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Ken Mitchell

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About Ken Mitchell

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  1. Also noticed that yes, not sure what caused this, the only adjustment I made were the levels. Ken
  2. Right, I didn't take that into account. Made some new side by side comparison, only used the background slider to adjust the values. So when I measured the background brightness values were the same. Hope this is better. Value 4 and 5 Value 10 and 20 Value 20 and 30 Ken
  3. During my first narrowband imaging a couple weeks ago, I decided to do a short test with my modded d90 vs my unmodded dslr d610 and 7nm 2" Baader Ha filter. This is the gear used : -Camera: modded Nikon d90(1 filter), stock Nikon d610 -Optics: TS-Optics Photoline 72mm f/6 FPL53+TSflat72 -Mount: Skywatcher Star Adventurer -Guidescope: TS-Optics Optics 50 mm DeLuxe Mini -Guidecamera: ZWO ASI120MC-S -Filters: Baader 7nm 2" Ha -Software: Photoshop I decided to use exact the same settings on both cameras so not compensating for the light loss with the unmodded camera, exposure and iso were the same. Camera settings for both were: 180sec subs at iso1600 First the single subs: These are the raw images with a minor stretch to reveal details. No other editing was done. Stock Nikon d610 (ff) Modded Nikon d90 (aps-c) First observations: Yes it is possible to image with an unmodded dslr + Ha filter, there is actually some data even with such a low exposure for Ha! Noise is more visible with the d610. I believe this is because of the low SNR and with 4 or 5min exposure it would probably be a lot less. The amount of detail/data captured is perhaps one of the most obvious differences. Next stacking: I was only able to get 9 images with the d610 so it gave me a total of 27min. For the d90 I selected 9 random images to get the same total amount of exposure. In both stacks all the calibration files were added. The image was slightly stretched just as in the single subs, no other editing was done. Stock Nikon d610(ff) Modded Nikon d90 (aps-c) First observations: roughly the same as with the single subs. Noise is slightly improved for the unmodded stack with the use of calibration frames. Conclusions: The amount of data gathered with the unmodded dslr just can't match the modded dslr. The 27min unmodded stack is imo very similar to the 180sec single modded image in terms of data capturing. As I said before, yes it is possible imaging with an unmodded dslr+narrowband(ha) but is it worth it? Well that's up to you, personally if I wouldn't have a modded dslr I would rather use that imaging time to capture extra RGB data. As extra I made a separate stack of 28min(7x240sec) RGB data, without Ha filter, taken with the stock d610. Just a slight stretched, no other edits were made. and the colored version When time permits I want to do some more testing with this configuration, how long a single unmodded sub has to be to match a modded sub for example. I know it's not much but hopefully this can be of help to some. Thank you. Ken
  4. I tried your method but didn't get a good result. Probably did it wrong though. Could you help me with a link or tutorial for this method? Thanks Ken
  5. Yes indeed. I'll see if I can find some time this weekend or next week and will post it in a new topic (with pics). Ken
  6. Thanks for that. With my unmodded d610 I normally take 10 or 20 darks per session/night. I imagine that number applies for each session, no? I never really encountered any problems with noise before(with the d610). Most of my images have low to almost no noise in them. Most of them have an integration time of minimum 4 hrs, would that have something to do with it? On the bias frames, indeed I've read that what you say but from the beginning I started using all the calibration frames and still do with every image. Never really tried to stack without bias, could it give you bad or undesired results when using both? Ken
  7. Thank you! I will definitely remember that for the future. Take more calibration frames! The reason I asked if 'only stacking the subs' eliminate a certain amount of noise was when I shoot wide field milky way with landscape, I take multiple shots and later stack them in Photoshop with a median filter applied to reduce the noise. There is definitely a difference with the final image on the noise level and no calibration frames were added. Ken
  8. The focus difference is roughly 10mm. Without the filter focus is at +-55mm and with the filter is +-45mm. Indeed I'll have to make the step to start controlling the camera through the laptop( what bobro suggests) so I can platesolve directly on the laptop outside. Now I remove the sd card and load it on the desktop(inside) to platesolve. Laptop's card reader doesn't work as it should so it can be time consuming at moments. It seems APT has platesolving function right? Thanks a lot for commenting and helping, much appreciated! Ken
