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Equipment Discussions >> Eyepieces

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Starman81
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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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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
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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
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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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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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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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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
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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
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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
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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
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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
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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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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
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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
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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
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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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slack
sage
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5566522 - 12/11/12 08:08 PM

Quote:

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.




Really? I've seen many references to TV coating issues and defects in posts on this board and others, going back many years. That's not to say it's a significant problem, only that it has most definitely come up before.

In this particular post, back in 2004, someone actually reports being told by TV staff that coatings defects could be cause for blem status. I have no knowledge of that subject, it's just one of many references to TV coatings issues or defects that I find when doing a proper search.
http://www.cloudynights.com/ubbarchive/showflat.php/Cat/0/Board/Eyepieces/Num...

Like I said, I've had people at TV acknowledge to me that they've seen coating issues on their EPs. And, of course they have.

As for me posting pics, I don't know when I will be on that computer again and can look to see if I still have them. If I do, I will certainly post them. I'm sure others have similar pics.


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Starman81
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5566524 - 12/11/12 08:11 PM

Quote:

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.




Gene, I don't hate TeleVue. On the contrary, I love them, including all the ones I own: 35 Pan, 13 Ethos, 10 Delos, 12 Nagler T4 and 32 Plossl binopair. Oh forgot to mention TV 2x barlow and 2.5x PowerMate. Definitely love, not hate.

After I had to send back my 22 Nagler T4, I quickly sought out others on the used market because I LOVED the one night experience I had with it. I really wanted one to keep in the permanent lineup but was not satisfied with the condition for the price paid. Only then saw that the next 2 out of 3 available had damaged coatings and started wondering. Yes I am talking about USED EP's, it is possible that perhaps they were cleaned incorrectly or in the case of a T4, has just been around a long time and has seen tons of use and experienced wear and tear along the way that has added up. Usually, however, anyone who buys a higher-end EP like a TeleVue Nagler (especially one in the price range of a 22mm Nagler T4), will most likely 'baby' it. After realizing that, my concerns came back.

I can post the pictures later tonight of my minty fresh 12mm Nagler T4 eyelens and a picture of the 22mm Nagler T4 that I had to send back. I was even careful to maintain the same reflections in each eyelens picture so as not to confuse that with the defects.


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Eddgie
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5566535 - 12/11/12 08:20 PM

In the context of the OPs post, I find it very difficult to beleive that the 22mm T4s he has observerd for sale have all had defective coatings.

I also have owned dozens of Televue eyepeices, and some of them are a decade old. I have not observed any coating failures on any Naglers, Radians, or Panoptic.

I have seen some very old Plossls with "Spotting" but this could be due to environmental conditions, and none of them had coating that was seperating from the glass.

I still maintain that what the OP is seeing are 22mm T4s that either have damaged coatings, or dirty coatings, but my own experience (and apparently that of many others) is that coating fairlures are very rare.

Not to say that they couldn't or don't every happen, but I just have never encountered it, and my eyepieces don't live shelterd lives.

And I would think that if Televue encountered such a condition, they would be inclined to repair the eyepeice because if the coating are applied properly they should never ever flake off.

So, damaged or dirty, maybe... A bunch of 22mm T4s that the coatings are failing on is hard to beleieve, and why would it be just limited to the 22mm T4s?


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slack
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5566558 - 12/11/12 08:45 PM

Quote:

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.




You know...

Is that really necessary? Did you miss the part about my appreciation and use of Tele Vue eyepieces? Or see in my sig that I use two Tele Vue refractors? A Tele Vue binoviewer? Or that I have come across defects with Pentax and other makes of eyepieces? Or the part about my experience with professional cine/TV coated optics?

C'mon, be objective. The odds that coating problems haven't occurred with all of the multi-coated glass that TV has produced would be astronomical.


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Starman81
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22 Nagler T4 especially prone to coating damage? new [Re: Eddgie]
      #5566651 - 12/11/12 10:04 PM

Quote:

In the context of the OPs post, I find it very difficult to beleive that the 22mm T4s he has observerd for sale have all had defective coatings.

