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Ricochet

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Posts posted by Ricochet

  1. I would go for the 200p as it is a full size dob and not a tabletop dob. With the 150p I suspect one of the first things you will want to change will be to swap the tabletop mount to something tripod based. 

    23 minutes ago, Girders said:

    if you are in an urban area it won't make any difference between the two

    Not true. The larger aperture will perform better than the smaller scope under all sky conditions. The only time the smaller scope wins is when it is small enough to be transported to a darker site and the larger scope isn't. 

  2. 21 minutes ago, Andreiiorg said:

    Hi! Thanks! @Ricochet  can you tell me the acclimation time for the bresser 8" telescope with and without the fan? And maybe a link to that computer fan you use?

    To be honest, I'm not sure. It's been years since I used it without the fan and I tend to get it out in advance to cool anyway. Low power views are fine straight away but high power planetary views are maybe half an hour with the fan, an hour without. If the air temperature drops rapidly a fan helps the mirror keep up, otherwise the mirror may never actually acclimatise. 

    The battery I use is like the one linked below, but I think it is a lower mAh, cheaper version. 12v battery

    The fan is an 80mm coolink fan. I also fitted a generic pc speed controller into the telescope base but it isn't needed, running the fan on full speed is fine if it is sufficiently isolated to prevent vibrations being passed to the scope. You will need to do some diy to change connectors so that everything ends up being compatible.

    I replaced the screws that hold the mirror cell to the tube with longer ones so that I could attach the fan via hair ties. There is also a baffle to ensure air passing through the fan enters the scope. The baffle has a length of p-strip around the circumference which presses against a second length of p-strip around the opening in the rear of the scope. The hair bands and p-strip are both used for vibration suppression. 

    DSC_1927.thumb.JPG.5038516280ba945cf69be347f622d421.JPG

  3. 14 hours ago, Andreiiorg said:

    The excellent large Hexafoc focuser has an aperture of 64mm making it impossible to notice any shading from the focuser tube, even with large widefield eyepieces.

    "Shading" is vignetting, not coma. I'm not sure if you would notice any vignetting visually even with a "normal" 2" focuser when used visually as you need to lose half the light to notice.

    14 hours ago, Andreiiorg said:

    The 2,5 hexafoc focuser is better than the 2 crayford? Noticeable in focusing or other way?

    It is a very strong focuser, with no flex at all at any extension so the weight of the eyepiece will never affect the collimation. The Stellalyra is probably a bit smoother to turn because it is a Crayford but I don't know how it handles heavy loads. If you want the best of both worlds there is a Feathertouch replacement available for the Bresser but it costs more than the scope. Another thing I like about the Hexafoc is that you can rotate it 45° so that the focuser wheels are always in a convenient position.

  4.  

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    Optically it provided a bright, high contrast, and controlled view that allowed it to keep up with even premium wide-field eyepieces like the Pentax XWs

     

     

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    excellent off-axis performance

    As someone who owns both XWs and a BHZ, I disagree with both of these points. Where the BHZ excels is when you want a quick grab and go session with only a couple of eyepieces in your pocket. If you're going out for an extended session with a case full of eyepieces the premium fixed focal lengths are superior, revealing more detail and having a higher optimum magnification than the BHZ.

    • Like 1
  5. 3 hours ago, John said:

    The SLVs have a very similar presentation to the Pentax XWs I felt, but with a smaller AFoV of course.

     

    I agree with this. 

    45 minutes ago, 12green said:

    Should there still be a marginal upgrade in performance using binoviwers with SLV over Starguiders in SCT? 

    Definitely. Most people concentrate on image correction when comparing eyepieces and internal baffling, light scatter and reflections are ignored. The SLVs are significantly better than the Starguiders in this regard. Space will be blacker, the object you are looking at will be sharper and there will be no reflections of the object floating around the view (although you may still see reflections and scatter from the binoviewer).

    • Like 1
  6. 18 hours ago, Andreiiorg said:

    I want firstly to go on planetary observing but after some time and on DSO.

