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A few things here: 1. Your exp time is too high, dial it way back as mentioned. 2. You may not have the camera sensor at the right focal point, backspacing relates to getting the sensor at the point of focus and usually applies when using a corrector lens prior such as a flattener, reducer or coma corrector. As I assume you may not be using any, the sensor therefore is not at the point of focus. You can test this very roughly by getting an eyepiece in a diagonal into focus, then swapping to the camera and adjusting focus nearby, itll need to be adjusted because an eyepiece will contribute to the focus point whereas a camera is relying on the focus point of the telescope only. But, if point (1) is not right, you'll never see the focus point. 3. Your telescope is a long focal length, so with point (1) all you'll see is a bright light, even if pointed somewhere off target but near the moon. The brightening is worse the longer the exposure time and your scope can be further away from target but youll still see a brightening on the camera. Potential solutions: A. Dial back the exposure to less than a second, not necessarily fractional ms or uS (micro seconds) at this point, this is what I do. Make sure the target is a white disc. Get to near your focal point, when you look on camera the bright disc will get smaller as you're approaching focus and larger when away. Then move the scope off target a little and repeat. The disc should get smaller and smaller, if you're near focus and your scope it pointed at the edge of the moon you'll be able to focus to a near sharp circle edge, this will get you extremely close to the focus point. B. Then dial back the exposure significantly to ms or uS exposure (most likely on the moon you'll use ms, uS is usually useful when doing solar). The bright disc will retreat to the moon colour, maybe a dim grey if the exposure it too short. The surface detail will show. Then very minutely adjust focus until areas of contrast are sharp as you can see, you'll have to work with the atmospheric seeing here and make a focus adjustment then assess when seeing "freezes" fractionally time to time. You'll have to to and fro a little here. The exposure should be such that your histogram peak isn't crushed to the left (you're "destroying" the darkest black/shadows areas merging them into one uniform blackest black, also known as clipping) and the whites/highlights also the same but on the RHS of the histogram. C. Try the camera with diagonal and without (straight through). Note the latter you may need spacer/extension/backfocus rings because a diagonal takes up that distance from the back of the scope up to the eyepiece and you have to compensate for that sometimes, or rack the focus on the scope further than it would be with a diagonal+eyepiece. You might find without the extensions you cant get focus when imaging straight through. D. Basic but be absolute sure your finder is aligned with the centre axis of your telescope, the finder will make it easier to ensure your camera is centred or slightly off target. With experience you can usually do without a finder and just use a deft touch with sweeping with your scope and using rough eye "finding". A larger camera sensor makes this bit easier, as well as not having to nudge the scope so much if you're not using a goto tracking mount to keep the target centered on camera.

I agree re seeing is so important of course. If a persons best view ever of, say Jupiter, was with a certain scope it doesn't mean its better than any other scope that wasn't available to compare it with at the time of the observation. Even having a quality 5 inch refractor along with a quality 8 inch Newtonian and comparing them directly is flawed. The comparison would have to be on a night when the seeing is good enough that the larger telescope, can be used to perform to its best resolution as well as the smaller one. If not then its not a fair comparison. Any differences would be more of a test of the observing conditions rather than the telescopes ability. So when I say that a such and such telescope gave me my best view ever of Mars, it may be interesting, but it doesn't meant it was the best planetary scope I've ever used. It happened to be a 16 inch SC one early morning just before dawn, when the seeing was exceptional. The best person to answer the original question would be one who has owned both a 5inch refractor and 8inch Newtonion simultaneously over quite a few years. Not only that, but they would have had to frequently used them side by side on numerous occassions when the seeing was good enough for both to perform to their respective maximum possible resolutions. Oh yes, and on a good variety of targets. Ant takers?

This is one of the threads on CN which has several contributors some of whom appear to be very well experienced visual observers. They have used several higher end refractors visually as well. It was from this thread and others that I gleaned the visual performance of the 120/140 Askars was good. Have I been reading this thread through a pair of rose tinted glasses? Thanks. https://www.cloudynights.com/topic/900932-askar-140-apo/

I have thought about putting a hand warmer in my eyepiece case! I think the small size of eyepiece lenses is also relevant. Even the largest ones will be quite rigid compared a big floppy newt mirror for example.

Here is one of my old posts from 2010 where my wife and I visually compared a 5” refractor to a Skywatcher 8” F/6 Newtonian… “I was really enthusing about how good the seeing was so Mrs Dweller25 decided to come out and have a look. Now this is a rare event as Mrs D and the cold night air don't mix so to spice things up a little I suggested a shootout between the 5" Takahashi FS128 and the Skywatcher 8" F/6 Newtonian. Each of us would take a turn observing and drawing Mars in each scope so we could compare and contrast. Seeing was very good - AII, temp was -4'C. We concluded :- 1. Mrs D25 has better eyesight than me - I have astigmatism 😕 2. The humble Skywatcher slightly outperforms the Tak 😱 🙂

I saw this in the challenge section but can't comment there of course. I like this version very much as the other ones taken during full darkness don't do you justice. It's a shame the dark sky park doesn't reach as far as the coast ! The star spikes look good and well controlled. The fact you've got nice reflections also draws me in Dave.