I also have owned dozens of Televue eyepeices, and some of them are a decade old. I have not observed any coating failures on any Naglers, Radians, or Panoptic.

I have seen some very old Plossls with "Spotting" but this could be due to environmental conditions, and none of them had coating that was seperating from the glass.

I still maintain that what the OP is seeing are 22mm T4s that either have damaged coatings, or dirty coatings, but my own experience (and apparently that of many others) is that coating fairlures are very rare.

Not to say that they couldn't or don't every happen, but I just have never encountered it, and my eyepieces don't live shelterd lives.

And I would think that if Televue encountered such a condition, they would be inclined to repair the eyepeice because if the coating are applied properly they should never ever flake off.

So, damaged or dirty, maybe... A bunch of 22mm T4s that the coatings are failing on is hard to beleieve, and why would it be just limited to the 22mm T4s?




I should have titled the thread with the wording 'prone to coating damage?' because that is what I really meant. I have changed it accordingly.


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stevetaylor199
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Re: 22 Nagler T4 especially prone to coating damage? new [Re: Starman81]
      #5566831 - 12/12/12 12:13 AM

Quote:


I should have titled the thread with the wording 'prone to coating damage?' because that is what I really meant. I have changed it accordingly.




I was thinking that a coating "defect" like the one cited in a post above -- which was caught by TV, and prompted them to identify such a new eyepiece as a blem item -- is not the same as coating "damage" or "failure."

I think an interesting discussion could be had about how coatings can become damaged -- or appear to be damaged. Also, I am not familiar with coating delamination or flaking, and how such an exceedingly thin chemical layer could separate from the substrate in that manner and with that visual appearance.


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slack
sage
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Re: 22 Nagler T4 especially prone to coating damage? new [Re: stevetaylor199]
      #5566864 - 12/12/12 12:42 AM

Quote:

Also, I am not familiar with coating delamination or flaking, and how such an exceedingly thin chemical layer could separate from the substrate in that manner and with that visual appearance.




It may be thin, but I have felt the edge of flaked-off coatings on an eye lens with my fingernail.


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Starman81
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Re: 22 Nagler T4 especially prone to coating damage? new [Re: Starman81]
      #5566876 - 12/12/12 01:04 AM Attachment (38 downloads)

22mm Nagler T4 eyelens. None of what you see here was able to be cleaned off with Zeiss wipes nor 50/50 isopropyl alcohol + distilled water with a drop of dish soap.

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Starman81
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Re: 22 Nagler T4 especially prone to coating damage? new [Re: Starman81]
      #5566877 - 12/12/12 01:05 AM Attachment (25 downloads)

12mm Nagler T4 eyelens in excellent condition, for comparison.

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Eddgie
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Re: 22 Nagler T4 especially prone to coating damage? new [Re: Starman81]
      #5567214 - 12/12/12 09:29 AM

This is exactly how the Radian that I sent back to Televue looked. I tried to clean it with alcohol. I tried glass cleaners and I tried everything else.

Under magnification, it even looked like damage.

As I said in my earlier post, Televue cleaned it with Acetone and the spots came off. They said it took some amount of effort, but that this was common for tree sap.

This does not look like coating failure at all to me.

From what I understand, when coatings fail, it is usually because the glass substrate was contaminated.

The coating does not form a molecular level bond with the glass, and when it comes off, it comes off in flakes with very irregular edges.

The top picture here does not look at all like a coating failure or even damage.

The picture here looks exactly like the tree sap that I mistook for damage (not failure) and that Televue was able to remove.

I see no evidence of coating failure in this picture. Looks like tree sap or some other foreign matter adhered to the coatings.

These are almost sure to come off with proper cleaning.

Dude.. It's a picture of a dirty eyepeice.

Edited by Eddgie (12/12/12 09:36 AM)


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star drop
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Re: 22 Nagler T4 especially prone to coating damage? new [Re: Eddgie]
      #5567231 - 12/12/12 09:42 AM

I have never had a problem with coating failure on any Televue eyepiece and some of mine are thirty years old.

