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Everything posted by michael.h.f.wilkinson
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Show me your eyepiece/accessories case, please.
michael.h.f.wilkinson replied to Leegsi's topic in DIY Astronomer
Another slight change, with an ES 17mm 92° EP replacing the Nagler 17T4 (leftmost EP, second row) The complete order of battle is: top row: Vixen LVW 42 mm, TV Nagler 31T5 "Panzerfaust", Nagler 22T4 (last T4 in the collection), UHC and H-beta filters, Orion Optics 2" Amici prism 2nd riw: ES 17mm 92°, TV Delos 14 mm, ES 12mm 92°, 2" dielectric star diagonal. 3rd row: Pentax XW 10 mm, TV Delos 8 mm, Pentax XW 7 mm 4th row: TV Delos 6 mm, Pentax XW 5 mm, Denkmeier filter-switch diagonal -
Another beast has arrived
michael.h.f.wilkinson replied to michael.h.f.wilkinson's topic in Discussions - Eyepieces
Or as anti-tank grenade -
Just received my Explore Scientific 17 mm 92° eyepiece. Veritable beast of an EP, and a worthy replacement for the Nagler 17T4. Very pleased indeed
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They seem to have a simple attachment to the tripod head using a 1/4" thread. That seems flimsy to me, as does the tripod. I use a much sturdier tripod, and use an M10 bolt as attachment directly to the tripod.
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I have been using my Sigma 50-100 mm F/1.8 zoom for wide-field imaging, and whilst it works well enough on comets, using my Canon EOS 80D, the smaller pixels and longer exposure times I use for DSO imaging with the ASI183MM-Pro show up deficiencies. As I have a Canon 100 mm F/2.8 macro, I would like to use that instead. It doesn't have the tripod attachment, so I have cobbled together this using a pair of guide-scope rings. Now all I need are clear skies. I will be giving up a whole f-stop (and a bit), but hopefully the image quality will be better. Or perhaps I should get that Samyang 135 mm F/2.
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Eyepieces befitting a Takahashi!
michael.h.f.wilkinson replied to Nicola Fletcher's topic in Discussions - Eyepieces
For my APM 80 mm F/6 triplet (which is actaully a bit more demanding of eyepiece quality given it is faster than the TFC76), when not using the 2" diagonal (something I would really consider getting, it gives a FAR wider FOV), my set either consists of MaxVision 24 mm 68 deg (works like a Panoptic 24 at these focal) Vixen SLV 15, 9 and 5 mm if I want to travel light, or MaxVision 24 mm 68 deg Delos 14 mm Pentax XW 10, 7 and 5 If I do take the 2"diagonal, I replace the 24mm with the Nagler 22 mm T4, or even add the Nagler 31 mm T5 "Panzerfaust". These latter give awesome wide-field views. -
ES 17mm 92° EP on its way
michael.h.f.wilkinson replied to michael.h.f.wilkinson's topic in Discussions - Eyepieces
Galaxy hunting is exactly what I have in mind for these EPs -
Rather excited that I have been able to find a second-hand ES 17mm 92° EP for a very reasonable price. I love my 12mm, which replaced the Nagler 12T4. Now the Nagler 17T4 meets the same fate. The new EP should arrive on Friday.
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Solar Image 7th March 2021 Baader K-Line
michael.h.f.wilkinson replied to Nigella Bryant's topic in Imaging - Solar
Double stacking a Lunt Ca-K module (1 nm bandpass) with a Baader K-line filter (8 nm bandpass according to Baader) should not have any discernible effect on passband, but can reduce overall throughput. What does help a lot in imaging in Ca-K is the use of an ERF that transmits Ca-K, to reduce heat and therefore turbulence in the optical tube. I was lucky enough to get a second-hand Beloptik Tri-Band ERF (apparently, there are only six of these), which transmits bands around Ca-K, Solar Continuum and H-alpha, but I gather that Aries Instruments makes dual band ERFs. I really notice an improvement in sharpness if I install the ERF. -
M45 - Pleaides Cluster LRGB with new QHY268M
michael.h.f.wilkinson replied to SyedT's topic in Imaging - Deep Sky
Cracking image! -
Solar Image 7th March 2021 Baader K-Line
michael.h.f.wilkinson replied to Nigella Bryant's topic in Imaging - Solar
Much depends on the exact shape of the passband. Double-stacking two H-alpha filters generally gives a 1.4x reduction of bandpass, as you would expect from Gaussian profiles. If however the bandpass has a roughly square profile, the resulting passband will not be much narrower. Much also depends on the centre transmission. If it is near 95% the result will be a maximum transmission of around 90% (0.95 squared). If it is much lower, the image will be much dimmed. -
Solar Image 7th March 2021 Baader K-Line
michael.h.f.wilkinson replied to Nigella Bryant's topic in Imaging - Solar
I was considering one of these filters until I got a bonus for working 25 years at the University of Groningen. That allowed me to go for the Lunt (one of the comparatively rare pieces of new kit I own). They are very pricey. I have heard of people double-stacking the K-line filter to get a narrower band. Would that help, do you think? -
Solar Image 7th March 2021 Baader K-Line
michael.h.f.wilkinson replied to Nigella Bryant's topic in Imaging - Solar
Nice images with great detail. Am I right in thinking the Baader K-line filter is wider in spectral transmission than the Lunt Ca-K modules? -
Just did some experiments by blending O-III into G and B bands and S-II and H-alpha into the R band of the RGB image in APP, then using hue and saturation components of the resulting image together with the H-alpha image as luminance channel to create a Ha-SII-OIII-RGB composite image. I still need to experiment more, but i quite like the result May have pushed saturation too far. I am thinking of constraining the saturation channel by the luminance channel, so the saturation is only pushed in bright areas, not in the background.
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Last night, with @MartinB's advice on going for Ha-RGB rather than SHO or the like on the Flaming Star Nebula in mind, I grabbed 2 h 40 minutes worth of RGB subs using the ASI183MC rather than the ASI183MM-Pro behind the Sigma 50-100 mm F/1.8 zoom. I would have liked more, but clouds cut the session short. The result after stacking wasn't too impressive: There is just a little nebulosity visible, and the stars tend to bloat a bit. Nonetheless, some of the blue reflection components are visible, so I decided to combine this with this image: Which is 2 hours (and 2 minutes) of H-alpha data obtained on February 27 and March 2 with the ASI183MM-Pro. After combining them in Gimp, denoising them in Affinity Photo and another stretch and crop in Gimp, I am quite pleased with the first result There are still some colour gradients I want to tackle, and I would like to see whether mixing in O-III and S-II data might help, but I am rather chuffed with this first result. More data to get rid of noise is of course also need.
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Managed 4 hours and 48 minutes on the Spaghetti Nebula, using my Sigma 50-100 mm F/1.8 zoom at full aperture and 100 mm, with the ASI183MM-Pro, and Baader F/2 H-alpha filter. Stacked, gradients removed and automatic stretch in APP, and some tweaks in Gimp I should perhaps use a bigger aperture for this, and create a mosaic, but I am quite pleased with this first effort on a difficult target
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Really transparent skies here, despite Clear Outside suggesting 96% clouds. I set up the ASI183MM-Pro with Sigma 50-100 mm F/1.8 zoom at 100 mm and full aperture with a Baader F/2 H-alpha filter. Will keep shooting until the skies cloud over. I am certainly in the right place, just one or two very faint hints of nebula showing. I will need a lot of data to make this work, I suppose