Gino Arcari Posted May 25, 2013 Share Posted May 25, 2013 hey folks! i have recently bought a celestron cpc 800 in an auction that had been previously been previously used as a show display item, when i got it home i noticed that there are weird marks on the inside of the front glass, it looks like dew but im not sure, what should i do about it because its making my images a bit burry thanks for your help, Gino Link to comment Share on other sites More sharing options...
nightfisher Posted May 25, 2013 Share Posted May 25, 2013 you may have to remove the front corrector plate and clean it with baader fluid and micro fibre cloth, there is a bit of a knack to removing the front plate, plenty of threads on here regarding it, have a look with the search feature, if i get time later i will post a couple of linkstry this for startershttp://stargazerslounge.com/topic/92979-corrector-plate/page__hl__+cleaning%20+c8#entry918901 Link to comment Share on other sites More sharing options...
Vince1963 Posted May 25, 2013 Share Posted May 25, 2013 Hi just to add to Jules thread Here is a link for a C14, But i would say there both the same procedure. Just take your time and be careful, I would like to know how you got on as i may need to do the same at some time Link to comment Share on other sites More sharing options...
umadog Posted May 25, 2013 Share Posted May 25, 2013 As the others say, maybe you need to clean it off. But before you go doing that, what reason do you have for thinking this mark is making your images blurry? I ask because perhaps it's not doing anything much at all other than creating concern when you look at it. Link to comment Share on other sites More sharing options...
LukeSkywatcher Posted May 26, 2013 Share Posted May 26, 2013 I agree that it does look like residue left over from dew on the inside of the corrector plate. However as umadog says, that may not be the cause of blurry images. The scope is secondhand and if the previous owner let the corrector get like that, then there is a good chance that the scope could be out of collimation. This would cause blurring more then the "water marks" on the corrector plate. So before you go removing the corrector plate to clean it, at very least check the collimation of the scope. Link to comment Share on other sites More sharing options...
bingevader Posted May 26, 2013 Share Posted May 26, 2013 I agree that it does look like residue left over from dew on the inside of the corrector plate. However as umadog says, that may not be the cause of blurry images. The scope is secondhand and if the previous owner let the corrector get like that, then there is a good chance that the scope could be out of collimation. This would cause blurring more then the "water marks" on the corrector plate. So before you go removing the corrector plate to clean it, at very least check the collimation of the scope.I think Paul is probably right.Optics can get pretty bogging before they impinge on your views.It may look unsightly, but I'd try collimating the 'scope accurately before taking it apart.Cheers Link to comment Share on other sites More sharing options...
Gino Arcari Posted May 26, 2013 Author Share Posted May 26, 2013 thanks to all of you for your replies, the reason i have to believe that my image is blurry is that i can notice a big improvement in the sharpness when i look through my skywatcher 127. when i say the image is "blurry" i dont mean very very burry, i'll admit the image is quite good but my smaller 127mm is much sharper..i just had a look at an LED light through it and it looked collimated, i will double check tonight on a star. if it happens to be that the dew is whats making it blurry then i will take it in to a shop to have it cleaned, i really dont want to risk doing it myself Link to comment Share on other sites More sharing options...
LukeSkywatcher Posted May 26, 2013 Share Posted May 26, 2013 thanks to all of you for your replies, the reason i have to believe that my image is blurry is that i can notice a big improvement in the sharpness when i look through my skywatcher 127. when i say the image is "blurry" i dont mean very very burry, i'll admit the image is quite good but my smaller 127mm is much sharper..i just had a look at an LED light through it and it looked collimated, i will double check tonight on a star. if it happens to be that the dew is whats making it blurry then i will take it in to a shop to have it cleaned, i really dont want to risk doing it myselfI seriously doubt that the blurry image is being caused by what looks like watermarks. If it was grease or something similar then maybe that would be a factor, but it doesnt look like grease to me.Also i dont think comparing the view between a 127 and an 800 is an indicative way of diagnosing the problem. Eyepieces that you use for the 127 may give sharp views etc, but they may not work as well in the 800. I would absolutely say check and double check the collimation in the scope before cleaning or taking it back to be cleaned (you will be charged).Can you take an image through the 800 and post it here. Link to comment Share on other sites More sharing options...
Peter Drew Posted May 26, 2013 Share Posted May 26, 2013 I agree with the other comments that the degree of whatever deposit it is, shouldn't significantly blurr the image, I've had good SCT performance with "wall to wall" light dewing of the corrector, just a slight dimming. Beats me how a display model could get into this condition. Link to comment Share on other sites More sharing options...
