Another OIII filter post

[woodmeister]

Well I finally made a decision and ordered the Astronomik OIII filter from Rother Valley optics. Estimated delivery date is Tuesday and I blumming hope that next weekend it is clear or I will cry.

Steve, Does that mean that people don't recommend the badder OIII for smaller scopes is because the exit pupil requirement would be to high in all but the darkest skies. But if they could get to the darkest skies it would work or is there more to it than that.

[jetstream]

Astronomik seems to refer to volume of light to make the filter most usefulhttp://www.astronomik.com/en/visual-filters/oiii-filter-visuell.html.Larger image scale (up to a point,with the proper exit pupil) obviously makes the finite surface brightness objects easier to see ie Clark,Bartels.This is why certain aperture ratios and focal lengths are wisely chosen,for the desired objects.

So I guess optimum exit pupil range + optimum magnified visual angle range + good filter = much fun and success!

[scarp15]

Well I finally made a decision and ordered the Astronomik OIII filter from Rother Valley optics. Estimated delivery date is Tuesday and I blumming hope that next weekend it is clear or I will cry.

Steve, Does that mean that people don't recommend the badder OIII for smaller scopes is because the exit pupil requirement would be to high in all but the darkest skies. But if they could get to the darkest skies it would work or is there more to it than that.

Enjoy your new filter.

Next wk-end is the solstice, no doubt the filter will darken the sky though twilight will be a bit of a challenge as from August, expect it will receive a lot of good use. 

[John]

Enjoy your new filter.

Next wk-end is the solstice, no doubt the filter will darken the sky though twilight will be a bit of a challenge as from August, expect it will receive a lot of good use. 

Thats good advice. While these filters are effective on the right objects, they don't work miracles and will perform much better under dark skies.

[woodmeister]

I totally forgot about the solstice, guess I got caught up in the prospect of a new filter. At least as of next week we can celebrate the coming of longer and darker nights

Thx to everyone for their posts and advice and clear skies.

[rwilkey]

This thread has just reminded me that I wanted one of these!

Depending on responses here, I am intending to go for the Explore Scientific OIII on the basis that I have their UHC and have been really impressed by the results.

Would this be regarded as having a good £ / Quality ratio??

Paul

Hi Paul, the last time I did this it covered VAT (aka import charges) as well, I was pleasantly surprised after paying 'import' charges on a number of items.  The smaller good independant sellers on ebay seem to do this and I would try it again.  The bigger retailers like AgenaAstro do not offer this, but often still worth it as quality items are hard to get in the UK.

[Paul73]

Hi Paul, the last time I did this it covered VAT (aka import charges) as well, I was pleasantly surprised after paying 'import' charges on a number of items.  The smaller good independant sellers on ebay seem to do this and I would try it again.  The bigger retailers like AgenaAstro do not offer this, but often still worth it as quality items are hard to get in the UK.

Yes. I've bought a few things from the Explore Scientific guys. They seem pretty straightforward. You pay what you see plus £9 or £10 delivery.

Paul

[Paul73]

I hate these threads. This one actually got me spending!!!

Result = Lumicon Olll + 20mm MaxVision (both landing later this week).

The classifieds really are great

Paul

PS. Please could the SGL collective resist the temptation to start any "Joy of Delos" type threads for the next couple of months....

[faulksy]

I hate these threads. This one actually got me spending!!!

Result = Lumicon Olll + 20mm MaxVision (both landing later this week).

The classifieds really are great

Paul

PS. Please could the SGL collective resist the temptation to start any "Joy of Delos" type threads for the next couple of months....

were did you get the lumicon from ? and was it 2"

[Paul73]

were did you get the lumicon from ? and was it 2"

It is coming from a nice chap on UK Astro Buy & Sell. It was advertised as a 1.25". If it turns out to be a 2", I shall consider it bargain of the century and enjoy the view with my 28mm 2" MV.

Had the ad been for a 2" I probably would have pointed it out to the OP as it was their thread that rekindled the itch for this "can't be without" piece of astro kit.

Paul

[faulksy]

2" oiii especially lumicon are utter rubbish, just to help you out we are like that on here, i will buy it of you so you dont loose out. how does that sound

[estwing]

I saw that and give it a miss because of it being 1.25" ....Grrrrr

[Don Pensack]

I am looking to buy a 2 inch OIII filter and looking for advice on which to get.

I am wondering if I should go with the Lumicon, Astronomic, or a cheaper one say Orion or Skywatcher.

I own a 8 inch dob and usually observe from a suburban area. Would the lumicon or astronomic be worth the extra cash for observation from a suburb?

O-III filters seem to vary in bandwidth.  Hence, they vary in effectiveness, too.

They basically fall into 3 categories: Too wide (not enough enhancement of the O-III lines), OK (narrow enough to get both lines and not much else), and too narrow (clips one of the O-III lines and reduces brightness too much)

Here are some graphs showing some differences:

http://www.karmalimbo.com/aro/pics/filters/o3a.jpg

http://www.karmalimbo.com/aro/pics/filters/o3b.jpg

Here is what you want:

1) transmission of the 496nm and 501nm spectral lines at >90%

2) a bandwidth of 15nm or less (from 50% transmission on one side to 50% transmission on the other side

3) nothing else in the 450-700nm range.

if you look at the graphs, you'll see some filters that do it right and some that don't.

Note: most energy is at the 501nm line, so photographic O-III filters center on that wavelength only.  Visually, you want both 496nm and 501nm.

[jetstream]

By the graph the Lumicon should show better contrast than the Astronomik by letting less light outside of the 496nm- 501nm in.It also appears to have more area under the curve in the desired range and at a higher avg transmission there.Have you used both filters?In actual use what, if any, are the differences?

[John]

By the graph the Lumicon should show better contrast than the Astronomik by letting less light outside of the 496nm- 501nm in.It also appears to have more area under the curve in the desired range and at a higher avg transmission there.Have you used both filters?In actual use what, if any, are the differences?

Swamp Thing (Steve) has compared the Lumicon and Astronomik O-III filters - see his post #16 in this thread.