KG3 IR Absorption vs IR Blocking filters? Same?

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by MalVeauX » Fri Jun 15, 2018 1:38 pm

TheSkyBurner wrote:
Wed Jun 13, 2018 9:28 pm
So today i let the baader planetarium b-ccd filter track direct solar focus for more than 4 hours, started at 1130pm. Just took it off. 100mm at f5 no other rejction filters added and it did not crack or break. This means it is rather enduring of heavy stress. I cannot measure glass expansion or optical performance characteristics but i can confidently say this filter will not break when it is close to the solar focus. I will stress test with an 8 inch f5 next.
That's great news. I suppose that's why others are using them in PST CaK mods over the years.

Was there anything in front of, or behind, the Baader B-CCD? Or was it just objective -> Baader B-CCD (in the focuser) -> something / Ca filters -> camera?

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Fri Jun 15, 2018 4:02 pm

It was just the bccd filter in the focuser. Directly on the hottest solar focus with zero barlow. 100% prime focus directly in the center of the b-ccd filter.

I then inspected the filter for visual defects, and then used it to look at various objects in my area such as mail boxes, roofs, chimney and birds and flowers. No degradation on the image was found with a 25mm eyepiece, nor with a 15mm eyepiece.

Your 120mm x 1000mm scope will not break the filter.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by MalVeauX » Fri Jun 15, 2018 5:49 pm

Interesting, thanks for the update. I'll have to give it a try and see if I can use this in my focuser and then the skybender with the 393nm filters.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Fri Jun 15, 2018 9:44 pm

i am actually going to sell my b-ccd filter and give the money to Apollo now that i have the two 81045 mirrors. I have no need for any additional rejection now that I have a pair! He is the one that pointed me into the direction of newport optics.

Would you like it for $80 with free shipping? It is 48mm. MAke me an offer on the 2" skybender and ill include that too since i have four of them now.

Just private message me and we can work something out.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by MalVeauX » Tue Jun 19, 2018 5:05 pm

Update:

With the Baader 2" B-CCD filter, with reflective surface and IR blocking, it serves great as a 2" ERF. I just used it all morning with a 120mm refractor and the heat was managed great. So I'm able to stuff the Skybender with 393nm filters and get back to it on a dime.

So now, I'm doing:

Baader 2" B-CCD Filter (ERF) -> 370~395nm Cut Filter -> 393nm Filter (in Skybender) -> 393nm Filter on nose of camera.

Heat is managed, works great. Transmission is great too.

It really does reflect light back out too, which keeps the heat out instead of trying to absorb it some where. I show the reflection by putting my hand in front of the OTA and you can see the wavelengths reflected back out of the scope. Also, showing the transmission at the camera end, basically nothing visible as it's fully blocked and we can't see UV, but the camera can. Managed around 1 hour without any issues with heat with a 120mm aperture.
Baader_Blue_ERF.jpg
Baader_Blue_ERF.jpg (197.08 KiB) Viewed 567 times
ERF_Demo_Skybender.jpg
ERF_Demo_Skybender.jpg (125 KiB) Viewed 567 times
Skybender_393nm_Demo.jpg
Skybender_393nm_Demo.jpg (171.96 KiB) Viewed 567 times
reflecting_light_ERF_demo.jpg
reflecting_light_ERF_demo.jpg (79.79 KiB) Viewed 567 times
Imagingsetup06192018.jpg
Imagingsetup06192018.jpg (224.16 KiB) Viewed 567 times
Very best,

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Tue Jun 19, 2018 11:31 pm

Very nice, the blue transmission coming out of the objective is bouncing off the 395 filter. I had a similar experience

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by MalVeauX » Wed Jun 20, 2018 4:23 am

Dunno why I even did that, I always do the dumb thing and put my hand in the light path to see if it's hot. It's usually hot on the business end. Was my first time experimenting with reflections from the objective to see if the filters were doing their jobs. They were! Was nice. I'm happy to be able to track and image without cracking a filter again. I have little time to waste during the summer in Florida with non-stop storming, so an hour of fooling with a filter is not worth my time. This blue ERF filter has really helped alleviate that problem so far!

Very best,

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by MalVeauX » Mon Aug 20, 2018 8:17 pm

Update,

Just wanted to update it's been a few months, and the baader blue CCD filter with IR block has still been a champ, handling thermal load in my now 150mm refractor no problem, with the 370~395nm pass filter. The combination results in removing all the heat and still letting me image in both white light and near calcium light, or anything in the blue spectrum basically, without any special big ERF so far.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by krakatoa1883 » Wed Aug 22, 2018 12:00 pm

Very interesting, Marty, thank you, I was looking for a blue ERF with the same purpose, the info you provided are very useful.
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