Contrast problems with reflector

[spaceboy]

Cheers John need to sort a filter now as I've just bought 1.25mm

[John]

Cheers John need to sort a filter now as I've just bought 1.25mm

Until you get a 2" filter, you could probably spot the Veil with the 16mm Nagler which I believe is a 1.25".

[pvaz]

Yes, of course

You will still need the filter and dark skies though - Naglers arn't magic

Hum... I don't think he will see it all in the same FoV. At least I can't frame both sections using my nagler 31T5 and a 1200 FL scope (TFoV = 2.11º) .

BTW in a dark site I'm used to an exit pupil slightly over 5mm and it has not been a problem (now with the nagler, before with an Agena 32mm SWA). I do notice the sky BG is brighter at lower mags/larger exit pupils, but so is everything else.

Then again, my 8" f5.9 is the only scope I have used long enough to get a feel for it, so I got no other basis of comparison.

[John]

Hum... I don't think he will see it all in the same FoV. At least I can't frame both sections using my nagler 31T5 and a 1200 FL scope (TFoV = 2.11º) .

BTW in a dark site I'm used to an exit pupil slightly over 5mm and it has not been a problem (now with the nagler, before with an Agena 32mm SWA). I do notice the sky BG is brighter at lower mags/larger exit pupils, but so is everything else.

Then again, my 8" f5.9 is the only scope I have used long enough to get a feel for it, so I got no other basis of comparison.

No, agreed Paulo - not with his scopes at least. The N31 + O-111 will show all 3 sections in my F/6.5 refractor though

Through most of this thread I'd missed the fact that the OP already had a 20mm Nagler and was trying to advise a suitable wide field eyepiece that would enable him to get a decent view of the veil when used with an O-III. While there are eyepieces that will show more sky, the 20mm Nagler is also pretty good for this purpose

Under moderately light polluted skies it might be better than a lower power eyepiece in fact.

[spaceboy]

Thanks guys. As the filters are both new scope and skies have agreed to take both the SW UHC & OIII back in exchange for 2" but they work out £43 more (total around £118) . My 2" adapter allows me to thread filters so it would be easier between EP changes but do you think it's worth the extra exspense when I only have the one 20mm 2"

How many nebula and galaxies would I need the 20mm for over the 16mm ? And do you think I will really need to change EP's all that often.I hear they do darken the object also so I take it you only need filters for the fainter nebs & galaxies? or are they worth using all the time? I will be under mag 5.5 skies

[pvaz]

UHC/OIII filters make galaxies fainter.

For nebula they can help on some, the veil is probably the one where you'll see the biggest difference. I only got a Baader 2" OIII. I found, under dark skies, filters don't help that much and I often prefer the unfiltered view, except on a few objects. Anyway I only tryed the one, so I'm planning to buy an UHC to see how it goes.

[spaceboy]

UHC/OIII filters make galaxies fainter.

For nebula they can help on some, the veil is probably the one where you'll see the biggest difference. I only got a Baader 2" OIII. I found, under dark skies, filters don't help that much and I often prefer the unfiltered view, except on a few objects. Anyway I only tryed the one, so I'm planning to buy an UHC to see how it goes.

So would you say it's not worth going into the extra exspense. I wouldn't mind but I could have got both the 2" Castell filters for £100 but SNS don't do these.

[pvaz]

My experience with 8" is that more then 100x and a filter is too much brightness drop.

In other words, I think either you get a filter you can use with your longer FL EPs or you don't. If those are in 2" format then you definitely need filters in 2". But that's just a personal opinion based on my limited experience with filters on an 8" and I may well change my mind once I try a few more filters/scopes. I guess it's one of those things you need to try and find if it works for you or not.

[John]

There are some nebulae that you can barely see at all without a UHC or O-III filter and on these, those filters make a big difference. Galaxies and clusters don't see any improvement though.

Personally I love looking at objects such as the Veil and Owl nebulae so the cost of the larger filter is well worth it to me, even though it does not get used a lot - when it does it makes all the difference.

