Replacing the Rusted BF30 Filter

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Replacing the Rusted BF30 Filter

Post by GeorgeIonas »

I'm looking at replacing my rusted straight through BF30 filter with a durable ITF Beloptik filter. I understand that I will also need a UV/IRcutKG3 filter as well since the double stacked Coronado (external) SM90's use a front red ERF filter.

Can somebody direct me where I can find the layout of the blocking filter, a simple diagram will do showing their positions. Is the ITF filter and UV/IRcutKG3 filter sandwiched together? If so, will the filters fit in the cavity left from the rusted BF30 filter? What is the orientation of the ITF filter? I would presume that the UV/IRcutKG3 filter is placed before the ITF filter? Is it an easy straight forward conversion in changing the filter?

Sorry about the large number of question but your advise would be appreciated.

George


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

This sounds interesting for me in a near future, but on the other side I have been getting all my new BF30 free of charge refunded by MEADE eg. former Coronado as when I bought them they came with Lifetime warranty.


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Re: Replacing the Rusted BF30 Filter

Post by christian viladrich »

Hi,
The Beloptik ITF includes the UV/IRcut and KG3.
Image


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Re: Replacing the Rusted BF30 Filter

Post by GeorgeIonas »

Thank you Christian.

George


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

GeorgeIonas wrote: Thu May 10, 2018 7:20 pm Thank you Christian.

George
Yesterday I did send an e-mail to Beloptik asking for BF30 filters. So far no answer.

Rainer


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Re: Replacing the Rusted BF30 Filter

Post by GeorgeIonas »

Hi Rainer,

Oliver at Beloptik said that Friday is a public holiday.

George


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Re: Replacing the Rusted BF30 Filter

Post by Merlin66 »

George,
We’ve had success using the Baader 35nm Ha CCD filter as a replacement for the ITF.
Just remove the old ITF, and screw the Baader onto the front of the body.


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Re: Replacing the Rusted BF30 Filter

Post by GeorgeIonas »

Thank you for the information Ken.

George


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

GeorgeIonas wrote: Fri May 11, 2018 12:04 am Hi Rainer,

Oliver at Beloptik said that Friday is a public holiday.

George
Hi,

I got an answer from Oliver. He quoted me Euro € 280.00 (sans VAT) + shipping.

He asked me if the BF30 has 34 mm diameter. Anybody knows or I would have to open one of mine in order to measure it.

I am keen to order 3 so I do not have to worry about the ongoing back and forth to USA of my BF30

Rainer


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

Merlin66 wrote: Fri May 11, 2018 12:26 am George,
We’ve had success using the Baader 35nm Ha CCD filter as a replacement for the ITF.
Just remove the old ITF, and screw the Baader onto the front of the body.
Hi Ken,

Interesting and thanks. Looking at my BF30 the elements are tilted and just screwing in a filter would mean the surface is not tilted. ¿ no Problems with reflections ?

Rainer
Last edited by rsfoto on Fri May 11, 2018 11:47 pm, edited 1 time in total.


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Re: Replacing the Rusted BF30 Filter

Post by Merlin66 »

Rainer,
No, no problems.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

Merlin66 wrote: Fri May 11, 2018 10:37 pm Rainer,
No, no problems.
Thank you


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Re: Replacing the Rusted BF30 Filter

Post by GeorgeIonas »

Hi Rainer,
I had an email from Oliver Smie from Beloptic suggesting that I would only require the UV/IRcutKG3 filter as an ITF replacement with diameter of 34mm for my double stacked Coronado SM90 Etalons.

What I don't understand is why I only require the UV/IRcutKG3 filter and not their replacement ITF ?

George


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

GeorgeIonas wrote: Sun May 13, 2018 10:15 am Hi Rainer,
I had an email from Oliver Smie from Beloptic suggesting that I would only require the UV/IRcutKG3 filter as an ITF replacement with diameter of 34mm for my double stacked Coronado SM90 Etalons.

