Dismiss Notice
New Cookie Policy
On May 24, 2018, we published revised versions of our Terms and Rules and Cookie Policy. Your use of AstronomyConnect.com’s services is subject to these revised terms.

IR Pass Filters

Discussion in 'Astrophotography and Imaging' started by Ed D, Jun 9, 2018.

IR Pass Filters

Started by Ed D on Jun 9, 2018 at 7:10 PM

14 Replies 182 Views 1 Likes

Reply to Thread Post New Thread
  1. Ed D

    Ed D Well-Known Member

    Joined:
    Jan 12, 2017
    Posts:
    272
    Trophy Points:
    43
    Location:
    Sunny South Florida
    For what seems like a very long time I have wanted an IR pass filter, something around the 685nm range, but they have been out of my financial range. Tonight, while looking at UV/Venus filters and cringing at the prices, I came across the Optolong 1.25" 685nm IR Pass Filter, on sale for $63.20 from its $79 regular price at Agena, which I ordered.

    While I was at it I also ordered the ZWO 850nm IR Pass Filter which at $24 is inexpensive enough. The IR band pass is pretty high on this filter, but it may be interesting.

    Although my camera is RGB, I have seen IR images taken with color cameras set to mono, and they look pretty nice. I really want to try imaging Mars, Venus and Luna in IR.

    The Optolong Venus and Ultraviolet Venus-U filter is also on sale, but the cost is still out of my range. Oh well, I can dream, can't I?

    Ed D
     
    Orion25 likes this.
  2. Dave In Vermont

    Dave In Vermont Well-Known Member

    Joined:
    Jan 5, 2016
    Posts:
    2,700
    Trophy Points:
    113
    Orion25 likes this.
  3. Ed D

    Ed D Well-Known Member

    Joined:
    Jan 12, 2017
    Posts:
    272
    Trophy Points:
    43
    Location:
    Sunny South Florida
    Hi Dave,

    Yes, I did, and I'm amazed, too. Back in 2012 I was observing during evening twilight with my old XT-6 using a Wratten #80-A and a Zhumell UHC filter stacked. I was able to observe cloud detail, as shown in the attached sketch I made.

    Venus 2012 01-23.jpg

    I have a Wratten #47 that does a good job on Venus. After reading Reggie's post I took out my TV-85 and had it set up and almost ready to image when.....I had to bring everything back into the house in a hurry! The recommendation for 8" and larger scopes has more to do with visual, but it's not etched in stone, as my sketch shows. Imaging Venus with small apertures is no different than imaging faint fuzzies with little refractors. It's a simple matter of taking longer exposures.

    An IR pass filter can be used to cut through less than ideal seeing, which seems to be the norm here. It can also increase the contrast of Martian albedo features, one of my main interests at the moment. IR pass filters can also sharpen lunar detail and enhance contrast, and it can bring out interesting details on Jove. On Venus it can have the effect of cutting through the glare. Similar to the effects of using blue filters on Mars to observe polar ice and clouds, and green filters to observe ground fog and differentiate it from clouds, IR and UV pass filters can be used on Venus to observe cloud cover at different depths.

    I'm also interested in imaging nebulae with an IR pass to see what I can capture. I imaged the Orion Nebula (who hasn't?) and found I could capture way more of the nebula when passing IR. Should be interesting on the Lagoon, etc.

    I know an RGB camera is not going to image in IR as well as a mono camera, even if set to capture mono, but I have seen some really nice results posted on various websites. Has to do with the Bayer Matrix. I do have in the back of my mind getting a mono camera with larger sensor sometime in the future, so...

    Ed D
     
    Orion25 likes this.
  4. Ed D

    Ed D Well-Known Member

    Joined:
    Jan 12, 2017
    Posts:
    272
    Trophy Points:
    43
    Location:
    Sunny South Florida
    BTW, I wanted to share with everyone the current sale price of the Optolong IR pass filter at Agena. They are good filters, but I believe there are only two left in stock now. This, just in case anyone has been looking for one, but didn't want to shell out nearly $100 or more.

