johnturley

Arrived yesterday from FLO, a 30 mm StellaLyra Ultra Flat Field eyepiece. I have been looking for some time for a low power wide field eyepiece that is both not excessively bulky and heavy, and will be sharp to the edges of the field of view in an f5 instrument, and after reading good reports hope that this will fit the bill. At first glance it appears to have as advertised, a genuine 70 degree field of view, unlike the 50 mm SuperView eyepiece that I once owned, which originally claimed a 60 degree APFOV, but only turned out to be around 45 degrees. Although at 70 degrees the APFOV is some what smaller than that of a 31 mm Nagler or 30 mm ES 82, but at 570g, although no lightweight, this is less than half the weight of the others, and at £179, about 1/4 and 1/2 of the price respectively. I do have a 36 mm 72 degree Baader Hyperion Aspheric which is even lighter, but the edge performance, especially in my f5 Newtonian, is not that great. John

Nice report, I'm seriously think of getting the 30mm StellaLyra variant (from FLO), and selling both my ES 24 mm 82 (which I understand is similar if not the same as the Meade 24 mm UWA), and Baader Aspheric 36 mm). The only thing putting me off is that I had for a short period a 50 mm StellaLyra eyepiece, which claimed an APFOV of 60 degrees, but in reality it was around only 45 degrees. John

Thought I would post some images of Mars, showing a similar area of the planet taken through different scopes, and different techniques to show the different image sizes obtained. The first image is of Mars taken on 12-13/11/2022 through my Esprit 150 and ZWO ASI 462 Planetary Camera using a 2.5 x Powermate (effective focal length 2,650 mm) giving f17.5 The second image was taken about 30 minutes later through my 14in f5 Newtonian with the same setup (effective focal length 4,500 mm) giving f12.5. The third image was taken in September 2020 (before I obtained my planetary camera) through my 14in f5 Newtonian, and Canon 6D digital SLR using eyepiece with a 9.7 mm Plossl eyepiece. The images were processed using AutoStakkert and/or Registax with a bit of polishing in Lightroom Note the superiority of the ZWO Planetary Camera over the digital SLR. I am also a relative beginner to planetary imaging, and my results are nowhere near as good as those of Neil Philips or Geoff Lewis, I would have thought that with imakebeer's Skywatcher 150P it should be possible to get results nearly as good as those with the Esprit 150.

Interesting read, in particular it states that :- 'ADCs are designed to work best at high f-ratios. At short f-ratios or with large amounts of prism correction, aberrations can be introduced which can start to offset the overall benefits. To reduce aberrations on short focal ratio scopes it is best that they are placed directly after the Barlow lens and a reasonable distance from the camera. For longer f-ratio scopes, such as SCTs, putting the ADC before the Barlow is less problematic and has some advantages in increasing the available amount of correction for low altitude objects. I've only tried using my ZWO ADC with my 14in Newtonian at its native focal ratio of f5, maybe I would get better results if I tried using it with a Barlow. There has been a lot of discussion on 'Cloudy Nights' with regard to to the very expensive (£3.5k) Gutekunst ADC's, and they are best used in conjunction with a Barlow. However the ADC didn't seem to give much improvement with my f7 Esprit 150 either, which incidentally unlike my 14in Newtonian, doesn't usually exhibit much false colour due to atmospheric dispersion, unless the object being viewed is very low down, which is why I thought 'imakebeer' would not notice much improvement with his Skywatcher 150P.

I don't think that you would notice a massive improvement with an ADC especially on Mars with its current high altitude, and with a 150 mm scope. In addition with a Newtonian Reflector, you may not have sufficient in travel to add an ADC to the light path. I do have a ZWO ADC but have never bothered using when it when imaging, I found last year when Jupiter was quite low down, it improved the visual view through my 14in Newtonian significantly, but not much difference this year. John

Which program do you recommend for upscaling, I tried upscaling some images in GIMP, but the results were not that great. Also if the initial image is too small you may struggle to get a sufficient array of alignment points in programs such as AutoStakkert and Registax. John

I had some thoughts of getting a 100 DZ as a potable instrument possibly to take on holidays to Tenerife, and possibly to the 2024 Mexico Total Solar Eclipse. If there is no discernable difference in performance, maybe the cheaper DF (which I understand is also more readily available) would be a better option with its shorter tube length, which could make the difference regarding what you are allowed in cabin luggage. Takahashi claim that the 100 DZ on be easily carried on most commercial flights, but someone advised me that this is NOT in fact the case.