    Jupiter and Saturn are now getting lower in the sky so I think you would be better off considering more DSO observation over the winter with planetary coming back into play next summer. Your choice of Celestron X-Cel LX eyepieces is a good choice, so long as you stick to the 12mm and shorter focal lengths. The 18 and 25mm will have quite noticeable aberrations in an f6 scope and you can make better use of your money elsewhere. I have the Bresser 8" and in my opinion no 1.25" eyepiece has a wide enough for your lowest power eyepiece. My lowest power eyepiece is the 28mm Nirvana and I think this eyepiece fills the role very well. You can buy the current version of this eyepiece from Telescope Express, and possibly some other brands that I am not aware of, for a very reasonable price: TS-Optics 28mm Ultra Wide.

    Going back to the Celestron X-Cel LX range, you definitely want the 12mm as this will give you an exit pupil of 2mm, which is ideal for extended objects  (12 / f6 = 2) and for DSO observations you could stick with just these two eyepieces. The 9 and to a lesser extent the 7 will also be useful for DSOs (where they fit into the field of view), and for planetary I always found the 7mm to be a goldilocks focal length under UK skies, although the 5mm should be the optimum choice when sky conditions allow it.

    Of the two scopes under consideration the altitude bearings, mirror cell and focuser are reasons why I would buy the Bresser again if I was making the choice again. I purchased the 1:10 dual speed upgrade for the focuser (as well as 1.25" and 2" Baader clicklocks) and bought a 12V computer fan and battery quite cheaply to cool the primary mirror.

    • Like 1
  7. 3 hours ago, OptymsticAlpaca said:

    Our current plan is to get whichever one comes back in stock first

    Given the current state of affairs this is a good plan unless you find yourself particularly drawn to one of the brands over the other. Personally, as an owner of an 8" Bresser, I would buy another over the Skywatcher or Stellalyra (GSO) offerings based on the larger altitude bearings, the mirror cell and the focuser.

    39 minutes ago, OptymsticAlpaca said:

    I definitely want to be able to carry it out to the garden on my own!

    I can carry my 8" Bresser from the shed into the garden in one piece (base + OTA) because the two holes on the sides of the rocker box make nice handles to lift the whole setup. The Stellalyra only has a single handle on the front of the base, which is fine for carrying the base by itself. If you add a pair of handles to the sides of the base I am sure it could be lifted as one piece like the Bresser. If you have any stairs or quite uneven ground to traverse you will probably want to carry the OTA and base separately even though the weight is manageable (for me at least). In this case, again the Bresser is easier to carry out of the box as you can use the altitude bearings as handles, although a central handle over the centre of gravity would probably be easier for both scopes.

    • Like 1
  8. 2 hours ago, Jakelol said:

    How would the 130PDS and the AZ-GTi be together just for visual? Sky-Watchers page says the 130PDS is 3.66Kg and the AZ-GTi can take a payload of 5Kg?

    Im thinking i might just start with visual for the first year or so and then upgrade to a HEQ5 if i feel the need to take photos?

    I suspect it would be too heavy. Manufacturers have a habit of overloading their mounts and the biggest AZGti combination uses a special lightweight 130ps, which indicates that they couldn't fit a standard 130p on it. 

  9. 14 minutes ago, ScotRod said:

    It's more like just spikes at the top but the nothing at the bottom (when in focus).  Imagine a single star point with those spikes along the top...

    I suspect you might be seeing coma. What happens if you move the position of the star around then field of view? Does the direction of the spike change? For a properly collimated scope there should be no tail when the star is precisely centered, with the tail pointing away from the center when the star is not centered. If you find that the tail directions all point away from a star position that is not in the centre of the field of view you need to recollimate your scope. 

  10. 2 hours ago, vlaiv said:

    length of drill + drill bit could be an issue?

    So long as you have enough room start the hole with a good sds drill and short drill bit, you can then drop longer drill bits into the hole, connect the drill and continue drilling. However, with the cramped conditions the drilling will be difficult. Your builders will probably have to take it in turns drilling.

  11. 12 minutes ago, vlaiv said:

    thin slab of concrete - 10cm

    This sounds way too thin. How deep does the existing pier foundation go? If deep enough I would be more inclined to drill down into the existing foundation and epoxy long rods into it to bolt a steel pier to. 

    • Like 1
  12. 4 hours ago, Don Pensack said:

    I may be a contrarian here, but I don't regard that as an "upgrade".

    A true upgrade to the Starguiders would be the TeleVue Delites.  They are optically better in nearly every way.  But don't expect miracles.  We're talking maybe 5% better.

