RebelT7i modified UV-IR @ Hutech thru a 152mm A+M Refractor(OfficinaStellare-1200mmF/L) using a TeleVue .8XReducer/Flattener for an effect of 950mmFL . Now ,,,, with the TeleVue 8mmEthos's dust and speck problem .... I took the thing apart by separating the black eyepiece end from the silvery front section which un-screws into two pieces . The silver front section is easy to clean because you un-screw the 1.25in. front section from the larger silver section part and there is a large glass in the large section that stays in there fixed and stationary and cotton balls can be used ... , ... the front 1.25in. section can be cleaned the same way and a 'bubble blower' is used to blow off the dust from the cotton balls . Here's the hard part ..... the back black section has a retaining ring that needs a small strong phillips screw driver inserted in small holes to try to get the retaining ring to un-loosen and move to you can un-screw the retaining ring to get the three glass elements and their spacers out of the black eyepiece section . " How I knew to have to do this which is hard to do because you have to carefully slide the elements out so you can see how the glass and spacers are positioned . I could see before I took them out by looking at a white washing machine cover with the top black section up-right and with a light I looked into the back of the eyepiece like when viewing and I could see the dust specks like they were floating in mid-air and they were sealed in there . That's why I had to take that section apart . I cleaned and side of each glass and used the 'bubble-blower' on them .... but the smallest glass which is the one the eye looks through must be put back into the black section ..... wearing plastics gloves and it is a tight fit and a little force is needed to put it back into it's original place which is tight against the back end . The I cleaned it a little again on the inside section and next I put the other glass sections and spacers in their correct position with a good balance because they can slide off each other easily and you must start again being careful . When ready ... you hold the black section of the eyepiece over the spacers and glass sections and lower the black section over the glass sections that you are holding in your hand and when you have in far enough ... you carefully and quickly turn over the black section while still holding the glass section with your hand so they don't fall out and then you wiggle the black section slightly and start screwing in the large retaining ring which takes awhile and every now and then you can tap lightly on the black section hoping the sections are situating correctly as you slowly tighten the retaining ring till it's almost tight and the do a few more taps and slowly tighten all the way . Then attach the silver front section and , viola . You hope you have done it correctly and it's clean . You must check for dust again at the Telescope and try some stars in a belt and hope the glass and spacers are in there correctly and you are ready to go . But , a Paracor will probably still be needed hoping to fix the coma across the images .x << I think if I try on another clear blue sky day using the Telescope and then the RebelT7i using a 2in. 'nosepiece' to do a Prime Focus shot and with a 'focus' position at a far distant horizon object and the back at the blue sky facing away from the Sun ... some 'flats' without a t-shirt covering on the front of the Telescope to then check the 'flat' frame for the above mentioned specks and large dust donuts .... and if they are there that means they are behind the 'sensor' glass and they can't be removed ... except with the use of 'flat' frames like mentioned above . It might also be possible to use this type of 'flats' on any Configuration without having to make them at a Configuration because with a mild 'flat' frame that mainly reveals the artifacts to remove them might be an all purpose Flat-DarkMaster and FlatMaster 'calibration' technique that might not add unusual vignetting to a 'light' frame using different PowerMates or eyepieces ... but something you always use might need it's own 'flats' if the specks and dust donuts can be seen using them especially if you know the artifacts are seen at just Prime Focus without any Flattener glass or filter . I DID do 'flats' and 'darks' and I made them into DarkMaster and FlatMaster frames today April 15 2022 as the PrimeFocus of my Telescope without any filter and just a 2in. nosepiece attached to the DSLR . I did eight each of the 'flats' and 'darks' for ISO400 to ISO25600 . This image was 'calibrated' with these . When I did a 'flat' I checked them and they seemed to be clean , but , after making the FlatMasters I saw there were those large faint donuts scattered about the FIT FlatMasters and those blemishes must be in the glass of the 'sensor' or coatings or the backside of the 'sensor' glass and I don't think they can be removed ; but the DarkMasters as the same exposure as the 'flats' and FlatMasters might do the trick to cleanup and image .x I did do PrimeFocus 'flat' frames on Friday during a clear bl;ue sky and when I made them into a FlatMaster I saw the same large faint dust-donuts which must be in the 'sensor' glass somehow . [[[[[ I did a "Convert Color" after the "Calibrate" with a DarkMaster that was Average and Auto-Optimize for Scaling .... but when I used the DarkMaster which still has the Bias included in it on the 'flats' for the FlatMaster , there wasn't any data in the FlatMaster . I tried making a FlatMaster without any DarkMaster and when I did a "Calibrate" the image was removed and the FlatMaster was the look of the image and total loss of the real 'light' frame . I tried for the Darkmaster 'calibrating' the 'flats' to make a FlatMaster with 'Auto-Scale' and that didn't work either . Then I did the 'flats' again with the original DarkMaster and this time I used the 'None' for the Scaling and the FlatMaster looked like a 'single' 'flat' frame . I did a "Calibrate" with the DarkMaster and the FlatMaster as 'None' for Scaling and the 'light' frame wasn't damaged . The images were done with a "Convert Color" , and after SigmaClip stacking I then did "Color Balance" with the 'Mouse' for 'Background' which made the background color look more normal . Then I did a "Resize" as 3.72microns to 6.5microns and then a "Half Size" which is a stronger Bin2 . I then used the "Kernal Filter-GaussianBlur to smooth the background around NGC2392 using 'pixels-restrictions' from 500 the about 16000 and Radius: 2 and Feathering: 3 which smooths good enough . I put the FIT IEEE Float image at Max-Val 'screen-stretch' and I used the "Digital Development-GaussianBlur: 1.0 and the two 'check' boxes 'checked' for 'Auto " ; then the "Color Smoothing as FFT Low Pass and FFT Hardness as Hard and Weight % 25.00 " . ]]]]]
