Cleaning a diagonal....

[Stu]

11 hours ago, F15Rules said:

Good to hear you have the diagonal back in service Stu. 

Did Baader give any indication as to what they thought the stain was caused by? It does make you wonder about the worth of such a high priced item versus something cheaper? I confess my much cheaper T2 prism (non Zeiss version) gives me superb views and I know that I could replace it for less than £100 if I had to..and I doubt that my much less than perfect eyes could see any difference between my diagonal and the Ultra high end units anyway😁.

Dave

Actually no they didn't. I may ask, just so I have an idea how to avoid it in future.

You may well be right about being able to see the differences, but I've taken the pain of the cost now so will carry on enjoying them.

I should at some point compare the two alongside my 2" Everbrite and see if I can see the differences. I recall being impressed by the Zeiss prism when I first got it as it appeared to support higher powers before the image degraded, and have less light scatter.

[Stu]

4 minutes ago, Carbon Brush said:

Mirror damage was an an unexpected and expensive outcome.

Do you have any idea how long the stain/slime could have been on the mirror?

The reason for asking is that I have always assumed that 'average' bug splats, tree sap or whatever won't do harm if dealt with in a few days.

Asking the question while reaching for the stuff that hasn't been out this soggy and cloudy autumn....

David.

I unfortunately have no idea how long the muck was on there, quite some time I should think as I hadn't used that diagonal for a while. I guess normal rules apply ie dust is pretty harmless, but anything looking like sap or grease should be cleaned off as soon as possible. I'm always wary of cleaning mirror diagonal though because I assume they are easy to scratch, similar to newt mirrors but that may not be the case.

[John]

I'm pleased that you have got the diagonal back in service now Stu. Not a low cost operation but at least you get a really excellent diagonal for the outlay.

When I bought my Baader T2 Zeiss prism diagonal I don't recall the spec mentioning BBHS coatings but the same model number (#2456095) one the Baader website now specifies this:

https://www.baader-planetarium.com/en/baader-t-2-stardiagonal-(zeiss)-prism-with-bbhs-r-coating-(t-2-part-01b).html

The dealer specs for this diagonal don't mention BBHS currently so I wonder if it is a relatively new change to the spec of this product ?

Whatever, it is a very good diagonal.

Like @F15Rules / Dave though, I stuggle to see any differences in optical performance between my Tele Vue Everbright, Astro Physics Maxbright and the Baader T2 Zeiss. Yet others say they can see them as clear as a bell 

I use my T2 prism with my Tak FC-100 DL pretty much exclusively now mostly because I feel that it's compact size suits the slender lines of that scope. Not too scientific I'm afraid

 

[Stu]

19 minutes ago, John said:

I'm pleased that you have got the diagonal back in service now Stu. Not a low cost operation but at least you get a really excellent diagonal for the outlay.

When I bought my Baader T2 Zeiss prism diagonal I don't recall the spec mentioning BBHS coatings but the same model number (#2456095) one the Baader website now specifies this:

https://www.baader-planetarium.com/en/baader-t-2-stardiagonal-(zeiss)-prism-with-bbhs-r-coating-(t-2-part-01b).html

The dealer specs for this diagonal don't mention BBHS currently so I wonder if it is a relatively new change to the spec of this product ?

Whatever, it is a very good diagonal.

Like @F15Rules / Dave though, I stuggle to see any differences in optical performance between my Tele Vue Everbright, Astro Physics Maxbright and the Baader T2 Zeiss. Yet others say they can see them as clear as a bell 

I use my T2 prism with my Tak FC-100 DL pretty much exclusively now mostly because I feel that it's compact size suits the slender lines of that scope. Not too scientific I'm afraid

 

I don't recall that when I bought mine John, I always assumed that the prisms just relied on total internal reflection so any external coating was irrelevant? Obviously not.

I suspect all your diagonal are pretty similar quality, compare them with one of the cheaper ones and I would hope the differences become clearer.

[Merlin66]

You can get reflections from the front and rear glass surfaces, these would be suppressed with good coatings.