What I don't understand is why I only require the UV/IRcutKG3 filter and not their replacement ITF ?

George
Yes that he said to me too. I talked by phone with him about it.

Because a BF30 has 2 elements in there. If you unscrew the rusted element you will see a second filter a bit deeper in the 2" housing.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

Merlin66 wrote: Fri May 11, 2018 12:26 am George,
We’ve had success using the Baader 35nm Ha CCD filter as a replacement for the ITF.
Just remove the old ITF, and screw the Baader onto the front of the body.
Hi Ken,

I found a 12nm 2" Ha filter from Astronomik in my unused filter collection. I guess I can use that one too as ERF in front of the ITF at the fron of the BF30?

I take out the rusted part and screw this filter into the 2" nosepiece.

Thanks Rainer


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Re: Replacing the Rusted BF30 Filter

Post by Bob Yoesle »

I went with the BelOptik UV/IR KG3 as my BF30 ITF replacement, and couldn't be happier:

viewtopic.php?f=9&t=14783

Oliver can turn it down to 34 mm in diameter as he did for me so it is a drop-in replacement. As long as you have another RG630 element in the filter stew,such as the etalon ERF, you'll have good to even better results than the OEM ITF.


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Re: Replacing the Rusted BF30 Filter

Post by GeorgeIonas »

Hi Bob,

I read your post "A filter journey" which explains all that I need to know - excellent post !

Oliver has sent me the replacement UV/IRcutKG3 filter for the DS SM90s. My other option was to use a Baader 35nm Ha filter as suggested by Ken.

I just don't know why Meade do not use this conversion on there BF filters, it would stop the filters continually going back for repair.

George


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Re: Replacing the Rusted BF30 Filter

Post by Merlin66 »

Rainer,
My experience is with the Baader filter, but the Astronomik should work OK.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

GeorgeIonas wrote: Fri May 18, 2018 11:05 pm Hi Bob,

I read your post "A filter journey" which explains all that I need to know - excellent post !

Oliver has sent me the replacement UV/IRcutKG3 filter for the DS SM90s. My other option was to use a Baader 35nm Ha filter as suggested by Ken.

I just don't know why Meade do not use this conversion on there BF filters, it would stop the filters continually going back for repair.

George
Hi George,

Did you order the 2" filter ? If yes I think I have bad news. I found a 2" Ha 12nm bandwidth filter from Astronomik Gerd Neumann and tried to thread it into the from part of the 2" nose piece of my BF30 and it does NOT fit :shock: and I tried it on 3 three different BF30 I have here and NO luck.

The 2" filters do not thread into the front part of the 2" nose piece of the BF30, at least 3 three of mine.

Rainer


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

Hi,

OK after finding out the 2" standadrd filters do not thread onto the nose piece what I did with my US $ 280.00 Ha 12nm filter was to take out the glass and glue it onto the front part of the original threaded holder.

Below 2 images with original rust and new 12nm Ha filter.

The focusing point moved and I gained speed in my camera eg the exposure time went down by about 20-25% :seesaw

Below two images which look for me absolutely the same. ;)

So now I will see how long lasts the 12nm Ha filter there.

2018-05-19_12-09-00_pp-1f_500.jpg
2018-05-19_12-09-00_pp-1f_500.jpg (602.87 KiB) Viewed 7261 times
2018-05-19_12-30-16_pp-1f_500.jpg
2018-05-19_12-30-16_pp-1f_500.jpg (560.83 KiB) Viewed 7261 times


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Re: Replacing the Rusted BF30 Filter

Post by Merlin66 »

TheSkyBurner <Name>?
The safety requirements for extended VISUAL solar exposure is ND5 across the full spectrum. This does not obviously apply to imaging situations.

There's a copy of the ICNIRP Review in the Solar Chat Reference Library.

Rainer,
Hmmm, sorry to hear the Astronomik didn't fit.....but the final outcome looks satisfactory.