[spaceboy]

Thanks guys. Think this is going to be a hard one to decide as for only a 3/4" increase in filter size the cost goes up by almost 2 3rds.

What is this deep sky filter I hear about?

[pvaz]

It's a broadband filter that let's more light through and filters some light pollution. It's said to do a lot of difference under light polluted skies.

The narrow band ones (UHC/OIII) look like mirrors when you hold them and they let only a carefully selected set of light bands/frequencies through. They are aimed at letting only the nebula light pass and blocking LP and even most of the star light, such as dimmer stars disappear once you insert the filter.

[spaceboy]

So a deepsky filter is basically a LPR filter??

[Moonshane]

hi Nick

I have the 2" Castell Oiii (I get mine from 365 Astronomy - Zoltan is a top bloke) and it stood up pretty well against the Astronomik - not quite as good but really quite good.

I have also bought the UHC version but not had chance to use it yet.

I'd recommend them based on the Oiii.

[spaceboy]

Hi Shane

I was going to go with the Castell but at the time I only had 1.25" EP's and the SW worked out cheaper. Given the choice I would return for a refund and go with the Castell but I have had to return stuff to SNS in the past and it took 3 mths for the refund and postage costs and SNS charges put me out of pocket almost £20 and I had nothing to show for it. SNS are cheap and offer free postage on most stuff but they have got such a poor reputation for customer care Scopes N Skies www.scopesnskies.com Reviews | Online Miscellaneous Shops | Review Centre so I would be better of getting a replacement, that is if they have it in stock as they tend to take your money and not let you know they haven't got the item.

[Moonshane]

just sell it at a slight loss - that's my usual MO. I bet you'd be glad you did.

[spaceboy]

I see from a few reviews of filters on the web that if your under dark skies filters are not really needed and often unfiltered views are better. Is this correct and what substitutes as "dark sky" in the UK. They bring out 1 or 2 very faint nebula though don't they?

[pvaz]

That's what I experienced in a mag5.5 sky with an OIII. The veil is greatly improved, almost invisible otherwise, and I saw mild improvements on a few others such as the roulette, swan, trifid and the Mexico section of the North America.

M27, M57, 1 and most others actually get dimmer, smaller and less detailed. The blue snow ball looses any hint of color, cats eye looses the bit of structure I can see on good conditions. On Orion its pretty bad, I loose structure, extent and any hint of color, not to mention the star field surrounding it.

By now you must be thinking why don't I sell it? Just because of the veil nebula as its one of my favourite objects.

Sent from my X10i using Tapatalk

[spaceboy]

Well I figured I may aswell return them for an exchange. At worst I can try them out under the light polluted skies of Brum. Just gutted I didn't get the cheaper 2" filters in the first place but such is life. I'm sure they may come in handy and if not I can always sell them.

Thanks for the help

SPACEBOY

[spaceboy]

Hi Everyone

Just a little update.

Although I'm still find it difficult to relate to the 9mm (111x 200p) no longer being a 9mm (222x 200K) I have realized the contrast improvements require a different eyepiece approach. It is hard to explain how awkward it all feel after years of picking out certain eyepieces to now having to try and do the math in my head to what I'm actually getting from the eyepiece and how this would compare contrast wise.

The hardest thing to get my head around is a 6 mm is required in the 10" to equal my favored 10 mm of the TAL. A 6mm in the TAL would be on the upper limits of magnification so it's years of conditioning makes it so unfamiliar to put it in the focuser now. This said though what would be the recommended maximum / shortest eyepiece that should be considered as even a 4mm falls short of the recommended max of 350x ?

Thanks

SPACEBOY

[sixela]

In an f/5, you can use 3-5mm eyepieces (provided the seeing cooperates, of course) fairly easily. Of course, if those have a simple design (Plössls, orthos) that might feel spectacularly uncomfortable to you if you're not used to these eyepieces, although I use my 3.6mm eye relief Pentax 5.1mm XO a lot.