    I would consider the SLVs as "optically better" than the Starguiders. They're sharper, with less scatter and no reflections (except some old ones, apparently). The only thing the Starguiders have over the SLVs is the extra 10° field of view, so it depends how much stock you place on that feature. Personally, 50° isn't wide enough for my taste (except for solar, where I use SLVs), so I see where you're coming from in that regard. In terms of image presentation, my SLVs, Delites and XWs all feel very similar, just with different fields of view.

  13. 1 hour ago, Jakelol said:

    Will the AZ-GTI Wifi Goto hold the Startravel 120 without any problem

    No, the ST120 is too big for the AZGti

    1 hour ago, Jakelol said:

    do i need the HEQ5

    For Astrophotography the HEQ5 is the minimum recommended mount. The EQ3 might just about be ok for visual but I've not used one to know.

    1 hour ago, Jakelol said:

    Im a bit put off the whole collimation of the reflector telescope and if Im right i dont need to do anything like that with the refractor telescope right?

    Refractors can also require collimation. Newtonians tend to require it more often but I suspect most people don't do the collimation screws up tightly enough.

    1 hour ago, Jakelol said:

    What does the reflector do better then the refractor and vice versa?

    The ST120 is a fast achromat. This means it will have lots of chromatic aberration and be suitable for low power, wide field views but not lunar/planetary or astrophotography. Visually, on those low power views the ST120 might be better than the 130PDS. If you want a Skywatcher refractor for lunar/planetary or astrophotography then take a look at the ED Pro range.

  14. One of the standard beginner's astrophotography setups is the 13PDS on the HEQ5 mount so that would be a good choice if you want to progress onto astrophotography. However, be aware that it isn't just quickly swapping an eyepiece for a camera and snapping whatever you're looking at. A single image can be comprised of exposures taken over a whole session or even multiple sessions. The goto eq mounts required for astrophotography are also quite big and heavy so you may prefer a second smaller set up for visual. If goto is a requirement for visual too perhaps look at the AZGti options, or without goto you could mount a 130PDS on an AZ4. 

  15. 1 minute ago, Stardaze said:

    Interesting. I did have a few minutes rolling the laser around in the click lock to see how that looked, wasn’t perfect. I’ve checked the laser and it was a tiny smidge out, so after half hour faffing, it’s probably slightly worse. I’ll sort that with a fresh head but led me to think, what if the click lock doesn’t centralise? 
     

    Centralisation isn't strictly necessary. If it clamps squarely and repeatedly in the same position then you can just make sure to always put the clicklock in the 2" clamp at the same angle and use collimate to that point. If it isn't repeatable or it is tilting the laser and/or eyepieces then I would try a different 1.25"-2" adaptor and if confirmed as the issue talk to Baader about getting it replaced.

    • Like 1
  16. 31 minutes ago, Stardaze said:

    If it has no proper way of aligning, surely most people don’t bother? 

    Exactly. As the optical axis and the mechanical axis of the telescope don't need to coincide, all you have to do is to be able to get the secondary mirror under the focuser and then collimate from there. However, the squarer that the focuser is, the easier it is to collimate the secondary, which is why I shimmed mine a bit.

    • Like 1
  17. 3 hours ago, Stardaze said:

    The hexaloc fixings are clearly different to the Quattro focuser, only two grub screws with small allen keyed screws. A basic measure isn’t so straightforward measuring 4 points around, I found earlier.

    I'm not entirely sure what you're talking about here but I suspect that you may be trying to do something you've seen in the video that isn't possible with the Bresser focuser. If you can wind the focuser though the full range of travel with it always pointing at the same spot then as far as I know there aren't any grub screws you should be touching. I've shimmed mine with washers because there are no "squaring collimation" screws. The small grub screw (hole) that you can see in the side of the focuser base plate on the left of the photo just holds the focuser to the plate as far as I can tell and the grub screw further up the focuser to the right of the photo controls how the drawtube runs in the focuser.

    DSC_2830.thumb.JPG.33a65b8930d88d5be080a621a092d04d.JPG

    3 hours ago, Stardaze said:

    Did you strip out and add a donut opposite the focuser to ensure the focuser is perpendicular?

    No, I just drew a cross on the side with a pencil. I may have even drawn it on some masking tape that I later removed as squaring the focuser only ever needs to be done once. If there is only a slight error you don't ever have to do it as you can just shift the secondary a bit. So long as the secondary is under the focuser that's all that matters.