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Re: Replacing the Rusted BF30 Filter

Post by GeorgeIonas »

Hi Rainer,

I went with the UV/IRcutKG3 filter cut down to 34mm so it would be a easy "drop in" replacement into the BF30.

Sorry to hear that the 12nm Ha filter did not thread into the BF30. An alternative would be to screw the filter into a short extension tube in front to the BF30.

On another note it is good to hear that you can reduce your exposure times, this helps to beat poor seeing.

George


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Re: Replacing the Rusted BF30 Filter

Post by mdwmark »

You got me worried here. When you start replacing part without knowing the design.
If you look at the blocker filter. It will be between .6nm-1nm HW. I'm petty sure its a standard coating. Well put it at 656.3nm +/-.3nm. Just the bandpass will turn back on at about 700nm on the red side and 480m on the blue side. If they designed it to be blocked to 1000nm. Then the KG3 or KG5 will block the long side just fine.But if it's not block that far in the red, then the ITF is what is required. The KG glass is still transmitting at 700nm. For the short side the RG630
can handle that. So if they have a ITF in the stack there probably a reason. If you can replace it for less then $300 then that is still a good deal. If made right they should last 5-8 years.
There was a comment about using a hard coated blocker. You still have the problem of the IR pass the 1500nm . There is still a lot of IR light making it way through. Once you get out to 2400nm the amount of IR making it pass the atmosphere is very low. You shouldn't have to worry about anything that far out. Besides the ITF and the KG are still working at 3000nm.
PS: I have been using hard coated blockers for two years on the TEC models . Also I do not use KG glass because of the problems that were stated earlier.
Mark W.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

Merlin66 wrote: Sat May 19, 2018 9:29 pm TheSkyBurner <Name>?
The safety requirements for extended VISUAL solar exposure is ND5 across the full spectrum. This does not obviously apply to imaging situations.

There's a copy of the ICNIRP Review in the Solar Chat Reference Library.

Rainer,
Hmmm, sorry to hear the Astronomik didn't fit.....but the final outcome looks satisfactory.
Hi Ken,

You do not need to be sorry.

Not the Astronomik and not any other standard 2" filter did fit.

Rainer
Last edited by rsfoto on Sun May 20, 2018 3:21 am, edited 1 time in total.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

GeorgeIonas wrote: Sun May 20, 2018 12:07 am Hi Rainer,

I went with the UV/IRcutKG3 filter cut down to 34mm so it would be a easy "drop in" replacement into the BF30.

Sorry to hear that the 12nm Ha filter did not thread into the BF30. An alternative would be to screw the filter into a short extension tube in front to the BF30.

On another note it is good to hear that you can reduce your exposure times, this helps to beat poor seeing.

George
Hi George,

Good for your but honestly when talking to Oliver the cost increased every time I made a question and so I just tested the simple solution putting an Orphan 12nm Ha Filter instead of the rust.

Let me see what happens ...

Rainer
Last edited by rsfoto on Sun May 20, 2018 3:31 am, edited 1 time in total.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

mdwmark wrote: Sun May 20, 2018 2:55 am You got me worried here. When you start replacing part without knowing the design.
If you look at the blocker filter. It will be between .6nm-1nm HW. I'm petty sure its a standard coating. Well put it at 656.3nm +/-.3nm. Just the bandpass will turn back on at about 700nm on the red side and 480m on the blue side. If they designed it to be blocked to 1000nm. Then the KG3 or KG5 will block the long side just fine.But if it's not block that far in the red, then the ITF is what is required. The KG glass is still transmitting at 700nm. For the short side the RG630
can handle that. So if they have a ITF in the stack there probably a reason. If you can replace it for less then $300 then that is still a good deal. If made right they should last 5-8 years.
There was a comment about using a hard coated blocker. You still have the problem of the IR pass the 1500nm . There is still a lot of IR light making it way through. Once you get out to 2400nm the amount of IR making it pass the atmosphere is very low. You shouldn't have to worry about anything that far out. Besides the ITF and the KG are still working at 3000nm.
PS: I have been using hard coated blockers for two years on the TEC models . Also I do not use KG glass because of the problems that were stated earlier.
Mark W.

