BF30

rsfoto · Post by **rsfoto** » Tue Jul 17, 2012 7:50 pm

Hi,

I just got a new BF30 as the 2nd old one is also starting to rust on the outer edges. This has happened already for the 2nd time

This means that I already had 2 rusted BF30.

When I replaced the first rusted one I just got a BF30 and this time I got a BF30 + a diagonal ¿?

Anybody knows why they ship out the BF30 with an additional diagonal ? This diagonal has an ERF in the barrel into which one sticks in the eyepiece.

Thanks

markmanner · Post by **markmanner** » Sat Aug 25, 2012 10:40 pm

Hi Rainer, did you get an answer to this question? Do you have to use the diagonal?

rsfoto · Post by **rsfoto** » Sat Aug 25, 2012 11:47 pm

Hi Rainer, did you get an answer to this question? Do you have to use the diagonal?

Hi Mark,

No answer. That red thing is not more then a ERF and apart from that if I use it also it takes even more light away and the result is absolutely the same.

The thing that bothers me is the fact that the new BF 30 needs 3x more exposure time then the Old one I have.

brianb11213 · Post by **brianb11213** » Sun Aug 26, 2012 4:33 am

Well I do not have any Coronado h-alpha kit but ...

That red thing is not more then a ERF and apart from that if I use it also it takes even more light away and the result is absolutely the same.
I definitely wouldn't want to use a h-alpha filter set without a ERF somewhere in the system. In the Solarscope system it's a Baader-type full aperture deep red filter positioned in front of the etalon package which attaches to the front of the scope.

The thing that bothers me is the fact that the new BF 30 needs 3x more exposure time then the Old one I have.
In my experience, the less light a h-alpha filter set passes, the smaller the bandpass is ... which is definitely a Good Thing. My SF-100 passes about half the light of my SV-60, working at the same f-ratio & when both are optimally tuned, and it definitely has a narrower bandpass.

rsfoto · Post by **rsfoto** » Sun Aug 26, 2012 3:50 pm

Hi Brian,

Thanks for your comments. Will make another comparison test at the next opportunity.

I already have an ERF at the first optical element in the setup eg. The 60mm ERF at the forefront SM60, ¿ So why should I have another ERF after the blocking filter ? but OK, they must have had a reason to deliver it with the BF 30.

Will make a comparison of that 30mm ERF with a 60mm ERF which I took off from a SM60 to find out the differences.

Look at this thread I made already about New and Old.

http://solarchat.solarastronomy.org/ind ... s-new-bf30

Here is anothjer interesting thread I made about Old and New.

http://solarchat.solarastronomy.org/ind ... ectroscope

Thanks again

markmanner · Post by **markmanner** » Mon Aug 27, 2012 5:14 pm

Rainer, and others, I just spoke to OPT about the 1.25" diagonal that now comes with the BF30. They say with some certitude that the red filter in the 1.25" diagonal is for contrast, and isn't part of the blocking filter or energy rejection system of the blocking filter. It is part of the package now as a convenience, primarily because some (presumably inexperienced) users of the BF30 2" blocking filter couldn't get to focus visually, and by using the included 1.25" diagonal it eliminated the problem.

rsfoto · Post by **rsfoto** » Mon Aug 27, 2012 7:06 pm

Rainer, and others, I just spoke to OPT about the 1.25" diagonal that now comes with the BF30. They say with some certitude that the red filter in the 1.25" diagonal is for contrast, and isn't part of the blocking filter or energy rejection system of the blocking filter. It is part of the package now as a convenience, primarily because some (presumably inexperienced) users of the BF30 2" blocking filter couldn't get to focus visually, and by using the included 1.25" diagonal it eliminated the problem.

