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Hi, I have an Esprit 100ED with what I believe to be some really bad collimation. I initially thought it was due to my filters but I was able to confirm that the issue persists across different camera+filter combinations and I'm not seeing any issues on a separate telescope with the same imaging setup. Is anybody familiar with this halo patterns around the bright stars and is it possible to fix without sending it to Skywatcher? If I do have to send it in for repairs, anybody know what the process for that is (US based)? Using a laser collimator, I was able to confirm that the laser is off-centered by several millimeters as well. Thanks in advance! Ivan   |
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I just bought the Esprit 100 ED a few months ago. My understanding is that refractors rarely, if ever, need to be collimated. Have you ruled out bad seeing, turbulence and moisture in the atmosphere? Here's an image taken with same scope. The brightest star, HD 37403 (arrow), has a similar look to yours. I assumed it was normal and it doesn't bother my eye. I'm not an expert by any means, just a beginner, but is it possible your stars are overexposed?  |
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I just bought the Esprit 100 ED a few months ago. My understanding is that refractors rarely, if ever, need to be collimated. Have you ruled out bad seeing, turbulence and moisture in the atmosphere? Your stars look very round to my eye, I would think poor collimationj would produce stars that are not so round. Here's an image taken with same scope. The brightest star, HD 37403 (arrow), has a similar look to yours. I assumed it was normal and it doesn't bother my eye. |
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| Have you contacted Skywatcher and discussed with them. They have fairly good customer service, at that was my experience a couple of years ago. |
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Collimation would affect star shape. Halos I think would be from something else, dew on lens, incorrect focus, or wrong backfocus, reflections from something in your imaging train. I use my Esprit 100 ED with the field flattener and have never seen this type of halo. Refractors can be collimated but I would not try unless you really know what you are doing, I would let the factory do that. Could be atmospheric if really hazy or foggy that night, so try on another night perhaps? Good luck. John |
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| I don't see it as being mis-collimated at all or you would end up with different star shapes. It is just that you off-axis stars suffer from clipping of the marginal rays. This thing has been discussed in a recent post, so no need to be worried about. |
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Jerry Gerber: That was my belief as well but seems that eventually collimation can be necessary after several seasons of heat/cold. I'm using dew heaters so don't think that might be an issue. I don't recall what the conditions were when I first noticed it last month but yesterday's conditions were for sure not the best. I'll have some good nights coming up this week and will have ready this Esprit and a redcat so I can compare with the same camera+filters. The brightest stars might be a bit overexposed but at least comparing with other similar setups and same targets on here, it doesn't seem that they were getting similar results. Nonetheless, I'll try shooting/integrating much shorter exposures. Have you contacted Skywatcher and discussed with them. They have fairly good customer service, at that was my experience a couple of years ago. I haven't yet but I definitely should at this point. Do you recall who you talked to or would suggest just contacting the NA support email? Collimation would affect star shape. Halos I think would be from something else, dew on lens, incorrect focus, or wrong backfocus, reflections from something in your imaging train. I use my Esprit 100 ED with the field flattener and have never seen this type of halo. Refractors can be collimated but I would not try unless you really know what you are doing, I would let the factory do that. Could be atmospheric if really hazy or foggy that night, so try on another night perhaps? Good callout on not attempting to collimate myself (might be why I can't find any documentation for it). Backfocus should be correct as I have a pretty standard setup with just an ASI2600MM + filter wheel and I'm using the recommended adapters and included field flattener. Also using an EAF with good focus curves. Haven't fully ruled out bad seeing yet but never saw anything similar on any of my other telescopes before with the same camera even on not great nights. |
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I did find this article specifically about an Esprit 80ED where the O-ring had to be replaced... http://interferometrie.blogspot.com/2014/08/esprit-tuning-how-we-finetune-esprit80.html Looking at their before images, it pretty closely matches what I'm seeing. |
