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iwatkins

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Everything posted by iwatkins

  1. Latest Met Office UKV run is in. Doesn't look good. Good luck everyone. Cheers Ian 04UTC, Wednesday, Cloud cover:
  2. It can't hurt can it? Whether it will improve anything, I really don't know being such a narrowband. But if you do, do report back if it improves the image at all. Cheers Ian
  3. Love them, very good. Anyone know who the photographer is? Cheers Ian
  4. Noted, thanks Kev. I'll try via the handset then Cheers Ian
  5. Indeed. I really like the look of the DSSR software (new release the other day) as I'd like to do day long time lapse of proms. Just waiting on a EQDIR box for the mount. Cheers Ian
  6. For the OP, how about a SkyTee2? Would be solid and you could get two scopes on it Cheers Ian
  7. Ant, Yes, Y800 if using a mono camera. Also would go with the DMK21 if you can handle the speed the sun will move out of shot. PST is monochromatic, so although colour will work, mono will work better. Also easier to get a good exposure too. Remember, at dawn, the sun will travel at a non linear speed due to atmospheric refraction, so a tracking mount won't help much immediately after it breaks the horizon. Also bear in mind that the luminosity will also change quickly at dawn. So the faster you can get your 1000 or so frames in the bag, the better. You'll have to keep checking the exposure before each capture. As for testing, you may get some clear spells up your way on Monday if you'll get the chance. Cheers Ian
  8. Camera also needs a shoulderless 1.25" nosepiece to get to focus. DFK isn't ideal for PST, a DMK would be much more suitable, but if it is what you have, it's what you have Cheers Ian
  9. Search the electrical inter web for a book named "Turn Left at Orion", sit outside, find your way around. Next, a quality pair of low power binos to get a better view. Then, finish your education, get a good job, then think about scopes. All IMHO of course. But is what my eldest did, and now he has more kit than I do, has darker skies (mid Wales) and earns double what I do now and is only 23. The git Cheers Ian P.S. the sky isn't going anywhere.
  10. Put an EP in, get to about the right focus *then* tighten the focuser grub. After that, don't use the scope visually. Sorted. Cheers Ian
  11. IR thermos require a surface of sorts as they detect reflected or emitted IR from said surface. But we are not really interested in surface temps as they don't affect the seeing, they are just the heat source. We are interested in the difference between the *air temperature* above the surface and the *air temperature* at the objective. This difference, the deltaT, is a direct measure of the local turbulence you'll see at the eyepiece. Bottom line, you are looking through about 80km of atmosphere (the air) plus any suspended particulates (smoke, ash, insects, haze etc). It doesn't matter what that mix is with height, we want it to be consistent. Constantly changing seeing especially is hard to image through, trans less though. Cheers Ian
  12. Not even that Seriously, the more the public facing side of the Met Office hears the public's needs, the more likely it'll happen. Cheers Ian
  13. Exactly right Carole. A "duvet"? I like that. Maybe we should measure clouds by their "Tog" rating rather than their thickness and water content But yes basically. At night, all the outgoing long wave radiation (we call it heat) is absorbed and reflected back again. So indeed acts as a duvet as that works in a similar fashion. Cheers Ian
  14. Sorry Luke, I wasn't clear (been a long week). I meant to say that *calculating* seeing and trans is well understood and easy to do. It's actually quite cheap in computer time to do as well. Agreed. We have all seen the graphics showing "percentage cloud cover", you can even get them on the Met Office site now. I envisage the same but for trans and for seeing, do it in shades of blue or something. Then on the website for site specific forecasts, instead of maps, have a graphic much like 7timer etc. It is easy to do, honestly. Just needs the will to do it for real. And that will only come if enough people actually ask for it. It is "our" Public Weather Service after all. Write/email/Tweet the Met Office. Do the same to your MP. It is really the only way to get things rolling. Just coming on a forum and saying "I wish...." doesn't cause change. Cheers Ian
  15. Trans and seeing are well understood these days so combine that with some of the high resolution NWP models the Met Office runs routinely and the results could be very good. Combine the output with the new map based products on the Met Office website and you get a great result. Just needs them to do it. I was working on them from the inside for a while, but got disheartened. I just run my own system now. Cheers Ian