Hi Mark,

Thanks a lot for your effort in clearing this up

Post by **Merlin66** » Sat Sep 01, 2012 10:43 pm

Rainer,
I obviously misunderstood your original post.
I thought the deteriorated filter you showed was the front "mini-ERF" element (I've see a few "mini-ERF" in the PST's fail exactly the same way..) and that the actual narrowband blocking filter was a second element closer to the eyepiece/ camera.
Can you confirm that the BF30 assembly supplied actually only has one optical element??

Post by **Merlin66** » Sat Sep 01, 2012 10:48 pm

Rainer,
I was also thinking that Coronado/Lunt don't really know which solar scope their BF assembly will be used on....
If, say, the up front ERF is just a Wratten/ red filter, the added "mini-ERF" element would also gives UV-IR blocking for additional safety and energy rejection??

rsfoto · Post by **rsfoto** » Sun Sep 02, 2012 3:56 pm

Rainer,
I obviously misunderstood your original post.
I thought the deteriorated filter you showed was the front "mini-ERF" element (I've see a few "mini-ERF" in the PST's fail exactly the same way..) and that the actual narrowband blocking filter was a second element closer to the eyepiece/ camera.
Can you confirm that the BF30 assembly supplied actually only has one optical element??

Hi Ken,

The BF30 has NO optical element. It consists of 2 whatever filters which are in there and in a tilted position.

rsfoto · Post by **rsfoto** » Sun Sep 02, 2012 3:58 pm

Rainer,
I was also thinking that Coronado/Lunt don't really know which solar scope their BF assembly will be used on....
If, say, the up front ERF is just a Wratten/ red filter, the added "mini-ERF" element would also gives UV-IR blocking for additional safety and energy rejection??

Hi Ken,

Acoording to a research Mark Manner did the red filter delivered nowadays is not more then a normal red filter in order to enhance contrast.

The 3 old BF30 I had never came with a diagonal and a red filter.

markmanner · Post by **markmanner** » Sun Sep 02, 2012 4:31 pm

As Rainer said, the diagnoal that comes with the new BF30 has a red colored filter in the 1.25" eyepiece tube. I looked at the sun yesterday afternoon through the diagonal(no telescope, just holding it up and glancing), and the sun was as bright through the diagonal as it was just glancing up at it, although through the diagonal it was red. I also looked through the BF30 and a BF15 at the sun (again no telescope), and they appeared to be about the same brightness. The BF30 view was bluish, the BF15 was reddish, however. In conclusion, OPT said the BF30 diagnoal isn't needed, and my admittedly non-rigorous tests seem to indicate it doesn't attenuate the sunlight at all. It was like using an inexpensive red filter.
I don't know why Coronado thought it necessary to put the red filter in the diagonal, however.

Post by **Merlin66** » Sun Sep 02, 2012 10:58 pm

Sorry guys, I'm still confused.....
1. There's a "red" filter at the front of the BF assembly?
2. There's a final blocking filter at the rear? (closest to the eyepiece/camera)
Which filter shows the deterioration? Front or back filter?
(In the smaller Coronado BF diagonals, the front filter is the "mini-erf" and is the one which seems to fail. The rear blocking filter seems to be OK.)

rsfoto · Post by **rsfoto** » Sun Sep 02, 2012 11:18 pm

Sorry guys, I'm still confused.....
1. There's a "red" filter at the front of the BF assembly?
2. There's a final blocking filter at the rear? (closest to the eyepiece/camera)
Which filter shows the deterioration? Front or back filter?
(In the smaller Coronado BF diagonals, the front filter is the "mini-erf" and is the one which seems to fail. The rear blocking filter seems to be OK.)

Hi Ken,

No problem. My setup is as following

ERF > Etalon > Etalon > Telescope > BF30 > CCD camera ...

There is no such thing as a golden Surface somewhere in this setup and this is how I started maybe 8 years ago with my original Coronado setup.

The last BF 30 came in the same way as the first BF 30 but with the difference that it incorporates now a small diagonal with a red filter with 30mm in diameter and the diagonal should be used after the blocking filter BF30.

Clear now ?

