Help I've got black dots in front of my eyes.

[steelfixer]

Hi all.

I have a good one for you to help solve.

I have noticed lately that when using my SPC 900 and the 5X Antares barlow I am getting black spots on the image.

These are getting worse and worse.

If I move the image out of focus these spots appear to be water mark type things. (dried up water droplets)

I have stripped the barlow and cleaned it to no avail.

I then removed the IR filter but the spots remained.

I then cleaned the chip on the camera with an air puffer but they still remain.

The final attempt to rid me of these pesky spots was to remove the secondary mirror and clean that.

On refitting and recollomating the spots were still there.

Is it possible that these water type spots are on the primary mirror?

Any one with any ideas please help it is driving me to distraction. :(

Many thanks

Graham.

[Cath]

A picture is worth a thousand words.

Have you got one to show what you mean Graham?

[Shibby]

How distinct are they? The more distinct, the closer to the CCD they will be. So primary mirror seems unlikely. If you turn the camera, do they stay in the same place relative to your frame? If so, they're on the sensor (or something physically attached to the camera)...

[steelfixer]

Thanks folks for the response.

I will take a picture tonight when I get home.

I haven't tried rotating the camera but I will do that at the same time.

When the image is out of focus the spots are like water mark type spots.

They are rearly noticable and I have to keep the image to one side on my screen otherwise the spot will show up in the image.

Thanks

Graham

[steelfixer]

Ok folks I have taken the pictures and they are as follows.

Picture 1 - camera facing N - S

picture 2 - camera facing E - W

picture 3 - camera facing S - N

picture 4 - camera facing W - E

All the picts are taken against an out of focus moon.

I got so fed up with it tonight I stripped the entire scope right down to its individual componants.

I checked and cleaned every componant as I rebuilt the scope and in doing so I solved the mystery of the black spots.

I have on offer 1000 cudos points for any one who can tell me what these spots are.

I will let you in on it but I want to see if anyone can guess what they are.

So come on folks lets have your ideas.

Thanks

Graham

[YorkieGraham]

Please tell us what they are as I have a similar problem.

[Shibby]

Surely dust on the sensor if it wasn't the barlow or filter??

[Photosbykev]

Definately dust bunnies on the sensor. A proper air blower and/or sensor cleaning swabs required.

[rfdesigner]

Definately dust bunnies on the sensor. A proper air blower and/or sensor cleaning swabs required.

agreed

and then take some flats to keep on top of the few you can't clean off.

Derek

[kenmyers]

was it the moon?

clangers.

[themos]

cotton bud (for cleaning ears) and Optical Wonder fluid. Spray the fluid on the bud and wipe the bud once over the sensor. Repeat if necessary. Keep the sensor covered as much as possible.

[Photosbykev]

cotton bud (for cleaning ears) and Optical Wonder fluid. Spray the fluid on the bud and wipe the bud once over the sensor. Repeat if necessary. Keep the sensor covered as much as possible.

Repeat if necessary ... with a fresh cotton bud

[steelfixer]

Ok people I will tell you what it was.

After stripping down the whole scope and cleaning every thing I put it back together.

When I started to collomate I could see these marks were still there !!!!!!!

It was when I looked through the focuser tube to align the secondary.

The culprit for all these marks was a micro fine spiders web in the tube.

It was so fine I could not see it just by looking down the tube in the Obs, I could only see it under the bright lights on the work bench.

God only knows how a spider got in there as it is always stored with the covers on.

So there you have it if you see strange black marks in your image check the tube for squatters.

Oh how I laughed when I finally found it.

Thanks

Graham.

[Shibby]

Lol, well glad you found it at last! I'm surprised it shows up that distinctly. (Although I guess it's less distinct when in focus?)

There was an old Helios that swallowed a fly... Were you gonna try a bird next?

[kenmyers]

Amazing! haha.

Glad to hear your scope and camera are OK

[Shibby]

Hang on - how come the pattern didn't move when you rotated the camera?

[themos]

Spiders web won't be visible like that, if anything, it would produce lots of diffraction spikes around stars, perhaps merging together to make the stars more bloated.

[steelfixer]

Do not ask me why the image didn't move or why it produced the effect it did.

I think maybe the dots were bits of dust ect stuck to the web.

All I know is sinced I evicted the offender and removed its home the problem no longer exsists.

Technical explanations I will leave to someone who understands optics.

Thanks

Graham