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About Tommohawk

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    Brown Dwarf

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  1. I seem to remember you did some cracking planetary images with your Orion so will be interesting to see if you can squeeze even more out of it with your 1/30 PV secondary - watch this space as they say! Interesting to know that your primary is 1/10 wave, must make all the difference I reckon a quality 300mm F5 in a purpose built truss frame would suit me well, but I don't have my own workshop so have to use a bit of ingenuity and adapt stuff. The flextube idea worked well because it allowed me to coarse tune the scope length, but its a heavy scope and I couldn't do the same with a 300mm.
  2. Thanks for that - somehow I studied the atlas for ages, and then about 5 mins after posting I figured it out. I used to work with low mag to start with just to plan what I was going to view/photograph and then switch to high mag. With the current setup that isnt practical - I have to start with high mag so getting oriented is problematic and a lot of the landmarks are washed out with full moon. Thanks Neil. The scope is a bit of an experiment - the idea was to use a fast mirror just to keep the scope length down to minimise momentum etc, and then use the powermate to give the hig
  3. I was trying out my modified Quattro with 5x powermate last night but difficult to get much detail with the moon being pretty much 100% full. This was the only image worth keeping TBH, but I blowed if I can figure out where it is. This rig is a bit unusual - I use the camera at prime focus with no secondary - which means I think it has one less plane of reflection than a regular Newt. Maybe not. This region ought to be South West - but I can't see it on any atlas. Grateful for any thoughts! Edit: Byrgius maybe? Quattro 250 with Powermate x5 and Omegon 385C. Captured with Toupsky
  4. Thats very nice - is it a single sub or a stack?
  5. Looks great, nice colour range and nice detail especially at the limb. Which scope was this I wonder?
  6. I think you also need to consider that if scope has 10x aperture and same focal length then above is true. But if has same F value then it will have 10x the FL, in which case you don't have any extra light per pixel. Doubtless someone will correct me if I'm wrong!
  7. Difficult to know whether your scope would be good for full frame - not sure what it is and what manufacturers claim - though might want to take this with pinch of salt anyhow TBH. I'd have thought that a full frame DSLR is going to be similar cost to astro camera, though not 100% up to speed with prices. I would say if you want to use the camera for non-astro too then go for DSLR maybe but you wont get such a good result as cooled dedicated camera. Also Canon software integrates better than Nikon.
  8. Guys there is a risk here that we may generate more heat than light, focused or otherwise. The question I asked is how can all of the various wavelengths comprising LUM be focused simultaneously in a system where RG and B have different foci, and I think the answer pretty unequivocally is that it's not possible. The LUM image will therefor be blurred to some extent and this can be minimised by restricting the bandwidth of the LUM filter. The sensitivity of the human eye is still relevant though because we use a human eye to evaluate the end result, and I think it must therefore be
  9. Not sure I can run with your X-Ray vision analogy! But there is another issue here - we can look at how photographic sensors work with OSC or mono images using filters, their sensitivity at different frequencies etc OR we can consider what the eye sees, eg at the telescope eyepiece. We would agree they are two different things. But the third comparison is what the human eye sees when it looks at a sensor/screen generated image - then we have to consider both aspects. And with astrophotography this is mostly what we are doing .My point here is that if an image produced by a sensor/telesc
  10. Re 2 previous posts...... this is exactly why I said previously "I need to think about it!" The thing is when making a call about how good the image is, "photographic CA" is in the end perceived and judged by the human eye.... .... I'm still thinking about it!
  11. The trouble with small newts is you need disproportionately large secondary to get fully illuminated sensor. Below is the spec for an F4 100mm. Even with the camera and EFW fixed direct to the tube (focusing done at the primary a la SCT) you need a 32mm secondary to get fully illuminated sensor (of decent size) But this doesnt allow for a coma corrector - if you allow 50mm for a CC that doesnt block the light path then you need about 42mm secondary which is too big a central obstruction. Its not so bad with an OSC because the camera sits closer, but that would make for a very niche
  12. Thats a good point Vlaiv - the 130PDS gets great results for a bargain basement price, and mosaics are becoming easier to do eg with NINA. The only box it doesnt tick unfortunately is the portability one. I typically fly to a kinder sky location a couple of times a year and although the 130PDS will go in a case (and frankly is cheap enough that it wouldnt be the end of the world if it got trashed) it does eat up a lot of luggage space. But your point about binning and achieving the same overall result is a good one. Having said all that, the Sharpstar 61 Mk1 - which has been referen
  13. Hi Craig - I'm onside with Newts for sure but no real options for a widefield newt sadly. There are a few 114mm but only with 1.25" focuser. I've tried designing from scratch but there are design limits especially if you need to get a coma corrector in the train. Thanks for the 3 dots tip - I tried that but on someone else's post so of course it dint offer edit! Whilst youre there - Ive also lost the signatures somehow - any ideas on that?
  14. Hmmm - just done some reading and looks like microlensing occurs with mono too. I've done quite a bit of BB and NB and although I've had some issues I've never noticed this effect. Also i seem to have lost my edit post option - not sure why!
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