    The Venus/UV pass filters are also on sale at a great price for what they are, but still out of my budget. I also don't see anywhere near the utility of an UV pass filter as I do an IR pass filter.

    Ed D
     
    Orion25 likes this.
  5. Ed D

    Ed D Well-Known Member

    Joined:
    Jan 12, 2017
    Posts:
    272
    Trophy Points:
    43
    Location:
    Sunny South Florida
    Agena Astro rocks!!! Four business days and the filters are here. In all the years I have been doing business with Agena they have always been great in every respect. THANK YOU!!!

    So, here is what they look like in their cases:

    IMG_20180614_212913.jpg

    On the left is the Optolong 685nm, and on the right the ZWO 850nm. Very nicely packaged. The Optolong 685nm has a coating that reflects a teal color. But, when I look through it, bright lights appear a very deep red. I can't see anything other than the light through the filter. The green lettering is a reflection of my phone.

    IMG_20180614_212956.jpg

    The ZWO 850nm is another story. It looks more like a black cap for the camera, and by that I mean it is solid black like a piece of plastic. I held it up to the lights and I couldn't see anything. I'm sure light is coming through the filter, just not at a frequency I can see. Nothing, nada, zip.

    IMG_20180614_213037.jpg

    Venus was up high in the sky and the clouds were nowhere near. I took out the CG-4 GEM and set up my AT72ED just to play with it. I centered Venus in the eyepiece, then swapped it for the camera. Once I had Venus centered in the screen and focused I installed the 685nm filter. I had to up the capture time to 7 seconds per frame, but it was looking good.

    At this time, start thinking of the oldies song RAINDROPS KEEP FALLING ON MY HEAD. :mad:

    Stay tuned. I'll get some images sooner or later.

    :( Ed D
     
    Orion25 likes this.
  6. Orion25

    Orion25 Well-Known Member

    Joined:
    May 23, 2016
    Posts:
    857
    Trophy Points:
    93
    Location:
    Georgia
    Looking forward to seeing your images, Ed. Nice set of filters there!
     
  7. Dave In Vermont

    Dave In Vermont Well-Known Member

    Joined:
    Jan 5, 2016
    Posts:
    2,700
    Trophy Points:
    113
    Orion25 likes this.
  8. Dave In Vermont

    Dave In Vermont Well-Known Member

    Joined:
    Jan 5, 2016
    Posts:
    2,700
    Trophy Points:
    113
    Hey Ed - got some new data on the IR-Pass Filters. While not cheap, the Astronomik I'll be posting a Pdf. about is absolutely what I'd be (and will) be saving up my scarce astro-$$$ for. And here's that Pdf:

    Astronomik ProPlanet 642 BP IR-pass filter.pdf

    First just look at that range it let's pass of IR. That's a 'FULL IR-Passband Filter' in my book (Dave the Filter-Nut here in full-uniform :p). And it's from Astronomik - which is German - and are the best filters going for many things. Leaving Baader in the weeds quit often. And other contenders too.

    Unfortunately Agena doesn't carry Astronomik. But just down the freeway around LA is OPT. And OPT does carry Astronomik. As for the ZWO 850nm - that is really too tight a bandpass IR for all but a very few uses. But I'm glad you have one to experiment with. As for the Optolong - it looks very interesting! I'm tempted. It's very tight, too - but should prove useful on the Inner-Planets of the Solar System. And I'd try the ZWO 850nm on those, too.

    Well I'm off to OPT to check prices on the Astronomik. It's sold for €63- in Europe. I wonder what Ill find here. But if they're the best IR-Pass Filter going, you'd never have to buy one again. From the top, the only direction from there is down.
     

    Attached Files:

  9. Dave In Vermont

    Dave In Vermont Well-Known Member

    Joined:
    Jan 5, 2016
    Posts:
    2,700
    Trophy Points:
    113
    EUREKA! I HAVE FOUND IT!

    This be the Astronomik ProPlanet 642 BP IR-Pass Filter:

    https://optcorp.com/collections/tel...k-proplanet-642-bp-ir-pass-filter-1-25-p642-1

    BEWARE: They make several filters with a very similar name. These differ in the '642' on them - '842' '712' etc. to name a few. So do watch out for that in OPT (as well as their buggy listings themselves). The price here in the US is actually lower than they pay over in Europe (Germany). So that's a first!

