Dew issue with brand new ZWO ASI071 MC Pro

alfredo beltran

Hi Sam

I’m having a dew issue with my brand new ZWO ASI071 MC Pro, purchased just in november 2018 from OPT in the Unitated States.

This is how a flat taken last night looks:

E9DDF211-6B9B-4191-8000-0D792B4488D0.jpeg

And the dew pattern is completely consistant with the dew formed on the sensor window (not the front glass):

74299CC6-098C-47D7-809F-56156EEBB9AC.jpeg

Obviously it’s very frustrating having this issue with a new camera which is designed to prevent this from happening. So, why is this happening? The anti dew option is enabled in the Ascom driver.

Should I proceed as stated in this ZWO document?

https://astronomy-imaging-camera.com/manuals/How%20to%20clean%20ASI%20camera%20and%20redry%20the%20desiccant.pdf

Thanks for your help.

Regards,

Alfredo

chad

Hi Alfredo,

For the current, I think it is yes. Please follow the Step 8 in the pdf to make a try.

After that, if it still does not work, please let us know.

Thanks

Chad

alfredo beltran

I had to do step 8 twice because first time I had the same dew forming on the sensor. On the second time I thought I had had success because no dew was forming.

I took some deep sky images two nights ago and no dew formed. So far, so good. BUT tonight I’m taking my flats at the very same sensor temperature as during the imaging session (-15C) and the same dew pattern appears again:

3B5001F3-D9F4-42CB-AD0A-227E5988750C.jpeg

And it also shows in the flat:

56907F6D-3908-4089-B7CD-D494BEFE8414.jpeg

This behavior is not fulfilling the expectations I had when I decided to buy the camera. It is supposed to work well out of the box.

Did I get a faulty unit?

Your help is much appreciated.

Alfredo

chad

Hi Alfredo，

Sorry for the problem.

Please try to cool down gradually. For example, if you want to set the temperature to -10 degrees and the ambient temperature is 20 degrees, set the target temperature to 10 degrees first, wait for the temperature reaches and becomes stable, then set the target temperature to 0 degrees, wait agian, after that, and set it to -10 degrees.

If it still does not work, please let me know. I will keep an eye on your problem.

Thanks

Chad

alfredo beltran

Chad

I have the camera set to cool down the sensor in 20 minutes from 20C sensor temperature to -15C in SGP. The delta of 35C is within the specification of the camera.

If you don’t mind, please ellaborate on what is the purpose of doing the procedure you’re suggesting, since it is not the procedure intended for the regular use of the camera.

Thanks for your help in advance, which is very appreciated.

Alfredo

chad

Hi Alfredo,

If you let it cooling it slowly, does it work?

I don't have the exact reason for it at the moment, because other customers' feedback is that they can do so. We guess that cooling fast, the sensor's temperature would be lower than elsewhere, making it easier to condense. But there is no more specific proof.

Thanks

Chad

alfredo beltran

Hi Chad

Thanks for your response.

I tried as you suggested, going from a sensor temperature of 22C to -15C in steps of a delta of 10C every 10 minutes (last step of course was of just -5C).

I did it both on a room temperature of around 20C and outside at a temperature of 11C.

No dew formed!!!

Question would be: which should be the duration to reach -15C from a sensor temperature about 20 or 22C?

Regards,

Alfredo

chad

Hi Alfredo，

Sorry, I'm not sure about that. You know, this slow cooling is still not a good solution for us.

Thanks

Chad

privateer

I've had a similar problem lately with my 071-Pro. Is stage cooling the key to not forming dew? I have had the camera for about about 1 1/2 years now. I've heard removing the tablets and microwaving them helps? How long do you microwave them for?

I noticed the power draw was 70%-95% to keep it at -15 with Outside air temp at 11C. Is the TEC robbing some of the current for Anti-Dew?

alfredo beltran

I did it for two minutes and it seemed to work well.

alfredo beltran

I'm sad to report that the dew issue appeared again tonight. Another wasted imaging night because of this very same issue.

I cannot understand how a brand new product can behave in such a way that the user cannot use it as intended. I'm clearly unsatisfied with a product that doesn't fulfill the specifications (anti-dew).

I'll ask the warranty from the dealer (OPT).

Regards,

Alfredo

stefanob60

Hi.

I too. I've writen "Strange grid on my new ASI071MC PRO's sensor".

I'm amazed.

IMHO, from a big growing brand as ZWO, for these problems in top gamma cameras the only possible serious approch should be to call back and rapair the brand new defective camera in warranty (or best, to replace with a well working one).

But the only classic support from ZWO is to suggest is to try a "do-it-yourself" solutions (hoping that it will work).

I hope this the approch will change. This isn't a good advertising, I think.

Stefano.

alfredo beltran

I agree.

This is no single case issue, but more a recurrent issue happening to a lot of users.

It should be fixed.

We need an answer from a ZWO representative

muratsana

I am having same issues with my brand new ASI 071 MC Pro.

I tried several methods including slow cooling to -15c in 20 to 30 minutes, changing dessicants with brand new spare ones, cooling and heating then cooling again... Nothing works. Serious dew pattern occurs on my sensor below 0c.

I am very unpleased with this camera because of this dew issue and gonna ask for replacement or refund if ZWO can't find a solution :(

alfredo beltran

For now, this is working for me:

1. I re dried the desiccant tablets with the microwave oven

2. Since then, I stored the camera on a hermetic jar with some small bags containing silica gel (see attached image).

ADEF2C8F-7A70-40E7-9349-82F6E36DBAC3.jpeg

The jar seems bigger than it is on the image. Take as reference the camera size.

This shouldn’t be necessary at all. But since it creates a dry environment for the camera, I haven’t had fogging issues since then. I only take the camera out of the jar when I’m going to use it. Let’s hope this keeps ...

glutch

I too am having dew issues with my ASI071MC Pro. I seem to have to dry the dessicant tabs every 4 months since getting it. I have done all the suggestions in the forums with no resolution. What is the resolution?

huubke

I bought a new ASI071 and yesterday was my first night out. I cooled slowly until - 5°C and saw this morning that all my images have some halo's around the stars. So, Also in the newest batch of camera's this problems keeps appearing :

alfredo beltran

Well, a few months ago I received from ZWO the thermal pad of the camera, which seems to be the of dew formation, to be replaced.

According to ZWO dew formation happens because in some cameras the thermal pad allows to cool to quick, making it prone to dew formation if the environment has high humidity.

Replacing it was an easy operation following the procedure suggested and seems to have fixed the issue.

Regards,

Alfredo

huubke

What is that thermal pad?

alfredo beltran

It’s a synthetic device that sits between the sensor and the cooling system. It doesn’t have any electronic connections, is just a heat transfer element.