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Fingerprints on the inside of a corrector plate?

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#1 ny65

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Posted 02 September 2021 - 10:01 AM

This is an oddball question... I recently bought an Orion 150mm Mak-Cass that I have mentioned in some recent threads in the forums. Last night was the first when the temperature in our area dropped appreciably while I was observing (went down to the low 50's from close to 70 during the day). Things were getting close to dewing up and I noticed a sheen of moisture on the OTA. When I picked up the tube to get back in, I noticed a fairly large fingerprint-like smudge on the corrector plate - it was visible when I shined by phone flashlight by chance on the front of the telescope while wrapping things up for the day. I was puzzled since I am really careful about not taking my mitts anywhere near the glass in optics and take pains to handle the scope only on the metal parts on the outside - I am close to 100% certain it wasn't me. The odd thing is that smudge is basically gone this AM after the scope has been indoors and warmed up to the 70s.

 

Looks like the cooling down and the moisture build up made the print visible. I was curious whether anyone has seen fingerprint marks left behind on the inside of the corrector plate during the assembly process? There seem to be some threads alluding to something like this, but nothing definitive. I didn't want to try cleaning the outside of the corrector plate since I'm always afraid that I will do more damage by pressing and dragging a piece of grit inadvertently on the optics, especially if it is on the inside which would make the effort futile.

 

Any ideas or experience with something like this?

 

[I didn't take a picture with a phone last night, unfortunately... so can't post any]


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#2 spereira

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Posted 02 September 2021 - 10:06 AM

Moving to Cats & Casses.

 

smp



#3 Mike G.

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Posted 02 September 2021 - 01:36 PM

well, you broke the first rule of Telescope Ownership - Never shine a flashlight on the optics!  that said, if it was me, I would not be concerned although I would likely wait a while until some additional dust/grime/insect droppings/pollen accumulate then clean it.  the coatings on modern telescope optics are actually pretty durable and as long as you don't drag anything solid across them, you can clean them quite safely with alcohol, etc.  see the numerous threads on this.

 

additionally, I have 3 SCTs, all with various imperfections on the correctors.  scratches, swirls, coating loss, none of that affects the image.  my C6 has the most imperfections, with a flashlight it displays all kinds of little spots and scratches yet it's the scope that gets the most comments from others about how great the image is.

 

put your flashlight away for now and just use it.  when it gets noticeably bad, then clean it.


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#4 ny65

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Posted 02 September 2021 - 01:42 PM

well, you broke the first rule of Telescope Ownership - Never shine a flashlight on the optics!  that said, if it was me, I would not be concerned although I would likely wait a while until some additional dust/grime/insect droppings/pollen accumulate then clean it.  the coatings on modern telescope optics are actually pretty durable and as long as you don't drag anything solid across them, you can clean them quite safely with alcohol, etc.  see the numerous threads on this.

 

additionally, I have 3 SCTs, all with various imperfections on the correctors.  scratches, swirls, coating loss, none of that affects the image.  my C6 has the most imperfections, with a flashlight it displays all kinds of little spots and scratches yet it's the scope that gets the most comments from others about how great the image is.

 

put your flashlight away for now and just use it.  when it gets noticeably bad, then clean it.

smile.gif Thanks! I like the rule and see that it makes a lot of sense. I wasn't worried about it per se and was perhaps more curious. I should have been more clear that I wasn't intending to clean the corrector plate (the second graf seems to sort of imply it when I read it again). It certainly doesn't impact the optical performance of the scope and I don't expect dust/fingerprints building up to an extent that it starts impacting the optics any time soon.

 

The flashlight was inadvertent, BTW. I was rooting around the mount to close up for the night and saw this by chance...

 

Appreciate your input.



#5 sevenofnine

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Posted 04 September 2021 - 07:04 PM

I've broken the "Rule" many times smirk.gif I can't help myself...There is one glove mark on the mirror of my Orion Apex 127. It happens but I doubt it effects the view through the scope. waytogo.gif


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#6 ny65

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Posted 04 September 2021 - 07:16 PM

I've broken the "Rule" many times smirk.gif I can't help myself...There is one glove mark on the mirror of my Orion Apex 127. It happens but I doubt it effects the view through the scope. waytogo.gif

Yeah, it's more of a nagging thing that some ugly fingerprint is marring the otherwise nice corrector plate - pretty much zero effect on the view (other than the one looking in with a flashlight grin.gif).


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#7 teashea

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Posted 04 September 2021 - 08:09 PM

Yeah, it's more of a nagging thing that some ugly fingerprint is marring the otherwise nice corrector plate - pretty much zero effect on the view (other than the one looking in with a flashlight grin.gif).

I can understand that.  I could not tolerate that.


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#8 alphatripleplus

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Posted 05 September 2021 - 07:49 AM

I've never seen fingerprints on the inside of the correctors of my SCTs, but a flashlight does reveal dust. Fortunately, no real impact on performance as others have mentioned.


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#9 ny65

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Posted 05 September 2021 - 09:24 AM

I've never seen fingerprints on the inside of the correctors of my SCTs, but a flashlight does reveal dust. Fortunately, no real impact on performance as others have mentioned.

Thanks. It was a bit odd in that it surfaced only the scope had cooled down for 4-5 hours and didn't show up when it then warmed back up to indoor temp. The only thing I'm reasonably sure of is that I did not touch the front of the plate; also, it was close to the rim, which is a bit harder to get to due to the raised edge of the OTA.

 

No harm, no foul, I guess, since it doesn't have an effect on the view - it was more of piqued curiosity...



#10 Asbytec

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Posted 05 September 2021 - 10:08 AM

Run the print through the automated finger print identification system. :)

I've seen huge smudges and sleaks completely covering my meniscus the day after an outreach. I asked the kids not to touch the glass. A good cleaning was in order, if only for my own edification.

As for the no flashlight rule of thumb, I use a flashlight to clean my meniscus hoping I won't see smudges when I do shine shine a light down the tube. Inevitably, we'll do that and there's gonna be a smudge.
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#11 ny65

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Posted 05 September 2021 - 10:26 AM

Run the print through the automated finger print identification system. smile.gif

I've seen huge smudges and sleaks completely covering my meniscus the day after an outreach. I asked the kids not to touch the glass. A good cleaning was in order, if only for my own edification.

As for the no flashlight rule of thumb, I use a flashlight to clean my meniscus hoping I won't see smudges when I do shine shine a light down the tube. Inevitably, we'll do that and there's gonna be a smudge.

lol.gif I don't know whether the perpetrators will be in a fingerprint DB - my outreach has primarily been family - though the search radius will be quite limited due to this!


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#12 Cpk133

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Posted 05 September 2021 - 05:56 PM

I accidentally touched a brand new filter once.  I inspected it with a flashlight and thought, cool, no sign of anything.  Huff just a smidge of moisture and there it is, nice big fingerprint.  Probably not going to hurt anything if its just left alone until a more serious cleaning is needed.


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#13 ny65

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Posted 05 September 2021 - 08:12 PM

I accidentally touched a brand new filter once.  I inspected it with a flashlight and thought, cool, no sign of anything.  Huff just a smidge of moisture and there it is, nice big fingerprint.  Probably not going to hurt anything if its just left alone until a more serious cleaning is needed.

I think you are right - must have been the condensation with the temperature drop that showed it up nicely. If it is on the inside, I wouldn't dare taking it apart anyway, so it may be there for ever laugh.gif, hopefully continuing to remain unobtrusive!


Edited by ny65, 05 September 2021 - 08:12 PM.

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