Heating ring QHY8

[allan gould]

I purchased one of these heating rings from Theo (Gama electronics) with the view to overcome adding a 2" dew strip around the QHY8 to stop potential icing up from moisture in the camera.
I let the camera equilibrate overnight with the outside atmosphere and then started up the camera. As expected the chip iced over, but then the heat from the ring slowly kicked in so that 3 min later all ice had disappeared from the surface of the chip. Works extremely well and I recommend it to all QHY8 owners.
I still will use the drying silica gel but this is such a smooth attachment and Theo has added the wiring so it works perfectly that I cant see why everyone doesnt have one, especialy for those hot humid nights here in Brisbane.

[toryglen-boy]

sounds like just the thing mate, was it pricey?

;)

[allan gould]

$105 but worth in IMO due to convenience and functionality

[multiweb]

Watching this with interest but there are a couple of things I don't understand. :shrug:

Moisture is the key here. No water no icing as far as I can tell. Temperature is not an issue unless the glass gets cold enough to form dew but that's contact with the atmosphere outside the camera.

What do you mean? Isn't your camera sealed?

Ice over the sensor is water. If you heat up you get droplets on the sensor. As the ice melt. But the peltier cools the sensor, so you're heating the sensor in the front and cool it in the back? I'm really confused.

Do you feed it 12V? or does it piggy back on the QHY8 power supply/TEC power?

[allan gould]

Marc
To answer you questions.
Normally my camera is in atmosphere with moisture removed by silica gel. The camera is normally sealed, but to let moisture in I undid the small rubber plug on the side and let it equilibrate with the external atmosphere which will have moisture in it ie not dry. Then I switched on the camera and dew formed on chip and small amount on filter as the camera cooled. Then plugged in heating strip and you could see the ice disappearing from the chip face and filter and being trapped on the cold finger in the back.
The heating element goes in front of camera between the camera body and filter and is just insurance in case there is a little moisture that can condense on the filter or chip.
Simple and it works.
12 volts supplied from the QHY8 power supply by a line splitter that Theo supplies. Very neat.

[multiweb]

Sounds pretty cool indeed. So you in your test you ran the camera open to normal atmosphere with the TEC on and you didn't get icing once you had the heat ring switched on, correct? Does it screw on the camera face in place of the nose piece? It's hard to tell from the pic. Do you have another couple of shots with it fitted?

[allan gould]

Marc
Yes, camera was run with the plug out initially after letting moisture in overnight. Chip and filter definitely iced up as camera cooling started, switch on heater and it gradually goes. Presumably sublimated ice then trapped on cold finger at the back of camera.
Fitting as follows.
1. Unscrew whole of camera nosepiece (with filter)
2. Screw heater into face of camera body
3. Screw nosepiece back into face of heater, you then have a sealed unit again.

[multiweb]

So your nosepiece is higher and the spacing to the sensor changes. I'm thinking MPCC spacing. How thick is the heat ring? 7mm.

Had a chat to Theo. Mine's in the mail now :thumbsup:

[allan gould]

Marc, thats good. I hope you enjoy it as it seems a very good and well thought out add-on.
Apparently increases the front distance from the chip by 7mm

[leinad]

As someone looking at buying a QHY8 and trying to find as much information on it as possible...

Why would you allow outside air to enter the housing through the desiccant plug ? Isn't this the cause of your frosting, fogging issues?

You mentioned 3. that the camera is now sealed once ring is attached.
confused...

My understanding is that the housing should be completely sealed and purged of any air/moisture within.
So isn't the heater ring only a band-aid solution to the problem ?

Not a critical objection to the method, but a curious question of the processes.

[multiweb]

I had a chat with Theo and there is a circuit board on the ring that slightly heats up the air in front of the glass nosepiece to stop any fogging. This ring can be used anywhere in the imaging train. I my case as I don't use a glass nose piece it is likely I'll fit it right before the glass of my MPCC.

Of course you still need to seal your camera and use dessicant but I can see many applications for this ring as any glass surface exposed to the cold air inside the camera can potentally dew up.

[allan gould]

I think you should carefully read all the posts. I was TESTING out the efficiency of the heating ring. The only way to do that is to let ambient air with moisture into the camera. You do that by opening the side plug. Normally you open the side plug to expose it to silica gel to remove any moisture that has condensed on the cold finger in the camera or since its NOT completely air tight - has diffused into the camera body.
Make sense?

[leinad]

Thanks, yes.

[multiweb]

If it helps, in my experience icing on the sensor is due to water inside the camera. A good hair dryer and electrical tape to "seal" around the body takes care of that prior to using the camera. Dew on the nose piece is another beast though because the glass gets cold and it dews on the outside. So in this case I can see the benefit of this ring heating the air around the glass surface.