GalaxyGael

Thank you all. I completely missed the replies to this thread. That 115/800 scope was sent back after I showed the vendors (slow day in the lab at work, decided to use my autocollimator built for optical alignment tests of a different kind) that there was some flexure in the drawtube that they could not eliminate on the first send back. As the scope was essentially pristine, they took it back for refund which was nice of them. Went back to enjoying my epsilon 130D, then I took down my 12 year old 90 mm f/6.6 triplet (similar to CF TLAPO906 that is now discontinued and the Stellarvue SVR-90T) which has such a nicely figured lens and it seemed to work well with ASI2600MC, and I imaged a little with it for a few weeks. These two images show the slight issues with the old 2.5" focuser (a feathertouch clone no longer made). There is no lateral or vertical sag at all, but I can grab the draw tube a rotate it to allow a little movement between the rack and the gap that it moves through. Some stars elongated vertically (although dealt with in the B169 region image from stacking of both side or meridian and a slight framing change from mount position change). Found this thread again after considering the same moonlite or FT upgrade for this scope, which would deserve one I think. Here it is, 90 mm, clear and color free but with a 3M vinyl wrap to cover and protect the CF tube (don't like CF tubes!). Might look for a more classic color wrap someday. The FTF2525 R&P is very pricey, but looks the long term ticket and would also transpose to another scope down the line if that ever needed to happen. And I have the M90 adapter to put one on the scope. [The refractor stars were an antidote to the epsilon, time I admitted it to myself ;)] Still a resounding Feathertouch recommendation?

Reviving this old thread as I dealt with a similar issue. Maybe outdated, but might be useful for someone else searching. This type of reducer came in two flavours - a 4 element and a three element. The latter is more common now as the 0.79x reducer. And it works with the focal length spacings outlined above. However, if it is the 4 element one, the spacings are different (larger). That reducer usually came with a T2 spacer already screwed on, that allowed 55 mm spacing from there, i.e. the reducer + ~8.5 mm spacer that was 63.5 mm or thereabouts, much larger than the 58 mm that the three-element 0.79x reducer requires for 510-600 mm scopes (to use one example). Here is the 4 element one, with the (for 80ED) spacer attached. It specified 55 mm, when the spacer is used. Otherwise, 63.5 from the end shown in your picture. It works great with my 600 mm f/6.7 scope, but the 3 element one at the same spacing gave cross (astigmatic) stars and I had to reduce it to to ~58 mm in the 3 element 0.79x case. https://www.astroshop.eu/flatteners-correctors-reducers/tecnosky-0-8x-four-elements-flattner-reducer/p,58722

I have and love my Intes MN56. Its the old version with the pebbled greige tube, and the awful helical crayford focuser, which I used for imaging a year or more ago. I use a 90 mm apo at the moment, but getting the MN56 back into imaging mode and found this thread while trying to sort out what thread is on the focuser base. I chipped the secondary when removing the front corrector (it tilt rapidly when you start to remove it) and replaced it with a large secondary that illuminated by APS-C (ASI2600MC). It corrects well out to APS-C but as the mirror was much bigger than the secondary holder, the curved stick-out edges created interesting diffraction spikes on edge stars. I've since replaced it with a 29 mm mirror that fits, and collimation was near text book perfect again. I know i will have severe illumination fall off with the APS-C, but at ~1"/px resolution (being at or just a bit to brave for my seeing), it will be used at 760 mm for galaxy imaging with cropping, or up close work. It is wonderful in terms of color correction of course, and no spacing to deal with at focus. I think I have a better handle on imaging to get the best out of it now, so looking forward to it. It strikes me that it would be great with the player one or new asi planetary cameras, which are highly sensitive, good pixel size options and the clean dark frame and shorter exposures can deal with the noise. Stunning with an eyepiece, no newtonian I have seen is flocked like these. It even has 1 cm tall knife edge baffles opposite the focuser, and 6/7 more down the tube. Mirror cell is also great, full circumference holder, no diffraction from 3 mirror clips. I changed the small locking screws with M5 allen bolts, easier to tighten everything down. Also, weight balancing is good, between corrector and the mirror. The metallic dew shield, like the OTA, is wider than the mirror and house about 4/5 knife edge baffles also. Such a rich field view, and does give the top end 4in APO a run for the money Apologies hijacking the thread, but can anyone who has this scope (min is in the attic right now behind a lot of stuff!) tell me what the focuser attachment threads are? I remember M66.5 or something odd, but I'm searching for focusers for it. Here was mine sometime last year on the old rig way before the sun faded everything.

