Cooled CCD Recommendations?

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Scarodactyl
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Post by Scarodactyl »

Nikon has a 1x/16 TV projective eyepiece which is pretty inexpensive. A 16mm diameter circle covers a 1 inch sensor but nothing more.
Nikon does have reducing optics, but they would sit further up the light path than what you apparently have access to on the diaphot--they're 38mm accessories, which would slot in the same spot as a projective eyepiece holder.
Plus side, Nikon optics are non-compensating, so a third party eyepiece adapter is probably workable.

genera
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Post by genera »

dickb wrote:If I understand the manual correctly the M42x0.75 lens mount is a separate piece, and can be replaced by f.i. a C mount. Perhaps this user replaceable mount system is the reason for the back focus imprecision (listed as either 17-17.5mm or "about 18mm").
In the side view of the flange the only meaningful measurement is the one from the bottom to the surface 4.50mm above the bottom. The mating dovetail will be pulled against that surface. The length of the tapered section of the flange is meaningless as far as registration goes. It has to be high enough to engage the screws coming in from the sides and not so long that it interferes with anything above it.
-Gene

ldflan
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Post by ldflan »

Scarodactyl wrote:Nikon has a 1x/16 TV projective eyepiece which is pretty inexpensive. A 16mm diameter circle covers a 1 inch sensor but nothing more.
I have the Nikon 1x/16 TV relay lens in the cine port now, as well as a 2x and 2.5x on a shelf somewhere. One of those should do the trick, I figure. Since the .75x was designed to cover 2/3" diagonal CCD sensor, I assume the 1x relay will get awfully close to covering the micro 4/3 sensor.


I am going to pull the trigger on the QHY 163M, I believe. Any advice on separation filters? The filter wheel uses 36mm filters, unmounted.

Leonard

Lou Jost
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Post by Lou Jost »

I can't help you there. I've only used mine as a monochrome camera.

ldflan
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Post by ldflan »

I thought I would provide some details for future reference if someone else goes down this path or a similar one.

I've fitted a QHY 163M with their 7 filter wheel and mounted it to the Nikon Diaphot's side cine port. Some pointers on doing so:

1. Select The Filter Wheel Control Pathway. Before mounting the wheel on the camera, you need to decide whether you are going control the filter wheel through the camera using a four-pin connector, or from the computer using a USB cord. To eliminate a proliferation of cords, the four-pin setup is cleanest. However, if you want to do that you need to open the case and change a jumper or depress a select button to enable the four pin cord to control the wheel.

2. Adapt Filter Wheel to Lens Mounts (Canon or Nikon Adapter, followed by C-mount Adapter). The filter wheel mounts directly onto the camera with a dovetail and three set screws. After that you need a camera mount (Nikon and Canon models are available) that screws onto the filter wheel. I bought the QHY version from Agena Astro. After that you need a C-mount lens to Canon or Nikon body (depending on what mount you chose) adapter.

3. Attach to Nikon Y-T TV Adapter and Mount on Scope. To get the adapted camera (now a c-mount) on the Diaphot you need either a Nikon Y-T TV adapter or a third party model. I got one off eBay from a seller called Newhope for $66. A bit spendy, but better than a real Y-T adapter. It comes with a C-mount attached. Once the assembly is mated to the scope, the focal plane registration of all these parts appears about perfect.

4. Relay Lens Coverage of 4/3 Sensor. I am using a Nikon 1X TV relay lens for this setup. It covers about 75% of the 4/3 sensor. A 1.25 or 1.3X relay would be ideal. I ordered a Lomo 1.7x Homal for $30 just to see how it does. Russian optics are often (not always!) a very pleasant surprise for the price.

5. Camera Power and Data Considerations. The camera requires a 12V DC power supply. The camera power cord (for the Peltier cooler) has a cigarette lighter plug on the end, which is helpful I guess if you are out in the desert shooting stars. Just be aware that you will have to get 12V DC to it one way or the other. The other cord that comes with the camera is a high-quality USB cord. You will want your computer to have a USB-3 port.

6. Capture Software. The Sharpcap imaging software that QHY recommends is free and excellent, but the pay version has a functionality for taking dark frames of your sensor and subtracting them from the final image, which is extremely helpful in noise reduction. That and a few other nice functions are available for $15 per year. Astrophotography image capture software is generally quite complex and powerful. The learning curve for getting the filter wheel operational and capturing images on the QHY 163M in Sharpcap is a bit steep. Plan to spend some time reading the Sharpcap manual (if you use it), understanding the ASCOM drivers, searching for answers on why the filter wheel is not responding, etc.

A couple of other initial pointers on Sharpcap. Find the Python script for automating LRGB captures in Sharpcap and download it. Remember to set your Peltier cooler temperature -- the program will retain the setting next time you open it, but always check to be sure it's on and has reached the target temperature before you start imaging.

7. Registering and Merging LRGB Frames. Registration of images, if needed at all, can be done through your normal stacking software, or Deep Sky Stacker, which is free (but designed to identify and stack star images). Actual stacking and merger into a single color image can be done in Photoshop or ImageJ.

8. LRGB Filters. I purchased the bargain ZWO brand LRGB color filter set with the camera from Agena. The filters seem to be excellent, and were easy to install.

9. Empty Filter Slots. I am leaving the final three slots of the filter wheel empty, but have designated them in Sharpcap as "FITC" "TRITC" and "DAPI" so that the software identifies what fluorescence filter was used in making a given image. It should be simple to make a false color composite of images using these three fluorochromes and treating each image as one of three RGB channels.

Leonard

Lou Jost
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Post by Lou Jost »

Excellent information, and I am glad this solution has worked for you. One additional point to add to your list of things to be concerned about:

The cooling and warming of the sensor should NOT be done all at once at full power. The manufacturer warns that this could cause thermal shock damage to the sensor. Ramp it down to minimum temp in steps rather than all at once. Same when turning off the cooling.

Smokedaddy
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Post by Smokedaddy »

For whatever it's worth. Sometimes you can find a QHY-163M (and other models) used on the Astronomy forums such as Cloudynights.com and/or Astromart.com. I've seen a few go for as low as $750.00.

Bob-O-Rama
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How long an exposure are you having to use?

Post by Bob-O-Rama »

I was just wondering how long an exposure you can tolerate with this technique? If you are running into dark current shot noise, multiple shots can usually help with that. However if you do not have the luxury of longer integration times, that is a non-starter.

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