Help with my CaK PST scope

[Astronut1982]

I recently bought a CaK PST scope from a member on here. I was out today trying it out but I was unsuccessful with it & was hoping for some advice.

I am aware that some people are unable to see the CaK line so I wasn't surprised when I saw nothing through the eyepiece but I was hoping that my SPC900NC webcam would pick it up. When I connected it up though & had a look on the laptop I saw nothing there either.

What am I not doing right?

Jeff

[Capricorn]

Possibly doing nothing wrong.

Searching round it seems that a standard ccd will have a cut off at around 400nM, they can go down to 300nM but form what I have found this need coatings and what may be a somewhat special build - back illumination.

Assuming that the SPC900 is a standard ccd then it could easily be that the chip simply is blind to 395nM, the CaK line.

Seems very little information on the spectral curve of a ccd chip.

I do know that they are often used for IR aspects and I have no heard of them being used for UV work. So would suspect that they have a cut off at the near UV.

Second site says: "spectral range of 400-1100 nanometers"

Also they are coated with a coating that is transparent from 400nM upwards.

Probably this that is the cut off at 400nM.

You are looking at 395nM, close but means that the wavelength is probably not seen by the ccd.

Ones that can see down to 300 are also inefficent, 20% or less.

To "see" UV the chip is coated in a phospher based coating, this absorbs the UV and reemits at wavelengths the chip can see. So it seems that UV is not a ccd's forte.

[Merlin66]

Did you resolve this issue?

The Sony QE curves for the ICX098BL chip shows a good response down into the UV...

Just make sure any UV-IR filter you may normally use is removed....

[Demonperformer]

Hi Jeff,

Hope you are now getting some results with the CaK.

Also, hope you have had no probs with the Ha scope (would hate to think you were a dissatisfied customer)

[Astronut1982]

Hi there Merlin66,

I haven't been able to use the CaK scope yet as I don't have a camera sensitive enough yet. I have taken a note of the chip you have recommended & will try to find a camera which uses it.

Hi John,

I have been out several times with the Ha scope & I'm very happy with it. The views have stunning, I've never seen as much detail on the surface as I have with this scope. I am a very satisfied customer!

Jeff

[Merlin66]

That's the standard mono webcam chip ie DMK21.

The DMK31 or DMK41 would be better.

[Astronut1982]

I just have another quick question. Would the Sony® color CCD ICX098BQ chip be receptive to the Cak line also or does it have to be the ICX098BL chip?

Jeff

[Merlin66]

Colour webcams loose a lot of resolution....

The colour chip has a very low <10% sensitivity below the 400nm....wouldn't work very well....