    • Like 1
  18. On 11/11/2021 at 11:22, WatcherF said:

    I didn't have enough room to take it

    What part of it was it that caused you the most trouble? Was it the OTA itself or the EQ mount and tripod? I would be inclined to look at alt/az mount options that use a 3/8" threaded mount so that you can pack a much smaller photographic tripod. The Skywatcher Pronto, AZ5 and AZGti ranges all fit the bill.

  19. 3 hours ago, apaulo said:

    1 for general observing dso, messier, etc,

    There is no such thing as a filter for general observing. A CLS might have been an option ten years ago but with the move to LED lighting they are less effective. Your choice of filter depends on the type of object you are observing. As a quick summary I would say:

    • Moon and planets: Neodymium, the Baader one if you can afford it.
    • Star clusters (open and globular): More magnification, so long as you keep the exit pupil at 1mm or higher, and the cluster fits in your field of view.
    • Galaxies: Sometimes a CLS seems to help a little, but really you need to get to darker skies.
    • Emission Nebulae: UHC and OIII filters. From a dark site UHC performs better on a larger number of objects, but with increasing light pollution the tighter filtering of an OIII becomes more valuable. Filters are the one item where going for a top end product 9e.g. Astronomik) really pays off IMO. 
  20. 2 hours ago, Stardaze said:

    Thanks for taking the time here. The laser seating is possibly the cause yes, though I have a click lock. I prefer the concentre to a basic cap. The Cheshire I find to be most accurate for the primary. I’ll have a look again this morning, realise it’s the focuser or secondary where the issue is. 

    Loosen the clicklock slightly so that you can rotate the laser in the clicklock. Rotate the laser and watch the dot. If it stays on the same spot the laser is ok, if it draws a circle the laser needs collimating.

    If the laser is OK move on to the clicklock. Loosen the 2" clamp a touch and rotate the clicklock. If the dot stays on the same point the clicklock is OK, if it draws a circle the clicklock clamping mechanism is tilting the laser. Also try unclamping the clicklock to check for repeatability. You should find that the laser always hits the same spot when clamped,

    If the clicklock is OK, move on to your 2" clamp. You won't be able to check for rotation here but you can check repeatability. If you have a clamp with more than one thumbscrew try different screws and see what happens. If you've got the standard Bresser Hexafoc 2" clamp this is one of the places where your problem lies. The inner profile of the clamp is 2mm fixed - 8mm compression ring - 2mm fixed. That lower 2mm fixed section will always coincide with the location of an undercut, such as the one on the clicklock, so that the top fixed part of the clamp inner barrel becomes a pivot against which the compression ring tilts anything with an undercut. The solution here is either to change the 2" clamp or to change your 1.25"-2" adaptor to one that is smooth sided and never use any 2" eyepieces with undercuts.

    My OTA is also slightly oval and to compensate I have added a couple of washers under two of the focuser faceplate fixing screws to get the focuser pointing closer to the correct point and then tweaked the secondary position by simultaneously shortening and lengthening the up/down spider vanes to get the secondary perfectly under the focuser. Having the secondary perfectly centred in the OTA is just a starting point, and not required for collimation.

    • Like 1
    • Thanks 1
  21. If you want grab and go I think you need to go with a 102 option, or even a smaller ED scope, that can be stored set up on the tripod and carried out in one go. I don't think that a 120 frac will be any more grab and go than your 150 dob. 

    Edit: in fact, why are you storing the dob base in the shed and the OTA indoors? If you store the OTA on the base in the shed you can just carry the whole scope out as one piece and there's your grab and go scope. That's what I do with my 8" and set up time is less than a minute. 

  22. 5 minutes ago, PeterC65 said:

    I was thinking about a Baader Hyperion 24mm or an ES 68° 24mm. The Baader has a slightly bigger field stop (28.5mm) than the ES (27.2mm) so the TFoV is a little wider, but not much. But I'm wondering whether the Baader Hyperion 24mm might be very similar (in construction) to the Hyperion Zoom that I already have and so maybe the ES would provide a more different comparator? Does anyone have a view about the Baader Hyperion 24mm versus the ES 68° 24mm?

    In your Skymax either will probably be ok, but if you ever buy a faster telescope the ES68 will be significantly better, so long as you don't need to wear glasses when observing. As far as I am concerned the options you should be looking at are the ES68, the TV Panoptic and the APM UFF.

    • Like 1
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