Depending on your system, you may also need to oversample and at a higher focal ratio than the theory suggests, to get a decent image size. John

Managed a brief session on Mars last night before it clouded over, conditions were rather unsteady with a breeze causing some movement of the telescope. The image of Mars below was taken through my 14in Newtonian, ZWO ASI 462 Planetary Camera, 2.5x Powermate giving f12.5, 2 minute exposure, Capture area 320 x 320, 14,000 frames @ 122 fps. Processed in AutoStakkert and Registax, plus a little polishing in Lightroom.

Viewed Mars again last night, but under significantly better atmospheric conditions compared to the previous evening, which allowed a smaller capture area of 360 x 292 giving a larger image . Attached is what is possibly my best Mars image of this apparition , taken through my 14 in Newtonian, ZWO ASI 462 Camera, and 2.5 x Powermate giving f12.5, 2 minute exposure, approx 16,000 frames at 130 fps, processed in AutoStakkert (stacked best 25%), and Registax, plus a bit of polishing in Lightroom. Incidentally, I always like to display images of Mars in the traditional astronomical format with South at the top, as I am used to seeing the features that way up, with Jupiter and Saturn it does make so much of a difference. I think it was only after they started sending imaging spacecraft to the planets, they started displaying erect images with North at the top. John

Braved the weather last night, according to the thermometer in my observatory shed it was minus 8, and had a look at Mars. Conditions were not ideal with quite a bit of unsteadiness, attach my best image of Mars taken through my 14 in Newtonian, ZWO ASI 462 Camera, and 2.5 x Powermate, 2 minute exposure, approx 10,000 frames at 90 fps, processed in AutoStakkert (sacked best 25%), and Registax, plus a bit of polishing in Lightroom.

Superb John

Would be interested to know how it compares with the Baader Hyperion Aspheric 31 mm, which has a similar APFOV. John

Second that about needing to use eyepiece projection with a digital SLR to get a decent planetary image size, although so many observers dismiss it as being rubbish these days. John

It also depends on the effective focal length of your system, to get decent sized planetary images ideally you need to aim for an effective focal length of not less than around 3-4,000 mm (achieved with a Barlow if necessary), which is one reason quite a few planetary imagers favoured Celestron C14's as they give this sort of focal length without the need for further amplification with a Barlow. Having said that as mentioned previously, I understand geoflewis still likes to use a 2x Barlow with his C14 and ZWO ASI 462 (pixel size 2.9 um) giving an effective focal length of nearly 8,000 mm at f22. I regularly do planetary imaging with my Esprit 150 (as 90% of the time it gives sharper images than my 14 in Newtonian), using a 2.5 x Powermate, which gives an effective focal length of 2,650 mm @ f17.5. With my ASI 462 camera (pixel size 2.9 um), the formula also suggests that I would get better results with the cheaper ASI 224, which has a larger pixel size of 3.75 um, not sure whether this would be the case. John

The formula given in Astronomy Tools is absolute rubbish, at least as far as Planetary Imaging is concerned, it suggests that with my Esprit 150 and ZWO ASI 462 under O.K. Seeing Conditions, I should be using a Focal Reducer rather than a Barlow. geoflewis I gather regularly successfully uses f22 (2x Barlow), or even f26 with his C14 and ASI 462. John

I've never had a problem running Registax with Windows 10, although as I mentioned it can be slow if you use it for aligning and stacking. John

The sky unexpectedly cleared at about 23.00 last night, so thought I would have a quick look at Mars, conditions weren't too bad, but with some unsteadiness. A heavy dew however came down after opening my observatory shed, so I was limited to less than an hour of observing time. Image taken through my Esprit 150, with my ZWO ASI 462 planetary camera, 2.5 x Powermate, 3-minute exposure, 28,000 frames giving 157 fps, processed in AutoStakkert, Registax and Lightroom. John

The images do however appear larger after cropping when you post them on this website, although they do appear the same size in Windows Photo Viewer, which confused me at first. When I posted my first Jupiter image (with Io shadow transit) on this site, I could not understand why it appeared so small compared to other observers' images, but it was because I had used the full capture area of my ASI 462 camera (no cropping), plus not used a Barlow. John

