Ricochet

Whether you can see the edge of the primary and/or clips depends on how far in or out you have the cheshire when you are collimating. Seeing those clips is not essential, the most important part is getting the crosshairs, the doughnut and the reflection of the hole at the top of the cheshire all lined up. For collimation to be absolutely perfect then everything should also look circular and symmetrical either side of a line running in the plane of the focuser as shown in the image below. Your focuser is at the top right, marked by the red F, and the centre line is extended from that point. we can see that the "top left" secondary shadow is slightly larger than the "bottom left" secondary shadow, so there is room for some minor improvement, but I think how you have it now is good enough for use, and I wouldn't worry about trying to improve it.

That presentation is a very good find. I like the idea of the film, as it provides an improvement without adding weight or bulk to the scope. I think that I may have inadvertently done something similar by flocking the inside of my dob. It doesn't prevent the radiative cooling of the tube, but I think that it probably prevents or lessens any conductive exchange between the tube and the air inside of the tube. I've not got any temperature sensors to confirm this, but the flocking feels "warm" and the inside of the tube does not dew up like the outside does. However, there is also a primary fan so the resulting small air current may be helping with respect to dew formation on the inside of the OTA. Now that I have properly isolated the fan from the tube with respect to vibrations, I have not noticed any difference visually between leaving the fan on all night, or turning it off for high power observations (nut perhaps I need to do longer testing on this).

For astrophotography, the only thing I know to suggest is to get yourself a copy of the book Making Every Photon Count. Reading and understanding this book should save a lot of aggravation and money in the long run. If you want to do some visual as well and can spare another £100 then maybe an 18mm Baader Classic Ortho and a 12mm BST Starguider would work well, which with your barlow would effectively give you 6, 9, 12, 18 and 28mm eyepieces (0.8, 1.2, 1.6, 2.4 and 3.7mm exit pupils). You could could choose the 18mm Starguider instead of the BCO, but it doesn't do so well in faster focal ratio scopes and I am not sure at what point the image cleans up. Alternatively, if you don't want to spend that much, perhaps just the 15mm Starguider for £50, so that you have 7.5, 15, and 28mm eyepieces (1, 2 and 3.7mm exit pupils). For visual there is the book Turn Left at Orion, and the accompanying web page. I would also suggest downloading Sky Safari if you have a smartphone or tablet, or Stellarium for a PC.

Your secondary needs adjusting. I think that you should buy a proper Cheshire/sight tube to do this. You need to adjust the secondary so that when you look through the Cheshire the doughnut on the primary mirror coincides with the crosshairs.

Do you have any other eyepieces than the 28mm eyepiece that came with the telescope? The 28mm is a 2" eyepiece but the barlow is 1.25". Only 1.25" eyepieces can be inserted into the barlow. The bottom of these two pieces is a 2"-1.25" reducer. You put this piece into the diagonal, then the barlow lens you have bought fits into the reducer. You can then insert a 1.25" eyepiece into the barlow lens. However, you also mention astrophotography. If you are doing astrophotography then you do not use an eyepiece or diagonal, the camera is attached directly to the back of the telescope, and you would only use a barlow if you are doing planetary photography.

Thanks, John. The cut off age is even higher than I had thought.

One good thing about Bresser is that they have a very good warranty department. I am sure, if your neighbour has the receipt, Bresser will take the telescope back for repair.

The best scope for £100 is the skywatcher heritage 100p, but you would be better off increasing your budget for a heritage 130p, or even doubling it for a 150p. With regards to your granddaughter, I am not sure if 3 will be a little bit young for using a telescope. Others will have experience of children this young looking through telescopes and be better able to advise.

Diffraction spikes are more obvious on brighter objects. If you increase the magnification they will become less obvious.

For the money, extremely good. It isn't perfect, there is a slight distortion of star shapes towards the edge, but I suspect the majority of people wouldn't even notice. It's slight enough that I can't remember off the top of my head which, possibly astigmatism. The face cup means you have to turn your head a bit to look through it but that really doesn't matter. The 31N is probably the only similar eyepiece that is (slightly) better.

Assuming that you've already determined the correct barlow/gpc to enable you to focus and have inserted the binoviewer into the focuser/diagonal then my process is as follows: Look through the BV with both eyes and adjust it so that the IPD feels right. Close one eye and make sure that the full FoV is visible with the open eye. Switch which eye is open without moving your head and see how much of the FoV is visible with the other eye. At this point you will probably find you did a really bad job in step 1. Adjust the BV so that both eyes see the full FoV. Pick one eye and focus for that eye using the telescope focuser. Technically you should use something to cover one eye instead of closing it, but just closing an eye seems to work ok. Use the dioptre adjustment to focus the BV for the other eye. It may be easier to adjust the dioptre for one eye than the other, for instance if you start with both dioptres wound fully in and can only adjust by winding one out.

Yes. 28, 14, 10, 2x TeleXtender. There's a gap at 20mm that almost had an HDC in it but I wasn't sure it was needed and so I've not bought one (yet).

Also, as an answer to the initial question, 10mm Delos, unless it is for use in a binoviewer in which case you will need a pair of Naglers.

