Let's talk filters

[Louis D]

I've used rubber O-rings to parfocalize my TV Nagler T4 12mm since it focuses so far out.  I even had to add an M48 spacer ring to the 2" skirt to leave enough 2" barrel to lock onto.

ebay is a good source for odd sized rubber O-rings.  You want to shop by inner diameter (ID) since that will be fitting around the insertion barrel.  Parfocalization rings generally have sharp set/grub screws that dig into the insertion barrel.  O-rings are harmless to the barrel.

[Ricochet]

1 hour ago, Stardaze said:

It’s this bit here?

Yes, that is part of the clicklock and included in the optical path length given on the Baader website.

[Stardaze]

Found the extenders at last. Not obvious on the web!
https://www.firstlightoptics.com/adapters/baader-m68-extension-tubes-zeiss.html

It’s adding up: £77 + £27 + £39 🙄😂

@Pixies just measured my collective focuser to change and I get this: extension tube = 45mm, 2" barrel is 18mm and the 2"-1.25" reducer is also 18mm (all screwed in ie. less thread)

The critical bit is the first two combined. So less the thread attaching the two, gives 55mm. The 2" click-lock has a path of 43.5mm so I'll need the 10mm 'tele-extender' too. It's quite a bit of outlay for what it is really. 

Edited June 24, 2020 by Stardaze

[Pixies]

2 hours ago, Stardaze said:

Found the extenders at last. Not obvious on the web!
https://www.firstlightoptics.com/adapters/baader-m68-extension-tubes-zeiss.html

It’s adding up: £77 + £27 + £39 🙄😂

@Pixies just measured my collective focuser to change and I get this: extension tube = 45mm, 2" barrel is 18mm and the 2"-1.25" reducer is also 18mm (all screwed in ie. less thread)

The critical bit is the first two combined. So less the thread attaching the two, gives 55mm. The 2" click-lock has a path of 43.5mm so I'll need the 10mm 'tele-extender' too. It's quite a bit of outlay for what it is really. 

Yes - but how far from full extension do you need to get focus? You'd only need to reach the extension required by the EP that has the shortest focal depth?

[Stardaze]

33 minutes ago, Pixies said:

Yes - but how far from full extension do you need to get focus? You'd only need to reach the extension required by the EP that has the shortest focal depth?

10mm isn’t a lot but I know most of mine were around 13mm on the focuser. There’s 10mm in it at that. I’ll have to double check the focal point on all EPs first 

[RT65CB-SWL]

Hi guys & girls,

I have just come across this article on Baader Planetarium website: https://www.baader-planetarium.com/en/downloads/dl/file/id/287/product/1540/faq_problems_with_filters_can_have_the_strangest_causes.pdf

Thought you maybe interested.

[Louis D]

2 hours ago, Philip R said:

Hi guys & girls,

I have just come across this article on Baader Planetarium website: https://www.baader-planetarium.com/en/downloads/dl/file/id/287/product/1540/faq_problems_with_filters_can_have_the_strangest_causes.pdf

Thought you maybe interested.

Or it could be the Baader filter itself causing halos, although I didn't see that mentioned in the article:

[Stardaze]

Well... I’m pretty pleased with myself this morning. The O-III filter worked a treat last night. I started off with the easiest target, M57, which probably gained the least amount of extra pop. The Dumbell definitely gained plenty and I finally found the owl, right at the end, quite easily. But, my primary target still took some finding, but the veil finally added to the list when I’d realised I needed my lowest mag EP. 😀
 

I took measurements of all focal points at the start of the session to review the click lock system. I am going to need an additional Tele extension as my lowest powered EP focussed at 33mm, leaving 9mm.

Back to filters, the O-III threaded onto the APM 13 and the 2”-1.25” reducer easily but wasn’t so clever threading onto the ES 24. Is the smallest slither of grease an absolute no, no? 

 

Edited June 25, 2020 by Stardaze

[Merlin66]

8 minutes ago, Stardaze said:

Is the smallest slither of grease an absolute no, no?

Definitely NOT the way to go!

Optics and grease don't play well together.

[Stardaze]

22 minutes ago, Merlin66 said:

Definitely NOT the way to go!

Optics and grease don't play well together.

It is obvious, yes. But I thought some clever folk might know of a safe solution. 

[Merlin66]

I have used a very thin smear of boot polish on adapter threads to prevent jamming for many years. Works very well, but you need to take care.....

 

[RT65CB-SWL]

I just screw them in to as far as it will go, (finger tight), then back off a fraction of a turn; before placing it in the e/p holder, star diagonal or visual back.
Not easy when wearing gloves or mittens in the winter months though if you do not have an obsy!

Edited June 25, 2020 by Philip R

[Louis D]

You could try "chasing the threads" with a cheaper filter.  Basically, keep threading and unthreading the filter to work it farther and farther onto the eyepiece until you feel confident it is threaded on far enough to avoid coming loose during observing.

[Stardaze]

I'll revive this thread as I'd like to know whether to buy a neodymium or Baader contrast filter. However, to finish the above click-lock debate (thought I had) the issue with the threads was that the click lock has a 0.75mm thread, whilst the Bresser is 1mm. There was a workaround with the Bresser to click lock attachment / 20mm extension - they just needed swapping around, which FLO discovered, so all screwed down properly and overall the click lock is a massive improvement. 

Anyway,  with the best of Mars being just around the corner I thought I'd try a contrast booster. The neodymium seems to suffer a split opinion but noted recently some using Baader's contrast booster. As a sub-question, I was going to add a neutral density filter a while ago to reduce a full moon, would either of these add some reduction anyway, negating an ND? 

