Image Intensifier and dark hydrogen clouds
Posted 08 March 2014 - 04:54 AM
Viewing those cold non-reflective cloudy regions painted against brighter regions is truly awe inspiring, especially with the aid of image intensifiers. An image intensifier literally breathes life into these contrasty region of the Milky Way, quite an epic 3d like experience.
Photographs of the views can in no way offer such an experience, they can however describe where words fail.
The system used for the above photos is pictured below...
Image Intensified System: Star-Tron MK-428
Image Intensifier: ITT F4845 (Gen 3 25mm format)
System Specifications: 170mm f/1.5 Catadioptric (magnification 6.8x)
Posted 08 March 2014 - 05:17 AM
Which areas are most impressive? Which magnification is best, seeing you are using one of your smaller lenses!
Something to go hunting for, great shots!
Posted 08 March 2014 - 07:30 AM
This so belonged in your thread, at least portions of it. Got your post confused and thought it had been posted in another IIE thread. Seeing that the IIE threads seem to diverge so much I made the mistake of being overly cautious. Sorry for messing up and confusing threads.
Now on to your questions...
The only filters I'd expect to be of any use would be an IR pass filter, a filter that blocks the usual unwanted and interfering wavelengths i.e. sodium and/or mercury emissions.
No filters were used when the above photos were taken.
I tend to use 6.5x, 6.8x, 11.4 and 12x systems for this type of viewing. Wide field low magnification seems to work the best for viewing the structures within these regions. Of course my take on this could be prejudiced by systems being used
Regions are the most impressive on a grand scale are within within Sagittarius, Ophiuchus and Scorpius. There are some equally impressive orphaned formations in other regions though I don't remember the specific regions.
Posted 08 March 2014 - 10:13 AM
Just holding up my Moon and Skyglow filter in front of the ocular with 6x lens fitted on my monocular, the background sky glow dimmed considerably while still letting through a lot of stars. I expect the narrower band filters to darken the background considerably.
im very interested to point at some of the larger Milky Way dust patches to see if I get good separation of dark nebula.
those are great shots Cnoct. Thanks too for your YouTube video on how to change PVS 7c tube. Most helpful. I changed my tube on mine right when I got home with both goggle package and new used F9810 tube for the goggle.
i can always use the narrowband LP for visual use with my regular eyepieces if it's no good with IIE.
The star tron is awesome. I'll be trying for some F/6 views with AT72ED or with focal reducer on AT72ED (.5x). I'll try dark edges of M42 bat wings first before looking at anything else and see if they reveal the billowing edges that turn into dark nebula.
Posted 08 March 2014 - 10:40 AM
how much is that lens - tube excluded
Not sure I'm ready to sell but if I were it would be right at $1500 for the complete system. If this system were for sale, I probably would not part out the lens.
For image intensified astro I've yet to see a better system than these MK-428's.
There's not a whole lot of documentation of photos of Star-Tron NV Systems so I've attached some extra photos of the referenced MK-428 so that you can get an idea the system and components.
As you can see, this system has the optional c-mount adapter plate which makes it super easy to attach it to a telescope. The system also has manual gain control (EGAC) which is a really useful feature that allows me to adjust MCP voltage. Manual gain control (EGAC) gives me ultimate control of over noise, letting me dial in the minimum gain while keeping noise to a minimum.
Systems that use 25mm format tubes such as the PVS-4, TVS-5, PVS-8, MK-426, MK-428, MK-429 etc... give the user such an immersive experience, one that 18mm format system fail to achieve, that the viewer literally gets lost in the views.
Posted 08 March 2014 - 11:43 AM
I'll look out for these at the next Starparty I go to, my comments came from looking round Cygnus.
Posted 08 March 2014 - 12:12 PM
Thanks and I'm glad the video helped make the tube change a bit easier.
The Litton M942 kit you got makes an incredible astronomy system. I believe you have all the components to do some serious viewing and video captures. The 6x afocal is phenomenal, really great combination of FOV and magnification, find a way to get the most out of it and don't let it go to waste.
Info for your 6x: 162mm FL, f/1.7, t/1.8, system FOV with 6x is 6.6 degrees.