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| In my opinion I don’t think it’s collimation issue. I use to have a sky watcher 100ed quad lens. It was the bane of my life and collimation could only be resolved by sending it to china |
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| Would have to say the Esprit 100ED plus flattener I received works really well, especially for the price range. Perhaps a QC or other issue that can be resolved. My 2 cents. |
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andrea tasselli: Do you recall if this is something I just have to get used to with this telescope? A search for similar equipment targeting M45 gives me some hope that it should be possible to have cleaner halos around bright stars. https://www.astrobin.com/search/?q=&subject=M+45&telescope=esprit&camera=2600mm&date_published_min=2011-11-09&date_published_max=2023-01-11&sort= |
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| I just called the support number. Don’t rule out filters, some do exhibit some fairly significant halo issues with bright objects, I haven’t had an issue with my Optolong LRGBHaSiiOiii. I have read that users have com-lained about Baader and Antlia warns of possible halos on their web sites. I did have a similar effect with Navi (gamma Cassiopeia) in IC63 which is very bright/completely saturated on the exposures I used to get the dim nebula. It is so bright that Star Exterminator/Starnet cannot remove them from tge starless images unless you shoot some very short exposures just for the stars. |
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Would have to say the Esprit 100ED plus flattener I received works really well, especially for the price range. Perhaps a QC or other issue that can be resolved. My 2 cents. I was just looking at your Horsehead nebula and I agree that yours seems to be working fairly well! At least I'm not seeing similar issues to mine. Pretty similar setup other than the filters but have seen the same effect on two different brands of filters + camera combinations. Right, might be worth sending out to SW if at all possible. |
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I just called the support number. Don’t rule out filters, some do exhibit some fairly significant halo issues with bright objects, I haven’t had an issue with my Optolong LRGBHaSiiOiii. I have read that users have com-lained about Baader and Antlia warns of possible halos on their web sites. I did have a similar effect with Navi (gamma Cassiopeia) in IC63 which is very bright/completely saturated on the exposures I used to get the dim nebula. It is so bright that Star Exterminator/Starnet cannot remove them from tge starless images unless you shoot some very short exposures just for the stars. Thanks, I'll try that out tomorrow. This was with a set of Chroma filters which should supposedly reduce halos fairly well. And I initially thought that was the issue, but so far it seems more like a telescope issue. Planning on preparing my redcat 51 rig to easily swap imaging systems between both this weekend. Fairly sure it shouldn't be an issue I had seen with them in the past but worth testing on the same night. |
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Also worth pointing out that I only included Lum filter frames since its more noticeable but seeing it across all filters. Here is an Oiii shot and an 11-hour integrated image as well. Not unfamiliar to Oiii halos but these looked different to what I'm used to which raised some red flags for me.   |
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Do you recall if this is something I just have to get used to with this telescope? A search for similar equipment targeting M45 gives me some hope that it should be possible to have cleaner halos around bright stars. https://www.astrobin.com/search/?q=&subject=M+45&telescope=esprit&camera=2600mm&date_published_min=2011-11-09&date_published_max=2023-01-11&sort= You got to get used to it, as we all have. It just cames with the thing. I have it on several lens too. If it doesn't show in pictures (and the ones I've seen do) it is because either the aperture was masked or because they minimized it in post-processing. My advice to you don't waste your time dealing with SW or get an AP. |
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What you see here is not a collimation issue, but definitely a halo from filters I think, but combined with something giving an asymmetric spike on top of it. The last one can be the result of an O-ring in the lens holder having some small opening in the O-ring ( so it is not a real closed ring , but one with somewhere a small disruption). Look at the lens and try to find it. If so the only thing you can do is having the ring replaced by SW or a dealer who can do this ( see link of ivnlpz above). Or accept it. This will only manifest on bright over-exposed stars. I face the same problem with an Esprit 100ED I bought around 2016, I did not touch it, just left it like that. I thought the problem was solved later on. When did you bought yours? The same can be seen with Newtonian having additional diffraction patterns due to the holders of the primary mirror. This can be ( easily) solved by adding a rubber ring over the primary mirror: https://teleskop-austria.com/Blende150 |
