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Equipment Discussions >> Eyepieces

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Starman81
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Reged: 03/06/08

Loc: Metro Detroit, MI, USA
22 Nagler T4 especially prone to coating damage?
      #5564719 - 12/10/12 07:01 PM

Recently for sale I have seen a high proportion of used 22 Nagler T4's that have some damaged lens coatings. I even took delivery of one that I had to return to the seller for this same reason. Afterwards I saw a few more pop at a discount due to the same issue I experienced. Being an avid buyer/seller of EPs and a watcher of the marts and classifieds, this is looking like a trend to me. Or hopefully just a coincidence...

Edited by Starman81 (12/11/12 10:06 PM)


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Rick Woods
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Reged: 01/27/05

Loc: Inner Solar System
Re: 22 Nagler T4 especially prone to coating defects? new [Re: Starman81]
      #5564794 - 12/10/12 07:57 PM

I hope it's a coincidence! I'd hate to see defective stuff coming out of TV regularly.

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Starman81
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: Rick Woods]
      #5564833 - 12/10/12 08:23 PM

I'm sorry, let me qualify that: I meant used sales. Those on the used market have recently had a high proportion of units with eyelens coating defects.

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GeneT
Ely Kid
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Reged: 11/07/08

Loc: South Texas
Re: 22 Nagler T4 especially prone to coating defects? new [Re: Starman81]
      #5564985 - 12/10/12 10:05 PM

I have never have heard of this problem. My 22 Nagler is perfect--well, almost perfect.

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slack
sage
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Reged: 05/02/12

Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5565015 - 12/10/12 10:24 PM

I've seen it on the 22mm T4, but I've encountered deteriorated coatings more often on 31mm T5.

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tomchris
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Reged: 12/22/10

Loc: Connecticut, U.S.A.
Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5565469 - 12/11/12 07:18 AM

I've never heard of the problem either. I have no difficulties with my 22T4 which I use quite often.

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csrlice12
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Reged: 05/22/12

Loc: Denver, CO
Re: 22 Nagler T4 especially prone to coating defects? new [Re: tomchris]
      #5565527 - 12/11/12 08:36 AM

A Naglervirus???

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Kon Dealer
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Reged: 01/05/11

Loc: Cambridge UK
Re: 22 Nagler T4 especially prone to coating defects? new [Re: csrlice12]
      #5565546 - 12/11/12 08:57 AM

Here's hoping!

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Eddgie
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: Starman81]
      #5565786 - 12/11/12 11:43 AM

I owned a 22mm T4 for about 8 years and when I sold it, the coatings looked fine.

Here is something that I think needs to be considered.. It is possible that what is being seen is not a lens coating failure. In fact, this is likely that it is not a lens coating blemish.

The reason I say this with such conviction is that coating technology is pretty much perfected and when done properly, the coating is just about molecularly bonded to the glass.

Coatings are also very hard.

So, if it is not a problem with the coating itself, what might it be???

About 6 years ago, I had a Radian with what appeared to be a chip in the coatings. The placement was such that under some conditions, It caused some slight inteference in the view.

I contacted Televue about having the lens replaced, and they told me to send it in.

A couple of weeks later, I called to check on it and talked with the Rep (who in fact told me that he did the work).

The lens as it turned out had a conaminant on the surface. The Televue person said that it took vigorous rubbing with acetone to remove the spot but that the spot completely disappeared. He told me that this was common, and that the most likley cause was airborn tree sap, and that rubbing it off with Acetone was the common cleaning procceedure for this condition. He also said that the lens coatings were very durable and that done with care, this was a safe proceedure to use.

Anyway, the eyepiece came back and what I could have sworn was some kind of coating blemish was completely removed.

I would be surprised if these lenses all had some kind of coating failure but the very large eye lens of these eyepieces seem to be a magnet for all kinds of airborne matter, and I have since gotten tree sap on a bunch of lenes.

But I clean them myself, and sometimes the difficult spots do take s very soft cloth with a bit of acetone on it to remove, but they always come out looking like new. The Televue guy said that sometimes it can take a lot of rubbing and even a lot of pressure, but that the lens coatings were very hard and that given reasonable precautions, I would not damage the coatings.


