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  2. Hi welcome to SGL from Peter in Bedfordshire
  3. I thought that exit pupil eyepiece (not scope's) FL in mm divided by scope F ratio? Is that what you meant Olly? Or have I got it wrong? Steve
  4. Hi welcome to SGL from Peter in Bedfordshire
  5. Hi welcome to SGL from Peter in Bedfordshire
  6. Hi welcome to SGL from Peter in Bedfordshire
  7. Hi welcome to SGL from Peter in Bedfordshire
  8. Pete Presland

    Hello again

    Hi welcome to SGL from Peter in Bedfordshire
  9. Just had a look at it, WOW £88 a bit pricey ! Nice bit of kit though. I think I might seen them at Astrofest last year, didn't realise there was a dual purpose to them. https://www.harrisontelescopes.co.uk/acatalog/baader-skysurfer-v.html?gclid=EAIaIQobChMIgZOogZrm4QIVSrHtCh1ulwXpEAQYAiABEgLIU_D_BwE
  10. Hi everyone, I am thinking about investing in a Newtonian probably a 10" f4 https://www.teleskop-express.de/shop/product_info.php/info/p5647_TS-Optics-10--f-4-ONTC-Carbon-Tube-Newtonian-telescope---fully-customizable.html, Various options exist for the focuser and the coma corrector. I was wondering if the 3" is worth it. Its advantage would be less vignetting and stability? I am planning to shoot mostly using CMOS / CCD cameras that are not that heavy + filter wheel so vignetting on that sensor (close to APS C) should not be a problem. Would it allow for better coma correctors in 3"? Thanx B
  11. I have put this on the Bay as well but I would rather sell it to an SGL member. It's the standard "kit" lens but it's like new with both caps. I can also let you have a lens hood and UV filter for it if you want. This image of Mercury was taken with this lens. It's going to cost about £4 to post so how about £40 all in - is that reasonable? Paypal only by friends or fees paid. UK only. Peter
  12. You can also try using the http://www.astrogb.com/astrogb/All_Sky_Plate_Solver.html cheers Martin
  13. Hiya Glen, no I put the scope in this position to show the clearance between the scope and the tripod legs. There is no fixed park position, thus you can leave the scope as you please
  14. Hi Stu/Super Nova, thanks for the comments. I was really shocked and pleasantly surprised. I won't get my hopes up for it happening very often, because as you say it's rare to get seeing that good, i'm quickly learning! lol. I actually almost got rid of my 3.6mm plassl almost the same night i first used it because due to me being a newbie, and not having collimated my 'scope, when i first tried it on a few stars the view was so dark and blurry. So i assumed i had a dud eye piece! even though i had bought it brand new from FLO lol! i've since learned about collimation, seeing etc. so i know better. For your information, i am on my second scope, my first was a SW 1145p ( 114/500 ), now i have a SW 130 eq2. ( 130/900 ). I'm 5 mon ths in to my new hobby. It's beyond amazing and i only wish i had got into it years ago!
  15. Quite. It's not clear if that's down to the author of the piece or the architects. If the latter then I think it's abundantly clear that they have no business designing an observatory. James
  16. Vixen High Resolution (HR) 3.4mm eyepiece. Beautifully built and NO undercut! I've been getting some very nice higher power views of doubles lately, and I think the FS128 can go higher with the right eyepiece. I just had to try this beauty, courtesy of Mike (iPeace), and wonderfully packaged as always. It's like new. Thanks Mike! This will give me x305 native and x489 with a 1.6x barlow nosepiece on the odd really steady night. I also have in mind more Lunar viewing and Jupiter/Saturn later this year Dave
  17. Just a quick progress report on the results of a first experiment with 'potentially-live' LRGB using LAB colour manipulations. Still some way to go and the whole process needs a lot of fine-tuning. The reason I'm using LAB is that it does allow easy separation of luminance and chrominance and seems to do the job of preserving hues regardless of stretch etc, which isn't easy to achieve in RGB space. (I've never used Photoshop but I believe it does everything in LAB internally?). The L component comes from those subs captured with a clear filter, plus synthetic luminance from the subs collected with RGB filters (there will be various options on whether to use synthetic luminance and how to combine with real luminance, but I wanted to test the full monty). All the black/white point setting and stretching is then applied to this 'total' L component. The RGB are individually stacked, then gradient removal applied, background subtracted, and combined using a colour-balancing approach based on equalising the brightness of a bright feature in each channel. This is a poor man's G2V technique for the moment but is said to work well 95% of the time. The RGB channels are then transformed to LAB space and the L channel thrown away and replaced by the total L component (the one which has been stretched). That delivers LRGB. But the interesting bit is to then change the chroma saturation using simple manipulations of the A and B components. This is what I'm showing below. Obviously one wouldn't necessarily go so far in saturation normally, but it is interesting to see it at work. One thing you can see in the high saturation case is the appearance of rings on the brighter stars. The centres were probably saturated in the original subs but in any case the effect can be ameliorated by smoothing the A and B components (like binning but preserving the original image dimensions). This is done in the lower right image. What I haven't yet done but I think is needed is to align the different colour channels separately as one can see the rings are somewhat offset from the centres. The main reason for doing this pilot is to see if it can be done in real time as there is a lot of computation just to do something simple like alter saturation. It looks like for Lodestar sized images the manipulations can be done in under 200ms on my 2015 MacBook Air, so that is useable. Obviously, things like stretching will also slow down when using LAB mode because of the need to convert between colour spaces constantly. The entire process is automatic. All the program needs is to know the filter used for each sub. Of course, the user will be able to control things like saturation and configure other aspects, but if EEVA users are going to use mono + filters then it is important that it can be done automatically otherwise it starts to become processing rather than observing. As always, comments and suggestions welcome -- this is all new to me although I believe it is pretty standard in astrophotography. I'd be particularly interested to find more LAB resources or hear from APers on where the rings are coming from and how to deal with them (within the EEVA canon of techniques!). cheers Martin
  18. I think I shall go for the simplest approach to this and try a sealed chamber for the camera again. I can use a 3D printed plastic adapter ring for the lens to thermally insulate it from the cold camera body and hopefully this may let the lens warm up above dew point. I've concluded that a standard axial fan should not fail from damp air as the motor part will be warmed by the current flowing through the motor coils and the air RH will probably be above dew point anyway. A standard CPU cooler on the hot side of the Peltier TEC may produce enough cooling whilst the warmed air can be fed up into the dome. Clearly this will be less efficient than water cooling but may be sufficient. It's worth a try. If the 60x65mm CPU cooler is not enough I have a heat pipe type with larger fan and cooling fins.
  19. upload the image to http://nova.astrometry.net/upload and this will come back with solved coordinates and an annotated image.
  20. "HK$10M of Astrological Equipment"
  21. Did it help to get that (those) off your chest, Stu?? Dave
  22. I'm interested in replacing my Vixen Polarie with one of these - like the no batteries concept + just seems easier to use. But has anybody got on feedback yet on actually using one please? Graham
  23. Cheers Olly. I'm not sure i ever remembered knowing about this rule of thumb but it's super helpful now that i know
  24. The "Greenhouse Effect" of the transparent dome etc. I would always hate being observed, while observing. I do sometimes "covet" a (flat top) roof observatory... Despite the known / specific objections to such things?
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