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I see ZWO has a set of inexpensive RGB filters for their own camera that they say is matched to the performance of the sensor. Has anyone tried them? ZWO states: " The new ZWO RBGL Filters have been fully optimized for the ASI 1600 Sensor, greatly aiding them in producing extremely accurate color images. This is achieved both through exceptional quality overall, and a design intended to approximately equalize the flux present in the ASI 1600 sensor. The new ZWO RBGL Filters also boast a small spectral “gap” to minimize effect of light pollution, precision off-band blocking, multi-layers anti-reflection coating, and a transmission above 92% at passband. " David |
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I bought this filters with my ASI1600 but I don't have to much experience with others. (could you check my LRGB images) I used to take some daylight pictures with great results using the same exposure and focus in all of them. At the end I substitute the L filter for a CLS filter due my problems with the light contamination. Jose |
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| I own them (i bought the bundle), however I'll say I haven't used them much. I lived in a Bortle 6 in an apartment complex, so I deal with quite a bit of light pollution so I typically just image narrowband. For the time I used them, they are pretty good. They are mostly parfocal and require just a teeny bit of adjustment between filters. |
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I still use the original ZWO set which are even half the price of the 1600-matched set. They seem to work, but are far from parfocal and balanced. You can can look through my images, but I suspect that filter set would do just fine. It's still not a "premium" set. |
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I find the optimized filters to be nicely 1:1:1. I will mention that they are not parfocal, so you will need to adjust focus at filter change. I have ordered a set of Astrodon I series filters to compare, and expect that I will end up selling the ZWO filters. For the price however the ZWO filters are a good deal. I use and IDAS LPS D1 in place of the L filter. |
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Hi David, have a ASI178MCC and am having difficulty with amp glow in the pictures how can you fix this? Dark image prints are taken and superimposed with DSS, but I still present in the images, the amplifier glow, what's not here right? Is possibly the camera broken? CS Toni |
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Anton: Toni, A little off topic but I think you are having problems with your dark frame calibration. Dark calibration should remove the ampglow. I have two ZWO ASI cameras and both exhibit ampglow with long exposure. Dark calibration removes it. I don't know about DSS, as I use Pixinsight, but there might be a setting in DSS that is incorrect. Alternatively your dark frames might not match up perfectly. How old are your master dark files? Sometimes you need to update them. Be sure that your dark frames match EXACTLY your light frame exposure parameters. (Exposure length, Temperature, Gain, Offset, etc...). Ampglow compounds with exposure length. Also, if you are using flat frames for calibration, be sure that you are taking short enough flat exposures so that you do not introduce ampglow at this step, or if you are taking very long exposure flat frames, make sure you take dark frames to dark calibrate your flats. |
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| Also, ensure that dark frame optimization IS NOT enabled. It does not handle amp glow very well at all. |
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All, Thanks for your perspectives. Do people find the 1.25"filter diameter to be adequate? David |
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| As long as you mount your camera directly to the filter wheel vignetting is not that bad. I image at f2.8 and f4, and don't find it objectionable. flat calibration or even DBE in pixinsight removes it. Plus, NB filters are much less expensive in smaller sizes and odds are you will lose an area around the edge of the frame anyway due to dithering. |
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Hi Chris, in fact, the darks are coordinated with the Light yet I have in the corners on the bottom left and right down light points, but the worst thing is that with proper radiation through that whole picture and can not be the can right above this are the darks ? This must have another cause, but which I can not imagining, perhaps it lies at the Auslesemodos here the chip is too hot? CS Toni  |
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Anton: Have you tried any other stacking programs? Such as Pixinsight? I am not familiar with DSS. You could always email Sam at ZWO and ask him. He may be able to help diagnose your problem. ZWO is very helpful and responsive. |
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Hi David, yes I have already contacted the company ZWO in China if the SAm was I do not know, but the support was the e-mail, to this day no answer, them I have also described the problem! will sit down again with our German dealer and some air out, but thanks for your info was but a help. CS Toni |
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I have the ASI178MC-Cool and the amp glow is ever present. I take darks for every session. The only reason is because I find the amp glow a bit different from a session to another. This has helped me together with Pixinsight processes eliminate the glow in my final images. You have to take darks when you are not imaging and maybe create a library at various set points. This and update them more often if you feel they are very variable in your camera. DSS is a god stacking software but I would only use it if I want to get a feel for the data. I perfer pixinsight. There are other options of course. Hope this helps. Faris |
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I have the ASI178MC-Cool and the amp glow is ever present. I take darks for every session. The only reason is because I find the amp glow a bit different from a session to another. This has helped me together with Pixinsight processes eliminate the glow in my final images. You have to take darks when you are not imaging and maybe create a library at various set points. This and update them more often if you feel they are very variable in your camera. DSS is a god stacking software but I would only use it if I want to get a feel for the data. I perfer pixinsight. There are other options of course. Hope this helps. Faris |