    Here's a Transmission Graph for this filter:

    Astronomik Pro Planet 642BP IR-Pass Filter.png

    Have Fun!

    Dave


    ps - Ed - Read the 2 reviews of this filter on the OPT website I linked above. 'Click' the 'Reviews' tab on the page. It takes awhile for that link to fully load. I think the 2 reviews are as good as the filter seems to be. OPT is also, like Agena, an honest outfit. D.
     
    Last edited: Jun 15, 2018
  10. Ed D

    Ed D Well-Known Member

    Joined:
    Jan 12, 2017
    Posts:
    272
    Trophy Points:
    43
    Location:
    Sunny South Florida
    As Gomer Pyle USMC used to say: "SURPRISE, SURPRISE, SURPRISE"

    Conditions were bad last night, lots of haze and heavy moisture mucking things up, which is where the IR pass filters shine. However, the surprise was that my best results were obtained with the TV-85 and ZWO 850nm filter. With a small aperture and such a dark filter I thought that combination would have been the wash. I also imaged with the 685nm and Wratten #47 Violet filters, but results were questionable.

    I need a good night so I can set up my 6" Mak and try the filters. I also need to learn how to combine images, similar to LRGB processing, so I can combine the results of the different filters into one image. Even though the 685nm and #47 filter results were questionable I could see different cloud layers/structure on Venus. Stay tuned.

    Ed D

    Venus 2018-06-16.jpg
     
    Dave In Vermont and Orion25 like this.
  11. Ed D

    Ed D Well-Known Member

    Joined:
    Jan 12, 2017
    Posts:
    272
    Trophy Points:
    43
    Location:
    Sunny South Florida
    I also want to mention that last night, while I was playing with the gain settings, I noticed that as I lowered the gain to where the planet was becoming dim on the computer screen, I cloud tell that I was capturing some detail. This is very similar to Reggie's great results using a polarizing filter to kill the glare.

    Ed D
     
  12. Orion25

    Orion25 Well-Known Member

    Joined:
    May 23, 2016
    Posts:
    857
    Trophy Points:
    93
    Location:
    Georgia
    Wow! Great results, Ed. I knew you would get some interesting images but...WOW! You've got me considering an IR filter, seriously. The TV-85 and ZWO 850 may need to go on my list. OMG, I never considered myself a filter-nut, everyone's good experiences with the various types and combinations have got me jumping on the filter wagon! NOw, to save my pennies :p

    Reggie
     
    Dave In Vermont likes this.
  13. Dave In Vermont

    Dave In Vermont Well-Known Member

    Joined:
    Jan 5, 2016
    Posts:
    2,700
    Trophy Points:
    113
    Reggie? I'm pleased to report that the ZWO 850nm IR-Pass Filter runs at $22.00 at Agena. Delivered free - as always.

    Ed & All Ships at Sea? Any thought on that Astronomik Pro Planet 642BP IR-Pass Filter? Which are $59.95 delivered from OPT. It would be fascinating to see a side-by-side of Venus (amongst others) with that peephole of transmission-bandwidth between an 850nm and the broadscape in IR from the 642nm -

    Astronomik Pro Planet 642BP IR-Pass Filter.png
    Oh, and Reggie? Welcome to the Filter-Nut Front! Always room for more!

    R&D.
     
    Orion25 likes this.
  14. Dave In Vermont

    Dave In Vermont Well-Known Member

    Joined:
    Jan 5, 2016
    Posts:
    2,700
    Trophy Points:
    113
    Where's Avani? We got to get him in on this! Imagine him loose with his C14 and some filters - and a polarizer too - but of course!
     
  15. Orion25

    Orion25 Well-Known Member

    Joined:
    May 23, 2016
    Posts:
    857
    Trophy Points:
    93
    Location:
    Georgia
    YIPPEEEEEE! :D
    I get the feeling our kindred spirit Avani is doing some fantastic things and will return with some jaw-dropping images!
     
    Dave In Vermont likes this.

Share This Page