Gino Arcari Posted May 26, 2013 Author Share Posted May 26, 2013 how do i upload the photos? Link to comment Share on other sites More sharing options...
LukeSkywatcher Posted May 26, 2013 Share Posted May 26, 2013 Beats me how a display model could get into this condition. I agree. I think it is not a display model be a scope that was sold to the store by a previous owner. Link to comment Share on other sites More sharing options...
LukeSkywatcher Posted May 26, 2013 Share Posted May 26, 2013 how do i upload the photos?When posting a reply, click on the FULL EDITOR button on the bottom right and then UPLOAD FILES.Click on the images you want from your hard drive and then attach them. Link to comment Share on other sites More sharing options...
Gino Arcari Posted May 26, 2013 Author Share Posted May 26, 2013 i took the photos and was weirdly surprised that the images seemed to be the opposite, the 800 was sharper than the 127, confused??? Link to comment Share on other sites More sharing options...
LukeSkywatcher Posted May 26, 2013 Share Posted May 26, 2013 i took the photos and was weirdly surprised that the images seemed to be the opposite, the 800 was sharper than the 127, confused??? So the image you took of the rooftop with the 800 (with the watermarks) is sharper the the same image with the 127?, no shock there. If that image taken with the CPC 800 that has the watermarks..............i cant see a problem. However those images were taken during the day. I'd like to see an image taken at night...................say using the Moon, just to check the collimation. Everything so far looks fine and i go back to what umadog said.....................you could be worrying about nothing. Link to comment Share on other sites More sharing options...
foundaplanet Posted May 26, 2013 Share Posted May 26, 2013 Have you been giving the 800 enough cool down time, it will take longer to cool than the 127. Link to comment Share on other sites More sharing options...
LukeSkywatcher Posted May 26, 2013 Share Posted May 26, 2013 Have you been giving the 800 enough cool down time, it will take longer to cool than the 127.True. An 8" SCT will take a good hour to cool down. You will also need some kind of dew prevention system installed for the scope (even during the summer). A simple homemade camping mat dew shield will do, or a heated dew strap and controller. SCT's are a magnet for dew. Essentially, i dont think the watermarks on the corrector plate are the issue. Its more of a collimation,cool down time issue. It may even be down to daily atmospheric conditions. Link to comment Share on other sites More sharing options...
Gino Arcari Posted May 26, 2013 Author Share Posted May 26, 2013 yeah okay,thank you, tonight i will take a photo of the moon with it and upload it, and yeah that could be part of the problem with the cooling down, Link to comment Share on other sites More sharing options...
umadog Posted May 26, 2013 Share Posted May 26, 2013 There are plenty of reasons for the larger scope producing blurrier planetary views than the smaller one. Longer cool down is one. Greater sensitivity to poor seeing is another. Collimation is a third. I don't imagine the defect you show in your first post could cause the views to be blurry. Fix the other stuff first before you worry about the mark. Link to comment Share on other sites More sharing options...
Gino Arcari Posted May 26, 2013 Author Share Posted May 26, 2013 Thank you all for your help..I will take a picture soon of the moon with my 800 and post it ...I'm only 15 so i don't have much experience with astronomy with big telescopes.. this forum is really helping me out Link to comment Share on other sites More sharing options...
umadog Posted May 26, 2013 Share Posted May 26, 2013 A star test would be more useful than the moon photo. The star test is not only capable of telling you if the collimation is off but will also, if you know what you're doing, diagnose optical imperfections. The moon photo, on the other hand, has the potential to look blurry for various reasons e.g. collimation, seeing, camera shake, etc. Link to comment Share on other sites More sharing options...
Gino Arcari Posted May 26, 2013 Author Share Posted May 26, 2013 Thank you very much, on my next clear sky I will take a photo of a star with it. Is there a way we can add eachother as friends so I can send you the photos when I'm done? Link to comment Share on other sites More sharing options...
umadog Posted May 27, 2013 Share Posted May 27, 2013 You can photograph focused stars, but slightly out of focus is better. Here's why:https://www.willbell.com/tm/tm5.htmhttp://geogdata.csun.edu/~voltaire/tmb/tmb4.htmlhttp://www.telescope-optics.net/star_testing_telescope.htmYou can PM photos, but it's better to post them on the forum so more people can provide input. Link to comment Share on other sites More sharing options...
Vince1963 Posted May 27, 2013 Share Posted May 27, 2013 I Also heard that these marks are from the grease in the baffle plate (i think or some other mechanism ) when the scope as got hot. I have now discovered that i have the same problem and i have only had the scope a couple of months. What i want to know is is this acceptable after spending such an amount of money?. (I will start another thread about this) Link to comment Share on other sites More sharing options...
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