Getting a barlow is one possibility (that will allow you to use your existing eyepieces, much in the way you were used to). If you want a good one that is not too expensive, consider a TeleVue barlow, although there are other choices (a Baader VIP barlow or even the superb but horribly expensive Baader/Zeiss).

Two eyepieces designed especially for that use is the Nagler 3-6mm zoom (nothing to do with the Nagler wide fields, by the way. It's a "zoom Plössl" on steroids with more eye relief).

Long(ish) eye relief eyepieces are also available. The TMB Planetary II is well regarded, and there are cheap versions (e.g. the Teleskop Service HR Planetary) of the first design around with even more eye relief, although on some focal lengths you have to tolerate some internal reflections.

[sixela]

I see from a few reviews of filters on the web that if your under dark skies filters are not really needed and often unfiltered views are better.

That's not really true if you're talking about emission filters and OIII or UHC filters. They help even more in dark skies! An OIII tends to render objects more visible but you might actually lose some subtleties of shading within the object that remain visible with a UHC filter.

What's also important is that there's a learning curve, because of you use an OIII you'll be using less magnification than with a UHC on the same object and with a UHC the optimum magnification will also be at lower magnification than with the unfiltered views. You can't just compare the views using the same eyepiece and arrive at a general statement valid for all objects.

They bring out 1 or 2 very faint nebula though don't they?

All emission nebulae, and there are more than one or two of them. I think it's actually essential to have at least a very good UHC filter (Lumicon UHC, Omega Optical NPB) for emission nebulae.

[spaceboy]

Thanks Sixela

Glad to hear I won't be wasting my money changing to the 2" filters.

I think it's actually essential to have at least a very good UHC filter (Lumicon UHC, Omega Optical NPB) for emission nebulae.

I would love good quality anything but I am a beggar not a chooser. My job is the best in the world (looking after my 2 lads) but unfortunately the pay is terrible

I have to fund my hobby by selling what ever I have and as this is such an expensive hobby I no longer have anything left to sell so compromises have to be made.

I take it regards the short EP's TMB's are the way to go regards exspense or would it be worth investing in a 2nd hand Nirvana/UWAN 4mm just so I have a little nudging room?

SPACEBOY

[russ]

Thanks Sixela

Glad to hear I won't be wasting my money changing to the 2" filters.

I would love good quality anything but I am a beggar not a chooser. My job is the best in the world (looking after my 2 lads) but unfortunately the pay is terrible

I have to fund my hobby by selling what ever I have and as this is such an expensive hobby I no longer have anything left to sell so compromises have to be made.

I take it regards the short EP's TMB's are the way to go regards exspense or would it be worth investing in a 2nd hand Nirvana/UWAN 4mm just so I have a little nudging room?

SPACEBOY

I know exactly how you feel Spaceboy. This hobby has to be self funding and not only that, has to sometimes aid other household projects. Which means a constant compromise, selling one thing to buy another or selling it all to buy a new boiler for the house. Not an easy juggling act.

There are some good value products out there though to ease the situation. I bought the 2" Skywatcher OIII and it works very well. Compared it to the much more expensive Lumicon filter and it didn't shame itself. A bit like the Castall Shane describes.

A dark site just enhances the effect of the OIII/UHC filter. The combination of low power widefield, OIII or UHC plus dark site has yielded some stunning views of the Veil this year.

[spaceboy]

Hi Russ

There are some good bargains to be had second hand but dam it's hard work. I feel I can no longer leave the screen incase I miss a cheap eyepiece. I have missed out on the 4mm UWAN the weekend that was for sale for probably 30 minutes. Some EP's are gone with in 3 minutes of being listed. I wouldn't say I'm unlucky as I'm in good health but being in the right place at the right time is not one of my strong points. The trouble is getting the focal length you want in the brand at the right price while your viewing that page

Maybe one day HEY!!!

[pvaz]

If you don't mind me asking: What's wrong with this "6mm Televue Radian, 9mm, 16mm & 20mm Televue Nagler"?

I would be pretty happy with that selection of EPs. Maybe add a long FL EP to find object and observe large DSOs but that would be it.