Hi Mark,

OK you are worried. I understand but I am not visual ¿ so what ?

I compared before and after. My camera is still alive. The filter did not crack.

If there is no risk there is no fun. If there would be no people risking something there would be no development and we would be still climbing trees and throwing stones at each other ( well, maybe that would be better then having G36 or AR-15 rifle or whatever)

Some time people like to make things more complicated then necessary ...

OK, Different strokes for different folks.

When I have time I perhaps will measure on of the rusted filters.

Rainer
Last edited by rsfoto on Sun May 20, 2018 2:46 pm, edited 1 time in total.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

mdwmark wrote: Sun May 20, 2018 2:55 am You got me worried here. When you start replacing part without knowing the design.
If you look at the blocker filter. It will be between .6nm-1nm HW. I'm petty sure its a standard coating. Well put it at 656.3nm +/-.3nm. Just the bandpass will turn back on at about 700nm on the red side and 480m on the blue side. If they designed it to be blocked to 1000nm. Then the KG3 or KG5 will block the long side just fine.But if it's not block that far in the red, then the ITF is what is required. The KG glass is still transmitting at 700nm. For the short side the RG630
can handle that. So if they have a ITF in the stack there probably a reason. If you can replace it for less then $300 then that is still a good deal. If made right they should last 5-8 years.
There was a comment about using a hard coated blocker. You still have the problem of the IR pass the 1500nm . There is still a lot of IR light making it way through. Once you get out to 2400nm the amount of IR making it pass the atmosphere is very low. You shouldn't have to worry about anything that far out. Besides the ITF and the KG are still working at 3000nm.
PS: I have been using hard coated blockers for two years on the TEC models . Also I do not use KG glass because of the problems that were stated earlier.
Mark W.
Hi Mark,

Look at the images and that is what is inside the BF30 ... all of my 3 three BF30

It is not only one but 2 cells inside the 2" nosepiece
Coronado_1a.jpg
Coronado_1a.jpg (119.21 KiB) Viewed 8033 times
Coronado_0a.jpg
Coronado_0a.jpg (113.17 KiB) Viewed 8033 times


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Re: Replacing the Rusted BF30 Filter

Post by Merlin66 »

Mark,
I'd appreciate hearing your comments/ concerns with the IR >1500nm.
This region is well beyond the sensitivity of commercial CCD/ CMOS cameras and hence should have no impact.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

Hi,

Well I warmed up my Spectrograph and measured the Original first filter towards the Sun as well as the Astronomik Ha 12nm filter which I am using now and that looks like this.

Interesting are the parasite lines around 5000Å and 5200Å in the Original Coronado Filters as well as in the Astronomik but by far not so pronounced at 4860Å and 5150Å

CoronadoFilter.jpg
CoronadoFilter.jpg (193.36 KiB) Viewed 8017 times
Astronomik12nmHa.jpg
Astronomik12nmHa.jpg (194.02 KiB) Viewed 8017 times
comparison.jpg
comparison.jpg (185.04 KiB) Viewed 8017 times


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Re: Replacing the Rusted BF30 Filter

Post by christian viladrich »

Hello Rainer,
Can you go beyond 780 nm with your spectrograph ? 1500 nm ?


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Re: Replacing the Rusted BF30 Filter

Post by christian viladrich »

BTW, I have some friends who are using the Astronomik 12 nm or the Astrodon 6 nm Ha filters to replace their rusted ITF.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

christian viladrich wrote: Sun May 20, 2018 7:42 pm Hello Rainer,
Can you go beyond 780 nm with your spectrograph ? 1500 nm ?
Hi Christian,

No, my Spectrograph is a poor man's LISA from Shelyak :oops:

What would I need or how does that work ?

