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I'm matt from the UK, essex to be more accurate. I had a skywatcher 150p around 8 years ago and had some amazing moments with it, Jupiter being one of the highlights despite the 150p's declination towards DSO's. Unfortunately due to some financial problems at the time I had to sell it. Astronomy was a hobby I locked away to a quiet corner of my brain until my very wise other half helped me realise how much I missed it.
We have just bought a skywatcher 150pds as i want to focus on astrophotography this time. Its currently on a eq3 pro mount with synscan. Not the ideal mount, i plan to upgrade to the heq5 as soon as possible, but its perfect for me to learn and practise on.
We bought the scope and mount second hand in an amazing deal, coming with the coma corrector, all 3 sky panorama uwa lenses, the canon t ring adaptors and a clubman flight case for £700. Everything in perfect condition, although the mount has some stickiness and i think maybe some binding in the gears, so I plan to strip it down, de and regrease and reassemble as soon as possible.
Have only had the opportunity for a couple of hours viewing so far, during which I very unsuccessfully attempted to polar align and then 2 star align the mount, but loved seeing it slew. I did get some amazing manual visual observation on the moon, but was surprised that despite my previous experience with a very similar scope just how much I don't know. Am very eager to learn as much as I can and am very excited to be back in the hobby, as you can probably tell from my extracted and probably boring welcome message.
Anyone with any experience of this scope or mount with any tips or little known tweaks I would be exceptionally grateful for any advice. Or any tips in regards to polar aligning and star aligning, especially in a class 6 bortle or similar.
One problem I struggled with was gaining any focus on any lens I have while using the barlow lens. Am sure it is either my error or cheap equipment but I gained a very nice focus with the 28mm supplied lens and the panorama range but struggled gaining focus with the barlow and said lenses. After looking into this though I'm wondering if it was due to me not accounting for eye relief?
I look forward to meeting like minded people on this forum.
I have a Celestron Starsense Explorer DX 102AZ on the way.
I was wondering if someone could please recommend which size EP to buy for viewing planets and the moon?
Sky watcher ULA Planetary (my budget is £40)
I've read on another thread that sometimes 9mm can outperform a 4mm with a fast telescope as more magnification can make the viewing duller? I was hoping for the best magnification that is also crisp.
Thank you for your help.
Probably an old discussion but lets review it with some measurements:
The dark noise should only have a small influence on the total noise of the final image. Most noise is generated by the sky background. Under good conditions SQM = 20.4, I measure using my ASI1600MM-Cool the following noise (standard deviation) in a dark and in a light for an area where no stars are visible (local measurement using ASTAP):
Dark 1 x 200sec, σ = 15 (range 0..65535)
Light 1 x 200sec, σ = 130
The noise in the dark is roughly 12% of the light, which seems acceptable to me. That would argue for about the same amount of darks as lights. With a worse SQM, you can probably do 2.5 times less darks for each (magnitude) step. So under light polluted sky you can do with much less darks than lights.
If you are going to photograph with the H-alpha filter, it will be super dark. In a single H-alpha (7nm) light I measure a σ = 25r. Of these, 15 are self-noise and 10 of the incoming light. In good conditions and using an H-alpha filter, this is an argument to make much more darks than lights
Above for a monochrome camera. To measure with an OSC (color) sensor I think it is better to first split the 4 Bayer pixels into 4 files and then measure them separately.
Some measurements with my ASI1600MM-Cool, monochrome:
1 x 200 seconds, σ = 16
1 x 200 seconds - master dark, σ = 15
4 x 200 seconds combined - master dark, σ = 6.8 This is approximately 15 / square root (4)
41 x 200 seconds combined, σ = 5
90 x 200 seconds combined, σ = 3.8 This is a limit value that arises mainly from unevenness of the pixels. The noise will be smaller, approximately 15 / square root (90) is 1.6
STACKED LIGHTS noise (lights corrected with darks and flats):
11x200 seconds, σ = 70 (measured at a star free area, standard deviation in 0..65535 range, sky conditions could have been different)
18x200 seconds, σ = 36
18x200 seconds, σ = 40
40x200 seconds, σ = 26
42x200 seconds, σ = 30
44x200 seconds, σ = 25
58x200 seconds, σ = 20
95x200 seconds, σ = 16
Apparently the light noise decreases considerably while stacking more lights and I reach σ values up to 16 a 20. You do not want to stack these images with a single dark having a σ = 15. If you want to keep the dark noise added below 10% of σ = 16 then you need 100 darks because they give: 15 / square root (100) = 1.5 noise.
So this confirms for a good suburban site (SQM=20.4) you will need about the same amount (or more) darks then lights. For a more light polluted area you can take less darks since the noise from the skybackground will be abundant. For H-alpha work you better take more darks then lights.
By Cedric Schweizer
Does anyone know if I can use a Skywatcher Explorer 130pds with a Sony alpha a7iii? I'm quite new to AP... I know that I need a T-Adapter but I'm a little concerned about the potential vignetting I could get...
Thanks a lot for the help!
Hi all - looking for some
advice on eyepieces. I have seen beautiful views of Jupiter with its moons and Saturn and of course the moon. I have two extra 32mm and 10mm plossls but am looking for better lenses for planets which will show more detail? Which ones would you suggest? Many thanks in advance!