Post by **Merlin66** » Sun Sep 02, 2012 11:38 pm

Rainer,
Hmmm - Getting there.....
So, the BF30 filter is a single filter element (no "built-it" extra filters?)and it's this single filter which you show deteriorated?
The latest "offering" included a supplimentary diagonal (for use between the BF and the eyepiece) which also holds a "red" filter?
If I've finally got it right, then:
- I'm surprised to hear of a BF filter failing
- The "added" red filter, if the BF is doing it's job properly, should not make any improvement to the system.
(It would be intersting to see your LISA results for
a. The BF on it's own
b. The "red" filter on it's own)

markmanner · Post by **markmanner** » Mon Sep 03, 2012 12:08 am

Hi, here are pics of a BF15 and the new BF30, inside and out, and finally the 1.25" diagonal with the red filter in the eyepiece drawtube. Note the surface on the BF30 and BF15 that faces the objective looks the same. The 1.25" diagonal that comes with the BF30 just looks like a cheap diagonal with a red filter in the eyepiece tube. It doesn't look like an ERF, and as the last item in the imaging train, if you used it, seems to be in the wrong spot anyway.

Post by **Merlin66** » Mon Sep 03, 2012 12:28 am

Mark,
Thanks for that!
Just one last thing...can you confirm the first and second images of the BF30 show the front and rear surfaces of the same filter element? ie there's only the one filter involved...
The reason for the question is that the front surface (on both the BF30 and the front "mini-erf" built into the BF15 diagonal), as you say, look very similar.
This would infer that at least the front surface of the BF30 HAS a ITF coating which will act as a UV-IR/ERF.....
The images of the eyepiece end concerns me...the typical BF filters I've seen on ALL the Coronado BF filters (BF5/BF10/BF15) looks like the red image in the last shot.
(this should be the case if it's only passing 6A or so centred on the Ha wavelength)
The "output" surface of the BF30 (image #2) doesn't show this narrowband pass width, and still looks like a reflective ERF??????????
Very strange!

markmanner · Post by **markmanner** » Mon Sep 03, 2012 5:06 am

Mark,
...can you confirm the first and second images of the BF30 show the front and rear surfaces of the same filter element? ie there's only the one filter involved...!

Yes, that pic is the same BF30, front and back.

The images of the eyepiece end concerns me...the typical BF filters I've seen on ALL the Coronado BF filters (BF5/BF10/BF15) looks like the red image in the last shot.
(this should be the case if it's only passing 6A or so centred on the Ha wavelength)
The "output" surface of the BF30 (image #2) doesn't show this narrowband pass width, and still looks like a reflective ERF??????????
Very strange!

It is odd. I don't know why the red filter is in the 1.25" diagonal. As I said above, OPT says it isn't functional (the red filter), and it doesn't seem to attentuate the sun in any fashion based on my crude test. I will call Meade Tuesday and ask them as well, however, and report. I will also do some imaging tests with a BF15 and the BF30 (with and without the diagonal), and see what I find.

Post by **Merlin66** » Mon Sep 03, 2012 5:16 am

Mark.....
Looking again at the BF30 photos...there seems to be two elements...one at the front of the chrome tube (image #1) and on at the base of the eyepiece holder (image#2)
There are retaining rings shown on both images - if this was a single piece filter construction then there would be only one retaining ring to clamp the filter to a shoulder????
What do you think??

markmanner · Post by **markmanner** » Mon Sep 03, 2012 5:23 am

Mark.....
Looking again at the BF30 photos...there seems to be two elements...one at the front of the chrome tube (image #1) and on at the base of the eyepiece holder (image#2)
There are retaining rings shown on both images - if this was a single piece filter construction then there would be only one retaining ring to clamp the filter to a shoulder????
What do you think??

That makes sense to me. There are definitely two retaining rings, one on each side of the elements that are in the BF30.