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Starman1
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Re: 22 Nagler T4 especially prone to coating damage? new [Re: star drop]
      #5567409 - 12/12/12 11:50 AM

Data point of 1: I had a 22 T4 for well over a decade (almost 2) and it was cleaned numerable times. The lens surfaces looked like new when I sold the eyepiece (it was replaced with a 21 Ethos).

Data point of hundreds: I worked for several years for a large retailer of astronomy gear. Tiny pinholes in coatings, mostly visible only with a loupe, were very very common. In fact, the brand with the most commonly-seen coating pinholes was Pentax.
Of course, none of those pinholes ever affected the views through the eyepieces, and most were only visible at high power through a loupe.

Only the Very cheapest (largely plastic-barrel) eyepieces had coatings that rubbed off or were easily damaged.

I have seen, in the field, and over nearly 5 decades, tons of eyepieces with scratches in the coatings. These were caused, by and large, by improper cleaning techniques. Also, they have been mostly MgFl2-coated lenses, not multi-coated lenses.

I have also seen hundreds of eyepieces with what appeared to be tiny pinholes in the coatings (like that pic of the 22 above), and they all came off when cleaned. But I have seen some grime that neither alcohol nor acetone removed. When you have to resort to MEK or something equally as strong to clean a lens, you wonder what the heck the stuff was that got on the lens. [as an aside: I had some mascara streaks on an eyepiece after a star party that required 5 cleanings with MEK to remove. It was like cleaning rubber cement off the lens--it dissolved in the cleaning fluid and deposited itself over the entire surface of the lens. Points out how valuable long eye relief eyepieces are at star parties!]


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Paul G
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Re: 22 Nagler T4 especially prone to coating damage? new [Re: Starman81]
      #5567532 - 12/12/12 12:49 PM

Looks like an eyepiece that needs cleaning. I have about 40 TV eyepieces, clean them after every use and the coatings are pristine after years of use and cleaning. I have found that some surface contaminants, particularly organics, look like coating problems but are not. Some of these won't clean off with Zeiss cleaning fluid, Kodak cleaning fluid, acetone, methanol, or MEK. They will, however, come off with saliva on the pad of one's thumb (tree sap in particular).

I've seen coating defects in a Meade SCT corrector, but it had a crazed effect and the coating flaked off in irregular shaped pieces. This pic just looks like a dirty eyepiece.


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stevetaylor199
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Re: 22 Nagler T4 especially prone to coating damage? new [Re: Starman1]
      #5567615 - 12/12/12 01:44 PM

Quote:


I have seen, in the field, and over nearly 5 decades, tons of eyepieces with scratches in the coatings. These were caused, by and large, by improper cleaning techniques.




I believe I am guilty of having inflicting these on a camera lens or two, which is why I am reluctant to clean anything, ever. Your point on those coatings being simple MgF2 is noted, though.

What is MEK?

Edit: thanks for answer below: methyl ethyl ketone. I'll look it up; I've always enjoyed chemistry.

Edited by stevetaylor199 (12/12/12 02:24 PM)


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star drop
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Re: 22 Nagler T4 especially prone to coating damage? new [Re: stevetaylor199]
      #5567682 - 12/12/12 02:16 PM

MEK is methyl ethyl ketone.

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GeneT
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5567686 - 12/12/12 02:18 PM

Quote:

Quote:

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.





You know...

Is that really necessary? Did you miss the part about my appreciation and use of Tele Vue eyepieces? Or see in my sig that I use two Tele Vue refractors? A Tele Vue binoviewer? Or that I have come across defects with Pentax and other makes of eyepieces? Or the part about my experience with professional cine/TV coated optics?

C'mon, be objective. The odds that coating problems haven't occurred with all of the multi-coated glass that TV has produced would be astronomical.




My main point is when we make allegations of this sort, we should provide the proof. Eddgie notes that in his opinion, the picture shown does not show coating defects, and Don also believes what the picture shows is a dirty eyepiece. Since the OP has photos of the eyepiece in question on another computer, I recommend he find and post the photo. Then we can see and evaluate for ourselves.


