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Cosmic Geoff

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Posts posted by Cosmic Geoff

  1. I can't identify the exact mount from "Celestron 114 EQ" but I have to point out that such kits are generally supplied with the cheapest and most flimsy mount that will hold the telescope up and not generate immediate complaints.

    Ideally you want a more substantial mount like the EQ-5 or HEQ-5 to hold your telescope while you try to image planets with it.  And you would get better results with a dedicated planetary imaging astro camera.   I fear that astro imaging, whether planetary or deep space, can be a money pit.

    And if you have got that far, you may that you can't get focus with a DSLR without modifying your telescope.

    • Like 1
  2. I have tried using a C8 SCT (in the form of a CPC800) for EAA.  I used a Celestron f6.3 focal reducer (probably essential) and an ASI224MC camera (because I had one).  Targets were in the main planetary nebulae, which I located using Celestron's 'precise goto' and the view on screen.  Got some good images. I tried platesolving on one occasion with this setup and it worked.

    I never got anything good without the focal reducer and using a flip mirror diagonal.

    A larger chip astro camera would no doubt be advantageous.

    I should point out that I do most of my EAA with a 102mm f5 achomat, the ASI224MC and a EQ-5 Synscan, finding the targets via plate-solving.  

    I do not recommend the Celestron Starsense (handset & camera) for EAA.

  3. Short answer: if this worked, somebody would have tried it already. 🙂

    Longer answer: adding a Barlow does not reverse the various aberrations (spherical, colour, coma) introduced by using a short focal ratio. Flattener/correctors available for short-focus imaging telescopes are usually wincingly expensive.  For visual, you can use a shorter focal length eyepiece, but these tend to be more elaborate than what you could get away with on a f10 telescope.

    I have tried adding a x2 Barlow to my f5 Startravel.  It seemed to improve the image quality a bit, but not enough to make it equivalent to a f10 Evostar. 

    There is a budget Newtonian telescope which incorporates a Barlow-type lens to shorten the overall length. It has a terrible reputation as a useless newbie trap.

    • Like 2
  4. I don't touch the RGB settings in Sharpcap.  Reviewing my old images, I note that the several ZWO cameras gave different tints.  For the ASI462MC, I increase the colour saturation a few points in Registax, and tweak the colour balance  to make the pale bits on Jupiter look white (Red 1.10, Blue 0.95, Green 1.0).

    Doing the same on Mars looks it look redder.

  5. There is some debate about whether (in the case of Celestron SCTs previously discussed here) the corrector needs to be matched to the primary (and secondary).  Perhaps earlier SCTs had individually figured and matched sets but the later ones don't, so that a replacement could work.

    Somewhere in response to another thread here somebody gives details of a company that makes replacement SCT corrector plates in various sizes. 

    And one hapless owner actually obtained a replacement corrector for a large SCT and was wondering how to get it fitted. (in the 'Whole setups' thread IIRC)

  6. I found the environmental specs for a recent Dell Vostro laptop (5490). It says:

    Operating: 0°C to 35°C (32°F to 95°FRelative Humidity: 10% to 90% (non-condensing

    Storage: -40°C to 65°C (-40°F to 149°FRelative Humidity: 0% to 95% (non-condensing)

    Note that with laptop design a challenge is to keep certain of the components cool, rather than prevent them from freezing.  If you take a laptop from a warm room and then power it up, its innards are never going to fall to ambient temperature.

    I used to use a laptop that consumed about 20 watts and emitted a constant stream of warm air. No danger of that one freezing up. 🙂

    One ought to protect a laptop from dewfall, but nervous owners may note that I have never bothered with either of my laptops and there have been no ill effects.

    • Like 1
  7. 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.).

     

    • Like 2
  8. 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.

    • Like 1
  9. 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.

  10. 19 hours ago, CharlyLeyequien said:

    good for astro photography, which I want to do at some point once I am comfy with the telescope, so why not already have something capable of it(OFC if there is any recommendations for something good that is a bit cheaper, I might look into it, the cheaper[for a good device] the better

    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. 

  11. 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.

    • Thanks 1
  12. 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.

    • Like 2
  13. 1 hour ago, gamermole said:

    Can you guys tell me your thoughts on this telescope, or if you know of any better options out there regarding my needs.

    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.

  14. 45 minutes ago, cloudsweeper said:

    I had a similar experience with my 8SE.  I hadn't secured it properly in the Celestron mount,

    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.

    • Like 3
  15. 1 hour ago, Ade Turner said:

    I’d always assumed/read that the camera’s sensor should always be as close to the recommended back focus as practical. Does it not make any difference then?

    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.

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