PST ITF?

[JB80]

I took a look at my ITF for the PST today and can see that it is possibly looking a bit degraded which I have suspected as I'm getting a bit of haziness to my images. I'm not sure to be honest but there is a darker spot in the middle with a lighter ring around the outside, I have a pic and it doesn't show all but you can see what I mean. There is also some speckled dots on the inside with I'm not sure what they could be but they may be cleanable, they aren't visible in the picture though.

The PST is 4 years old and was brought new but who knows how long it was sitting in stock somewhere and I would say it has had pretty heavy use in the last couple of years..

Anyway a few questions.

At what point should I regard the ITF as needing replacing?

Secondly, is this the type of filter I should look at for a replacement? http://maierphotonics.com/656bandpassfilter.aspx

If so are there other brands or different ones with differing specs that would be better or worse and are there any EU suppliers of them?

Also I'm a bit annoyed I didn't notice this yesterday as I have just been to the hardware store and could of grabbed a couple of strap wrenches but only looked afterwards and as it is I can't open up the eyepiece holder as I'm guessing it's loctited shut.

Any ideas or tips of how to separate it with no access to a vice or wrenches?

[JamesF]

My recollection is that the two halves of the eyepiece holder are indeed threadlocked.  However, that bottom filter can be removed just by undoing that bottom section using a pin spanner (a pair of dividers works at a pinch) in the two holes visible in the photo as far as I recall.

James

[JB80]

That is probably the part I will need to get to anyway, I'm going to dig around and see what I have got.

[JB80]

Hmm, can't find anything around to get the job done. Hopefully I can find something this week.

I'm reading there may be a few options for a replacement ITF, trying to interpret it all but not sure what is best or if I even need one.

[JamesF]

I'm sure you'll need an ITF.  Up to that point there's still a fair bit of energy getting through I think.  If I recall correctly it's the older models that had the ITF at the front (that went "rusty") where it may not have been an issue.

Really needs discussing with someone who knows a bit more about the PST design than me though.

James

[JB80]

Yeah, I think I will. It would explain a lot too.

Think I might pose the question at solarchat as well, I have been reading a few threads there and it's very informative but there are a lot of different things being thrown around.

I'll be looking for a quick fix and hopefully can have something sent to me by the 20th.

[jetstream]

The ITF is needed, kind of a fail safe filter. From what little I know I wouldn't even consider going without one. Just my 2 cents.

[JB80]

Yeah it's not something I would go without, I kind of worded that wrong. What I meant was if I need one because mine is duff and I need to replace it or if it's OK, I don't really know.

[Merlin66]

Jarrod,

Go for the Maier replacement.

You can still use the existing set-up until it arrives.

[JB80]

I think I will, I can contact them and see if they can express deliver it, if not I can wait.