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Equipment Discussions >> Eyepieces

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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]
      #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
sage
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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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Reged: 06/24/03

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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
sage
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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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