[Don Pensack]

I never was a fan of the Moon & Sky Glow filter on the Moon, though I think it does well on Jupiter and Saturn's rings.

With the additional minus violet feature of the Contrast Booster (essentially a M&SG with minus violet added), it works well on Saturn's disc

and improves contrast on Mars without affecting the coloration of the planet, like turning up the contrast without changing the image otherwise.

It's possible the M&SG might bring out limb clouds and polar caps on Mars a tad better than the CB, but with a notable bluer tone to the image.

Both filters do great on dust storms, light colored features, and enhancing the dark markings.

[orions_boot]

Sorry to bring up an old thread but this seems to be THE thread for filters.

Despite reading all of it I still haven't answered my question for my self.

I have a oiii filter.  Relatively bright sky internet estimates bortle 6.  I know oiii is different to UHC, but given how bright my sky is, is there much benefit in buying a UHC?  I was looking at the explore scientific 2" so it fits all EPs I have and may buy.

[John]

My sky is bortle 5, sometimes 6 (depends which direction I look in !).

I recently had the Explore Scientific UHC for a while. It was not that effective I thought. I have now got an Astronomik UHC and find that having more impact on responsive targets. I will still use the O-III (Lumicon) more I think but I feel that a good UHC like the Astronomik will earn it's keep.

I think the band pass of the ES UHC was a bit to wide which reduced the impact that it had. 

 

[jetstream]

If I could only have one filter for dark or lighter skies it would be a top quality OIII, hands down ( just my personal preference).

[Don Pensack]

1 hour ago, orions_boot said:

Sorry to bring up an old thread but this seems to be THE thread for filters.

Despite reading all of it I still haven't answered my question for my self.

I have a oiii filter.  Relatively bright sky internet estimates bortle 6.  I know oiii is different to UHC, but given how bright my sky is, is there much benefit in buying a UHC?  I was looking at the explore scientific 2" so it fits all EPs I have and may buy.

1) Yes, because a good UHC filter will pass the hydrogen emission from the nebula and reveal a larger size to most nebulae.  If you only view planetary nebulae, or the Veil, stick to O-III.

Pass on the Explore Scientific filter--it is too wide a bandwidth to be useful.  Literally twice as wide a bandwidth as the good UHC filters.

Stick to Astronomik, TeleVue Nebustar , Lumicon, DGM NPB and ICS for a UHC filter.

[Don Pensack]

27 minutes ago, jetstream said:

If I could only have one filter for dark or lighter skies it would be a top quality OIII, hands down ( just my personal preference).

Excellent on planetary nebulae, supernova remnants, and Wolf-Rayet excitation nebulae.

However, removing the H-ß line in the spectrum hurts the large H-III regions like M42/43, M8, M17, M20, M16 and the large gas clouds like

NGC1499, NGC7000, the nebulosity around Gamma Cygni, , the Horsehead, and most of the Sharpless nebula.

So it's worthwhile having both a narrowband UHC type AND an O-III filter.

But if you had just one, it should be a narrowband so that all emission nebulae get enhanced.

[orions_boot]

10 hours ago, Don Pensack said:

1) Yes, because a good UHC filter will pass the hydrogen emission from the nebula and reveal a larger size to most nebulae.  If you only view planetary nebulae, or the Veil, stick to O-III.

Pass on the Explore Scientific filter--it is too wide a bandwidth to be useful.  Literally twice as wide a bandwidth as the good UHC filters.

Stick to Astronomik, TeleVue Nebustar , Lumicon, DGM NPB and ICS for a UHC filter.

Thanks for making this so simple to understand.  I had not considered the type of nebula I am looking at.

 

[bingevader]

On 12/01/2021 at 21:54, Don Pensack said:

1) Yes, because a good UHC filter will pass the hydrogen emission from the nebula and reveal a larger size to most nebulae.  If you only view planetary nebulae, or the Veil, stick to O-III.

Pass on the Explore Scientific filter--it is too wide a bandwidth to be useful.  Literally twice as wide a bandwidth as the good UHC filters.

Stick to Astronomik, TeleVue Nebustar , Lumicon, DGM NPB and ICS for a UHC filter.

Sorry, couldn't let this pass for those on a budget!
At half the price, my useless, poor ES UHC filter has enabled me to see the Veil Nebula!

Stick to the useful, good filters if you can afford them, by all means.

[Don Pensack]

To be fair, ANY contrast enhancement will still be.....contrast enhancement.

But some economical filters with better bandwidths include DGM, Orion (US), Omegon, SkyWatcher, Zhumell

 

[SiriusB]

23 hours ago, Don Pensack said:

To be fair, ANY contrast enhancement will still be.....contrast enhancement.

But some economical filters with better bandwidths include DGM, Orion (US), Omegon, SkyWatcher, Zhumell

 

Any chance you could expand on this please for the benefit of all?

I'd been given  to believe the best(bandwidth) nebula filters work best with larger scopes due to light loss? If you've only a small scope......

Thanks.

[John]

7 minutes ago, SiriusB said:

Any chance you could expand on this please for the benefit of all?

I'd been given  to believe the best(bandwidth) nebula filters work best with larger scopes due to light loss? If you've only a small scope......

Thanks.

I used to think that but I have found both UHC and O-III filters effective with apertures from 80mm and upwards.

I used to stick with the "generous" (bandwidth) Baader UHC-S filter with smaller scopes but having tried more regular UHC's and more recently O-III's with such scopes I find them more effective despite the smaller light grasp of the scope.

Hopefully Don will see this and explain some more.