From the pictures I believe you have an ANVIS-6 minus blue objective as the 1x lens on your M942. You'd need to confirm with Ed wether it is and if it's Class "A, C or B". The minus blue filtered lenses really help contrast, cutting down the effects of light pollution.
It's good you bought a replacement tube for you 7's, the tube that came with it has a fatal condition that has the potential to render the tube useless within a matter of weeks, though it could be longer. I've only ever seen this particular condition afflict Litton tubes though it could very well affect ITT tubes as well. If you look closely at the affected area in the right lighting condition you can see a crystalline like lattice.
? for you:
Are you placing the Moon and Skyglow filter between your eye and the ocular lens?
Suggestions for you concerning your 3x and 6x objective lenses and H-a filters:
If your H-a filters are 1.25" and can be removed from their threaded mounting cell take them out and mount them with some blue tack (or similar material) directly on the input of the image intensifier i.e. between the most rearward (last) lens element of the objective and input window of the image intensifier. I'm not sure if there's enough space between the most rearward element and input window to do this but if there is you'll have some killer views.
If the above isn't possible, you'll be limited in your use of the H-a filters, at least with the 3x and 6x lens. In this case I'd defer you to the LP filter setup jdbastro has for his 6x lens. Here's the thread on his 6x PVS-7C: http://www.cloudynig...s-for-astronomy
If you decide to make use of the relay lenses that came with your Litton M942, keep to camera's with micro four third sensors or those with sensors similar in size to super 16 format. Relay lenses work best for video while afocal imaging setups work best for photographs.
Hope you take to image intensified astronomy and keep us all updated.
Thank you, I appreciate it.
You may want to contact Marc He may have a line on something similar or know someone who does.
Posted 08 March 2014 - 02:18 PM
if the Ha or LP work very well, then I can get and unmounted filter to try what you were saying about placing it in between the 6x lens and tube. All three lenses for the M942 have very blue coatings.
i saw the slip fit mounting that was used on the 3x. You can get unmounted filters fairly easy though, so I might go that route as I really like both 3x and 6x lenses.
thanks for the tips. Just seeing what the M&SG filter did was hopeful. it definitely dimmed the background to a less bright green while keeping the starlight coming through. Hopefully it wont be that difficult to get working in my scopes.
i do have an 85mm (objective measurement) lens I got from surplus shed a few years ago for a project I never even started. It has 48 mm rear objective, 85mm front and is about F2 if I recall correctly. Has Picatinny mount style on it. I might make a custom lens that accepts those filters too.
Posted 09 March 2014 - 02:02 PM
Cnoct, yes I was placing the filter between my eye and ocular.
There must be some confusion on where the filter is supposed to go, not sure if it's on my end our yours.
Filters that isolate selective wavelengths, such as your Moon and Skyglow filter, are placed in front of the photo cathode, objective lens or between the objective lens and input of the image intensifier
These filters are a means by which the spectral response of the image intensifier can said to be manipulated thereby enhancing its performance under certain conditions and for specific tasks.
Of course the filters aren't actually enhancing performance or altering the spectral response of the image intensifier, they do however cause the intensifier to focus all it intensification energy on selected wavelength to be intensified. So selectively filtering the light reaching the image intensifier focuses the performance as apposed to enhancing it.
Posted 09 March 2014 - 05:09 PM
That's why I went ahead with the Thousand Oaks narrowband LP -2 even though it's not ideal for image intensifiers spectral curve. The gen 3 spectral curve declines rapidly where the LP-2 filter allows emission lines through, but it also has some curves in higher than 600nm response and goes back up to 95% on 700 and up. The signals will already be weaker on the IIE around the H-beta and OIII lines, but since I'm cutting off all sodium and mercury lines too, it should provide some contrast by amplifying the transmission lines at least a little where the narrowband's OIII and H-Beta go back up to 95%. We'll see. I have no expectations of it performing optimally.
I expect the 7nm and 35nm H-Alpha filters to perform better.
Posted 11 March 2014 - 12:16 AM
this type of view is what I was hoping for. Backyard, full LP and 3/4 moon, no magnification, and there is Andromeda. Clear as a bell.
i really liked all three filters. I think I did alright and should be prepared now for a few different sky conditions.
