What to expect?
Posted 01 June 2013 - 01:22 PM
Posted 02 June 2013 - 04:59 AM
I live on red/orange border with LVM around 5.0-5.5m. I only have 120mm atm, but ordered C9 recently. It depends on DSO - stars shine well through LP - open and globular clusters should be good, those are my primary DSO targets. Bright planetary nebulas should work well with UHC or OIII filters, I can detect them easily but can't birng mag. up enough in 12cm for most. However galaxies and diffuse nebulas will be problematic - check their SBr (surface brightness) and choose only those that have it high enough, this will be more important parameter (esp. with 14'') than total visual magnitude. You will detect many, but you will probably not see much detail. That being said, on good nights I've seen quite a lot galaxies with 12cm, even some faint like M33, M67, M110 - but it is bordeline work - just detecting it is there, only very faint outline seen with averted vision. But larger scope should help to make this outline brighter.
Big aperture should not be detrimental due to LP. True, it will not increase contrast of diffuse targets, but it will make them brighter (together with background sky) - and in bright image the eye will detect small contrast better.
However 14'' will probably take very long time to cool down and the seeing will limit it a lot. But this has nothing to do with LP.
You can check this site:
Messier Guide: Introduction
It explains various aspects of observing in LP with small or large scope. There is also a list of all Messier objects with evaluation how they are seen in urban/suburban sky with small and larger scope. There is also surface brightness listed for diffuse targets so this should help you start choosing good targets and you can also notice the relationship between SBr and target appearance. I myself use Uranometria 2000, the 3rd book where I can find all the crucial information that helps me to choose a target (like SBr, magnitude of brgihtest stars in clusters, dimensions etc.).
Big problem is to reach dark adaptation which you need for such faint targets. Unfortunately I can't stay away from streetlights - so I use black T-shirt which I roll of as if I was going to undress it (but it is still around my neck) - in this position it covers the head nicely and helps to block the streetlights somewhat.
Posted 02 June 2013 - 07:12 AM
Posted 02 June 2013 - 11:07 AM
While living in the red/orange zone, I bought an 11" SCT and the views improved. However, I discovered video-astronomy and adding a low-light video cam with LP filters to my scope made a dramatic improvement, plus I no longer needed to worry about dark adaption. I have since moved to a yellow/green zone, but have have kept using video-astronomy, (without LP filters) and the views/contrast are much better.
A couple of live view images to show how LP affected my C11.
First image a 8.5 sec exposure from red/orange zone. Camera used high gain and LP filter.
FR was f/6.3.
Posted 02 June 2013 - 11:11 AM
Same scope, but at f/4. Camera gain low, exposure 4 sec, no LP filters. Not a completely fair comparison as I used different focal ratios and I've improved my video-astronomy skills.
Posted 02 June 2013 - 03:15 PM
At times under the right conditions I can still make out the glow of the Milky Way and on Tony Flanders web link MCUH Provided above(thanks MCUH) he states that the MW is a good gauge of how much detail you should be able to see on other galaxies.
I don’t think there is much hope in moving to a less LP area anytime soon so I will have to make the best of the situation as the 14” LX850 is basically too much of a behemoth to be considered a mobile telescope.
Posted 02 June 2013 - 06:26 PM
....... I know planetary should not be much of a problem but what about DSO?
I had a friend who did some great CCD stuff with a Meade 8" SCT from Berlin Germany. However, the exposure time to reach any desired signal/noise ratio will be much longer than under dark sky.
Posted 29 June 2013 - 04:47 PM