It's the square root of two (ish). Using that spacing between eyepiece focal lengths results in a doubling or halving of image brightness (for extended objects), which is equivalent to one step in brightness as far as the human eye is concerned. For DSOs I think it is the ideal spacing. At high powers you may need tighter spacing so that you can match your magnification to that supported on a particular session (e.g. for planetary observation).

This is not right. Are you sure that you have properly tightened the fasteners that hold it together? The large fasteners that go in the sides of the base are like a pair of hooks that grab onto the head of the parts that go through the end grain. My base has always been quite solid with nothing other than the supplied fixings.

I would only try to loosen the central screw. Turn it anti clockwise, but only use a manual (PH, not PZ) screwdriver, not a powered one. It looks like you've already damaged it and you don't want to make it any worse. Once you have loosened that screw the others will be easier to move, but if the heads are damaged I would suggest that you remove one to deduce the size, and then purchase replacements.

A neodymium filter is the best for planets I think. For nebulae you should consider UHC and OIII filters, but you will need some longer focal length eyepieces for larger exit pupils and fields of view.

This type of eyepiece is manufactured by a Chinese factory who do not sell their products under a brand. Instead, when placing an order, the company ordering can specify the branding they would like added to the eyepiece. We are used to seeing these sold in the UK as "BST Starguider/Explorer", but with any other brand name it will still be the same eyepiece. In this case, it has come with @FLO's "Astro essentials" branding on. I do not know whether this is a deliberate change in branding, or a mistake made at the factory because they also supply items to be sold under the "Astro Essentials" brand, but in either case it does not matter unless you feel the need to have all your eyepieces with matching brand names.

People mounting floodlights on the back of sheds, to needlessly illuminate the couple of feet between shed and fence.

Unfortunately, you have to remove the secondary/spider from the tube. Once that is done you should take a piece of paper/card thin enough that you can bend it around the inside of the tube, but thick enough that it isn't flopping all over the place. With the OTA horizontal place the paper inside the tube and butt one edge to the edge of the focuser or focuser hole and push the paper so that it follows the curve of the tube. Use the other end of the paper to draw a line on the inside of the OTA tube. Do this once with the paper going around the bottom curve and once around the top curve as you look into the tube. you may have to cut notches to avoid any screws protruding through (eg for the finder shoe). Once you have your two lines place the paper inside the tube so that you can transfer the lines on the tube onto the paper. remove the paper and measure the distance between them. Make a new mark on the paper half way between the two lines. Now put the paper back inside the tube, align the outer marks on the paper with the marks on the tube and then transfer the centre mark onto the tube. This line should be roughly inline with the secondary spider hole opposite the focuser. Secondly measure the distance from the front edge of the OTA to the centre of the focuser. You may find it easier to measure from the OTA edge to either side of the focuser and then average the result. On the inside of your telescope mark this distance in from the edge onto the centre mark you made earlier so that you have a cross on the far wall of the OTA from the focuser. You can now put a sight tube into the focuser and compare the location of the crosshairs to the cross you have drawn on the far wall. This alignment doesn't have to be exact, but the closer it is, the easier it is to collimate the telescope. While your secondary is out of the telescope, roughly measure the distance between the centre of the secondary mirror (the front, mirrored side, not the back), to the plane of the threaded part of the spider arms that protrude through the tube. Also measure the distance from the edge of the OTA to the holes that the secondary spider passes through. At maximum extension you want Secondary spider "Length" > Distance from OTA edge to focuser centre - Distance from OTA edge to spider hole + 5mm I hope that makes some sense without pictures.

A good site for filter comparisons is https://searchlight.semrock.com/?sid=a08a1af9-84ee-49d2-959d-153d7e7c0eb8 I think this shows the differences between filters better than the pictures on the Castell page. From a suburban site I think a narrower passband will be even more beneficial than at a dark site as it cuts out more light pollution. I certainly wouldn't dismiss OIII filters based on aperture, you just need to be mindful of exit pupil and that you will need long focal length eyepieces to generate the required exit pupil with your scope (i.e. >32mm).

Which 4mm did you buy and do you have any other accessories than those bundled with the scope? There is a 4mm Nirvana for sale in the classifieds that should do quite nicely.

I also use Sky Safari 6, but with any app I wouldn't try to use the compass mode where you can hold the phone up to the sky to identify things. The compasses in phones are not accurate enough and easily confused if they're near something metallic, like a telescope. Instead it is better to learn to identify the major constellations and then use the app as a map to get from something you can easily identify to wherever you need to get.

I think that photography would show up a touch of CA, and you might find that you can't reach focus. I know that with my PF65EDA I can't focus if I try to use a barlow in front of the eyepiece. For a spotting scope that will be carried on walks I think 65mm is a good size. If I was to replace it I would only be looking at Swaro/Zeiss 65mm scopes, not larger objectives.

You should adjust it so that it appears central. The offset is towards the primary, your secondary appears to be too far away from the primary. Assuming that TS calculated the correct length of secondary collimation bolts and collimated your telescope as stated, I would start by looking at the focuser and checking whether it is square on the tube and pointing at the correct point on the opposite tube wall. If it has taken a knock during transit it is possible that it is no longer pointing where it should. The point where the focuser connects to the adaptor plate is probably a weak point so I would loosen off the grub screws around the outside of the plate, reseat the focuser and tighten them up again to see if it makes any difference.