  16. Indeed, better to say "why colder on clear nights" rather than the other way around. But it's all to do with shifting heat about. Lots of cloud = more trapped heat/reflection of heat from said cloud. Simplification, but close enough. Actually BadgerChap, warm or cold air can both be moist or not, there is no rule on that. But warm air can hold more moisture than cold air so I see where you are coming from. Even so, it is the relative differences between different parcels of air that affect seeing the most. Wind does affect seeing actually. Totally still nights all the way to the upper atmosphere gives you very stable seeing but that could equally mean very stable but awful seeing. Or, if the wind is light but steady that can actually mix the boundary layer up a bit so you don't get sudden changes of temp and humidity as light passes through it. But then stronger and gusty winds can make things worse again by changing the refractive index quickly over time. You'll still get pockets of good seeing though. If you do any solar astronomy on windy days, and your scope is looking upwind, you can usually "see" a gust of wind coming before it hits you on the ground. It looks a little like someone just kicked your tripod leg. But assuming all conditions are good at ground level, you could have a strong jet stream up around 300mb which just trashes seeing altogether. Now throw in transparency, on which water humidity has a much larger effect (plus trapped pollution, dust etc.) and you have another whole issue to deal with. I sometimes wonder why we bother with this hobby Cheers Ian
  17. Flockboard is excellent. Glen did the inside of my 6" frac with it and it's as black as a black cat in a coal cellar, at night, with the lights off. Doesn't even need glueing in, it just sits there. I've also got a section of make a lightweight dew shield. Recommended Cheers Ian
  18. Steve, Assuming you'll be capturing to a PC of some sort rather than just viewing on a TV monitor, you'll be much better off with a USB camera. You could buy a colour Imaging Source D**41 type camera (1280x960 pixels output), a quality lens, a domed enclosure etc. for a lot less than the Orion. Hook up to a PC, control exposures, frame rates etc from there. Would also give better quality results as you wouldn't have any of the analogue to digital conversion artefacts you usually see in converted video. I think the Orion can do a maximum of 4 sec exposure IIRC. Whereas the IS USB cameras can do from 1/10000th all the way up to 60 minutes and they include noise reduction, debayering and lots of other nice machine vision tools. Shot below is a slightly cropped version of a 10 sec exposure on a mono DMK41 fitted with a wide angle lens I bought for £12. I haven't done any noise reduction or editing, just the crop. Of course, there are other USB cameras, but all have similar features. Cheers Ian
  19. Yep, the shorty nosepiece doesn't have a "shoulder" so when you insert the camera, it's front face will sit snug against the top of the eyepiece holder on the PST. Those extra few mm make all the difference for achieving focus. Cheers Ian
  20. Two words: SUN GUN Or one of this design (needs a mirror too): Cheers Ian
  21. Jules, If you decide on the orthos over the kellners, Glen at Lyra Optic does them: http://www.lyraoptic.co.uk/Eyepieces.html Cheers Ian
  22. "Moony 11 Rule" At f11, set the shutter speed to the ISO. E.g. Aperture: f11, ISO: 100 and Exposure: 1/100th That should get you close, then adjust to suit. I.e. if you open up the aperture by two stops, you can speed up the exposure by 2 stops etc. Cheers Ian
  23. At around £770 plus mounting hardware and somewhere to display the image, it is very expensive. Also note it is a video camera, output is video so you capture it for display. It also doesn't have any remote controls, so changing any settings requires you to climb up/or take it down to change anything. You can build something similar for around a 1/10th of the cost though. Or is you already have an astro camera, you can reuse these with a suitable enclosure. Really depends how you are going to use it. You may find this thread useful: http://stargazerslounge.com/showthread.php?t=160629&highlight=sky Cheers Ian
  24. Do bear in mind that the BBC only broadcast the weather, the Met Office provides them with the content. Even so, good idea, after all, they do a forecast specifically for the farmers (on Countryfile) and they do one for the skiers (during the season). I would also like to see the Met Office produce a quality astro forecast on their website. I've asked several times from external contact (even though I work there) and it is being considered. If you contact the Met Office, do it via Twitter, seems to the be the best way. Just send a tweet asking for astro specific forecast, including seeing/transparency. With enough requests, it'll push the priority up to get a routine product up on their website. The Met Office people who man the Twitter feed (24/7 I should add) have won awards recently, they really are very good. As for this petition, yes, go sign it. However, I will say this, I think this is the fourth one on this specific subject raised. If there was a bit more coordination, one of them might have made it through by now. Cheers Ian
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