GalaxyGael

Handsome rendition and natural too. Epsilon looks to be singing. 

4 hours ago, Icesheet said:

Thanks for the informative, detailed reply. I guess my main interests at this focal length are nebulae, both in broadband and with a dual narrowband filter, and the dark dusty nebulae that have become more popular recently. As I write that, it’s  obvious I should prioritise signal over everything else. Especially, since I’m rarely collecting more than 4-6 hours on one target. Also, I notice I’m pushing my images too far when processing. The remedy to that is likely more integration time or something that collects signal faster. 
 

Interesting comments on the Tak star shapes. I was aware of the reverse lighthouse effect and it’s not something that bothers me in terms of an aberration or artefact (halos are my pet peeve). Hadn’t heard about cats eye bokeh though. Had a look online and see its inherent of the Petzval design. Is that what the new flattener was/is trying to correct?
 

I’m curious to hear of the other refractors that operate at f4.8 that you think are better than the FSQ-85. And those designed like the AP 110? (I’m in that lottery!).

 

I’ve learned that I’ll likely be a OSC man with dual narrowband filters. Tried the mono route and had so many unfinished images. I’ve also learned that weight and complexity of set up hinder me. Had an EQ6R and could never be bothered to take it out. Now have a Rainbow RST and with the Askar FRA400 I’ve never been so productive, albeit I feel I’m lacking something in my images.  

The comments here are largely pro RASA, or fast reflector of sorts. I think my main worry is that if the set up ends up being a nuisance I’ll give up. However, won’t know until I try. I think I’ll probably just sit on this until later in the year as come April the night will already be short. That gives me a chance to keep an eye on the market for a deal. 

 

 

Well, if nebulae and dust regions in wide to medium field are of interest, signal is key, and the case in particular for osc. 

Tak epsilons are among the easiest newts to collimate IMO and like Rasa, retain collimation long term. They are also almost impervious to temperature focus drift. My experience is with the steel tube epsilons, remarkable flat line hfr values all night long.

Any scope at f6 will reduce with 0.8x flattener to f4.8, whether 90mm f6 or the wide range of excellent 80mm f6 scopes.

Your fra400 can also be reduced to f3.9, just under 300 mm focal length and corrects out to aps c sensor size. Fast and wide, big chunky of sky. And it is smaller than the Rasa, so consider whether you lug it in and out for sessions, if that's matters to you. Unless the fov is a concern, can't see much better options than a reduced fra400 you already have really, apart from the f3.9 fsq85 with new reducer, but it's a big outlay for something very similar.

The TS 110flat f/4.8 is big and expensive, but slower than a reducer on your fra400, which might be the best option to see if wide field and speed is something that gives you the improvement you are testing the waters for?

The new reducer does t fix the aperture vignetting of inverse lighthouse beams on fsq85, nothing can formally as it's part and parcel of the optical design. It just shows more when reduced with modern sensors, but mitigated for narrow bandpass (3-5nm) NB imaging. The new 3 or 5 nm dual band filters might be good there if the star shapes matter, personal taste.

47 minutes ago, Icesheet said:

Not off topic at all! Where are they available? I’m on a waiting list at Kyoei in Japan, where the Tak gear is available quite a bit cheaper than Europe. Since I have to deal with customs wherever I order from it makes sense for me to order from there. 

Pm sent

Depends on your imaging preferences and how to tackle each night. Fsq85 is arguably easier overall if you get a good sample, but osc-only imaging as I do benefits from speed and wide-ish field. You get all the tones and colour NB does not, with the option of adding to it if you wish. But to be fair, it depends on the types or targets. For those focal lengths, are you nebulae in broadband, galaxy clusters, dust, or?

Both need setup time at the beginning. But fsq85 small star shape is fine with 2600mc with the 1.01x flattener. I know it's also perfect with 5.94um pixel full frame imx410. Extreme astigmatism comes from miscollimated fsq85 that shows more with small pixels, and that is more common than you think and takes a lot of time waiting for repair. With a good sample, assuming the focuser doesn't have slop, the fsq85 is very sharp. New reducer looks tempting, but the fsq85 with modern sensors is back focus sensitive, no way round that unless you go backwards in sensor tech and size. There are easier lens systems with in built flatteners around if that matters to you.

Now star shape....Rasa never appealed to me in that department, but it gives signal at the fl unmatched by almost nothing else. That matter to some, maybe you?

Fsq85 to me is worse. Cat eye bokeh from the virtual field stop of lens 3 in the stack that gives almond shaped out of focus stars and causes cracked stars, or inverse dark lighthouse beam effects in focus. These used to be hidden behind stumpy little 'newtonian-esque' spikes in older cc'd cameras with bigger pixels from the significant periodic texture of microlenses on the side that the light hits. With planar back side lit sensors, you'll see huge unavoidable dark beams that rotate around the frame, markedly pronounced with osc cameras in broadband where the stars are not suppressed like NB imaging. To me, it's worse than any system with diffraction, and from a scope where stars should be round. And it gets even worse if you do mosaics where they don't line up etc.....Do you need round stars? There are better apo out there for that. 

But, there are too many decent triplets with flatteners that work at f4.8 now, and even the 110mm flat field options that are almost identical to the AP 110gtx in design (can't say anything about execution). Esprit 100 is a great example of similar focal length, round stars and good sharpness tbh.

The FRA300 in a good sample is fantastic, very easy setup and the whole thing melts in to the background. Probably since it is small and tidy, but corrects 2600mc and larger.

But from my experience in bortle 6, and knowing others in bortle 4, osc imaging is better with fast optics. You're forced to use shorter subs (balancing zero gain options to use the whole full well capacity too), which takes care of stacking statistics, and you can get an image in broadband or NB in a single night.

To balance that, I quickly realised that fast optics tempted me to image the same duration as I used to, but get what F5/6/7 refractors could not in a sensible amount of time - depth. I'll caveat that by saying its not general, and big aperture, long focal length, big pixel systems are not so f-stop dependent. So a tak epsilon takes the same imaging time for me over a few nights after owning it for a while, but I see more because it can do that at a decent pixel scale with high snr. That's what happened with me, though...

Fsq85 is fantastic in NB, but you may get such good data that you realise you want more to complete an image given it's relative speed. For osc targets only your image quality preferences will dictate whether one winter night will be sufficient. It can be from f3.3 down to f2 though.

The fast mirror scopes have their limitations as you know, and paying for the stable collimation options is a hurt-once problem, but takes that nightly concern away. and some of the concerns you read about online are sample variation, but an OSC camera setup are a little less taxing on a focuser compared to the mono setup with additional components. Aperture resolution benefits at short FL are in the weeds, and I doubt you will see night and day differences sufficient to be swayed by that criterion alone.

17 hours ago, Icesheet said:

I’m actually on a waiting list for the Epsilon 160ED but have been told it will likely be years before it materialises. The 130D seems as scarce these days. I’m not sure it would be any easier getting dialling in an Epsilon over the RASA. Although image circle and field correction should be better. Not quite as fast though. 
 

Are you saying the flat field on the FSQ is not good even with the new flattener? When I look at the spots and some examples I’ve seen on forums it seems pretty much as good as it gets at this FL with a refractor and the IMX571. The new reducer looks fantastic too. That being said, you are paying a premium and not guaranteed the performance. The Vixen VSD90 looks like it may have the best correction and performance but it’s more than I want to spend. 
 

I’m not ruling out ever going back to mono but I plan to stick with  OSC at the moment so the filter issue doesn’t affect me. 

There's a few epsilon 160s available in Europe right now just fyi ( but off topic a bit)

23 hours ago, Astr0Kaz said:

Hi Paul, thanks for the idea 🙂, but I don't think so. Any dust in the optical train shows as a large circle, so the insect would have to have been hovering a meter or so above my scope to appear so small.  It also disappeared when capturing the Orion Nebula and reappeared the following night when I went back to the Pleiades.  It also stayed still for each 3 minute exposure, but then moved location as my mount dithered.  I really think it must be a reflection of light from somewhere, I'm just not sure where 🤔

I think my stacking software will remove it, but it's just weird! Lol

Would be the other way round. A very tiny dust mite moving around on the sensor is better resolved, and would be bigger and more diffuse further from the sensor. No idea what it is though....is that movie a collection of subs and what's the length of the sub, the length of the movie overall and the plate scale? We could work our roughly the speed in pixels per second and get a rough size estimate just for fun.

It does look like something imaged in the sky, spooky!

Agree, lovely image of this object and you can see through it just enough to appreciate it is a clouds of gas with various degrees of density, but still see the structure of the various parts.

True, but there is no problem caused by a camera that is smaller than central obstruction from that point of view.

I'm guessing the illuminated and corrected circle is smaller than rasa8. That's where the old 4.5um atik 460 1 inch sensor might be useful for those who have them on a shelf, or the 178mc or maybe the 585mc or other zero amp glow planetary type cams in the non cooled variants for 30s subs etc.  

On 08/01/2024 at 20:50, Mogster said:

I have read previously that Celestron had discounted the RASA 6 as regular cameras would cause too large a central obstruction. Maybe the RASA 6  needs a particularly small diameter camera.

Bring back the atik 460/490 camera bodies with new sensors and usb 3. Ideal for any Rasa, including Rasa 6. Cooling I think was the limitation there though.

Ah, so some sort of turnkey robotic 6inch Rasa with inbuilt camera maybe, celestron version of the small robotic systems but faster?

Nothing to do but think when waiting at the bus stop.....😃

They emphasized BIG, so what if they went the honders route, or some variant as a fast, short astrograph a la Riccardo honders e.g.? 

Forgot to add, maybe they'll go with focusing built-in to the camera attachment optics at the front? Unlike RCs, i dont think there is any primary to secondary distance to respect, so that might work...

I wonder if the innovation will be in the optics, covering aps c properly in a 6 inch.

Then again, listening to many users, collimation and tilt adjustment in situ would be useful.

On the other side, I wonder if they are going for a smaller system with wider field to give an option for 1inch and smaller sensors with tiny pixels, which are now available as cooled options?

That's a way to get a decent fov like a smallish frac with easier tilt needs and ok pixel scale on 2.4 -2.9 um pixels?

But, this announcement could show something from left field, we only see the rasa-esque front part. I'm curious though, come to appreciate small imaging packages in a backyard setup these days.

Astrobin's platesolver shows another asteroid, 35 Leukothea, a carbonaceous 'lump of coal' but I can see nothing in the image. Maybe it is the tiny orange speck at 11 o clock?

It doesn't pick up on 101 Helena or 62P comet though

Hmm, while some are re-processing to beat the band with new iterations of pixinsight tools, I can see a rabbit hole with asteroid chasing in heaps of old data in my future. Dont know if that's a good thing or a bad thing

8 hours ago, MalcolmP said:

I used Stellarium, just done a double-check in CduC and it shows it ok,
 and for good measure this is an extract from JPL Horizons (for tonight)
101 Helena (A868 PA)  RA10:25:2 Dec+16 35'20" V.mag13.4

No more photo-ops for it and 62p they are parting company, you caught Helana at the right time just as it is beginning a retrograde loop from now until March next year.
For followers of little rocks I have made this plot in Stellarium (5-day intervals):

Fascinating, thanks. I found it also with stellarium. What a bit of luck on my part...

18 hours ago, MalcolmP said:

 

Very nice

With a guest appearance by asteroid (101)Helena !

 

 

Thank you. I saw that in the stack and could just about make it out between first and last sub when blinking. 

Glad I found an asteroid too, thanks for identifying it. It did not show in my astap analysis, what did you use out of curiosity?

Comet 62P/Tsuchinshan captured on Dec 11 while it was wandering through Leo. There are a plethora of distant galaxies and galaxy groups here, with some nice dispersion of larger foreground stars of various color temperatures. We also see NGC 3239, an irregular galaxy called the Loony Galaxy (Arp 263).
 

With hazy high cloud and gradients, some work was needed to sort out the background and deal with compositing a stack on stars with a stack on the comet nucleus, worked out ok.

It's going to get brighter into January, seemed to have caught a little of a tail but it's short, maybe it's direction at the moment.

Captured Dec 11 with TS Hypergraph 6, 420mm @ f/2.8 with asi2600mc pro at gain 0, -10C.