You will get much better results with a dedicated planetary camera than with a digital SLR, not only does the much smaller sized sensor give you larger planetary images, but you can reduce the capture area of the sensor (or ROI) further to enlarge the image even more, which you cannot do with some digital SLR's. In addition, most planetary cameras enable frame rates of up to around 200 frames per second, whereas most digital SLR's are limited to around 30 fps. I attach for example processed images of roughly the same area of Mars, the first was taken on 15 September 2020 (when the South Polar Cap was visible and Mars exhibited a 20 arc second disc) through my 14in Newtonian, using my Canon 6D digital SLR (which has a maximum frame rate of 30 fps) and eyepiece projection with a 9.7mm Plossl eyepiece. The second was taken through the same telescope on 13 November 2022 (when Mars exhibited just a 16 arc second disc) using a ZWO ASI 462 Planetary Camera (which I did not have in 2020) with a 2.5x Powermate giving an effective focal length of 4,500 mm at f12.5, the capture area being reduced from the full 1936 x 1096 to 544 x 548, and a 2-minute exposure of 13,000 frames at 111 fps. Images were processed in PIPP (for the one with the Canon 6D), AutoStakkert and/or Registax, plus Adobe Lightroom. The differences between the 2 images are quite obvious, both in terms of size and detail, despite Mars being further away in November 2020, and if I recall correctly more detail was visible through the eyepiece in September 2020. I should stress that I am a relative beginner to planetary imaging, my images are nowhere near as good as those of other observers such as Neil Philips, and I made all sorts of mistakes to begin with, such as using the full capture area of the camera and then wondering why my images still appeared very small. I've also tried enlarging the images in programs such as GIMP, but generally this did not seem to give very good results. John

It's not the focal ratio that determines image size, but the effective focal length, so your f5 8 in Reflector with a focal length of 1000 mm, will actually give you a slightly larger sized planetary image than your 80/90 mm f11/f10 refractors. To get a decent sized planetary image even using a dedicated planetary camera with a small sized senor, such as the ZWO ASI 224 & 462, ideally you need an effective focal length not less than around 3-4,000 mm (which you would achieve with a 2.5 - 3x Barlow), one planetary imager in particular likes to use a 2x Barlow even with his C14 giving an effective focal length of nearly 8,000 mm at f22. Although some observers will disagree with me, in my opinion if you are using a digital SLR, then you will probably need to use eyepiece projection (which can provide greater amplification than a Barlow/Powermate) to get a decent image size. To those that disagree with me I would love to see some large scale detailed planetary images taken using a digital SLR, using no more than a 2-3x Barlow for amplification. If the initial image size is too small it can be difficult to achieve correct focus, and to obtain sufficient alignment points in processing software such as AutoStakkert and Registax. I don't understand why so many observers rubbish eyepiece projection these days, it was the method commonly used 20 years ago before the advent of digital cameras. An observer recently posted on 'Cloudy Nights' some quite nice images taken with a small Takahashi Refractor, using a Baader Zoom eyepiece, coupled directly to his planetary camera. John

Last night was the first clear night for me for a week, and not likely to get many, if any, during the coming week so took the opportunity to image Mars. Conditions were not ideal with quite a bit of unsteadiness, a heavy dew coming down, and the best view was through the Esprit 150. The image below was from a 3-minute exposure with my ZWO ASI 462 Planetary camera using a 2.5 x Powermate, 28,000 frames, average frame rate 156 fps, capture area 296 x 296, processed in AutoStakkert and Registax.

Last Night was misty, but some of the most stable atmospheric conditions I have experienced recently, in fact one of the rare occasions the 14in Newtonian gave a better view of Mars than the Esprit 150. North Polar Hood stood out quite nicely and was easy to see visually. Image taken using a ZWO ASI 462 Planetary Camera, Baader UV/IR Cut filter, 2.5x Powermate giving f12.5, 2 minute exposure, 13,000 frames @111 fps, processed in AutosSakkert and Registax, plus a bit of final polishing in Lightroom.

Do you find the ASI 462 with its smaller pixel size a definite improvement over the 224. John

Fantastic image Neil, Mare Erythreaum and North Polar Hood showing up really well. I could see the North Polar Hood quite clearly visually at about 12.30 last night, I was just about to take a few images, but then it clouded over. I regularly use a 2.5x Powermate with my Esprit 150 (f17.5), which gives reasonably good results, yet some observers suggest that I should be aiming for around f9 (1.25x Barlow) to optimise the sampling rate, and Astronomy Tools ridiculously suggests that under O.K. Seeing Conditions I should be aiming for around f5 (0.7 Reducer). John