Imaging near the Zenith produces massive image rotation. Even if the Seestar can compensate when stacking, the useable field of view reduces from a tall rectangle towards a square. The image below has been black level adjusted to demonstrate - M51 was about 82 degrees altitude.

Curves will give you more control on width of peak, or use selective colour.

It’s advertised as 1.52KG for the OTA out of the box - that must include the built-in mounting ring and dovetail. Sorry I don’t have any scales at the moment.

Thanks Mr Spock, Pulling out one particular comment, I was interested in the variable polariser. How does it affect the appearance of jupiter, wrt bands, GRS, etc?

Thinking about a newt. A mirror at uniform temperature, whether 0C or 40C, has the same shape, and therefore consistent performance. A decent mirror has very low thermal expansion, which means cold edges and hot middle should have a small effect on shape. How much this matters depends on the temperature difference. It is all a matter of degrees. OK I'll get my coat. An eyepiece (even a jam jar size multi element) is small and low mass compared to a 10" or 12" mirror. Temperature difference from centre to edge is going to be small. So performance hit should be small. Cooling is going to be fairly quick. So by the time you have thought much about whether view it good, temperature has become stable. In 2011 I trialled a solution to the 'foggy eyepiece' and 'not enough pockets' problem. A fibreglass box (strong enough to stand on) containing large resistors and a fan on the aluminium plate. Power from a 12V supply. Just keep eyepieces in there when not in the scope I posted about it on SGL and there was zero interest!

Yep - the lower setting of the 3-8 is closer to 3.5mm I reckon.

Great picture! 🙂 Exactly one year ago it happened that I captured the Markarian's Chain. When I run a StarXterminator on it I found 63 galaxies. How many of them you have in your picture? 🤔🙂 https://www.astrobin.com/v6wchq/

Following on from this, I’ve done an analysis of my mount’s performance using sets of raw frames that I took a few weeks ago. As it is SharpCap specific, but may be useful to others, the write up is on that forum. https://forums.sharpcap.co.uk/viewtopic.php?t=7630 Geoff

I found that there is a mechanical stop at about 85 degrees in elevation (altitude), so there will be a "blind" cone within about 5 degrees of the zenith. The "voice" confirms the end stop when you hit it. If clouds permit, you can wait until the target drops in altitude. Geoff

Thanks Dirk. Interesting comments!

Thanks Alan, Thanks to many people in the forum, plus other research, I decided early on that the az-eq6 was to be the foundation stone, and building from that. So, a 200pds and 120ed will be OK. But, it could handle bigger. Problem is, my ability to handle the larger scopes is inversely proportional to my age now. But, I may decide, 8" is all I need. 😊

Indeed the beauty of the Az-eq6, is it can hand both simultaneously, so I could build up a record of differences. Obviously there will be times when I only want to have one set up, but the options there.

Probably not with a mak.

Thank you Paul. I ran the same in PixInsight using the TypeCat script and pulled out a lot of quasars. Currently, calculating the distances on a few to see if I’ve beaten my most distant object captured.

I keep mine in a tray with the eye dust cap on to prevent misting. I don't have enough pockets for all of them anyway, especially the larger ones

Those histograms do not look like the histograms of linear data. White balancing cannot be performed on non-linear data. It raises the question about what kind of workflow you are following. For instance, are you raw-converting your images before stacking or do you put your raw files directly into DSS?

I haven't started my review yet. I still have to give it a full workout on the 4" Tak. On the 12" I was able to use it at the 5mm, 4mm and 3mm settings on the moon a couple of nights ago. Field curvature wasn't as evident as longer focal lengths and not intrusive. The eyepiece was sharp at all settings against the 4mm Nirvana, 7mm, 6mm and 4mm Circle-T orthos, 6mm SLV, 3.5mm and 5mm LVWs, with some variation - it wasn't a match for the 8mm LVW and the orthos looked 'cleaner'. It couldn't match the 4mm and 3.3mm TOEs in any area; the TOEs were sharper, clearer and had better contrast; they were able to pick up the tiniest of craters - I won't be selling them! I did note the magnification looked the same as the 3.3mm TOE at the 3mm setting - objective rather than scientific. I also had to fold down the eyecup to feel comfortable. My tiny 4mm ortho was easier to look though!

I moved the exposure time right down to 1ms. Earl - When you "You might need to add an extension tube to achieve focus." - what do you mean? Can you show me a link please?