Post by **Merlin66** » Mon Sep 03, 2012 5:28 am

Mark,
That makes a bit more sense now....
The first "element" I wager is a "mini-ERF" and the rear "element" SHOULD be a narrowband (around 6A) blocking filter!!
Rainer: Which element on your BF30 failed? the front or rear???

markmanner · Post by **markmanner** » Mon Sep 03, 2012 4:31 pm

Mark,
That makes a bit more sense now....
The first "element" I wager is a "mini-ERF" and the rear "element" SHOULD be a narrowband (around 6A) blocking filter!!
Rainer: Which element on your BF30 failed? the front or rear???

I looked a bit more, and there are definitely 2 elements in the BF30 main body. They are separated by about 2 cm. It is hard to photograph, but looking in from the eyepiece end of the BF30 you can see there are two elements. See pic below for location.

rsfoto · Post by **rsfoto** » Mon Sep 03, 2012 7:28 pm

Rainer: Which element on your BF30 failed? the front or rear???

Front ... the one facing the Sun ...

Post by **Merlin66** » Mon Sep 03, 2012 9:42 pm

OK, we got there!
The front element that failed was the "mini-ERF" filter.
The rear element, the actual blocking filter I assume is/ was OK.
I'm still surprised to see the blue reflections from that rear filter. Has anyone seen similar (on a blocking filter)??

markthais · Post by **markthais** » Tue Sep 04, 2012 2:34 am

The BF30 looks red when you look through it right?
The back side looks like a heat mirror or and multi coated AR.
There must be at least one piece of red glass inside. The red glass that's on the eyepiece side is there so that you won't be looking at your eye reflecting from the mirror of the blocker.
The front looks like the ITF.
Now if they use a blocker that has all the coating on one surface, then the front would be silver. The back would be red and it would only be one piece.
Mark W.

markmanner · Post by **markmanner** » Tue Sep 04, 2012 4:29 am

The BF30 looks red when you look through it right?
The back side looks like a heat mirror or and multi coated AR.
There must be at least one piece of red glass inside. The red glass that's on the eyepiece side is there so that you won't be looking at your eye reflecting from the mirror of the blocker.
The front looks like the ITF.
Now if they use a blocker that has all the coating on one surface, then the front would be silver. The back would be red and it would only be one piece.
Mark W.

Hi Mark, the 2" BF30 when pointed at the Sun, no scope in the way(and with the 1.25" diagonal removed), the sun looks bluish. However, when the BF30 is put in the scope, with the Coronado front ERF/Etalon on the scope, the image looks red.

Post by **Merlin66** » Tue Sep 04, 2012 6:58 am

Mark,
The really sounds very odd.
The function of the blocking filter is to "block" the etalon "spikes".
To do that effectively, it must be a very narrow band filter (around 6-7A max)centred on Ha wavelength. This results in seeing a red image through the filter.
All my blocking filters show a red image of the sun.
Does it actually work??
Rainer...do you agree??

astroflyer · Post by **astroflyer** » Tue Sep 04, 2012 1:23 pm

I'm still surprised to see the blue reflections from that rear filter. Has anyone seen similar (on a blocking filter)??
I checked my BF10 & BF15 - both have blue front reflection & red rear filter.

All my blocking filters show a red image of the sun.

Same here.

markmanner · Post by **markmanner** » Tue Sep 04, 2012 1:36 pm

Mark,
The really sounds very odd.
The function of the blocking filter is to "block" the etalon "spikes".
To do that effectively, it must be a very narrow band filter (around 6-7A max)centred on Ha wavelength. This results in seeing a red image through the filter.
All my blocking filters show a red image of the sun.
Does it actually work??
Rainer...do you agree??