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slack
sage
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Reged: 05/02/12

Re: 22 Nagler T4 especially prone to coating defects? new [Re: Eddgie]
      #5565838 - 12/11/12 12:16 PM

Eddgie, what I have seen was coatings failure. I can prob find pics on a diff computer later. Most often, it was worse at the edges, or seemed to originate at the edges, and it was obvious that the coatings were missing from the affected areas, with the appearance of flaking off (similar to delamination, with delineated and ragged edges), not having been rubbed off or damaged externally.

You're right; quality coatings are very durable. You can find examples of me posting on this site about cleaning optics and what I consider a silly fear in the amateur astronomy world of properly maintaining scopes by careful cleaning. I specifically point out that quality coatings on glass lenses are unlikely to be damaged by responsible cleaning methods. That said, what I have seen happen to some TV eyepieces is, IMO, obviously a coatings defect resulting in the failure of the coatings to remain bonded to the glass. It is not a widespread problem, but it is not uncommon with TV eyepieces as evidenced by the occasional reference to the issue.


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John Rhodes
Vendor (Televue Rep)
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Reged: 02/21/06

Loc: Torrance, CA.
Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5566027 - 12/11/12 02:13 PM

Quote:

That said, what I have seen happen to some TV eyepieces is, IMO, obviously a coatings defect resulting in the failure of the coatings to remain bonded to the glass. It is not a widespread problem, but it is not uncommon with TV eyepieces as evidenced by the occasional reference to the issue.




We find based on the fact that we just donít get any service calls on coating failures, these comments are unjustified and without merit.

If anybody is worried about the quality or longevity of their Tele Vue eyepiece, beginning in 2011 we extended our warranty from 5 years, to lifetime.

http://www.televue.com/Pdf/Literature/Lifetime%20Limited%20Warranty%20for%20E...


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slack
sage
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: John Rhodes]
      #5566076 - 12/11/12 02:41 PM

Quote:

We find based on the fact that we just donít get any service calls on coating failures, these comments are unjustified and without merit.




Let me reiterate, explicitly and publicly, that I have seen coating failures on multiple Tele Vue eyepieces. I have been working professionally for decades with many of the highest quality optics (Zeiss, Panavision, Cooke, Arriflex, Fujinon, Sony, Canon and other lenses valued up to several hundred thousand dollars each) and know what I am looking at. That said, I've never asserted it is a common problem and you are welcome to doubt the reports (though it's somewhat concerning that you aren't familiar any instances yourself).

In my experience speaking with folks at Tele Vue on the phone, I was informed that such problems, while very rare, do happen. It's a reasonable and common sense response from a company that makes high quality products but in great volume, overseas. Respectfully, as a representative of Tele Vue, your public assertion that mine (or others') comments are unjustified and without merit is unprofessional and false.

If I can locate the pics in the future (they are on a different computer), I will post pics of eye lens coating failure on a Nagler 31mm T5. It was well out of warranty and I sold it to someone with full disclosure. The flaws did not affect use.


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DaveJ
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5566118 - 12/11/12 03:11 PM

Quote:

Quote:

We find based on the fact that we just donít get any service calls on coating failures, these comments are unjustified and without merit.




Let me reiterate, explicitly and publicly, that I have seen coating failures on multiple Tele Vue eyepieces.




That certainly hasn't been my experience. I currently own 24 Tele Vue eyepieces, all purchased new, and I have yet to see any coating failures on any of them. Just another data point.


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John Rhodes
Vendor (Televue Rep)
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Reged: 02/21/06

Loc: Torrance, CA.
Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5566141 - 12/11/12 03:27 PM

Quote:

Quote:

We find based on the fact that we just donít get any service calls on coating failures, these comments are unjustified and without merit.




Let me reiterate, explicitly and publicly, that I have seen coating failures on multiple Tele Vue eyepieces.




Iím not saying you havenít seen eyepieces with damaged coatings, itís simply your assertion that itís a factory defect that has happened
ďmultipleĒ times, and questions the quality and manufacturing of our product, that is being challenged.†
That just doesnít bear out with our experience.† Where are all the calls to Tele Vue with complaints ?