  9. I've tried different stacking modes but all are giving the same result on the noise. The reason I just took 10 darks was that I just had over 1hr data and thought that would be enough. In the future I will definitely take more darks. Is there a some sort of % between the subs and how much calibration frames needed? Should you take more(or less) darks for example when shooting 5 hours vs 1 hour? Does the stacking of subs remove some noise by itself? With the full frame camera I could not get more than 7min before any drift showed, most of my subs are 5 minutes at iso800. I haven't imaged much with the apsc sensor but 5 minutes exposures should be possible(hopefully). I'll also experiment with higher iso, although I'm not a fan of the iso performance on the d90 and not just in terms of noise but in terms of loss of detail. Yes indeed I used an intervalometer. Just had a quick look at 'Astro Photography Tool', interesting to say the least. It would be a nice upgrade to control exposure from the laptop! Yes it has and will help! Thanks so much for all the info! Ken
  10. One of my latest images with the Star Adventurer, the Blue Horsehead Nebula. Nikon d610 camera TS-Optics Photoline 72mm FPL53 APO with TS-flat72 Tracked with the Skywatcher Star Adventurer TS 50mm f3.6 guidescope connected on a zwo asi120mc-s Total exposure time: 7hrs 56min, iso800 f6 Stacked in DSS Processed in Photoshop
  11. Thanks Geordie! That sounds like a lot of work if I understand correct what you mean. Every sub push the Ra buttons wait a few seconds and take another sub? Do you know if the dither function in phd2 works together with the SA? I have no knowledge how dithering really works in terms of communication between software and mount/guiding camera. Never looked into it as I've never encountered this type of noise with the full frame camera. Ken
  12. As the title says I've finally, after owning a 7nm Baader Ha filter for more than a half year, did my first imaging session in Ha. My target was the Lagoon Nebula because the weekend before I captured 4.5 hours on it and wanted to see what difference it would make. It's also very bright so easy to locate and it helped my getting focus as well. Focus was kind of a challenge as I had to locate the nebula without the filter first ( the Star Adventurer has no GoTo), screw on the filter and take numerous amounts of test shots (max iso at 30sec) to finally get the focus right. Though I still think the focus was a bit off. For some reasons I had problems with the B-mask and focusing will have to do more tests in the future on this. That said and done I was ready to start clicking, used settings of iso 1600 and 180sec subs. This was what I saw on the back of the camera after 3 minutes. Pretty exited! Just the fact that I had something showing up amazed me. Decided to keep the exposure at 3minutes and planned on getting 1 hour of data at least before calling it a night. Quick info on the gear used here: -Camera: self modded Nikon d90(Ha data), Nikon d610(RGb data) -Optics: TS-Optics Photoline 72mm f/6 FPL53+TSflat72 -Mount: Skywatcher Star Adventurer -Guidescope: TS-Optics Optics 50 mm DeLuxe Mini -Guidecamera: ZWO ASI120MC-S -Filters: Baader 7nm 2" Ha Back on imaging. After 1hour and 18min I stopped the session, took 10 flats, 10 darks and 20 bias frames and called it a night. The day after loaded everything in DSS, imported the stack in Photoshop and did a little stretch on the red channel. This was the result (1hr 18min at iso 1600). First there is so so much more data than I'd captured the weekend before with my unmodded Nikon d610 and almost x4 as much integration. That was a real excitement! Second is a question(s), the diagonal pattern you see is this walking noise? Will dithering remove these lines? and is it even possible to dither with the SA? I've seen the dithering option in PHD2 but not sure if the combination with the Sa works. So I've left the noise ,to be hopefully resolved in the future, and tried to combine the Ha with the previous captured RGB. The RGB data ,as said before, was captured using a full frame Nikon d610. Aligning the two was kind of a challenge but eventually with all the twisting and turning managed to get it almost perfect. This is the fully processed image from ONLY the RGB data the week before. 4.5hrs of data with the unmodded d610. Combining the datasets I decided to re-edit the RGB set with just a curves and levels stretch and some minor tweaks in Adobe raw. Followed a simple tutorial of changing the red channel of the RGB set with the red channel of the Ha set and adding another Ha layer on top to use as a luminance layer. The result was a bit weird to be honest, green in the background and pretty ugly colors in the nebula. ( I didn't had the original to show so just now I made a quick alignment just to show more or less the results. Should it look like this? Hope to find out what caused this. Made some tweaks in the channel color mixer in Ps to get rid of the odd colors(in my eyes at least) and did more editing to get a final image. Besides some tweaks here and there I added an extra layer from the RGB set and used 'color' as blending mode. This is the result I came up with. Apart from perfect alignment of both data sets and maybe a better color balance I'd have to say the image itself looks a lot cleaner and more pleasant to the eye. Though it seems the image is not as sharp as just the RGB image, maybe that's because it has less stars and it only appears to be more fuzzy? Hope to get some input and cc on my workflow and/or the images to improve my results. Thank you, Ken Mitchell PS. For those interested I've also did some imaging with the unmodded d610 + Ha filter to show the differences and if it is worth it to use a Ha filter with an unmodded dslr. I'll see if I can make a separate thread for this.
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