happened, more or less.
  8. should have added that one night, after a selection of the above mishaps, when it didn't cloud over and I thought I'd get a good few hours of subs, the camera slipped out. Fortunately the very first sub was ok.
  9. a lovely target and very nicely captured. Lots of individual stars can be seen.
  10. yup, sounds like one of my typical evenings, although it usually clouds over once I'm finally ready to go....at least you got some images!
  11. well, it's not quite captured the same detail as this one.... APOD: 2009 September 15 - NGC 6888: The Crescent Nebula but it's a good attempt. Only joking , it is fantastic!
  12. Richie, that is stunning. Can I ask a favour....would you be able to post just the OIII image. I'm interested in trying this with my OIII filter and it would be useful to see what I should expect. Thanks
  13. I couldn't find its characteristics on the net, but I received it yesterday from FLO (very quick as usual) and it has a photocopy of its characteristics stuck on the back of the box. It's in Chinese, but easy to understand the graph. I'll scan it and post it here for information. From memory, I think it was a 10 or 20nm bandwidth, but I'll check. I guess the proof of the pudding will be in using it. So if it's ever clear again, I'll attempt the Dumbell and Ring nebulas, which I imaged before with the CLS filter, to see what the difference is. I'll keep the CLS clip filter in place as I don't want to remove it ......and start saving for a Ha filter!
  14. My understanding was that if the CLS CCD filter lets through 95% O3, Hb and Ha and blocks IR for example, then adding another filter which passes 95% of O3 only would result in about 90% of O3 only. Additionally, as the bandpass of the CLS filter is relatively wide around O3 (70nm), then the bandwidth of the O3 passed through both filters, would be limited by the Skywatcher O3 filter as it is more narrow. I realise there's no actual gain in keeping the CLS filter in place other than negating the risk of removing it, dropping it and dust getting on the sensor, but if the only loss is a few % of O3 then I thought it would be worth leaving it fitted.
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