How do you clean your optics?

[JSeaman]

Lately I have an issue that I'm struggling with on my ED80, I have marks on my images. I have tried using soft cloths, water and lens cleaner on the front lenses but I'm not managing to shift it. As soon as I wipe it I can see smears start to appear that look a bit like greasy marks. It's almost as those the coating is coming away but as it dries they disappear.

I then take images and have this sort of effect (attached)

The sensor looks clean on the camera so I think it is the glass but I'm really struggling to address this, any thoughts welcomed

 

[RayD]

You probably wouldn't see issues like this with dirt on the objective.  This looks like something closer to the camera, such as a filter or field flattener.  It isn't likely to be the actual camera sensor, but if it has a glass cover (CCD) then it could also be this.

If you let us know what the imaging train is it may help a little to identify the issue.

[JSeaman]

Hi, it's a very simple one, objective then CCD. It's a QHY8L with no filters or field flatteners. I did check the glass cover last night and it was clear

 

Thanks for the feedback

 

James

[RayD]

2 minutes ago, JSeaman said:

Hi, it's a very simple one, objective then CCD. It's a QHY8L with no filters or field flatteners. I did check the glass cover last night and it was clear

 

Thanks for the feedback

 

James

I'd say this is very likely to be on the CCD glass, James.

Give it a good blow off with a puffer bulb first, then try giving it a little clean.

I'd recommend getting some of this from FLO, and using a very small amount applied to the microfibre cloth (not directly on the glass) use just the weight of the cloth to wipe over in single straight motions.  Turn the cloth with each wipe.  Always use a puffer ball thingy before wiping, and I generally give a last couple of puffs just as I'm about to screw the camera on.

Don't use normal tap or mineral water.

I really don't think this is on the objective.

[JSeaman]

OK thanks for your input, I'll give it a try tonight as it is due to be clear again Thursday evening - appreciate the help

[Tim]

For a blob that size, check the inside of the objective for a speck of dust, it wont be much.

There is a formula somewhere that will tell you exactly where in your train the dust lies, but it is too complicated for my llittle brain

[MarsG76]

I agree with the above statement of this must be closer to the sensor.... have a look at the glass that is near your sensor.. also make sure there is no dust on the sensor itself.

As far as cleaning optics, I blow any loose dust away with a blower, spray it with Isopropyl 100% alcohol, top to bottom quite aggressively... than wash it all away with distilled water and let it dry on its own.. this way I do not ever touch the mirror/glass and it dries streak free and clean.

 

[JSeaman]

Great thanks all, appreciate the help

[spaceman_spiff]

Apologies if off topic...

The best solution is to take regular Flat, dark and bias frames and calibrate your images. The flat frames will capture all the dark patches and allow you to correct them as you process your images. I only clean my optics once every 2 years or so.

Dan

[JSeaman]

Thanks Dan but sadly I need a bit more than that, it's blocking all the data and a massive splodge in the centre of the picture doesn't calibrate out very well!

 

[spaceman_spiff]

33 minutes ago, JSeaman said:

Thanks Dan but sadly I need a bit more than that, it's blocking all the data and a massive splodge in the centre of the picture doesn't calibrate out very well!

 

Shame, I guess there's a limit to what flat frames can achieve. I have a splodge in the centre-right of my light frames, the flat calibration does correct it but I have to be so careful when moving the telescope, any nudge to the camera and my flats will be useless!

One way to find out where the location of the dirt is to rotate the camera but not the telescope. If the dirt rotates with the frame then it's on the camera. If the frame rotates but the splodges stay still then...lens.

[JSeaman]

Indeed, on the plus side I may have just found a mark, waiting for the condensation to disappear so I can say for sure.

Thanks again for the input

[JSeaman]

It was indeed a mark next to the CCD, all sorted now and thanks for the suggetsions

[RayD]

Great stuff, glad it's sorted