May I ask why is over 1500nm so important ?

Rainer


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Re: Replacing the Rusted BF30 Filter

Post by christian viladrich »

Hi Rainer,
At sea level, 89% of incoming solar energy is at wavelengths < 1500 nm.
By comparison, 80% of solar energy is at wavelengths < 1100 nm, and 46% < 700 nm.
So, the knowledge of the transmission up to 1100 nm (or better 1500 nm) is good information.


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Re: Replacing the Rusted BF30 Filter

Post by Merlin66 »

Christian,
Agreed. But that’s the total energy....our visual systems function <700nm and the commercial CCD looses all sensitivity beyond 1100nm, beyond that we experience “heat”.
I have not seen any evidence that IR beyond 1200nm has any negative impact on solar observing.


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Re: Replacing the Rusted BF30 Filter

Post by christian viladrich »

My point was to give a general information on the amount of energy beyond 1100 nm. Indeed, most of multicoated filters block IR up to 1100 nm while there is still some amount of energy beyond this limit.

I agree there is no problem for imaging on small size telescopes.
In larger size telescopes (> 150 mm), the amount of energy beyond 1100 nm is not negligeable. It is difficult to assess the impact of this on actual solar observing.


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Re: Replacing the Rusted BF30 Filter

Post by Merlin66 »

Christian,
We really need to find an objective method of assessing the issues of NIR radiation Re solar observing/ imaging.
IMO there are no safety or performance concerns.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

Hi,

I just got an e-mail from Oliver Smie from Beloptik.

He wrote me that using for example the Astronomik Ha filter for photography is OK but not for visual as the filter blocks only up to 1150nm and for visual is it not recommendable to use it due to the Optical Density of this filter.

He also wrote that with Optical Density 3 it should block up to 1500nm and with Optical Density 4 it should block up to 1000nm.

Now I have to ask how is the Optical Density defined ? Glass thickness, refractive index, etc. ?

What amazes me most is how is Coronado (Meade) not able to make a good filter ? The BF30 has a price of US $ 1,600.00 ... and at the moment at one US Big shop with waiting list ...

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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

Hi TheSkyBurner,

We are talking about BF30 filters and not PST = Personal Solar Telescope ...

... but thanks anyway as now I am understanding all this a bit more then before.

So the optical train of a Solar telescope using a BF30 is in my case as following

1 one SM60 with ERF then another SM60 with no ERF, 4 optical lenses from a Petzval telescope (Takahashi FSQ 85ED), then first element of BF30 (be it the original or as in my case a 12nm H-alpha filter DSO purpose) then the second original filter from Coronado BF30 (Blocking Filter 30mm Ø)

Rainer


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Re: Replacing the Rusted BF30 Filter

Post by GeorgeIonas »

My BF30 has been used on double stacked SM90 Etalons (having the ERFs on both Etalons) and has lasted for only 6 years. The "rust" in the ITF filter now covers about half of the filters diameter.

So my option were; buy another BF30 at US$1600 which is expensive or send it back to Meade and wait months for it to be repaired which will deteriorate again or get a UV/IRcutKG3 as a ITF replacement filter from Beloptik within a couple weeks for 137.50 Eur shipped to me here in New Zealand.

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Re: Replacing the Rusted BF30 Filter

Post by Bob Yoesle »

Thank you very much Mark for your input and expertise ;-)


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

TheSkyBurner wrote: Wed May 23, 2018 12:13 am How long have you had your bf30, and are you the original owner?

Getting rust on a bf30 from such a small etalon/ objective with its ERF still in place is quite worry some!

If you had the thing less than 3 years I would say there is something seriously up with the danger zone coming out of the back of the SM60. Only way you can control by adding a secondary IR UV cut filter over the face of the etalon, or before the blocking filter....

etalon is transmitting a range of IR/UV intensity strong enough to cause environmental damage.. That is a slightly upsetting considering the cost of a bf30,. (obviously its first element was intended to be sacrificial)
Hi,

Yes I am the original owner and since around 2007 I have exchanged the three BF30 I have already one and a half time. They even rust when not in use and I have them in a more or less dry climate ...


