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Sporadic Dobstronomer

Rosette Nebula at 1.1x through light pollution

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I dunnit last night; first time I have seen it!  Fairly easy and confirmed the location on SkySafari after seeing it. :grin:

Equipment used:
Olde fashionede profoundely heavie millitarie surplusse 1987 vintage imaege intensyfier tube
58mm f/2 Helios lens off old Zenith camera at one end
8x magnifier loupe (with bits sanded off) at the other end
UHC filter and IR/UV block filter (first light!)

Without the filters it wouldn't have been possible.  The UHC on its own would have let through infrared light pollution so I didn't even try it without the IR/UV blocker.
 

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Ye haw! Another of the "green brigade".... I am using a slightly newer system, with an halpha filter to help the nebulae! Great to hear your success, there are loads of other big nebulae to see, Milky Way is stuffed with them. California, barnards loop, monkey head, heart, soul, flame,'ic434, North America, rosetta, seagull. I was within an inch of the horsehead a few nights back with an 80mm Finder. Need to use my 8" with its better straight shielding. Keep looking for stuff! You using a cascade build?

Cheers

PEterW

Edited by PeterW
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I dunnit last night; first time I have seen it!  Fairly easy and confirmed the location on SkySafari after seeing it. :grin:

Equipment used:

Olde fashionede profoundely heavie millitarie surplusse 1987 vintage imaege intensyfier tube

58mm f/2 Helios lens off old Zenith camera at one end

8x magnifier loupe (with bits sanded off) at the other end

UHC filter and IR/UV block filter (first light!)

Without the filters it wouldn't have been possible.  The UHC on its own would have let through infrared light pollution so I didn't even try it without the IR/UV blocker.

Congrats!   I would quite like to have a go at this myself...

>> 58mm f/2 Helios lens off old Zenith camera at one end

Check - I have one of those on an olde Zenith camera too, or alternatively an even faster f/1.8 50mm 'nifty fifty' might do also?

>>8x magnifier loupe (with bits sanded off) at the other end

Check - I have one of those I could 'bodge'

>>UHC filter and IR/UV block filter

Check(ish) - I have the IR/UV block but would beed to buy a UHC filter

>>Olde fashionede profoundely heavie millitarie surplusse 1987 vintage imaege intensyfier tube

Errrm... can you provide more details on this please?

Having assembled the above, any idea what the effective f-number might be?

Thanks,

Mike

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I am guessing that we are talking about a cascade build... If so her are some links to help you.

The man who seems to have all the answers is cj7hawk.. On a number of forums.....

http://www.ar15.com/mobile/topic.html?b=6&f=18&t=359614

http://www.cloudynights.com/topic/341592-diy-intensified-iit-setup-for-around-200-project/

Here is his main page Including 3d printed part designs if you want….

http://aunv.blackice.com.au/cgi-bin/nightvision/forum?index=projects&story=cascade

You'll need some c-cd mount adapters to get the thread attached. Also you'll need a c-m42 adapter for using camera lenses. There are cheap 135mm f2.8 which you could use as well.

I built one, but I use another system for astronomy. If anyone in the UK builds one I have a small packet of the little screws to secure the wire to one of the contacts, PM me and I will pop one in the post you you.

Cheers

PeterW

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...You using a cascade build?

Cheers

PEterW

Don't know what it is called. I have been told it is a three-stage generation-1 unit and that in the centre of the field of view it is better than a not-expensive generation-2 unit.

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Congrats!   I would quite like to have a go at this myself...

>> 58mm f/2 Helios lens off old Zenith camera at one end

Check - I have one of those on an olde Zenith camera too, or alternatively an even faster f/1.8 50mm 'nifty fifty' might do also?

>>8x magnifier loupe (with bits sanded off) at the other end

Check - I have one of those I could 'bodge'

>>UHC filter and IR/UV block filter

Check(ish) - I have the IR/UV block but would beed to buy a UHC filter

>>Olde fashionede profoundely heavie millitarie surplusse 1987 vintage imaege intensyfier tube

Errrm... can you provide more details on this please?

Having assembled the above, any idea what the effective f-number might be?

Thanks,

Mike

Thanks! :grin:

Here is a picture of it:

post-39514-0-71557400-1420490599_thumb.j

The metal parts are 42x1mm extension tubes (standard for Zenith and Pentax cameras of the 1970's).  You see that one extension tube is trapped between a piece of MDF and a piece of plywood; that was the inspired bit of the whole thing. (Materials based on what I could find)

The lens and long tube together unscrew and can be replaced with an adaptor for a 2" focuser. No, I have not managed to see the Horsehead yet! The intensifier sometimes helps with light pollution simply by making everything brighter (including the light pollution) and sometimes makes things worse because the image is noisy and the noise can do more harm than the benefit of the gain. For example, the one time I have seen the part of the Veil nebula with my Dob it was invisible with the intensifier.

The tube came from here:

http://www.anchorsupplies.com/image-intensifier-tube-1st-generation.html

And I cribbed some ideas on how to do it from here:

http://www.imageintensifier.org.uk/

It is more awkward than you might expect to get everything working because the tube has no convenient fitting points but you can see from the picture how I finally did it by trapping the tube between two wooden plates.

I was able to get an adaptor so 2" filters (48mm thread) could fit on the 49mm filter thread of the Zenith lens.

Effective f/number:

I don't think it works like that. Used as an eyepiece it has an effective focal length of about 40mm (the output screen is not the same size as the input screen). A 40mm eyepiece would not normally be usable in my f/4.5 Dob but exit pupil is not an issue here because the light comes out in all directions and is not directed into your eye in the same way a normal eyepiece does. That is why you need 10,000 gain to get a useful intensifier: only about 1% of that actually gets into your eye.

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