UHC filters

[ronb]

While searching for advice on which UHC filter to purchase I came across the following article which may be of interest

http://articles.adsabs.harvard.edu//full/1994JBAA..104..231B/0000231.000.html

By the way, what is an EHC filter? How does it differ from UHC? Thanks.

[Charon]

faulksy has a great link to what type of filter is'supposed' to do what, drop him a line.

[mikeyrea]

Wotcha Rob

This is a looks like a great article for describing the science behind the filter, but to be honest I was struggling to get past the 1st page... ...I've bookmarked for the next time I have insomnia (only joking)! As it seems to emanate from 1994 the discussion on currently available deep sky filters is maybe not the most helpful!

If you're on the hunt for one you might like this article... http://www.cloudynights.com/item.php?item_id=1520

Some other punter was discussing these recently on SGL. If you fancy a UHC it would appear that the Baader & Skywatcher are the most popular, and retailers like First Light Optics have both. I think the SW one blocks out a bit more light as it has a narrower band pass, resulting in greater contrast but less less overall light, so the most suitable filter will depend on the aperture of you scope.

This might help as well....

[ronb]

Many thanks for your comments, much appreciated and most useful.

I am looking for a UHC but am trying to find out how much better the likes of the Lumicon or Astronomik perform than the Skywatcher or Baader at half the price. Posts on SGL suggest that users of all makes are happy with them but no one appears to have experience of UHC filters at both ends of the price spectrum.

I currently use a 1.25" EHC filter sold me by OOUK for LP. It works well on M42 but I want a 2" UHC for my larger EPs. The EHC is also unbranded so I don't know its spec.

[John]

I've used the Baader UHC-S, Telescope Services UHC and the Orion Ultrablock (which is a UHC) filters. Currently I use an Astronomik O-III.

The main difference I notice with the more expensive Astronomik is that star images are better defined than with the lower cost filters which is nice, but I could live with the lower cost ones quite happily, and did for quite a while

Of the ones listed above, in terms of effectiveness at enhancing the contrast in nebulae, the Orion Ultrablock and the Astronomik O-III had the greatest effect. An O-III is more selective than a UHC with regard to the band pass width although the Astronomik is not as selective as some - more like a UHC in some ways, which is slightly odd !

At the present time I'm quite content with the Astronomik as my only DSO enhancement filter and it works well with scopes from 4" and upwards.

[Dunkster]

The best way would be to try the low and high cost filters with your own eyes

If you have the disposable cash for the experiment, you could then sell the unwanted one as nearly new!

[ronb]

Many thanks John, this is the sort of information/advice I was hoping for.

In spite of your preference for the O-III, from posts elsewhere on this site, it would appear that the UHC is more often recommended. Perhaps it's a little more versatile than the O-III?

So I'm now decided on either the Lumicon or Astromik. Decisions, decisions.....

And, do I buy now while the weather is too bad to use it or wait for better weather and risk even more wrath of the gods?????

[Jiggy 67]

So I'm now decided on either the Lumicon or Astromik. Decisions, decisions.....

Good luck in finding a Lumicon in thhe UK, I searched high and low for a UK supplier and failed. I bought a SW instead but havn't had chance to try it yet

[John]

...In spite of your preference for the O-III, from posts elsewhere on this site, it would appear that the UHC is more often recommended. Perhaps it's a little more versatile than the O-III?...

Thats probably correct. I don't do a great deal of nebulae viewing and my filter does not come out often. When it does get used it's on objects where it makes a big difference such as the Veil and Owl nebulae. Most of the time I prefer to view the brighter nebulae without a filter.

[Space Dragon]

I was asking the same question a couple of months ago and I ended up buying Skywatcher UHC and Olll and a Televue Bandmate OIII.

Using a filterswitch to A/B the filters, I found the stars to be tighter in the TV and the transmission seemed better. The TV OIII is also a wideband OIII, I think similar to the Astronomik that John talks about above and some wouldn't call it an OIII but more of a UHC.

Anyway, suffice to say I settled with just the TV, for the meantime.

Sorry to put another one into the mix, that's the curse of modern life......too much choice.

[ronb]

John, as mentioned, I have had an OOUK EHC filter for several years and never used it until recently so I don't know how often I would use a larger one.

Jiggy67, you may be right, Telescope House list them on their web site (http://www.telescopehouse.com/acatalog/Online_Catalogue_Light_Pollution_39.html) but I haven't yet checked whether they are in stock.

I also found http://www.cloudynights.com/ubbthreads/showflat.php/Number/4774938 dated August last year which infers that they were in short supply across the pond.

Mind you I don't yet know about availability of the Astronomik either.

Space Dragon, must admit I had not thought about TV. (Logs out of SGL muttering to self.....)