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slack
sage
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Reged: 05/02/12

Re: 22 Nagler T4 especially prone to coating defects? new [Re: DaveJ]
      #5566154 - 12/11/12 03:34 PM

Data point? Well, of course it is unlikely that you would encounter this issue in a sampling of 24 eyepieces. It's unlikely that you would encounter it in a sampling many times that. But it has been reported on occasion, on this board and other sites. Just like debris inside TV eyepieces. It happens.

Just like there are hundreds of people who have praised ES eyepieces, but then someone posts about a defect and certain people go on attack and others get defensive. I've seen flaws with Pentax XW eyepieces, which I happen to believe are superior in build quality to any TV eyepiece. But, you have to put all of this into perspective. They are all mass produced, consumer items. And while they represent high quality options in this particular market, they are quite inexpensive in comparison to most professional and truly high quality optics.


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slack
sage
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Reged: 05/02/12

Re: 22 Nagler T4 especially prone to coating defects? new [Re: John Rhodes]
      #5566166 - 12/11/12 03:44 PM

Quote:

Quote:

Quote:

We find based on the fact that we just donít get any service calls on coating failures, these comments are unjustified and without merit.




Let me reiterate, explicitly and publicly, that I have seen coating failures on multiple Tele Vue eyepieces.




Iím not saying you havenít seen eyepieces with damaged coatings, itís simply your assertion that itís a factory defect that has happened ďmultipleĒ times, and questions the quality and manufacturing of our product, that is being challenged.†That just doesnít bear out with our experience.† Where are all the calls to Tele Vue with complaints ?




To be clear, I asserted that I have seen TV eyepieces with deteriorated or failed coatings. Not damaged coatings. Yes, absolutely a defect, but one that manifested over time, out of warranty. The fact that this can happen is not necessarily an indication of poor manufacturing and I did not challenge anything; those are your words, not mine. To repeat, this has come up in my phone calls with people at TV, and they stated that sure, not every eyepiece they sell is perfect and things like this can happen. But, as you point out, an advantage to purchasing more costly TV eyepieces is probably less likelihood of such problems (at least when new), and a warranty.

I'm obviously not the only person who has encountered this issue, uncommon though it may be.


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Kon Dealer
professor emeritus


Reged: 01/05/11

Loc: Cambridge UK
Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5566183 - 12/11/12 03:55 PM

Pass the popcorn

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DaveJ
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5566187 - 12/11/12 03:57 PM

Quote:

...but then someone posts about a defect and certain people go on attack and others get defensive.




I was neither on the attack nor defensive - I merely stated my experience and even called it "another data point."


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slack
sage
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Reged: 05/02/12

Re: 22 Nagler T4 especially prone to coating defects? new [Re: DaveJ]
      #5566216 - 12/11/12 04:14 PM

Quote:

Quote:

...but then someone posts about a defect and certain people go on attack and others get defensive.




I was neither on the attack nor defensive - I merely stated my experience and even called it "another data point."




The line you quoted was a general observation; it was not directed at you or anyone in particular.

Myself? With regard to astro eyepieces I'm an equal opportunity, totally objective critic. I currently own TV, Pentax and ES eyepieces. I have compared various offerings from those companies to each other and against different manufacturers. I prefer various models from all three companies to other offerings from the same three companies. I have encountered defects with eyepieces from all three companies. But based on my own experience, I would rate the general quality in this order: Pentax, TV and then ES. (Anecdotally, right now I really like the 17 T4, 22 T4, 24 Pan, and 31 T5. I have a love/hate relationship with the 12 T4. I prefer Pentax XW to Delos. I prefer ES 85 to T6s. But I reserve the right to change my mind tomorrow. )


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GeneT
Ely Kid
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Reged: 11/07/08

Loc: South Texas
Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5566493 - 12/11/12 07:40 PM

Quote:

If I can locate the pics in the future (they are on a different computer), I will post pics of eye lens coating failure on a Nagler 31mm T5.




Find and post the pictures. I have never heard of this problem before. Even if this was a rare event, someone would have brought it to our attention by now. There are a lot of people who 'hate' TeleVue--and for no reason. I am suspicious of anyone who posts information of this type without any proof.


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