Cosmic Geoff

Getting an ASI224MC camera to focus with your scope is possible with your 127mm Mak, but is a skill that you will just have to master. First of all, forget about 'back focus'. It is largely irrelevant when imaging a planet or other object of small angular size, and is relevant for deep-space imaging with large-sensor cameras. You can use an diagonal or not - it's your choice. Personally I find it convenient to use a diagonal and perform the necessary 'flip' in software. You can use a Barlow if you want, but with a focal ratio of f12.5 or so you may find it does not improve results, and makes finding and tracking the target much more difficult. The difference between eyepiece focus and camera focus will be enough to cause you some grief. A trick you can try is to get focus with an eyepiece on some really bright object, then pull the eyepiece out by about 5mm and refocus, then center the target and substitute the camera. The target should now be close enough in focus for you to see it, if you have the exposure time turned up enough. As for what to fine focus on, you can try to focus on planetary detail, or on one of Jupiter's moons (very handy) or on an alignment star. I focus using the scope's standard focus knob. You may also need an infrared-cut filter, and an ADC (q.v.).

Two easier to use alternatives: Mars mapper 2022: http://www.nightskies.net/mars/mars.html# Mars Profiler: https://skyandtelescope.org/wp-content/plugins/observing-tools/mars_profiler/mars.html#

My Dell Vostro laptop does not appear affected by the cold. Remember that they generate internal heat - about 8 watts in this case. There is probably an operating temperature range quoted for your laptop if you can look it up.

I find that even cardboard works quite well for a dew shield, so there is no need to spend money on it if you are a tightwad.

You don't have to balance the C8 on the SE mount at all. It is an alt-azimuth mount and does not require balancing, unless you add so much weight that the altitude clutch starts slipping. Balancing is only really an issue on equatorial mounts, where the scope is liaible to start swinging as soon as you release a clutch if not properly balanced. My C8 is pushed forward as far as it will go in the clamp of its SE mount to maximise the clearance when aimed near the zenith.

It doesn't look right. From my earlier post: "FYI, with the legs retracted, the three tripod feet should form an equilateral triangle about 61 to 62 cm. on each side. If yours differs, you should be able to figure out where the problem lies." IF you think there is a problem, stop asking us, and send it back under warranty.

Meade mounts do not have a great reputation. The 497 is just the handset? The EQ5 is made by Sky-watcher. Lack of upgrades should not stop the mount working, unless some GPS function is involved. Unless this mount is really cheap, complete, and in working order, I would suggest that you pass.

I had that happen with my EQ5 Synscan. The DEC part collided with the cables when pointing near the meridian at a certain Declination. I don't know of a solution though. The problem has not recurred.

Please be aware that the telescopic requirements for visual, for planetary imaging, or for deep sky imaging are all substantially different. Also note that while a 127 ED may be a fine scope, look great and be cool, there are other options of the same aperture that will work almost as well and cost far less (as well as weighing much less, probably.) For visual you want a scope of significant aperture (as much as you can afford) while the mount is less critical. For planetary imaging, you want a telescope of significant aperture, and it helps to have a really rigid mount that is at least powered for tracking. For deep sky imaging, you want a scope with a short focal ratio (e.g f5), but the aperture is not important and can be small. Though optical quality should be good. A large aperture (also at f5) will allow you to capture images at larger scale, but smaller actual sky area (not necessarily what you want in all cases.) And a solid mount of the GoTo variety is essential. There is no scope that ticks all boxes, and if you find a mount that ticks all boxes there may be some other considerations, like its weight. In fact you should consider the size and weight of any kit before you rush to purchase. Do you have dark skies? If not, you can forget some kinds of imaging. Can you observe from your backyard, or do you have to put the outfit in your small car and then carry it up a hillside? If the latter, you don't want a big heavy scope and mount.

Depends what you want. The AZ Pronto with 90/660 would make a handy starter outfit. On the other hand, the 90/900 is a classic achromat design that should work well for its size on planets and double stars, but I wouldn't have the AZ3 even as a gift.

It depends on your camera's infrared response. IR850 should give a greater improvement as regards seeing, as the deterioration is worse at shorter wavelengths, but only if the camera has useful sensitivity at that wavelength. Less response = longer exposures, which may be a problem. ZWO offer an inexpensive IR850 filter for use with their cameras. I use this with my ZWO ASI224MC and ASI462MC cameras, and it definitely improved the resolution with the ASI224MC, but I have yet to observe an improvement in IR resolution over the already good colour performance of the ASI462MC. Another result of infrared imaging is that it can show up things like transiting moons that are more or less invisible in visual band colour imaging. The OP apparently has an ASI290MC, which has a strong response at IR850.

