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My ITF is not in the usual place

Posted: Sun Mar 17, 2019 6:43 pm
by Starry Jack
I'm trying to check my ITF but I can't find it per all the posts I have read. I have a Coronado PDT #95471 and have had it since new for years.

There is nothing between the BF 5 and the pentaprism and then nothing until the etalon assembly where I find a clear piece of glass where I would assume is the ITF.
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Thanks,
Jack

Re: My ITF is not in the usual place

Posted: Sun Mar 17, 2019 8:19 pm
by marktownley
ITF coating is on the objective. An older PST?

Re: My ITF is not in the usual place

Posted: Sun Mar 17, 2019 9:08 pm
by bart1805
I think so too, when you look at the serial number it is quite low. Could you post a picture of the objective? BTW, it looks like a pretty well used PST.

Re: My ITF is not in the usual place

Posted: Sun Mar 17, 2019 9:38 pm
by Starry Jack
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Glad to hear I am not crazy. By the way, in order to achieve an image with a camera info have to place a Baader UV/Ir Cut on the camera to cut out what I thought the ITF was supposed to cut off.
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Re: My ITF is not in the usual place

Posted: Sun Mar 17, 2019 9:51 pm
by marktownley
Yeah, you have an older PST, the ITF coating is on the objective, that's why it has that cloudy red colour.

Re: My ITF is not in the usual place

Posted: Sun Mar 17, 2019 10:22 pm
by bart1805
marktownley wrote: Sun Mar 17, 2019 9:51 pm Yeah, you have an older PST, the ITF coating is on the objective, that's why it has that cloudy red colour.
Agree, but is the cloudiness caused by rust or is it ok?

Re: My ITF is not in the usual place

Posted: Sun Mar 17, 2019 10:28 pm
by marktownley
The cloudiness is the rust.

Re: My ITF is not in the usual place

Posted: Sun Mar 17, 2019 11:01 pm
by MalVeauX
Don't suppose there's an objective replacement? Nor support?

Take it, if we have an old PST etalon like this, it's basically only good for being harvest as a PST mod?

Very best,

Re: My ITF is not in the usual place

Posted: Sun Mar 17, 2019 11:08 pm
by bart1805
MalVeauX wrote: Sun Mar 17, 2019 11:01 pm Don't suppose there's an objective replacement? Nor support?

Take it, if we have an old PST etalon like this, it's basically only good for being harvest as a PST mod?

Very best,
Yep, you could replace the objective or use the etalon for a mod.

Re: My ITF is not in the usual place

Posted: Sun Mar 17, 2019 11:11 pm
by Starry Jack
So I'm enjoying my mod, but what do I do to replace the ITF functionality? I've been using a Baader 1.25" on the camera nosepiece. I just tried moving it into the eyepice holder (well, just laying on top of the pentaprism which I have had to wedge into a single focus since the mechanism has failed) and I think I like it better than after the BF. Is that my imagination?

Should I get a Meier ITF instead? or alternative?

Jack

Re: My ITF is not in the usual place

Posted: Sun Mar 17, 2019 11:12 pm
by marktownley
Best bet is to keep an eye on fleabay and all the usual 2nd hand haunts for a PST objective, sometimes they come up minus the etalon if it has been used for a mod.

The Maier or beloptik ITF could then be used in conjunction with the blocking filter...

Re: My ITF is not in the usual place

Posted: Mon Mar 18, 2019 12:34 am
by Starry Jack
Thanks, Mark, but I don't want an objective. I have been using my mod for several years now. The objective is useless to me and I'll never go back! :)

I started this thread to see if I should check my ITF on my mod. Turns out I don't have an ITF. Should I try and mimic one somehow? I think I've must have been doing that by using the UV/IR Cut on the end of the camera but I certainly don't know.

My mod is a PST Stage 1 on a 152mm achromat with an ERF from Val. I have a glasspath as well to bring it to f11. I kept reading about rusty ITFs so I just thought to myself..., "Self! Maybe you should check!". :)

Jack

Thoughts?
Jack

Re: My ITF is not in the usual place

Posted: Mon Mar 18, 2019 8:38 am
by DSobserver
Luckily it’s a valery erf that block most wavelengths. A baader one would have gave you a greenish sun as FP and BF doesn’t block all of them

Re: My ITF is not in the usual place

Posted: Mon Mar 18, 2019 4:00 pm
by Starry Jack
marktownley wrote: Sun Mar 17, 2019 11:12 pm Best bet is to keep an eye on fleabay and all the usual 2nd hand haunts for a PST objective, sometimes they come up minus the etalon if it has been used for a mod.

The Maier or beloptik ITF could then be used in conjunction with the blocking filter...
Mark,
Sorry I missed this comment...that I could indeed use the aftermarket ITF in conjunction with the blocking filter. Thank you for the insight.

I'll look for one. I'm assuming that will give me better performance than the Baader UV/IR cut filter I am currently using?

Thanks,
Jack