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GeneT
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5567718 - 12/12/12 02:26 PM

Quote:

C'mon, be objective. The odds that coating problems haven't occurred with all of the multi-coated glass that TV has produced would be astronomical.




You have raised a different issue. I agree that there well could be issues raised by the OP, but even if he is correct, we are generalizing from one data point, and that one data point exists in photos on another computer. I would have preferred a posting that identified the problem, what TeleVue offered in the way of a solution, whether or not TeleVue solved the problem, and a photo showing the problem. What we have at stake here is the professional reputation of an outstanding company. We need to be a little more precise when making comments of this sort, and avoid sweeping generalizations.


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Starman1
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5567726 - 12/12/12 02:31 PM

By the way, the pinhole gaps in coatings to which I referred in an earlier post were much smaller than the ones in the picture of the 22T4. They were invisible to the naked eye and required magnification to see. They were, I believe, due to incomplete cleaning of the lenses before coating on a very small scale.
And they were invisible in use.


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slack
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5567762 - 12/12/12 02:44 PM

Quote:

Quote:

Quote:

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.





You know...

Is that really necessary? Did you miss the part about my appreciation and use of Tele Vue eyepieces? Or see in my sig that I use two Tele Vue refractors? A Tele Vue binoviewer? Or that I have come across defects with Pentax and other makes of eyepieces? Or the part about my experience with professional cine/TV coated optics?

C'mon, be objective. The odds that coating problems haven't occurred with all of the multi-coated glass that TV has produced would be astronomical.




My main point is when we make allegations of this sort, we should provide the proof. Eddgie notes that in his opinion, the picture shown does not show coating defects, and Don also believes what the picture shows is a dirty eyepiece. Since the OP has photos of the eyepiece in question on another computer, I recommend he find and post the photo. Then we can see and evaluate for ourselves.




In response to another's post, I shared a factual observation, based on professional experience, that I have seen failed (read: defective) coatings on TV eyepieces. It has come up before, and I have shared the same info before, and nobody has challenged the validity of my report. In fact, as I indicated (and provided a link to just one of many substantiating reports going back about a decade here), TV has acknowledged that it has occurred. I have spoken directly to TV about it.

The flaked off coatings that I have seen appeared nothing like what is pictured above. Based on the pics posted above, I would not wager on what caused them. You can, but I'll pass. However, when and if I can locate the pics I have of a defective 31mm T5, it should be obvious to any well informed person that it represents a failure of the coatings. I suspect that some people won't be convinced no matter what and, well, ignorance is bliss. With regard to my "data," I would gladly make a significant wager.

As with most things like this, the truth is usually somewhere in the middle. Have there been coatings failures and defects with TV eyepieces? Of course. (It's interesting that a couple of TV dealers have posted suggesting otherwise, given that TV has acknowledged that their products do not magically levitate above any potential real world problem or defy statistical odds.) But are many reports of damage or other issues misattributed to a production defect? Of course.


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slack
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5567776 - 12/12/12 02:54 PM

Quote:

I would have preferred a posting that identified the problem, what TeleVue offered in the way of a solution, whether or not TeleVue solved the problem, and a photo showing the problem. What we have at stake here is the professional reputation of an outstanding company. We need to be a little more precise when making comments of this sort, and avoid sweeping generalizations.




I don't believe I've made any sweeping generalizations or spoken negatively of TV. To the contrary, I have explicitly defended TV in my postings on this issue.

With regard to my telephone discussion with TV about the failed coatings on the 31mm T5, as I reported, based on my explicit description they agreed with my diagnosis and stated there was nothing they could do to repair the eye lens. (Which we all know. They also can not repair the coatings on their scope objectives.) The out of warranty cost to repair the EP was not sensible. I sold it to someone with full disclosure.

This has little to do with the reputation of an outstanding company, other than my having bolstered that reputation by reporting on their common sense discussion with me about it (that bad *BLEEP* sometimes happens, even with their stuff), which stands in stark and positive contrast to a couple of dealers chiming in to denounce any negative reports from the real world, no matter how few and far between they might be.


