michael.h.f.wilkinson

I used to have a pair of Helios Apollo 15x70 (similar to the Oberwerk, I gather). Excellent bins, but the newer Helios LightQuest 16x80mm are not only slightly sharper and have a bigger aperture (30% more light), they are actually a touch lighter, and just as easy (or hard) to use handheld. Highly recommended. However, if you stumble of a pair of Helios Apollo 15x70s, and they are going for a good price, you should certainly look into it.

The SN-6 I have has essentially the same focal length as the Esprit, so it should be possible

I forget where I heard this, I think it was some facebook group. I then used google to find the relevant pages

That looks absolutely brilliant

Lovely shot. Hope I get a chance to image it with the 6" Schmidt-Newton some day

Not my deepest image in terms of data gathered (around 2.5 h), but I was alerted to the presence of quasars in my image of NGC 3718, NGC 3729, and Hickson 56. There is a useful map of the area here I was quite amazed to see I got 6 out of 8 listed. There are some very faint hints of the other two, but having captured an object 11.2 billion Ly away from my back garden is quite amazing, I feel. Makes me want to grab more data on this lovely target.

Very nice and sharp image. Like the very natural look, crisp, but not over-sharpened at all

Really lovely sunshine this morning. These are the full disks I snapped with the APM 80mm F/6, Beloptik Tr--Band ERF, and ASI 178MM camera. For WL I used a Lunt Herschel wedge and Baader Solar Continuum filter (no UV/IR block needed with the ERF). For Ca-K I used my Lunt B1800s Ca-K module. WL, grey scale: Ca-K, grey scale: Ca-K, pseudo colour: Ca-K, part inverted: Ca-K, part inverted + pseudo colour: In each case I stacked 25% of 2,000 frames in AS!3, sharpened in ImPPG, and postprocessed in GIMP

Was treated to some glorious sunshine this morning, so set up the APM 80 mm F/6 triplet with Beloptik Tri-Band ERF first, and rattled off some WL and Ca-K full disks (to be posted in part 2), before switching to H-alpha. I recorded 16 1,000 frame SER files with the ASI174MM, stacked these in AS!3, sharpened in ImPPG, stitched in MS-ICE, and final tweaks with curves in GIMP. Seeing was good enough to use 50% of the data. Grey scale: Pseudo colour: Part inverted: Part inverted + pseudo colour: I took a single, 4,000 frame SER file of the section of the disk with the biggest ARs, for some detail images Grey scale: Pseudo colour: Part inverted: Part inverted + pseudo colour: Finally, I got out the Tri-Band SCT, and made a small mosaic of the big ARs: I am not sure I nailed focus, and seeing was turning choppy, but I am still quite pleased with the result

Many cookbooks (well used, on the whole) here as well, but at least half of them are mine. Shoes, however, proliferate without my assistance.

OK, I have two 8" SCTs, one 80 mm F/6 APO triplet, a 6" F/5 Schmidt-Newton, and a 60 mm Coronado SolarMax-II, also making 5 scopes, with quite a gaggle of mounts (5 EQ mounts), guide scopes, finder scopes (guide scope and finders don't count, I would say). The only reason the missus doesn't complain is probably that these things live in the garage, not the living room. The two SCTs seems a bit odd, but then the one is for solar work (A Baader-Celestron Tri-Band SCT), the other for all other targets. My Coronado 60mm, together with one tripod and my mini-giro mount, is permanently stationed at my work, so I can have the odd solar H-alpha session over lunch.

It's King's day in the Netherlands, so I have the day off. It started sunny enough, and I spotted some massive ARs on the sun with the Lunt SUNoculars, so I rushed out the Tri-Band SCT on the Vixen GP mount, and managed to rattle off a few 2000 frame SER files with the ASI178MM and green filter (Solar Continuum doesn't play nice with the Tri-Band SCT, as the O-III band it transmits doesn't overlap with the Solar Continuum passband). Clouds hastened in to spoil the fun, and seeing wasn't great, but at least I got something out of this. ARs 3285, 3286, and 3288 are putting on quite a show.