At that focal length you are right, but with a 0.8x reducer (I assume) to get to ~720 mm and the 3.76 um pixels on the 533 sensor gives just over the 1"/px, probably the max that seeing will allow. OP: are you interested in smaller objects like galaxies, cluster, etc. or larger ones like nebulae or...? do you guide and does it give you 0.5-0.8" rms guiding on average maybe? FOV is the limitation for the smaller player one cams if larger DSO objects with your scope are your interest. The 533 cameras with cooling and an excellent chip (one of the cleanest technology out there now for noise, amp glow etc.) are great. Second hand APS-C would be the ticket if they come up, OSC likely more readily available too. Adam J's advice on checking Astro buy and sell is a really good idea. Maybe variants of the ASI071 with larger pixels or similar options are worth considering. RisingCam, Omegon and Bresser (among othesr) make their own versions of these with identical chips. I would avoid the ASI1600 color versions based on the vagaries of those panasonic chips. If you ever want to go down the route of ASIAir control, I think you need to stay with ZWO cameras and gear.

The new player one series are quite good. The cooling is passive as opposed to set point thermoelectrically cooled below zero celsius, but the chips are very clean. If you plan to stack a lot of shortish subs, they come out very nicely. Fields of view are narrower because of the smaller chip size. There is also the option of a active air cooling system you attach to the back of the camera for about $50. the IMX533 chip is the Saturn series of their camera, same as the ASI533, color or mono. Prices are decent IMO.

Good to see Tom, and nice form factor for this size sensor. Might even be possible to use this with a RASA8, as the 2600 and 6200 ASI versions are too bulbous. The brightness of your light source might help to get the flat exposure times down to tenths of a second. These chips IMX 571 and 455 work very well with short exposure flats and bias (darks if you wish), rather than the longer flat darks and flats of the ASI1600 variants and some other camera. side note: On flats, I have found that sharpcap's flat option is useful sometimes in one regard. You can obtain a single master flat, or save of each frame if your stacking software requires it. But, you can get the flat in monochrome, with CFA bias signal included. That really helped with color balance issues in flats and the bias is corrected with the master bias. normal flats still work fine, but I found the monochrome flats to be stable in every situation.

It's a really nice image of an interesting nebula. Maybe my phone, but the slight lavender hue to the central region is nice. Reminds me of the pastel palettes i sometimes see.

The epsilon takes a ZWO EAF. There is an adapter that can be 3D printed from a freely available file on the web (I have a bunch of these) and it slots on, attached the EAF as normal. The OTA orientation will always remain the same really to maintain overlaid spikes, so nothing should change unless you are taking the scope out of its rings, which you probably don't do anyway with your other scopes. the epsilon is easier to balance when then camera et al. are point straight up, rather than pointing down parallel to the counterweight bar like most imaging newts do. You can do it either way, but pointing up for the short length of the epsilon works very well. The 107PHQ intruiged me too, but I wonder did sharpstar just lengthen the focal length to deal with the documented color issues on the FRA series, notably the FRA600. It looks to be a nice scope, although quite heavy as there is a trend for big CNC parts that give a good fit and finish, but are (I think) a little heavier than needs to be. the TS 115/800 option is another and I had that. It is light, easily carrier on your mount and you get 800 mm at f.6.9 or 632 mm at f/5.5 with the 0.79x TSRED379 reducer. That could be a good option too.