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Hi Faris, will try it with pixinsight the next time! Many is this program more suitable for the ASI camera, than the Deepsky stacker program? CS Toni |
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Faris Al Said, I use DSS with an OpticStar DS-142C camera which has a lot of amp glow, but I'm able to keep the problem under acceptable control. What has not been mentioned in any of the above posts is the need to have at least 30 subframes for all lights and controls subframes for cameras with more defects (i.e. low grade sensors). The technical reason for this is the statistical distribution for averaged subframes is binomial, however, binomial distributions can have large variations for small numbers of samples (i.e. subframes). The more samples taken the more the binomial distribution looks like a Gaussian distribution. The rule of thumb in statistics is you can get a reasonably accurate reading with an average of at least 30 to 40 samples, thus the 30 subframe minimum rule. To match the fixed noise profile between lights and darks, both sets must have near Gaussian distributions, and therefore both lights and controls need lots of subframes. Above 30 the distribution differences will usually be less of an issue, so having more light subframes than dark subframes is not an issue. If you are using flats, then you need either flat darks or bias frames. The reason is fixed pattern noise is present in all subframes and using flats without controls for the flats will reintroduce the fixed pattern noise back into the lights. There are two kinds of fixed pattern (non-random) noise. One is caused by read noise, and the other is caused by dark current noise. If your flats have exposures of less than 1 or 2 seconds then read noise predominates, you can ignore the dark current noise, and use bias frames. Bias frames have exposure times of less than a second, and do not need to be taken at the same temperature as the frames they are controlling. If you have longer exposure flat frames you will need to compensate for dark current noise in the flats and use flat darks. Flat darks are darks taken at the same temperature and exposure time as the flats. Use either flat dark or bias controls but not both. The same sample rules apply here, you need at least 30 each flats, flat darks, and/or bias frames. One other thing is controls must be taken with the same gain as the lights or flats they are controlling. Given the proliferation of combinations, it is best to try to standardize your exposure times, gain levels, and temperatures that you are using to be able to share the controls among a number of sessions. At the normal rate of sensor degradation controls typically should be able to work for about a year. However, the more fussy you are, the tighter the deviation between lights and controls you will accept, and the shorter the useful life of the controls. Median stacking is better for controls especially when you have less than 30 subframes. However, median stacking does throwaway data, so if you have 30 or more subframes, then one of the averaging methods gives finer control for smaller details. |
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| I forgot to mention that Pixinsight has a feature for modeling controls that interpolates between different sets of controls to estimate what the controls might be at different temperatures, gain levels, and exposure times. Using this feature frees you from needing standardized operating procedures. Deep Sky Stacker does not have this feature. |
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Gilbert Ikezaki: all, I hope you all realize that my original question about filters and the responses got buried by this completely off topic stuff about DSS, stacking, amp glow, PI, etc. It discourages people like me from posting here and it makes people not read the thread that might be seeking similar information. David |
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David Goldstein:Gilbert Ikezaki:all, I agree 110% |
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I am using the LRGB Filter by ZWO for the Asi 1600mmc. Since I am using the 1,25 size in the Zwo filter wheel with an f4 Newton, I am experiencing a little bit of vignetting. The RGB Filters are almost parfocal, the L filter needs a small correction to be sharp. I am still making tests using the above filters in combination with an Idas lps d1 filter to fight light pollution. cs Christoph |
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| I also use the newer ZWO LRGB filters. They are not precisely parfocal, but I think I need to adjust focus every few hours anyway, so it is not a burden to refocus when changing filters during a session. |
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David Goldstein: David, knowing several people who use the ZWO filters, they do seem to be well matched for the performance and Q.E. curve of the ASI1600 sensor. They are a pretty good deal for the price. The only real potential issue I've heard about them is that they are not as parfocal as they could be. I think it depends on the scope and how thin your depth of focus really is, whether it matters or not. Some users don't seem to have much of a problem with it, and others have had more of a problem with it. I honestly don't know for sure exactly how they compare to Baader or Astronomik LRGB set parfocality, which I also know are not perfectly parfocal. I use AstroDon filters myself, which are very parfocal, and I never have to refocus when switching filters. However, I also spent a premium on all my filters. ;P |
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| Does anyone have experience with the ZWO narrowband filters? High Point Scientific has a bundle package that includes the 1600MM, the EFW8, and the LRGB, Ha, OIII, and SII filters. It costs a fair bit less than what the camera & FW would cost with Baader's LRGB+Narrowband filter set, plus the NB filters from ZWO have a bit lower bandwidth than the Baader OIII and SII. I just wonder if there is a difference in quality. |
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| I have the ZWO LRGB+narrowband 31 mm set from High Point. So far of the narrowband filters I have only used the Hα, but it seems quite comparable in performance to the Baader 7 nm Hα (which I have used for several years). I've used it with my f/4 Newtonian (with a coma corrector, so actually a little slower than f/4) and with a camera lens at f/2.8, and it does vignette significantly with both setups; for some reason, vignetting is much worse with the narrowband filters than with the LRGB filters, which vignette only slightly. I intend to try some SHO imaging in the near future but will have to wait until the weather cooperates! |