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GeneT
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5568227 - 12/12/12 08:23 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.




Show us the pics so we all know exactly what you are talking about.


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slack
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5568515 - 12/13/12 12:20 AM

This is the only pic of the Nagler 31mm T5 with bad coatings that I can find at this time. The portion in the reflection of the lights, that appears bright white, had recently flaked off when that pic was taken (hence the sharper edges of that patch).



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GeneT
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: slack]
      #5570053 - 12/13/12 10:13 PM

Quote:

This is the only pic of the Nagler 31mm T5 with bad coatings that I can find at this time. The portion in the reflection of the lights, that appears bright white, had recently flaked off when that pic was taken (hence the sharper edges of that patch).






Thanks for posting the picture. I am sure that there are some who are qualified will evaluate and comment on the condition of lens.


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slack
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5570154 - 12/13/12 11:37 PM

Quote:

Thanks for posting the picture. I am sure that there are some who are qualified will evaluate and comment on the condition of lens.




You're welcome. Though having worked with and evaluated professional lenses for nearly 25-yrs, I regard myself as qualified to identify something so conspicuous as failed and flaking coatings. And, as I've said numerous times now, I got a concurring opinion from Tele Vue on this matter when I still owned the eyepiece.

It is what it is. An example of an uncommon issue.


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Eddgie
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: GeneT]
      #5570511 - 12/14/12 09:20 AM

I agree that this picture shows coating flaking off.

The previous picture though looked like a dirty eyepiece.


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Starman81
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: Eddgie]
      #5570687 - 12/14/12 11:27 AM

Thanks for the input on the issue that I faced. I had researched CN and found some threads on cleaning with acetone that some of you had also posted in and considered cleaning the 22 Nagler with it. However, reading the precautions about what acetone could do to the eyepiece if not applied very carefully, I resisted, especially because the seller was allowing me to return it. I did not want to take the risk of potentially damaging the eyepiece with any potentially harsher cleaning methods.

With that being said, I found the Nagler 22 an excellent eyepiece (the one night I had it out) and the dirt/grime whatever may have been on the eyepiece did not affect the views in any way that I could tell. On that night, I was able to observe the E and F stars of the Trap for the first time with the 22 in the focuser, I attribute that to the amazingly steady seeing that night but it goes to show that whatever was on that eyepiece couldn't have been holding it back, in terms of performance, much if at all.


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Eddgie
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: Starman81]
      #5570811 - 12/14/12 12:53 PM

The key to using acetone is to be very sparing with it.

Apply it sparingly to a cotton schwab and use light pressure to scrub the spot itself. Be generous with the schwabs. They are cheap.

If you put so much on the schwab that it squeezes out when you touch the glass, you have put to much.

Never apply any cleaner of any kind directly to the lens. The cleaner can be wicked up by the retaining part of the housing and get into the space between lenses.

Only apply to the cloth or schwab, and only a tiny amount. And when it is no longer showing on the glass, get a clean schwab and apply a tiny amount of acetone and go again.

Or, do as you did and just leave it alone.


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stevetaylor199
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: Eddgie]
      #5570975 - 12/14/12 02:54 PM

Quote:

The cleaner can be wicked up by the retaining part of the housing and get into the space between lenses.





Is that the concern involved when using acetone, as mentioned above? Or is there another reason?


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Starman81
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: stevetaylor199]
      #5571012 - 12/14/12 03:20 PM

I also recall reading that it can dissolve plastic and that it is highly flammable.

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csrlice12
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: Starman81]
      #5572386 - 12/15/12 11:12 AM

But you can do your nails AND clean your eyepieces.....

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Starman1
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Re: 22 Nagler T4 especially prone to coating defects? new [Re: csrlice12]
      #5572418 - 12/15/12 11:29 AM

It helps to mention here that we are talking reagent-grade acetone, not fingernail polish remover. The former is pure, while the latter has lanolin and food dye and other junk in it you wouldn't want on your lens.

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