Hi Ed, I understand you, and many who like to bring nebulosity to the fore. I was curious as to whether anyone did starless processing vs stars in tact processing and saw any specific difference. Maybe some do this as its often stated as a workflow step, without processing with stars at all. Hard to call, when the main aim for an image can be different to a lot of us. Reduction etc is another matter that is more personal I think. I'm in the camp where stars are the all there and nebulosity is best supporting actor. This image of Ic1396 I took a while back keeps all the stars, and some NB folk were pleasantly surprised how many and how colourful they can be. But it's par for the course for broadband color imaging conceptually. But, their palettes and filters that suppress star intensity show a lot more nebula detail, so there's that.

Image scale as mentioned above is a good guide, and if your skies are bortle high then go down in scale from your 1.9 "/px to roughly double your average guiding rms so that you get all the resolution your scope gives you for given skies. With 2600mc, 650 mm is about 1.2 "/px and 760mm hits about 1" /px. If you look at your average star fwhm (maybe asi studio fits viewer has a star size button now), divide that value by 1.4-1.6 as a guide for your best seeing, and that might help decide the focal length and image scale. I'm guessing around 700mm will be your limit, any longer and you may not see the benefits compared to a crop ay 700mm. Then, I would decide aperture for brightness and some resolution benefit, and then the size and weight and use all these criteria to narrow down. And the there are spikes. If you don't like them, the Mn190 is great if you have the mount payload capacity and the right pixel size, or a long, expensive heavy apo. The TS 130/910 is very good, and with 0.79x reducer is about 715mm or so at f/5.5. Perfect in my view. A 6 inch imaging newt, decent one is a good option, such as the ontc range from ts which are outstanding. Or an epsilon 130d with the 1.5x extender to give 650 mm at f/5 ( there is one available, hint hint, about to put mine on the block). The f ratio for objects that will now span across more pixels compared to the FRA5. 6 is partially moot once you are above the noise and plan do long longish integrations. Its longer, but does t scale with ratio of squares of f ratios unless the focal length and pixel scale are the same. So slower f ratios are no thin to be feared unless its f/12 or something! TS also have fcd 100 106mm apos with beefy focusers at f/ 6.something. Lastly, you are osc so binning in software is an option for ~1200mm mm at bin 2, giving you the same pixel scale as 600 mm with bin 1 on the same camera.

Interesting to see the differences between everyone. I never remove stars but I image from OSC. In that case, most images I see around the place show some signs that stars were reimposed on a processed starless image even my the myriad ways of removing, processing, adding, layering etc.. My eyes seem to be 'sensitive to it' without pixel peeping the image. In other cases it can be done so it looks perfect (in those cases I only know when the workflow stated it, I could not tell from the image). Narrowband folks like reducing and removing many of them too. Depends I think on the target whether the pre-stretch removal or post-stretch removal is better. APP still provides excellent background removal, or close to as good as it can get, and it does this with stars intact in linear state so avoids blending/overlaying artefacts from some types of images with complex background and stuff behind the stars, and post stretch removal is a little cleaner once the background is flat and sorted. But as a broadband imager for all types of targets I never found a need for star removal during processing. query though: how many of you do it because it is a workflow process, and have you processed the smae images without a star removal, using masks instead. Any noticeable improvement, worsening, artifact?

That dust feature in the second one looks interesting, like some seahorse or dragon on wheels.

Of course the images look horrible in the post....should they be 2048 px at widest point? EDIT: the seem OK when clicked on.

Been a few weeks or more since I posted here. Some of my recent images where I took a fancy to some golden and silver starfields, some dusty LDNs and an experiment to image NGC 7129 while adding spitzer IR data on top. Hope you like them. 1. B142 and 143 - E nebula (50 x 120s) 2. LDN 769 (180 x 120s) 3. LDN 810 - Coalman nebula (84 x 90s) 4. M39 (123 x 90s) 5. NGC 7129 (cropped a lot, 120 x 240s) - without and with Spitzer IR data Tak Epsilon 130D with ASI2600 Mc Pro at -10C using gain 0 and gain 100 (I prefer gain 0, I think one of them has gain 100). iOptron GEM45 with ZWO OAG Right now I am using my 11 year old 90 mm f/6.6 with that nicely figured triplet that is not made anymore. Smaller stars than the epsilon, sharpest scope I have ever used. The little round stars are like a document in calm easy to read arial font, while the epsilon sometimes feels like a serif times font with all nouns capitalized 😉. That's my little analogy. I hope I got the image posting resolution OK and that the clear hot day gives you a clear night.

