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PST Ha or CaK


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Hi Guys,

I'm giving serious consideration to changing my entire setup for a PST.

Now I have a few questions, I could probably find the answers but you guys may already now.

1. How does the scope focus?

2. How much focus travel does the scope have?

3. Can I use the toucam pro to image through these scopes?

4. Can I use the 300D to image through them?

5. Which would be trhe better buy? Ha or Cak. From what I've read the Cak is mainly for imaging - as the eye(as it it gets older) doesn't see this wavelength very well...

6. I could find any images taken through the Cak scope.

7. I could mount this scope on a small EQ mount (EQ3) right?

8. I've always had issues with focusing with the sun - in fact I find it a blumming nightmare - the image always seems to be "boiling". How does the PST deal with this issue?

Think that's about it!

Cheers for you help...

Ant

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Ant, i have no experience of the PST. And until yesterday I had no interest in Solar observing either. But yesterday changed that and like you the PST seems a whole load more appealing today.

Been having a look round the web and it appears the PST works very well with a Toucam. Some knockout images around.

Pete has a PST thread running in the Solar section with images he took using a Canon 10D. As usual Pete's images are the pinnacle of what can be expected but it shows the PST will work like a charm with the 300D.

http://stargazerslounge.co.uk/index.php?topic=2743.0

Regards

Russ

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Hi Ant,

I'll try and help as best I can...

1. How does the scope focus?Not entirely sure, I thing I've read somewhere that the focussing knob moves an internal prism. I might be talking garbage here though.

2. How much focus travel does the scope have?Not a lot but it's workable.

3. Can I use the toucam pro to image through these scopes?Yes

4. Can I use the 300D to image through them?

Yes

Now I'll do 1 again :lol:

Natively, the Toucam Pro and the Canon cannot achieve focus through the PST, the point of focus is too far into the eyepiece holder. My solution to this was to unscrew the eyepiece holder from the body and then unscrew the holder itself - it comes in two parts. The part that's normally closest to the body is just an empty tube. If you unscrew it and put it aside, the other bit (the eypiece holder and blocking filter) will screw into the main body. You can now achieve focus. One word of warning though. The empty tube appears to be treated with Locktite or something and can be a bit tough to unscrew. If you try it, the best tool is one of those rubber strips used for rotating tubes (no idea what they are called). Update - I've found a photo of one being used on a PST here http://www.astrosurf.com/re/pst_dslr_20050505-02.jpg.

Barlow lenses can be used to boost image scale but usually you need to unscrew the lens itself from the end of the Barlow and screw it directly onto the 1.25" adapter attached to the camera.

5. Which would be trhe better buy? Ha or Cak. From what I've read the Cak is mainly for imaging - as the eye(as it it gets older) doesn't see this wavelength very well...

They are both good. Personally, to start I'd go for the Ha scope as it gives some great visual views as well as being ok for imaging.

6. I could find any images taken through the Cak scope.

I think Gary Palmer had some on show.

7. I could mount this scope on a small EQ mount (EQ3) right?It has a standard tripod threaded hole in the base of the body so as long as you can rig something to fit on the EQ3 with a tripod screw presented, then there shouldn't be a problem.

8. I've always had issues with focusing with the sun - in fact I find it a blumming nightmare - the image always seems to be "boiling". How does the PST deal with this issue?

Image scale is small and the boliing doesn't detract that much. Focussing for visual use is quite easy. Focussing for imaging is harder - a dark cloth over the head works a treat.

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Cheers Pete, I think that all the questions just about covered....

I've already decided against the CaK line version.

The "tool" used to remove the extension tube looks like one of the tool a mechanic used to use for unscrewing the oil filters on cars...

Now that I've realised that the images it gives are Blue - there was a live feed from Turkey in the CaK line - not a patch IMo to the Ha :lol:

Thanks again Pete,

Ant

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The thing to remember about CaK is that it's at a higher temperature than Ha and thus higher in the atmosphere. It shows different details, just as white light shows different details than Ha.

Pete answered most of it, but as an aside, the boiling you mention is more a local heating effect and is not visible at Ha wavelengths.

I plan to get both. The only factor here is which one's cheaper? :lol:

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Cheers Steve,

It's good to know that the boiling won't be an issue.

From what I've seen on the net (both state side and here) the Cak and Ha are the same price.

I have some friends coming over from Texas in September - I may be cheecky and ask them to get me a Ha and bring it over... Keeps the cost down to under £290.

The only snag is the pound may well fall through the floor with regad to the Dollar - as interest rates are about to go up by 1/4% - always increases the value of the dollar.

Cheers Guys

Ant

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