M42 with an O-III Filter

[Naemeth]

Last night I got a quick session with the 10" dob, and just for fun I thought I'd try seeing M42 with my O-III by holding it up to the eyepiece (it's 2", and most of my eyepieces are 1.25", definitely should've got the 1.25" ). Low and behold the view was astounding, I could see a lot more detail in the dust of the nebula, and I could see it filled a lot more of the eyepiece. 

Something to try if you haven't already .

[emadmoussa]

Humm...apart from a little bit of fringes hue ...I really didn't see a lot of difference as apposed to no-filter at all.

[Naemeth]

Humm...apart from a little bit if fringe hue ...I really didn't see a lot of difference as apposed to no-filter at all.

Really? Even with the 10" dob?

I definitely wasn't imagining it, the extent of the dust of the nebula doubled in size .

[emadmoussa]

I have to say that I was amazed by the amount of details I saw in the Delos 6mm as apposed to other eyepieces. I agree the filter brings out more details, but in all honestly it didn't show much of a difference. It's either my skies are good or my filters are rubbish.

Yes, I'm talking about the 10" Dob

By the way, I've used both the Baader UHC-S  and SW O-III. I found the UHC more pleasing as usual...

[swamp thing]

I totally agree with you Jonathan.

The O-III filter improves contrast considerably showing dark areas and structure off much better.than without.

You need good dark adaption to get the most from an O-III though.

Not tried using one in front of an eyepiece though.

[RikM]

I find that filters make more of difference on some nights than on others. Here is a sketch I made a while a go showing the sort of difference I get with/without a filter. With the UHC, all the same detail is visible, it just seems to be easier to make out with the filter. An OIII has a stronger effect and seems to give more detail in the dark areas, while the UHC shows more extensive nebulosity at the edges. I prefer the UHC on this object.

[Naemeth]

I totally agree with you Jonathan.

The O-III filter improves contrast considerably showing dark areas and structure off much better.than without.

You need good dark adaption to get the most from an O-III though.

Not tried using one in front of an eyepiece though.

I didn't really have a choice, why I got a 2" filter in the first place I don't know - useful for my ED80 perhaps? .

You don't get the whole FOV, just a fraction of it (depending on how close the filter is to the top of the eyepiece), but was worth it nonetheless. Looks like I might need a 1.25" Astronomik O-III Filter *, the views are just too good to ignore .

* Will still be waiting until after my astro holiday though, just makes the list of stuff I'm getting when I get back longer .

Thanks Rik, I may look at a UHC too.

[RikM]

I didn't really have a choice, why I got a 2" filter in the first place I don't know - useful for my ED80 perhaps? .

You don't get the whole FOV, just a fraction of it (depending on how close the filter is to the top of the eyepiece), but was worth it nonetheless. Looks like I might need a 1.25" Astronomik O-III Filter *, the views are just too good to ignore .

* Will still be waiting until after my astro holiday though, just makes the list of stuff I'm getting when I get back longer .

Thanks Rik, I may look at a UHC too.

Can you screw the 2" filter onto the underside of your 1.25"/2" eyepiece adaptor? You might need a short Baader FTR as a spacer to be sure your EP barrels don't hit the filter but this is a good way to keep your options open with regards future eyepiece purchases.

[emadmoussa]

Jonathan, all my filters are 2" and I usually screw them on the underside of the 1.25"/2" adapter in the 10" Dob - like Rik does - and with refractors I only have 2" diagonals ...so it comes natural.

[emadmoussa]

Something like this...

This is a UHC-S filter screwed into the adapter. All 1.25" eyepieces shouldn't reach the filter....so it's safe. However, I have the GSO 2.5x barlow and it's a bit long on bottom bit, and if you insert it fully into the adapter it  might hit the filter glass.

[scarp15]

Nice drawings. I have not used an UHC filter, last night whilst observing at a dark site, I used my Lumicon 2" OIII filter, which screws onto the focuser extension tube and 26mm nagler for the first time on the VX14. M42, M43 was quite outstanding and dramatic and held my attention for a long period. Only the stars in the trapezium are slightly compromised with the use of a filter.

[Tiki]

I find that filters make more of difference on some nights than on others...

Me too. When it's a filter night i find the lumicon UHC gives the best views but the OIII tends to show the best detail in the brighter parts but with less overall nebulosity.

[swamp thing]

I have to say that I was amazed by the amount of details I saw in the Delos 6mm as apposed to other eyepieces..

Strange. I don't see a 6mm making amazing gains in detail over a 10mm when I observe it through my 10" Dob. What's so special about 6mm?

[emadmoussa]

Strange. I don't see a 6mm making amazing gains in detail over a 10mm when I observe it through my 10" Dob. What's so special about 6mm?

I can't say really  as I don't have the 10mm yet to compare it with. But I compared the 5mm Hyperion and the Delos 6mm and without a doubt the Delos produced a darker sky and more defined stars which naturally increased contrast.

What I noticed was the Delos showed more nebulosity and dark areas than the Hyperion...not a massive difference, but when it comes to certain subtle details the Delos was more pleasing. On the other hand, Jupiter looked almost identical, with a very slight advantage to the Delos; perhaps related to longer focal length.

[swamp thing]

Oh your on about the superiority of the Delos. Sorry, I though you meant a certain mag made it so much better silly me.

[emadmoussa]

Oh your on about the superiority of the Delos. Sorry, I though you meant a certain mag made it so much better silly me.

I always thought the Hyperions were great eyepieces - they still are - but there's something more superior about the Delos I still use the Hyperions in the fracs and I'm happy with their performance, but in the f/5 Dob the Televue are steps ahead.