michael.h.f.wilkinson

I gather the new software version didn't support the feature any more. Pity, as I was on my way from neutron star to supernova, as I recall

Very nice shot indeed, Especially at such a modest integration time

Regarding eye relief: I need to wear glasses while observing (due to cylindrical astigmatism), and require a minimum of 16 mm usable eye relief, I find. The Vixen SLVs are perfect in that respect, as are the (far more expensive) Pentax XWs, which give a larger FOV. If you don't need glasses, by all means use the cheaper short-eye-relief EPs. Note that a 12" Dobson is a fast scope, so it does put correction of eyepieces to the test.

I don't think so. They look much more like the earlier Helios Apollo 10x50s or TS Marine 10x50s

Lovely image!

I have no experience with the 150PL, but I did build a 6" F/8 "planet killer" Newtonian in the distant past. Mine had a secondary of just 36mm or so, just some 24% secondary obstruction (SO), which made it perfect for planets, and no slouch on deep sky viewing. The 150PL has the same 36 mm SO (according to this pdf), so performance should be similar. An 8" with 33% SO will show more detail, but with slightly softer contrast. My current C8 shows more detail on planets, despite its higher SO.

My portable solar set-up. Currently the tripod, mount and Coronado scope are permanently parked at work, so I can have a look at the sun during lunchtime. The little APM 80 mm F/6 triplet is at home, and usually sits either on the Great Polaris mount, or on the EQ3-2.

I would need to find space to store it first, or better still, a permanent observatory

Great image. If (when ) I buy myself a RASA, I will almost certainly say something like "Now look at what you made me do, Olly!" 😛

The short form (with some arms waving) for me has always been: When the universe cooled enough for ionized hydrogen to recombine into neutral hydrogen, visible light could travel largely unhindered. By contrast, the universe became opaque to the 21 cm wavelength of neutral hydrogen. Thus, transparency is wavelength dependent. Only when stars and galaxies formed, and the neutral hydrogen got partly ionized, and concentrated in regions of higher density around galaxies and clusters did the universe become (largely) transparent in the 21 cm wavelength.

Incidentally, much depends on the type of varifocals. The usable field of view varies a lot. Cheaper ones have the narrower usable FOV.

Hi Jason. It is not so much the varifocals (I use them too) but glasses by themselves combined with eyepieces with comparatively short eye relief (the optima distance between rear of eyepiece and eye). If you do not have problems like (cylindrical) astigmatism, observing without glasses is fine. However, if you do have such astigmatism (like I do) then the best option is to get eyepieces with long eye relief (like the Vixen SLV series and many others). These tend to be more expensive, however. Varifocal glasses can cause issues with only part of the field of view being in focus at any given setting. This depends largely on how strong your reading part of the glasses is, and the width of the field of view. I tend to get along quite well with my varifocals, others prefer to keep a separate pair of glasses without varifocal lenses for observing.

A simple way to test whether the EPs where at fault is to rotate them in the binoviewer, which is easier than rotating the whole binoviewer. I have never noticed any difference in sharpness between top and bottom and left and right edges (until I started using varifocal glasses, obviously). EPs are generally very close to perfectly rotationally symmetric, so I would not expect any difference between the north-south and east-west edges

Outstanding image, as ever!

I have had a chance to look through a Baader Hyperion Aspheric 36 mm in an F/8 scope, and the TMB Paragon 40 mm I had at the time (of which the Aero 40 mm is a clone), and the edge performance was noticeably better in the latter, even at F/8. I have used the Paragon 40 at F/6 and that worked fine. Having said that, the Paragon 40 mm is reported to be better than the 35 mm, so it is hard to be sure about the 35 mm vs the Baader 36 mm. I must say I was a bit underwhelmed at the performance of the Baader 36.

First of all, they are sold separately. I did a quick google for illuminator for eyepieces and this was one of the first hits: https://www.stellarvue.com/ei002-illuminator/ Have you replaced the battery of the illuminator? Is it really broken or is the battery just flat? These illuminators usually can be opened by unscrewing one half, exposing one or two small batteries inside.

Great catch! I did have an observing session over lunch, but must have just missed this

Just had a quick look at the comet again, using the Helios LightQuest 16x80 binoculars once more. It is a really easy find at the moment, neatly placed near the centre of the triangle formed by epsilon, eta, and zeta Aurigae. Very easy object in the big bins, although it seems a bit fainter than before (might be moonlight, of course). I hope to get a better chance tomorrow, when the forecast is good, and I don't have all sorts of other tasks in the evening. The comet should be close to the Flaming Star Nebula, and I might try to get it with the good old EOS 550D and Samyang 135 mm F/2. I also aim to set up the big comet catcher, i.e. my Meade SN6 6" F/5 Schmidt-Newton with the Tele-Vue Nagler 31 mm T5 (24.5 x 152mm with a true FOV of 3.34 deg). Maybe I can spot more detail with that. Fingers crossed

Since getting cooled cameras, I create a dark library at frequently used exposures with the camera shut off from light, by placing a cap over the camera, and cooling it to the set point I prefer (generally -10 Celsius). There can be reused until the chip degrades for some reason (pixels can become defective), or I decide to use a different temperature. I make flats at the start or end of every session, as I have to build up the rig every time (no obsy (yet))

The diameter of the sun is about 1.3927 million km. assuming a marble 13.927 mm in diameter, the sun is one hundred million (100,000,000) times larger

Very nice result!

There are some reviews here: and here (including a comparison to the Fujinons) https://www.cloudynights.com/topic/564698-apm-16x70-ed-vs-fuji-16x70-fmt-sx-round-1/ The APM clearly comes out ahead, which does not surprise me, as the APM is a much newer design I don't know how they would hold up against the Helios LightQuest, but I have the Helios LightQuest 16x80 and compared that to the Helios Apollo 15x70 I had before. The LightQuest has a definite edge over the Apollo, and not just because of the 10mm extra aperture.

Probably something like 20 to 25x to keep the field of view wide. Happy hunting!

The comet is actually quite easy to spot in moonlight, I have just seen. It is near zenith for me at the moment

Had another quick look. The comet seems to have moved visibly in the half hour or so between observations. Still not sure about the ion tail. I also tried the Zeiss Victory SF 10x42 mm bins, but the Helios LightQuest 16x80 mm bins showed a much better image. Aperture is king, once more