With a Barlow, you have an 1800 mm focal length. That means the slightest shake can cause blurring, even at 1/60s. Focus might also be off. If your focuser is fully extended, this might mean you need an extension tube to reach focus. Venus clearly shows signs of chromatic aberration, which can come from the Barlow, or possibly atmospheric refraction. Furthermore, I see that this scope comes equipped with eyepieces down to 4mm, which with a 2x Barlow gives an effective 2mm focal length. However, an F/8 telescope like this works better at 8mm or perhaps a bit shorter. Pushing to far larger magnifications does not yield more detail, it just smears out such detail as there is over a larger area. Finally, turbulence in the telescope tube if it hasn't cooled down (or warmed up) to the ambient temperature, or turbulence in the atmosphere can cause severe blur as well. If there are large differences in day time and night time temperatures, this can be a severe problem, especially for objects low in the sky, and at dusk or early in the evening. Just my tuppence

I regret selling the TMB Paragon 40mm. I wasn't using it much after buying the Nagler 31 mm T5, but it did give a slightly wider true field, and it was a far easier EP for inexperienced people to use, so it was great for outreach. I since got a Vixen LVW 42 mm to replace it, but that is a very good EP, it is definitely not as easy to use as the Paragon, and shows a lot more distortion.

Incidentally, I have got pretty decent results with the ASI178MM (uncooled) on M13, with my APM 80mm F/6 triplet and 0.8x reducer. This camera is close to your budget (depending on where you get it). It has very high QE (up to 81%), and is also a very good planetary camera

I had a look at the specs of both, and although I haven't experience with either camera, the specs raised some red flags. The SV205 is listed as having a maximum exposure time of just 0.5 seconds, which is very, very short for DSOs. It also sports 1.4 x 1.4 micron pixels, which is very small indeed. This usually means the well depth and therefore dynamic range are relatively small. The SV105 does not list a maximum exposure time, and has 3x3 micron pixels. It does however only have a USB2 interface, and according to the data sheet delivers its maximum frame rate of 30FPS (which is OK, but not great) in compressed form (MJPEG) which is something you definitely don't want. I would have a good look at other options (especially second-hand, if your budget is tight)

Sorry to hear that, Michael. Hope you recover soon

That is interesting, especially for airline travel, with all the weight restrictions that brings. Where did you get the HEM15? What does it cost?

I think I will aim my Samyang 135 F/2 with high-speed O-III filter at that area some time in autumn. Just to see what happens

They may have been taken through slightly different filters. There seems to be more continuum emission in the lower one, especially in the outer reaches of M31

What I imagine could be done is to use a broader band filter (one or more) to to estimate the background continuum contribution (e.g. by scaling it to the correct level using least-absolute-deviates linear fitting) That should work reasonably well. Ideally you would block the O-III line, but even without that, estimating the background continuum contribution boils down to solving a large set of linear equations.

I have spoken to a couple of colleagues in the astronomy department, and they think it is a legitimate detection. The fact that the same structure appears in data from different scopes in the same location is highly unlikely to be the result of a processing artefact. There have been more such detections (think of the Squid Nebula, and several very faint PNs) in O-III by amateurs willing to spend loads of time on a single target. It does of course help if others can confirm the detection.

I have three variants of the ASI183: an ASI183MC (non-cooled), which I now only use for planetary and lunar imaging, an ASI183MC-Pro, which I now use for DSO OSC work, and an ASI183MM-Pro for narrowband/luminance shooting. The latter two are way better for DSO work, not just for reducing noise, but in particular due to the fact that I can simply always shoot at the same temperature of the chip, allowing me to use the same darks every time, or shoot darks at any time I like, rather than at the start or end of each imaging session, which I had to do with the ASI183MC. That doesn't mean the non-cooled camera is bad, given the results I was getting on the Meade SN-6 6" F/5 Schmidt-Newton. The M101 below represents just over 4 hours of data from a Bortle 4-5 site.

For solar, the only diagonal I use is a Herschel wedge. Both my Ca-K module and H-alpha filter system are straight-through types.

See report here: