GalaxyGael

Ah, I did misunderstand or misread, apologies. Maybe recent sales on astromart or astro buy sell might give you an indication on the likely price for a similar state 190MN. Likely a few historicals on ebay also as in indication.

show this. For sale by APM in Germany. Mount, pier and car are extra !! I mean... Addams family portable setup https://www.apm-telescopes.net/de/6-f24-lichtenknecker-halbapo-refraktor

Well, you can get one brand new for 1750-1800 EUR, so with conversion you can see how well 1300 GBP is. Sounds a bit steep to me (maybe?) unless it is in near perfect condition. Imaging versions can often be well loved since they are biggish and most I known keep them in the lonely cold in personal observatories (depends on climate too though). Does it have any upgrades, like a change to the focuser? No need to change that for visual use though really. It does hold collimation well. Visual or imaging for yourself?

The mak newt is fantastic, and rarely will you find a focal length of a meter at f/5.3, and without requiring any correctors. The law of conservation of benefits has balance though😊. Collimation is not like a Newtonian, as much as you will read. Principles are similar but a mak newt has one golden rule that newts dont need to satisfy in perfect Collimation: the front corrector and the primary mirror must remain parallel to each other while being centered with the eyepiece. That means limiting tilt of the primary, never moving the secondary up and down the tube and using only focuser lateral movement (mak newts allow for this) to sort out the offset and centering. In a perfect mak newt, tilting of the mirrors is not needed, just focuser offset and secondary rotation. Anyway, the butt of this is to make sure whoever had this scope did not use classical newtonian approaches to collimate and that they did not move the secondary up and down the tube. If not and alignment is close and optics look good, it's a great scope of you can handle the size and weight. This method clearly outlines the crux of the mak newt needs compared to a newt, in case it's needed. https://www.cloudynights.com/articles/cat/articles/collimating-a-maksutov-newtonian-with-a-howie-glatter-laser-collimator-r3377

Hope I am in the right sub-forum for this request... I have an old but good 90 mm f/6.67 apo triplet and would like the whole lens cleaned, reassembled, centered and collimated again so that I can screw the cell back on to the OTA. Is there a service such as Esmond Reid where that could be done? Much prefer to do this than get a new apo, and not many f/6.67 90 mm triplets around anymore. I'm sending from Cork, but dont mind where within reason. Cannot find such a service online. CS everyone

Looks like astrotech have a version and accordingly will tecnosky and a bundle others. The Tecnosky version is available now https://www.tecnosky.eu/index.php/prodotti/telescopi-e-ota/apo-sld-110-f-4-8-fcd100-owl-pro-series-tecnosky.html They seem to be variation on the OWL/CF APO/GEAR etc. etc. design, the 110 looking like a short tube based on the 90 mm scopes, with inbuilt 4 element flattener rather than separately screwed on. Maybe there is a difference in reducer/flattener configuration, but pricey perhaps. Its a tidy looking instrument and if long perng will hopefully be well made like the current triplets. Spot diagrams look good and frontal cell tilting is there. The 102 triplet come with 3.7 in focuser as standard, but the 528 mm focal length at f/4.8 is enticing - almost band on the fsq values.

There isn't one really in practice, it's a darling sensor at the moment and one of the best in the OSC flavour, with something wide and fast or long integration to replace lrgb for some people. It's a camera used by all levels of experience and good enough for essentially all focal lengths, running the gamut between as captured undersampling and rank oversampling...and people can still process the data well in all cases. File size for DSO lucky imaging might be an issue but looks like that's not an issues for you, so enjoy the imaging. I love mine, but also like my atik 460ex OSC too, and love it even more so with my 300mm 60 mm scope at 3 "/px. Lovely smooth bright images, with fov being the only real difference for me in reality between the two cameras and the weight difference (I like that tank of a cc'd camera and I have it so I use basically). The 2600 at aps c has the fov benefit. Tilt plates better than the zwo one readily available, and the risingcam and omegon version are solid, as is player one version from what I have heard. Zwo is handy if you want to use asi air. Get a bucket load of data regardless of your skies and you'll be hard pushed to find a different camera that will be better in a way that is stark, or at all, my 2c.