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Re: Replacing the Rusted BF30 Filter

Post by christian viladrich »

Unfortunately, it is not usual to have rusted BF30. This is really a pity considering the cost of these filters. This leaves us to experimenting and find more cost effective solutions (at least for imaging) ;-)


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Re: Replacing the Rusted BF30 Filter

Post by GeorgeIonas »

Hi Christian,

I agree with you, we need to find a cost effective solution but at present even if the Beloptik UV/IRcutKG3 filter lasts for 6 years as did my BF30 it is still at present the cheapest option.

George


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

christian viladrich wrote: Wed May 23, 2018 7:01 pm Unfortunately, it is not usual to have rusted BF30. This is really a pity considering the cost of these filters. This leaves us to experimenting and find more cost effective solutions (at least for imaging) ;-)
Hi Christian,

¿ what do we need as filters ?

Do you have specifications ... ?

I think there is more of a mistery behind it in order to cash a good amount of money ¿ or am I wrong ?


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

Hi,

As far as I know Valery a member of this forum makes such filters ¿ right ?

What is his opinion about this ?


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

TheSkyBurner wrote: Thu May 24, 2018 7:55 pm nobody makes blocking filter replacements because the specifications vary so widely between all the filters and brands. from 5mm to 34mm all the specifications are completely different because they are designed to operate at different focal lengths. The filters are probably hand selected based on spectral response from a large batch production and the rejects are just tossed/returned as unusable B stock.

bf5 designed for full disc at 500mm bf30 designed for full disc at 2000mm

ITF replacements is all you will find, and it seems like this is a gamble for visual use.
Interesting and I guess that is for visual use because if that would be valid I would have strong vignetting with my equipment using a BF5

My telescope is 450mm focal length and my camera has a diagonal size of 8.2mm and using a BF 5 that would look like this ...
BF5.JPG
BF5.JPG (192.4 KiB) Viewed 7524 times


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Re: Replacing the Rusted BF30 Filter

Post by Merlin66 »

The size of the the solar disk image at a focal length of 450mm is 4.22mm.


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Re: Replacing the Rusted BF30 Filter

Post by rsfoto »

TheSkyBurner wrote: Thu May 24, 2018 10:32 pm I think the solar image is much smaller than 5mm coming out of a 450mm scope so this is why you have no vignetting. The full image transmits right though the port hole.
I do not use a 5mm BF but I am using a BF30. Below the reasons why I use a BF30 as well as I do not like diagonals as they make life hard in regard to focusing distances.

Look at the image below which was taken with 450mm focal length through the BF30. It has a diameter of 4.18mm on the chip I am using. My chip is 1616 x 1216 pixels and the image is a ROI of 1200 x 1200 pixels.
2018-05-20_13-02-34_pp-1f_500.jpg
2018-05-20_13-02-34_pp-1f_500.jpg (917.98 KiB) Viewed 7516 times
Now as I do mosaics with the same setup but just with a 2x extender and so I have 900mm focal length then I would have vignetting in my images because when making the center image of the SUN this fills up the 1216 x 1216 ROI ...

Look here how I do assemble my mosaics
2017-02-10_14-19-10_pp-1f_944_500_mosaico.jpg
2017-02-10_14-19-10_pp-1f_944_500_mosaico.jpg (1.16 MiB) Viewed 7516 times


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Re: Replacing the Rusted BF30 Filter

Post by ronatu »

So there's no replacement for bf? Even substitute?


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Re: Replacing the Rusted BF30 Filter

Post by Merlin66 »

Ronatu,
It's very rare that the final sorting/blocking filter fails...usually the ITF goes first.
Do you have a "failed" BF?? If so can you upload an image of it.


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