145 x 60s exposures, B7 skies

For what it is worth, there is a newer version that just slipped in without fanfare since they released the smaller 13028 version. The three copper studs under the mirror in original 15028hnt version (that I had to remove and replace) now have cork pads instead. The entire cell now has 6 holding screws in the base rather than relying on the push pull system to hold it in place. collimation is with grub screws like the epsilon instead of those large and easily loosened bolts on the original version

Hope they fixed the need for ED glass in the corrector too, but overall is a version with changes implemented by the cries on forums and other forms of contact I believe.

Here is the back of the current version, and sharpstar's diagram on the screws when I asked for it, just fyi if anyone finds this.

I've found it to match the epsilon 130D, slightly better stars (if you dont get a turned down edge) since the epsilon has mirror clips rather than a retaining ring.

1 hour ago, tooth_dr said:

Wife sent me this photo half an hour ago 😊

Well wear with VC200L. Had the older one years ago, and have this one in an online shopping cart for a while now....and in case anyone mentions it, the need for the evaporation refiguring of the primary back in Japan is more or less moot, it wont need recoating till your too old to run your rig .

Lovely scope, and surprisingly lightweight, enjoy.

It's a curious machine, the objective shape looks like to 80 mm shape on the askar v. I think the 103 and the 120 are a larger version of that model, but kept separate. It's a good size aperture, not many triplets in 120mm, aside from the well regarded 115/800 scopes from several vendors. The mechanicals look very nice to be fair. Might be good with the flattener for a long focal length imaging apo other than the range between esprit 120 to TSA 120 

On 11/09/2023 at 19:39, BrendanC said:

I got a great response from Michael, the maker of the spider vanes, and in fact just realised he's accounted for this on his website too. From https://www.backyard-universe.de/en/i/installation-secondary-spider

This approach solves this particular problem. That CNC milled spider vanes is mechanically sound, but has significant reflectivity. You should see what happens when the moon is up, even with a dew shield. Big elliptical blueish orb in the frame shown below (this is a sharpstar hypergraph 6 aka sharpstart 15028hnt).  As Olly mentioned, stove paint or non-dye based ones are best. Takahashi epsilons use their concoction that is somewhat similar, but it can be brittle if banged or hit with an allen key by accident, fyi. Easy to remedy.

Here is the moons reflection from the spider.

Indeed, I might try that sometime in the future. I was more interested in the dark structures and the nice golden starfield in my case and I did not know about the scream at all, but its nice to see what else is there from your image with some extra signal in the ionized emission lines. Might be nice to layer the dense starfield image with narrower band data sometime perhaps.

Oh, that is interesting. I guess the scream is the feature up to, and its a good name for that object - looks just like the picture in shape.

The wavy dark dust feature under the scream reminded me of an image I took last year, below. I guess am just starting to see the scream at the top of the image, but never knew about it until now. Nice to see where all the Ha is located too.

12 hours ago, wimvb said:

That was my main requirement. Thanks.

Do you need aps-c? I used the ASI174MM-Cool for a few years. Great little camera for dso, apart from the horrible amp glow. But if zwo ever release a cooled version of the ASI482 with 5.8 um pixels, I will be seriously tempted to get one.

I think that asian focusers have improved so much over the last few years that Starlight Instruments and the likes must be hard pressed to keep up. And with so much going on at that company, I wouldn't be surprised if they go out of business.

Agree, I use a TSFOCR25 on another refractor that is almost identical to FT in all practical aspects, very good. Focusers that comes with Askar are almost the new benchmark, really excellent stuff. I don't need APS-C per se but I have one and its USB 3 and generally prefer it to other cameras, so much easier to work with. I use the Atik 460ex 1-inch sensor on the MN56 which works pretty well.

I think there is alrady a move to release cooled version of planetary cameras. the 290 mm has been I think, so larger pixel cameras with slightly smaller sensors will have a following I think. Not from a FOV needs but for ease of field correction, well depth, and good sensible pixel scale in our skies for small targets, to me at least.

Good to know. There are lots of feathertouch on TS optics for a long time now, even a few second hand ones in APM, but pricey. The powerbox advance is something I am interested in too. Nice upgrade for you.

I was contemplating the SW make newt. My mn56 corrected circle doesn't quite do aps c with the tiny secondary...and my atik 460ex usb 2 is so slow for autofocus and polar alignment😐, but otherwise a great sensor.

And a good idea to go with that SW base plate so your focuser position is unchanged for this type of scope.

Good luck with it this season