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PVS7 with high end tube due to arrive soon 😀from OVNI. 55mm and televue 67mm converter on order. What filters/size would you recommend? I’m thinking Astronimik 6nm ha based on quick research. I’ll be doing viewing from light polluted city back garden in my 18” dob. If I venture out with a handheld set up, e.g. x3 magnifier, can I use the same size or is that 2” only?

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I made a pushfit adapter to hold a 2” over the front of the 1x, fits the 3x with another adapter. Then 2” will fit on the 55mm plossl. 6nm is pretty good, the high spec tube people like the narrower Chroma filters, but they cost a bit more. A 685nm long pass is the other one you’ll want (especially from town). I had a nice session looking at Milky Way structure (found B312), with 1x/3x from a local park.

 

peter

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Thanks Peter, looks like the filters aren’t going to be cheap. I see the Chroma 5nm 2” is almost double the cost of a 6nm Astronomik. Is the performance difference likely to be so great? Looks like I need to do more research before pulling the trigger...

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Many people are happy with the normal ones... it’s just some people have tried the more expensive ones and they do a bit better. Have a look at comparison posts. I reckon if you never compare yours against the chroma you’d probably never worry... but like not having a 5000FOM tube (if they existed).

Peter

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  • 3 weeks later...
On 30/07/2020 at 19:27, Trentend said:

Thanks Peter, looks like the filters aren’t going to be cheap. I see the Chroma 5nm 2” is almost double the cost of a 6nm Astronomik. Is the performance difference likely to be so great? Looks like I need to do more research before pulling the trigger...

Congratulations!
I wouldn’t say the Chroma 5nm is a worthwhile step up from Astronomik 6nm. I’d go all the way to a 3nm, but it depends how bad your light pollution is. Mine is almost as bad as it gets, so a Chroma 3nm was worth the investment - although I balked at the cost of the 2” and stuck with the 1.25”. That in turn means I have to use it with a 40mm plossl instead of the 55mm plossl, losing out a bit on the speed of the system - so swings and roundabouts......
However, the 3nm Chroma is a little firecracker! Showcase nebulae like the N America and M42 are more substantial and brighter than with my Baader 7nm. I can see more intricate detail in objects like the Veil. And that’s only through a 130mm Tak Epsilon, which is my largest scope.
If you’re dealing with suburban rather than city centre skies, then the Astronomik 6nm would be fine. Supposedly a very nice filter - and with your dob is going to transform your ability to see deep sky objects under any skies. And who knows, you might want to upgrade in the future to a Chroma 3nm? These filters always seem to sell well on the used market. Look forward to hearing about your new gear. 

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I’ll wait till I see what the achromat does with my grey haired system, I fear it would kill the brightness too far....

I have a 12 and 7nm and a smaller 6nm astronomik. Sometimes I stack them to help keep the out of hand transmission down, especially if there’s a lot of lig about.

 

Peter

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On 19/08/2020 at 18:18, PeterW said:

I’ll wait till I see what the achromat does with my grey haired system, I fear it would kill the brightness too far....

I have a 12 and 7nm and a smaller 6nm astronomik. Sometimes I stack them to help keep the out of hand transmission down, especially if there’s a lot of lig about.

 

Peter

Interesting Peter. How do stacked filters perform compared with a single 6nm? Would there be benefits to adding a 7nm to my 3nm? 

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“Achromat”... I meant Chroma.... auto correct is beginning to drive me nuts. 
t

With such narrow band filters, when you have lots of light at other wavelengths even 0.1% could be an issue. Normal filter transmission plots are with a linear scale, so you can t tell 0.1% from 0.01%. It’s quite common for these filters to have regions where they are less blocking, but you won’t know unless they provide a logarithmic plot in ND units (which I think Chroma do). If you add a 12nm to a narrower one then the loss of hydrogen alpha will be trivial compared to the additional blocking of those undesirable wavelengths. I haven’t done a lot of testing as if I filter too heavily the image starts to get hard to use. Maybe in the coming months.