There a 102 APO from tecnosky that fits the bill for binos. Aperture maybe too small for your wishes, but it allow part of the rear of the tube to screw off, then you reattach the focuser to accommodate longer path length adaptions. Its the SLD apo, so an FPL53 upgrade from the standard APO from Tecnosky. Its the SLD102APO model. Focuser looks decent also, classic black and white.

Beautiful result for 1 hr in Bortle 6. How did you processes away or deal with the diffraction spike, which would ordinarily appear for some of these stars. SW have thin vanes and the spike are normally not too thick and the stars retain their circular core, but curious to know how 20 sub stack dealt with them. Lovely job.

They really are great cameras in OSC version, and you can choose exposure on the fly without (absolutely) needing darks - flat and bias working just fine. Is the 250 px newt a skywatcher dob on your mount ? Lovely M81 too, the newtonians work so well for galaxy imaging with OSC.

Very nice, clear and no oversaturation. Nice way to end the imaging year. At least, with the guide camera and the Mak-Newt, there is some nice sun spot activity...

That looks like a case for bigger dithering steps as Win said. If that image if the imaging focal length, and you are using an OAG, you can double the dither step in your software or change the scale option in PhD2 setting to 2.0, depending on whether your software has an inbuilt maximum for dithering (sharpcap wont go above 30). It looks like the random dithering directions were biased toward top left to lower right (just eyeballing). The random selection usually allows a lot more variation in the dithering, but bigger steps might sort it out for you. Are you using OAG or guidescope option at that FL?

I've not seen the red fringing on mine. I have the 3" TSRED379 reducer/flattener. Unless using full frame camera, its a bit overkill. The 2" version would be fine, any mild vignetting correctable with flats. At least with the 3" version, there are no internal reflections I can see and 55.5 mm is the right backfocus. I also got a second hand Hotech 2" flattener to image at 800 mm f/7 when I want to. when testing for tilt with the cheshire, put in into the visual back as normal without too much compression and leave the lens cap on. Remove the cross hairs on the cheshire too, might be screw out like mine. Use a flashlamp to give a good brightness to the side angled mirror on the cheshire and look through to see all greenish circles reflections are concentric with a single centre. Best to do this without any reducer in. The smaller inner circle should be centered and no displaced north, south , east or west (or some other direction) away from the centre. Start this way and see if you see anything off centre first.

Dusty regions really have some interesting nicknames. Here's my latest and my first go at a definitive dusty region. NCG 7023 and surrounding Iris Nebula. Tak epsilon 130D, ASI2600MC Pro, Gain 0 and -10C 92 x 240s (~6 hr). April 8, 2022. Processed in APP.

Very nice Wim. I have a soft spot for dwarf galaxies and curious/funny to be talking about (just) the 48 stars identified in the galaxy. There are usually more people on a bus . That one looks very faint. Leo II looks interesting too.

IC 1396 imaged over a few nights recently. Full of the dark dusty regions and captured in RGB to show the various color tones from neighboring bright stars on the nebulae. The garnet star shines on the region at the bottom, just out of frame. Takahashi Epsilon 130D ASI2600M Pro, Gain 0, -10C iOptron GEM45 with ASI290MM mini on OAG 377 x 180s (~19 hrs) Processed in APP. Reduced to 2048 px on a side (I hope this resizing works).

Always like discussions on grammar and intricacies of words and language. My supervisor years ago gave me an image like this to soften a drilling on oxford commas, semicolons and which vs that etc. I used binocular and monocular, binoculars was two sets of binocular, but not two monoculars..... No judgement is being made

Supernova SN 2022ewj - NGC 3367, comes out quite bright viz the galaxy arms for those of you with long focal lengths and the skies to benefit from its resolution. example FOV https://www.astrobin.com/akwlqf/0/?fbclid=IwAR2fpo190bvlCVhaFqLUPnrMQO46YefxRGZNtECyy4sSFsZNS-EoOjjXSqY