Love it. Remind me, tangentially of course, of a curmudgeon academic we suffered many moons ago: Why do it the easy way, when you are able to do it the hard way.

Lovely, and that brings another topic up, maybe for the Lounge forum through. Astro gear patina. I wont sell my lovely figures 90 mm f/6.67 triplet since its still lovely to use but has black alu hardwear (dew shield rim and back, rings, etc.) that in the sun, wind and the odd drizzle has oxidized to that lovely browny/gold color. Your rings and dovetail look like they owe you nothing, well -loved and I hope not used in anger...

If it works, it works! although it poked me to daydream a kind of wallace and grommit mechanism of an imaging setup with twine, clamps, gizmos and cogs compensating for all sorts of issues together.. .!

that could be an option. What I must do is check whether the 1 mm thickness difference is on the main OAG block, or the adapter that clamps into it. Together, the unit is off by 1 mm. If its the adapter, and the OAG is sound, I might go your route or similar

HI Lee, I just posted on a related topic since I had slightly stretched stars in a quint FRA300 and I knew my guiding, sensor squareness, polar alignment etc. were OK. Issue in my case was caused by the OAG having a difference in thickness of 1 mm! If you're friend notices this same tilt after rotating the imaging train and also proving there is no sag from imaging either size of meridian compared to being at zenith, then maybe check the consistency of thickness of any adapters being used - just a thought. It does look like classical too far from the sensor issue on the left hand side, but given you have a system that is flatfielded all ready at best focus, something else is cause that side of the sensor to be a little too far away compared to the rest of the frame.

A recent set of images showed stretched stars that were, to me, awful. Given the poor weather, I could not test tilt options but I knew that my camera sensor was dead square from my laser alignment rig. This was previously tested on the Tak e-130D and gave good stars across APS-C so tilt was not the case. I also rotated the imaging train after having calibrated guiding, but tested that again and it was not the issue. Polar alignment, guiding all good (no excursions, DEC and RA both with similar rms and the guiding spread graph was a neat gathering of tight dots forming a circle). I decided to examine the imaging train and always in the back of my mind I was waiting for the OAG to cause an issue, since hot-cold working of the screws last summer loosened it during a session. It bugged me that a screwed imaging train had a three pressure screw attachment from the OAG in the train, similar to having a screwed imaging trains and then attached it to the 2 in visual back like an eyepiece. But there is plenty of evidence that such as approach is fine once everything is set square and the screws are tightened symmetrically and gently etc. Getting the the crux: the OAG was machined with a 1 mm difference in thickness around it! Thankfully I didnt try to vary the camera tilt to compensate for the non-square OAG, and just removed it. Result: perfect round stars across the frame. I nearly ended up on a wild goose chase with tilt, guiding except that they checked out. I checked thickness of all adapters and they were good to about 0.1 mm in all cases, but the ZWO OAG was way out by 1 mm. Maybe a useful tip or cautionary sanity check for someone who has odd stars - clearly some product QC in machining is not up to scratch and my first time being affected by it. Anyone know of a full screwed OAG option by the way?

And for those using OTA that cause diffraction spikes, cone error is similar to OTA rotation within the rings, changing the position of the secondary spider with respect to the sky and cause pre- and post-meridian flips to stack so that diffraction spikes don't align.

It's one of those regions with so much going on, and with a lot of beautiful stars, density, color and clustering/spreading, that you can go one of two emphasis routes. That's a lovely version though, with sweeping clouds od H alpha and dust nodules coming to the fore. With OSC and no filter boosting of H alpha, say, there is the option of the reds, browns and other tones to come through. I personally prefer the stars with nebula as best supporting actor. This is a WIP, only 4 hrs at 300 mm fl, f/5 again with OSC 2600mc. It's gone behind the houses and needs at least 10 hrs more to give the chance to stretch the background nebulosity some more to show the features - the light grey around the blue of Dreyer's, the colour within the lower knots under Dreyer's, all the dust etc and the red, magentas and blues around the cone while keeping them behind the colorful stars - well that was the plan at the start. 😊 Mind you, it might be worth playing with the processing again to see how it changes personality.