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Your problem appears to be pinched optics caused by cold weather. This is a well known issue with the Esprit line. Here are a few discussions, although you will find many more when searching: https://stargazerslounge.com/topic/345575-esprit-100-pinched-optics/ https://stargazerslounge.com/topic/373510-how-common-is-pinched-optics-in-the-winter-on-esprit-apos/ On my Esprit 80 I wrap a dew heater around the tube near the objective lens and another around the corrector, with decent results. There are also mechanical fixes that involve opening the cell, which I haven't tried. |
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I have been told that the two wedge-shaped aberrations in the star halos are due to something obstructing the edge of the light cone, like Andrea said above. I have not seen this problem with my Esprit 100ED, but I have seen it when I put a crude dew shield on my C11 EdgeHD that wasn't quite round. If you have the filters held in place by little plastic washers, I'd start looking at the possibility that one of those washers is intruding into the part of the light cone that hits the sensor. If the filters are mounted and the edges are perfectly symmetrical, then look elsewhere for something jutting out into the light cone. With my Esprit 100ED, I get halos in green and blue with my old Baader filter set. Just switched over to Chroma ($$$  ) and there are no halos to speak of. I have heard Astronomik is just as good, but filters are only 1 mm thick. With the new Chromas, I found two red spikes on a couple of bright stars in my initial testing. Again, I think it is the washers that hold the filters in place, and only the red filter is affected in my case. I may have to open up the filter wheel and adjust those washers on the red filter.With my Esprit 100ED, the pinched optics in cold weather produce six-pointed stars. If you zoom in on the stars and see hexagonal symmetry in the halos, it's the pinched optics thing. I bought the Esprit 100ED specifically for use in cold weather when the corrector plate of my C11 EdgeHD quickly gets frost on it, so it was a disappointment to find out the Esprit also has a problem below 0 degrees C. I've decided to just live with the six-pointed stars because I don't get many good imaging nights in the winter anyway. |
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| I haven't read all of the comments, but when I purchased my Esprit 100 it had similar spikes around the large stars. I don't really know, but I thought that it had to do with the spacers. After several months of communications with Sky Watchers, and some pretty pointed e-mails from my side, Sky Watchers finally agreed to replace the telescope with another one. The new one was much better. |
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Dominique Callant: From what I could find, looks like you might be somewhat right. I still think its some fault with the telescope and not the filters. I'll need to test it without any filters at some point. I also found that the same company that made that article about the Esprit O-rings, does offer to fix it on the Esprits they sell: https://teleskop-austria.at/TelTest-3_TELESKOPOPTIMIERUNG-Tuning-und-Uberprufung-von. Been meaning to reach out about shipping it out to them but sending to Austria from the US is probably not cheap at all... Your problem appears to be pinched optics caused by cold weather. This is a well known issue with the Esprit line. Here are a few discussions, although you will find many more when searching: Interesting - I'll try bumping up the dew heaters way up to see if it makes any difference. I'm in central Texas so the winters don't get anywhere near as cold as other places (tonight its 53F and its cold to me). Thanks for the suggestion! It'll also be interesting to see how bright stars look in the summer. I have been told that the two wedge-shaped aberrations in the star halos are due to something obstructing the edge of the light cone, like Andrea said above. I have not seen this problem with my Esprit 100ED, but I have seen it when I put a crude dew shield on my C11 EdgeHD that wasn't quite round. If you have the filters held in place by little plastic washers, I'd start looking at the possibility that one of those washers is intruding into the part of the light cone that hits the sensor. If the filters are mounted and the edges are perfectly symmetrical, then look elsewhere for something jutting out into the light cone. Sorry to hear that you're running into a similar issue with your Esprit! Not sure where you're located but if its anywhere near Austria, I wonder if this might be an option for you? https://teleskop-austria.at/TelTest-3_TELESKOPOPTIMIERUNG-Tuning-und-Uberprufung-von. My ZWO EFW doesn't use those plastic washers around each individual screw but instead like a plastic gasket all around the filter. I think its very likely the O-ring in the telescope itself, but will need to do more testing without the filters to rule them out. |