Posted 11 March 2014 - 12:22 AM
edit - just looked again and the part on the objective tube looks like a mount part, not electronics, but I could be wrong.
Posted 11 March 2014 - 12:57 PM
There were at least two commercial adapter plates manufactured for the AN/PVS-4, one with a c-mount interface and one with an m43 interface. I only have the c-mount interface which you'll see in the attached photos.
There is an electrical component (reticle illuminator) in the objective of the PVS-4 but there is connector interface between the wired body and the objective. This interface does not present an issue when using the c-mount and m43 adapter plates.
Star-Tron used modified PVS-4 housing for a number of their units, this included the MK-428. There are also several different wired bodies for the PVS-4, with the main difference being the battery types and boxes.
You could also make a very simple adapter (pictured below) as I did.
FWIW: I really like the using the PVS-4 as a finder scope, and use it with both a Gen II (crossover focused) and fiber input Gen III (proximity focused). A tube of the Gen II crossover type (MX9644 etc...) work quite well in the finder scope role so don't discount just picking up a Gen II PVS-4. The used market is pretty flush with them right now so the prices should be favorable for buyers.
Posted 11 March 2014 - 02:57 PM
Posted 12 March 2014 - 04:08 AM
There are some interesting characteristics to the 25mm format tubes, the absent halo effect on the Gen II variants is the most notable. For both Gen II and Gen III, the immersive experience, created by the larger format, is for me the most desirable characteristic, especially for astronomy.
The PVS-4 system also has a huge FOV (14.5 degrees) for being a 3.7x system. Such a wide FOV would be difficult to achieve in 18mm system with that magnification.
For a wide FOV (14.5 degree) 3.7x finder scope look at the PVS-4 or for a 6.2x viewer/finder scope with narrower FOV (9 degree) look for a TVS-5.
It's difficult to do a realistic comparative video between 18mm and 25mm format tubes though this one may be sufficient.
Here are a couple of videos focusing on 25mm tubes.
In closing, if your looking for all out performance, stick with the systems you currently have and invest in the best possible tube technology for them (Aviation grade unfilmed tube from L3). This all depends on what you currently have, you may already have or be so close that the gains would be non existent or marginally perceptible.
Posted 12 March 2014 - 09:19 AM
I see some interesting potential there for a different view out of a different system.
C-mount for PVS 7 is due by fedex today and forecast is clear. Not going to rush out and buy another device without first confirming the existing devices will work on my current scopes.
I have officially cancelled my order for Istar 6" F/5 R35 Comet Hunter having been fed confusing info for over three months and still no scope. This opens the doors for a potentially better imaging oriented scope to use with IIE's. Very excited to see some results soon. Tests with 1x and filters were extremely promising. Probably another ED refractor bigger than my AT72ED will be purchased soon, although based on my planned use of narrowband filters with IIE's, even a well figured achromat might just fit the bill.
Posted 12 March 2014 - 03:09 PM
Looks like we pretty much build the ideal system in this thread!
Posted 13 March 2014 - 02:11 PM
I have yet to hear or see any true 3+1 hybrid production tubes from L3.
According to the former head of ITT"s warranty department (Monte Martin), tubes of the F4845 type are 3+1 hybrids.
Posted 13 March 2014 - 02:42 PM
Posted 13 March 2014 - 04:32 PM
sorry I seem to miss this one
Posted 13 March 2014 - 04:51 PM
Posted 14 March 2014 - 04:24 AM
No correcting needed, you did a fine job of summing it up.
So my guess on the "magic" reference was wrong, what was it actually referencing?
I've got a bit more to say (show) on the super inverters but that will have to wait for a bit.
Posted 17 March 2014 - 10:04 PM
Now to wait for next project at work with more OT. Just got done with all weekend worth of it this weekend and more to come, so I'll at least make my money back quickly.
next is my final telescope purchase. Knowing my lazy ways, I decided I'll buy an Orion EON 110 ED Doublet at F/6. Found I liked F/6 for brightness with 7nm H-Alpha filter and the 110 should bring this in a little closer than AT72ED and still give me the nice background I like.
I don't doubt I'll enjoy the PVS-4 with the gen 3 upgrade.