Welcome, nice to hear you like the skies with and without the scope. any sky for sale? Do you do bulk clear sky discounts? I have 4 months of Tog 13.5 clouds, looking to offload....

Here is a 120s sub of the lawnmower regions with my asi2600MC. Bear in mind this sensor has a lot of tilt, which I nearly have ironed out (there a 1 mm air gap now between the tilt plate and the camera body such was the poor assembly). Calibrated with bias and flats, no other processing, saved as png from fitsviewer. ASTAP tilt assessment of the same frame also.

Here is a 5 min sub using the ATIK 460ex OSC (GRBG pattern). I put this camera directly on the scope without testing for any tilt, so I think there is a small bit across the frame here. Mind you, the atik chip is nearly perfectly square compared to any ZWO camera I have had. Its a png file saved from fits viewer no calibration, don't have siril or other at work to separate out the RGB channels. I'll have a look for other subs when I get home on the atik and the 2600MC. This is M106 at 3.1 "/px, 60 mm aperture etc.

So far it has been good, aside from my hiccup in the first few images where I rotated framing about 70 Deg after calibrating the OAG. Very tight stars on the 3.76um asi2600mc and fully aps-c flat. I don't have any bigger chips to test. Works just lovely also with the 460ex. I'll put up some subs here when I get a chance. With the astroxap dewshield made for the meade etx 80 , I get rid of spurious light and haven't needed a dew band yet. The astroxap flocking nucleates any dew, lens is bone dry. It's spots are better than the rest of the fra line, seems to behave as designed when I separate out r, g and b channels from OSC subs

Lovely image and fully agree that keeping the stars is both nicer and adds to the image. I'm biased in that I like the stars as much or more than nebulosity. And great to see the higher end of the sampling range again. with tiny apertures, large fields etc. 4"/px in this image leaves nothing at home. I recently picked up an askar fra300 (60 mm, f/5), which is a delightful dinky scope and very well built. I use a smallish Atik 460ex sensor at the moment, at 3.1"/px and also find it great. there is a lovely 'sheen' for these sampling scales with long integration. Processing is very nice too, thanks for sharing.

Dunno, I would assume it is. There was a later interation of the SD doublets that dealt with this since the ed and sd81s and bigger sisters had awful three way dark lighthouse beams on stars. The diagrams above look like clean stars from what I can see.

Likely to be that, or a call back to Pentax afficionados... Rumor has it Tak are developing new apos, the petzval is getting old in the tooth for modern small pixel cameras, but is a treat for the slightly larger pixel options (don't buy the need for a flattener with backfocus restraints for a scope designed to avoid that). The quads and quin's from China might be waking things up and the star shape and lack aperture vignetting of bright stars are better than the baby q in the main (not to mention corrected image circle limits of the fsq85), and some Taiwanese shops have widely airspaces triplets on the go, modelling the Tak toa design as a principle (cannot say anything from my knowledge on the figuring of the lenses though). My two cents of course

That's a new one to me also, especially the black livery and, to me, decidedly non-japanese flavour hardware. I did see a 70mm ss scope, the bigger brother of the fl55ss fluorite wide field one.

Its a nice looking machine this 5 ball lens barrel (I do love reading translated japanese reviews of scopes !). My favourite remains the triplet AX103s, still waiting for international prices to come down. Wonder where the VSD90ss is targeting in terms of competitor. Still no spot diagrams yet I think, and the Askar new product mania (to me at least, even new models have gone through focuser cosmetic modifications during their announcement..) has some fairly well throughout out imaging scopes.

Interesting, thanks for the additional info. Looks like one speed but it might have the dual speed on the other side? Although the knob sure look like the older single speed, but better than the previous helical focuser and an autofocus would likely run the focus I am guessing. There's a real Pentax feel from the picture...