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I haven't read all of the comments, but when I purchased my Esprit 100 it had similar spikes around the large stars. I don't really know, but I thought that it had to do with the spacers. After several months of communications with Sky Watchers, and some pretty pointed e-mails from my side, Sky Watchers finally agreed to replace the telescope with another one. The new one was much better. Glad to hear that you were able to get it replaced! Gives me some hope! I've emailed SkyWatcher several days ago but I've yet to hear anything. Did you end up having to show proof of purchase or anything like that? I bought it used on CN so it might end up being a blocker for me, unfortunately. |
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I purchased new so I had all of the receipts. Your seller may have the receipts, I don't know what I would do in that case. I also had to do a lot of tests and send them images and that took a long time because the weather was not cooperating. In the end it was clear that it was the telescope and nothing else. Some of the tests involved turning imaging train to see if the optical things (camera, field flattener) were at cause. Someone mentioned pinched optics, and I've heard that term relating to this telescope, it may have been "pinched optics". Once it was clear that it was the brand new telescope, I had to get nasty, in the nicest possible way, and it was replaced. Julie |
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Thanks, I'll try that out tomorrow. This was with a set of Chroma filters which should supposedly reduce halos fairly well. And I initially thought that was the issue, but so far it seems more like a telescope issue. Planning on preparing my redcat 51 rig to easily swap imaging systems between both this weekend. Fairly sure it shouldn't be an issue I had seen with them in the past but worth testing on the same night. One thing I should mention (forgot about it since it's not an issue anylonger). The SkyWatcher focuser on the Esprit 100ED is "OK" for values of OK, but not great. With the short OTA tube, the focuser (w/Field Flalttener installed) has to extend around 2/3-3/4 of its full stroke extension to get to the focusing point. That, with an imaging rig (OAG/EFW/Camera) installed is a lot of leverage against a focuser that is more appropriate for visual. It WILL sag with gravity as the scope follows an object during an imaging session and while it is not much it is enough to affect star shapes toward the edges (I also noticed it with some off center halos around very bright stars when using the Optolong L-Extreme filter). Since I wanted a reliable field rotator and didn't have the back focus space to install a separate unit, I opted for the MoonLite Express Nightcrawler focuser. It is built like a tank compared to the OEM focuser, plus it uses very heavy duty extension spacers between the OTA and focuer to keep hte focuser stroke short (less leverage). It is rated for about 10 lbs more payload weight than the OME focuser, if I remember correctly. You can see them installed on the OTA's on AmyAstro's YouTube channel - she has put them on all of her OTA's - given the cost that is a significant investment. As a comparison of focuser performance, I started out with a Pelican FocusCube2 (using its universal bracket to install on the OEM focuser). It worked well, maybe not quite as precise as the Nightcrawler although that could have been the drive train for the OEM focuser as much as it was the FocusCube. If you decide to go that route, I think you will be quite happy with change. I do want add one thing since it is a new scope, should you decide to just return it. For very close to the same price point there are options that are, based on company reputation, of much higher quality. Both the Takahshi FSQ106ED and the Stellarvue SVX102T are very close in price point to the Esprit 100ED. Both companies have a reputation for telescope optics that are a step above almost everyone else. Stellarvue has the advantage of being US made (if that matters). The Tak is a bit faster than the Esprit with an F5.0, while the Stellarvue 102T is an F7.0. Both have larger image circles with the FF installed than the Esprit (40mm). That only matters if you are considering a full frame camera at some point or wish to install a field reducer/flattener. Optical physics mean that the image circle will be smaller by some amount than the image circle with just the field flattener. In the Esprit 100ED the Starizona field reducer also reduces the image circle to 30mm which does result in some vignetting with an APS-C size sensor like the ASI2600 camera series. At my last check, Skywatcher does not make a FR for the Esprit 100 or 120/150. The unreduced 40mm image circle will likely exhibit some vignetting with a full frame sensor camera and it would be more severe with the reducer installed. Both the Tak and Stellarvue has image circles in the 43-44mm range so slighly larger. (I think the image circle champ is the Stellarvue SVX152T with an image circle of 90mm... ;-) ) |
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| I will admit, I did not read everything here -- but I wanted to state that you cannot use in focus star images to make decisions about collimation of the optics. |
