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This will be a thread detailing some of the changes and additions I will be doing to my ASC/Weather Station project. This is version 2.0 as I'll be making some very big changes from the initial project and I think continuing on in the existing thread would not have made much sense.
So, I still want to use an APS size sensor as after seeing the quality and light capturing capabilities of the now defunct Opticstar DS-616C XL camera and Meike lens I simply cannot go back to using a smaller lens/sensor combination. One thing is certain, I won't be paying £400 or potentially more for another APS astro sized camera so with that in mind I plan on heavily modifying a Nikon D50 DLSR and use the same lens. I chose the D50 primarily due to it having a CCD sensor (ICX453AQ) very close in specs to the one in the Opticstar (ICX413AQ) and the fact that I got a hold of a fully working body for £25.
Now there's a few issues with going down the DSLR route which I plan on addressing as follows:
The oversized camera body can be stripped down to bare essentials and fitted in the existing case with some moving of parts around Uncooled, the sensor is quite noisy so to cool it I plan on using the existing Opticstar enclosure with the TEC and hopefully get it purged with Argon to avoid dew formation. Also, since the box will need to be completely sealed to achieve this, there's simply not enough room inside for the main board to which the sensor connects to. The only way around this is using an 39pin 150mm long FPC extension which I managed to find and will be arriving shortly. This means I can have the sensor completely sealed with enough slack in the connection to place the mainboard anywhere I want. The D50 uses the NEF file extension as a "RAW" file format but it's not truly RAW and a heavy median filter is applied to all long exposure images to smooth out the noise. It works great for day to day shots, but in an application such as mine it'll most probably eliminate or severely affect my stars as most of them at the FL I'll be using the camera at will be a few pixels across and the Nikon median filter is very aggressive with such small features. The way around this is what's commonly known as Mode 3 on Nikons. Nikons have a additional Noise Reduction mode which takes the long exposure light first then straight after an equal length dark with the shutter closed, then applies the dark on the light and you get a further noise reduced image which again works very well, but not so much for AP. With mode 3 you essentially have the NR feature on and take an exposure but then immediately shut down the camera after the light has finished exposing. What this does is it causes the camera to dump a REAL RAW image onto the SD card without applying the median filter OR the Noise Reduction process. This obviously results in a much noisier image as expected, but all the stars will still be there and the image in this way can then be dark-subtracted and processed to my liking. I'll post some test shots I've taken to illustrate this. The D50 uses a hybrid shutter, both the CCD electronic shutter and mechanical shutter are used depending I think on the exposure length. If a high enough exposure is used, from what I understand, one can use exclusively the electronic shutter, but for longer exposures the shutters work in conjunction. Now I know the ICX413AQ in the Opticstar is more than capable of taking long exposures solely with its electronic shutter despite the fact that in its datasheet they recommend a mechanical shutter for proper use. So, my thinking is since the D50's sensor is similar to the ICX413AQ the only thing preventing the camera from being able to take any exposure using exclusively the electronic shutter is that its mechanical shutter is in the way and I don't think that the camera would prevent the CCD electronic global shutter itself to still open and close when required. However, this is all a theory at the moment and the only way to confirm it is to test the camera with the sensor outside when the FPC cable arrives. More on this later... In terms of capture software available, the D50 is actually very poor and I could only get digiCamControl to see and control the camera via USB. But I won't be using this as when the camera is hooked up to the PC its SD card is identified as a storage drive and the camera can be used as it would normally with the images appearing on the drive after being written to the SD! Since I'm using my VB app to process the images I would just point the app to that folder and should work. That's all I can think of for now but if and when new ones come up I'll add them here.
Next I'll be describing some of the other changes planned.
So my birthday just past so money to splash on astro stuff , i will have my 1000D modded by juan at cheapastrophotography and also have ordered an autofocuser from deepsky dad https://deepskydad.com/autofocuser i know they can be done DIY but this is a neat package and costs about the same as a SW autofocuser and a hitechastro focusmaster and i`m no electronic wizard and pavel seems to have a good product and works with ascom and confirmed it works with APT i will update in a few weeks time when hopefully i will have received and tried out .
I would like to share my design of a smart barn door tracker. It is a simple to build isosceles barn door tracker with tangent error correction through a Arduino micro-controller. I have shared all the details about the tracker including the mechanical design, electrical circuit and the software source code here:
If you are interested in the math and other details about a barn door tracker, more details are there in the blog. Also find an online calculator which helps in calculating various parameters while designing a barn door tracker. The blog is here:
M46 and M47 shot with this tracker.
135mm lens, ISO800, 15sec X 200 subs (50 minutes) exposure. Cannon 500D.
Comments and suggestions most welcome!
I've been working on a DIY fan for my 10" Skywatcher newt. My plan is to measure the ambient temperature and the mirror temperature with two separate thermistors and control the fan speed depending on the temperature difference.
My question is, does it make sense to use the fan if for some reason the ambient temperature is higher than the mirror? The fan is sucking the air out the tube at the moment.
I want to display FWHM values on a homemade focuser handset over USB from either BYN or Metaguide.
Does anyone know if these programs even output their data, and can it be obtained?
I have an arduino, and access to some good programmers thankfully.