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Hello, Quick'n sweet, is this contamination on the Nikon D5300 sensor or on scope lens? I can hardly confirm this pattern on either. I haven't used exp times over 30 sec before in that I only faintly noticed these dark patches until today trying 60 sec. Used 20 flat frames taken hours before when stacking, but they made things even worse while the pattern on this image differs from those flats taken hours before. We also have rapidly changing air humidity. Thanks a lot Robert  |
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hello, it might be some dust. As it is focused, I would say close to (on the window) or on the sensor. JF |
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I have same issue in one place and wet clean sensor, work great: Sigga Clean Sensor I do after careful read of this: Sensor Cleaning and Diagnosis Sigga |
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| I agree with Sigga. This is almost certainly dirt/dust on the sensor. The cleaning is not too difficult, but do be careful with the sensor and mirror. If in doubt get it cleaned by a professional. But make sure they do a good job. |
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| Hi. Take an exposure of the blue sky or a wall (out of focus) with another lens at the smallest possible aperture e.g. f/22 or f/36. Expose enough for the image not to be black. Around 3 secs should do it. If you see the patterns, it's the sensor. |
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Definitely seems like dust (the circles) and other debris like hair/fuzz (long ones), as the others have alluded to, although I'll admit that my dust/debris usually looks more donut-shaped (lighter in the middle) than disk shaped (even throughout) like yours. I happen to image with the same camera, but I've had that happen on any of my Nikons, especially after disconnecting something from the imaging train and opening it up to the surroundings. It's crazy how fast it can build up debris that you can't even see. If it's sitting on the sensor, the particles are almost invisibly small, but out of focus there, so they appear large in the images. Here's a recent light frame I took of IC342 that has one (I keep it very clean):  The best solution here is to get a filtered air squeezer (really cheap) and squirt/pump the air into your camera to remove the debris. Hold the camera with the opening facing down once disconnected, and even lock the mirror up for cleaning to get right to the sensor. Blast everything out, and see the results afterwards. If things change, your sensor is fine. If not, you could have a problem, although not likely. Note that material on the aperture of the telescope is very unlikely to be visible like this; it's way too far down the imaging train to come to a close focus at the sensor. Once cleaned, try not to disassemble the optical train as much as possible. I don't care how hard I try, something always ends up back in there without another cleaning. Finally, it's amazing how well flat frames will fix this, assuming nothing moves before taking them (dust has a tendency to shift, which can't be fixed), so take the flats right after imaging without moving the scope, and they'll pretty much vanish when you calibrate it, it's pretty surprising. |
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Hi AwesomeAstro, Wholeheartedly agreed. On top of this, I am living in a region with high humidity (throughout the year) which attaches dust to the sensor. I guess I did not remove all dust particles before wet cleaning with a mix of isopropyl and distilled water and possibly applied the wrong cotton as well as too much power. Beginners fate and own goal I'd say. You wrote you are using the same camera. Which exposure time did you use for the flats (assuming the same ISO as for the lights) when you saw that flats removed your artifacts pretty surprising? I tried with 1/4000th sec at ISO3200 with the D5300 on the scope (F6.3) but can't detect the pattern and positions of the scratches even after stretching the image. Perhaps Deepsky Stacker can do it with 20-30 flats anyway. To all who replied: Thanks so much friends, it was the sensor but not dust or so, I found scratches probably a result of my previous improper cleaning. The camera dealer assumed that Nikon would replace the sensor for 400-500USD. A used DSLR would be a better deal I guess. For the time being, this ends my DSO imaging fun for a while. At least scratches don't move like dust and you can take flats any time :-) Cheers Robert |
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A few points in response to your message: ~ I don't recommend ever wet-cleaning a DSLR sensor. You risk getting the electronics wet, but more importantly, this type of sensor doesn't seem to get things pasted onto it like a telescope aperture does (and I've only wet-cleaned by 8se's corrector plate 3 times in 3 years). Get a static-charged paint brush with soft bristles (search online), and simply gently drag it across the sensor to dislodge anything that's stuck. We're not scrubbing, but simply dragging, the brush. I've only done this twice in my life. No more pressure than a drag should ever be applied. ~ Yes, don't clean with anything, like cotton, that leaves pieces. You'll end up worse off from where you started. ~ Are you sure all of these were scratches? I'd be very surprised to see dot-like scratches. Perhaps the long, linear ones are, but I just can't picture scratching the sensor producing such small dots. You may have to wet clean it (with something softer) again if you've pasted on some material onto it. Get a super bright light and shine it right on the sensor to see if that's the case. I'm not convinced all of those artifacts are scratches. Definitely don't do away with your camera until you're sure. You still might be able to get away with using it; proper flat frames are likely to help even this. ~ Concerning flats, I'm somewhat nontraditional. I've tried it all, mind you, but I've found, consistently, that even though I image at ISO 200 (which you should be imaging at as well, with this camera), my flats work substantially better when done at the highest ISO possible, 25600. I've tried all types (TV, sky, etc.) with perfect methodology. This may not work for others, but with my setup it is substantially and certainly better to do this. For this reason, and because the brightness of your light source matters, I wouldn't recommend you concern yourself with the exposure time value. Ours will likely differ. Traditional wisdom is to set the ISO to match your lights (if your flats are biased calibrated, I have never heard a good justification for this), and the exposure to make the histogram peak right around the 50% mark. I use the highest ISO and peak the histogram around 95%. I deviate from the usual here, but it always helps my calibration substantially. ~ Some artifacts will be obvious to your eyes in the flats. Others won't. You should measure their success based on how they do in calibrating your lights after they're calibrated and stacked, not how the flats appear alone. You'll know after processing if the flats helped or not. |
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Hi AwesomeAstro, Thanks you sooo much for your time and views!!! Regarding scratch or not, I was wondering about the near "round scratches". Anyway, giving up is the last option, I will experiment with flat frames keeping all your good piece of advice in mind. Flats will also help reduce the effects of vignetting and dust on other surfaces in the optical train. Cheers Robert |
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| Sounds good! Be sure to keep the optical train closed once you've cleaned out the material, preferably using a filtered air bulb, to prevent what gets inside. Shoot me a private message if you have flat frame questions. |
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Hi Robert , This is dark and tight, it is dust on the sensor. I cleaned my sensor (full frame Canon 6D ) with the cleaning set from Rollei (bought from Germany I think?), nice brushes and liquid for sensor cleaning. A special LED lens can be useful to see the dust specks on the sensor. You have to sweep with a continuous motion from one lateral end to the other without pushing too hard. Works really well Cheers Bogdan |
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[quote="Bogdan Borz"]Hi Robert ,This is dark and tight, it is dust on the sensor. I cleaned my sensor (full frame Canon 6D ) with the cleaning set from Rollei (bought from Germany I think?), nice brushes and liquid for sensor cleaning. A special LED lens can be useful to see the dust specks on the sensor. You have to sweep with a continuous motion from one lateral end to the other without pushing too hard. Works really well Cheers Bogdan[/quoteand cleaning] Thanks so much Bogdan, Last weekend, I brought the D5300 to a camera dealer for inspection. The sensor is full of scratches in that cleaning won't help. My cleaning method was inappropriate, so I learned it the hard way. In future I will definitely consider a cleaning set like yours. Cheers Robert |