 

peter

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Kit arrived today and a clear night here in Edinburgh. Filter to follow soon but had a quick peek upwards in the back yard 5 minutes ago handheld with the x1 lens. Wow, stars everywhere and even a shooting star as a welcoming gift in the first 5 seconds! Young one also had a go indoors with the lights off and really enjoyed it, especially the IR mode, which was pin sharp. Only concern is you have to twist the IR switch quite forcefully and I can see that breaking if used often (not the intention, but a pretty “cool” feature). Also initially concerned as a lot of scintillation when used indoors but this pretty much vanished when outside in its natural habitat. Great start.

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9 hours ago, Trentend said:

Kit arrived today and a clear night here in Edinburgh. Filter to follow soon but had a quick peek upwards in the back yard 5 minutes ago handheld with the x1 lens. Wow, stars everywhere and even a shooting star as a welcoming gift in the first 5 seconds! Young one also had a go indoors with the lights off and really enjoyed it, especially the IR mode, which was pin sharp. Only concern is you have to twist the IR switch quite forcefully and I can see that breaking if used often (not the intention, but a pretty “cool” feature). Also initially concerned as a lot of scintillation when used indoors but this pretty much vanished when outside in its natural habitat. Great start.

Excellent news! The best description I’ve read of the sky with night vision is that it’s: “filthy with stars”. You have a lot of fun ahead of you. Do keep us informed of how you get on.

Afraid my strength weakened after my post above - I’ve now ordered the Chroma 3nm 2” ha filter for use with 55mm/67mm TV ‘superplossl’ and Panoptic 27. Here in London I need all the help I can get. 
But there are also cheaper narrow options. I’ve just been reading about a new brand - Antlia, which apparently does a good 3.5nm. 

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IR?? Never used the one on mine! Outdoors there is always plenty of light as the night sky is rich in NIR, indoors I was disappointed as you were. With the filters added you’ll kick it up a notch!

Mark, I need to try some of those other filters to see if it’s worth me investing....

Peter

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I ended up going with the Antlia 3.5. Will let you know how I get on with it (perhaps upgrade at a later point if needed). Not sure if the IR button is just on the PVS7? When used everything around 2-3m indoors in front of you is crystal clear, compared to lots of scintillation without (although still cool). I think the guy with the pit in Silence of the Lambs had it on his...

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  • 3 weeks later...

I have a generic camera 680nm IR and the Altair 685nm, as I want to maximally purge light pollution, but some people are praising the 642nm... maybe I should get the shorter one, though I don’t get to dark skies often.

Peter

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  • 5 months later...

 I know chroma filters (6nm and 12 nm) went up before xmas and they are no longer listed by FLO.

3nm Chroma is an eye watering £1199, which is more than some people telescopes here.


Any ideas of other makes, Anitila or Astrodon are they any good? I expect Chroma to be the best but given the price hike any other choices the would be good?

Backyard 20.5 SQM. 


Device (I'll buy it once my scope final turns up) OVNI-M Night Vision Eyepiece White Phosphor FOM2100

Asking now given the time delivery takes.

Edited by Deadlake
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The Chroma price rises are crazy! Can only presume they are pulling out of the mainstream market. My 2” 3nm which I bought in the autumn has gone up over £500. If you can find Astrodon filters at acceptable prices then they’d be a first class alternative - on a par with Chroma

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18 hours ago, Highburymark said:

The Chroma price rises are crazy! Can only presume they are pulling out of the mainstream market. My 2” 3nm which I bought in the autumn has gone up over £500. If you can find Astrodon filters at acceptable prices then they’d be a first class alternative - on a par with Chroma

Order of presence is Chroma > Astrodon > Anitila 

Where does 
Astronomik fit it, I would of placed them the same levels as Chroma?

 

I see the OVNI are stocking Antila

https://www.ovni-nightvision.com/en/content/36-accessories-ovni-b

Edited by Deadlake
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