Most of the Sky-watcher scopes have this feature in the lens cap - a single central hole +cap for a refractor, and an offset hole + blank holder for a reflector. But what's it for? Clearly it is meant for stopping down the aperture to around 2 inches (otherwise why offset it to avoid the secondary mirror of a refractor?). But what is it for? Nothing to do with focusing, as there is only one hole, not two. Reducing the brightness for Moon viewing? This is a dumb idea, as you don't need to reduce the brightness for Moon viewing (it is about as bright as a black asphalt road in sunlight) and if you think you do, you could accustom your eyes to the glare, (as discussed in a recent thread elsewhere in the forum), or use a Moon filter. Reducing the aperture to improve the image when the seeing is poor? Another fairly dumb idea. Why turn your expensive scope into the equivalent of a cheap long-focus one of 2 inch aperture? If you think this works for you, carry on. Another thing you can use it for is to stick some solar film behind the hole. This is quick to do, and the cap is not going to fall off at the wrong moment. The disadvantage is that you have reduced the aperture to 2", which may cost resolution even with poor seeing caused by the heat of the sun.

90 fps seems very low. I'd have to look up the fps I got with my ASI120MC, but with my ASI462MC I get 275 fps and sub-1ms exposure times on Mars at f10. That's with a SSD equipped Dell Vostro, USB3. With an ASI224MC and an older Vostro with HDD, USB2, I got 250 fps.

It is a good starter scope for visual use, if you have thought about what you want. As for imaging, you should do some serious reading about what this entails, and gain some idea of what you can accomplish with this scope + mount and a smartphone. If you want to take award-winning photos, you should be prepared to invest far more money on quite different kit. For a start, read the imaging threads in this forum, and check what kit the contributors used.

Does the mount work? If so, I suggest you leave it alone until it doesn't, and resist the temptation to tinker. 🙂

Here's a tip for C8 SE owners: do NOT remove the scope from the SE mount head. The OTA and the mount head seem intended to be kept as a unit, which will avoid nasty things as in the posts above happening. The OTA, being fat and not having any handle, needs three hands to securely fit or remove it from the clamp on the mount arm. (unless you fit a second bar to it.) It is possible to keep the whole outfit including tripod as a unit and carry it through a domestic doorway and outdoors.

I have one of the Skywatcher tri-piers. The previous owner had Araldited a hook to it, which gave me an anchor to hold up a belt that strapped the GoTo box in place. I had a handset holder lying around, and used a bit of string to hang it from a screw projecting from the mount. One could, I suppose, drill and tap holes to attach brackets.

Perhaps it makes more difference with the Edge version. But whether you will see any difference if you deviate by a few cm is the question. Celestron's quoting the back focus to 0.01mm is clearly idiotic, to my mind. You can unscrew the top and bottom of the ADC which may allow you to reduce the spacing. I have yet to demonstrate that using a Barlow improves the planetary imaging results at all.

I have never bothered my head about "back focus". I use a CPC800 + Celestron prism diagonal + ZWO manual 5-filter wheel + ADC + ASI462MC for planetary imaging. The diagonal is for convenience, and for preventing the image train colliding with the bottom of the forks. It also gives the right spacing when I use a f6.3 reducer for deep space shots. A 3x Barlow on a scope with a 2000mm focal length is probably overdoing it.

"I have the same legs and spreader/tray., in white.." Alan, that looks like a Skywatcher tripod to me, not a Celestron SE tripod. That might be a good tip about the washers though, and the spreader is identical asides from the colour. My used Skywatcher EQ-5 tripod has legs that are too loose after some idiot dismantled it completely for shipping.

As Peter says, turn the tripod upside down to check that the legs all splay to an equal angle and there is no manufacturing defect. The spreader should touch all three legs. FYI, with the legs retracted, the three tripod feet should form an equilateral triangle about 61 to 62 cm. on each side. If yours differs, you should be able to figure out where the problem lies. (In practice I don't touch the spreader unless I am transporting the setup to a remote site. With the telescopic legs retracted the tripod (and scope) can be carried through a domestic doorway so there is no need to dismantle anything.) We have seen problems with faulty Sky-watcher tripods, but not with Celestron SE tripods AFAIK.

Don't use an eyepiece. Remove the eyepiece and connect the camera directly. (will require an adaptor.) Do not add a Barlow until you have tried it without. A dedicated planetary camera will probably give better results.

I have tried two setups for EAA, both using equipment to hand: 102mm f5 Startravel achromat, ASI224MC, EQ-5 Synscan. CPC800 f6.3 reducer, ASI224MC EAA is not the same as visual. You don't need a large aperture. If you want to go fainter, lengthen the exposure. I have found that the 102mm will show me as much or more from an urban location as a 203mm will visually at a dark skies site. If you want a larger image scale, e.g for imaging planetary nebulae, you need a bigger scope. However, if the focal ratio remains the same, you will not record fainter objects with the same exposure. I found that my CPC800 f6.3 setup requires a longer exposure to image planetary nebulae to the same image brightness compared with the f5 Startravel.

You are not comparing like with like. I have all the above-mentioned items, and find that the supplied 25mm Plossl is an adequate eyepiece. The X-Cel LX are mid-priced eyepieces which perform quite well, but the C8 at f10 is not going to challenge any of these eyepieces. The 5mm will give a magnification of x400 which will be too much magnification for a clear view under average seeing conditions.

What setup do you have in mind and what do you intend to image? I have a flip mirror but I only ever used it for imaging relatively faint things. I have since found that an alternative is to use Precise GoTo. With a little luck, this gets the image on the camera chip, especially if you are using a focal reducer. Or try plate-solving. My cameras screwed onto my flip mirror via a T2 adapter that came with the flip mirror assy.