-
Posts
29,785 -
Joined
-
Last visited
-
Days Won
22
Content Type
Profiles
Forums
Gallery
Events
Blogs
Posts posted by Pete Presland
-
-
22 hours ago, drjolo said:
I have found link to some useful calculators in my bookmarks, and also for CCD sampling http://www.wilmslowastro.com/software/formulae.htm#CCD_Sampling . For green light and 2.9um pixel it gives f/14.
The calculators also suggest some where between F11-F14 for the Asi290mm. But it also suggests a Focal length of between 2578mm (red) and 3528mm (blue).
-
A very interesting thread @vlaiv thanks for sharing.
Using Dawes limit to solve the resolving power of my C9.25" telescope it can resolve 0.49 arc-seconds.
According to sampling theorem i need to sample at twice the frequency of the signal being sampled. So the ideal resolution for my C9.25" would be to sample at about 0.25 arc-seconds/pixel, which would be no Barlow. Just seems a bit low at F15, let alone F11.2
-
2 minutes ago, drjolo said:
I also have this camera for planetary and lunar imaging. I am not an expert in this kind of imaging, but I was told and also read, that for this pixel size optimum sampling is at f/15. So maybe f/18 is a little bit too much, but also Jupiter now is far from perfect position in northern Europe, so it will be hard to get decent images this season I think
If you have regular barlow (not powermate or other teleextender) you can decrease its magnification a little by shortening distance to sensor (if it can be done at all).
I forgot you could do that, I have X1.8, X2 Barlow's and a X 2.5 Powermate.
-
Having recently purchased a Asi290mm, I have some fairly decent Lunar images and some average Jupiter images (still a work in process)
I have been mostly imaging at the native focal length, possibly a little more with the focuser/filter when in position. This gives me resolution of 0.25"/pixel, if I use a x1.8 Barlow this will be approximately 0.14"/pixel. This seems a bit oversampled, especially for the UK seeing conditions and the position of the planets.
The native set up seems to give an image that lacks a bit scale to ne honest. The image below is a work in progress from the 25th
-
4
-
-
I have done a few manually tracked images as well over the years, mostly when my battery has gone flat. You can let the area drift through the field of view and still get a decent image.
-
1
-
-
I was surprised there are 2 sites just up the A1 from me, until I read what they consider a dark site was. I would have thought most of the country was an Orion site, apart from maybe areas of the larger cities. I also prefer the other map to be honest as guide as well. There is a fairly nice area that I do visit regular, that shows up very well on this map. https://www.lightpollutionmap.info/
-
Becoming a little disillusioned with the UK imaging conditions. I did think the other night while observing M42, it might be nice to try some sketching. I was so heavy handed at school though, for technical drawing!
-
1
-
-
I have pretty much all the TV plossl's that are available between 8mm-40mm. A rock solid eyepiece in all my scopes, the only temptation to change is to another TV eyepiece. They Barlow nicely as well, so a decent Barlow would effectively double your eyepiece collection.
-
1
-
-
If you look here you can see the images posted https://stargazerslounge.com/forum/235-imaging-challenge-9-rgb/
-
1
-
-
A few searches gave a couple of clues. A few searches gave a couple of clues, I would think if the Toucam Pro would work so would your SPC900
Unfortunately on the Philips website there is no reference to windows 10 drivers though
http://www.p4c.philips.com/cgi-bin/dcbint/cpindex.pl?slg=en&scy=nl&mid=Link_Software&ctn=SPC900NC/00
-
I do neglect our nearest neighbour too much, this will encourage me to visit the Moon more often!
-
Have no regrets getting my Feathertouch focuser at this years Astrofest, it makes fine focusing especially with a Barlow much easier. I would imagine it would be possible to automate it, if Lunt don't offer anything.
-
-
Favourite prom
-
6
-
-
I just remembered I promised to post a few favourites from 2016, to add the already superb collection here. The obvious place to start is with the Mercury transit!
-
6
-
-
7 hours ago, niallk said:
@alanjgreen Thanks again for the great feedback
Right now, an LS50THA, B600, LS50C, and FT focuser upgrade is what is on my 'wish list'. I think the 60mm version is more than I can justify (although hung for a sheep as a lamb comes to mind...). Ordering from the US, taking advantage of exchange rates, and taking a chance on customs would be the only way. Right: so what do I sell?!!!
Exactly what I eventually ended up with, LS50THA, B600, LS50C, and FT focuser upgrade took a lot of saving for the upgrades. The double stack/focuser for imaging has made a big difference!
-
2
-
-
Lovey sketch, just like the view I had through my C9.25 tonight as well.
-
1
-
-
Looks like an excellent investment to me. It will be interesting to see what the results are, especially on double star's and planets.
-
1
-
-
Hi welcome to SGL from Pete in Biggleswade
-
I regularly Barlow my Lunt, which does involve using an extension as well. This puts the B600 diagonal around 160mm away from the focuser, add the webcam and then the old focuser really struggles. It will be nice to have a good solid focuser for those close up moments!
-
2
-
-
Where will be the best place to purchase one I wonder, I guess there are a few UK retailers.
-
Not spent my birthday money yet, I think this is going to be top of the list!
-
1
-
-
Hi welcome to SGL from Pete in Bedfordshire :-)
-
13 hours ago, Cometeer said:
I don't know if you guys saw this:
https://luntsolarsystems.com/product/1-25-feather-touch-focuser-2/
A feathertouch for the LS50. Looks like it's only single speed.
Looks similar dimensions to the helical focuser. Minimum focuser height of 48 mm and 15mm of travel. My replacement focus was a little under the minimum height and the travel is around 13mm on both of mine. The minimum travel is not an issue for ZWO camera uses threading direct in to the blocking diagonal. "In focus" is certainly of interest to myself as I still use a imaging source camera.
-
2
-
Jupiter with Asi290mm and C9.25, to Barlow or not to Barlow that is the question
in Imaging - Planetary
Posted
It has been a very interesting discussion. I have not understood all of it, but it seems pretty clear that My Barlow is not going to be used much with the Asi290. If I get some decent conditions, I will try a few experiments with it and post what I get in comparison to the native focal length.