If the weather ever improves, I will test it to confirm it works (without the 1.25" diagonal). As usual, I received the BF30 last Thursday, just in time for the last 4 days of cloud cover from the hurricane. Maybe this afternoon I can give it a proper test. I had about 30 sec of Sun last Friday, and got the scope setup, and saw red in the eyepiece for a few seconds. However, I saw no detail in the brief glimpse I had. Rainer, I assume your new BF30 also looks bluish on the eyepiece side, without the diagonal?

brianb11213 · Post by **brianb11213** » Tue Sep 04, 2012 2:20 pm

Mark,
The really sounds very odd.
The function of the blocking filter is to "block" the etalon "spikes".
To do that effectively, it must be a very narrow band filter (around 6-7A max)centred on Ha wavelength. This results in seeing a red image through the filter.
All my blocking filters show a red image of the sun.
Does it actually work??
Rainer...do you agree??
The blocking filter that came with my Solarscope SF-100:

(a) looks like blue/green glass when viewed from the objective side

(b) has a peach coloured reflective coating on the eyepiece side

(c) obviously consists of multiple elements which are tilted, presumably to move reflections out of the field of view

(d) has a total thickness from the front of the first element to the rear of the last element of around one inch

(e) acts as a pale blue filter if looked through on its own. Transmission is quite high, my CdS photo exposure meter says 2.3 stops = approx. 20% over the visual band.

I presume what it is doing is acting as a minus red filter with a transmission spike to accommodate the wanted spike transmitted by the main etalon.

It does not need to block way-out-of-band transmissions because that job is done by the deep red full aperture ERF which is mounted at the very front of the etalon assembly.

I suspect the Coronado BF30 is built pretty much the same way ... though mine was supplied without a diagonal, it looks like a short 2" extension tube. Oh, and there's no sign of rust on mine.

With the etalon hung on the front of the scope but no BF fitted, if you point the scope at the sun and stick my hand in the beam I see a BRIGHT red spot of light which is not noticeably warm to feel. With the BF fitted, the prime focus image of the sun can no longer be seen by scatterring off skin ... so it is obviously removing quite a lot of the radiation transmitted by the etalon assembly. It does seem a little odd that it transmits such a lot of light when averaged over visual wavelengths but it does work.

rsfoto · Post by **rsfoto** » Tue Sep 04, 2012 4:20 pm

Mark,
The really sounds very odd.
The function of the blocking filter is to "block" the etalon "spikes".
To do that effectively, it must be a very narrow band filter (around 6-7A max)centred on Ha wavelength. This results in seeing a red image through the filter.
All my blocking filters show a red image of the sun.
Does it actually work??
Rainer...do you agree??

Hi,

Well this got confusing now :woohoo:

My Old BF30 shows the Sun red when looking through ( NO additional diagonal anywhere)

My New BF30 shows the Sun bluish when looking through (NO additional diagonal anywhere)

Look at this posting the first 2 images http://solarchat.solarastronomy.org/ind ... s-new-bf30

By the way. At the very beginning I got a BF30 in which the 2 elements were loose and I remember when looking at them there was absolutely no red filter anywhere in there and also none of the 2 bluish filters had a mirrorlike coating anywhere.

rsfoto · Post by **rsfoto** » Tue Sep 04, 2012 4:21 pm

[quote]Mark,
The really sounds very odd.
The function of the blocking filter is to "block" the etalon "spikes".
To do that effectively, it must be a very narrow band filter (around 6-7A max)centred on Ha wavelength. This results in seeing a red image through the filter.
All my blocking filters show a red image of the sun.
Does it actually work??
Rainer...do you agree??

If the weather ever improves, I will test it to confirm it works (without the 1.25" diagonal). As usual, I received the BF30 last Thursday, just in time for the last 4 days of cloud cover from the hurricane. Maybe this afternoon I can give it a proper test. I had about 30 sec of Sun last Friday, and got the scope setup, and saw red in the eyepiece for a few seconds. However, I saw no detail in the brief glimpse I had. Rainer, I assume your new BF30 also looks bluish on the eyepiece side, without the diagonal?

Hi Mark,

Yes, both surfaces have a bluish tint.

markmanner · Post by **markmanner** » Tue Sep 04, 2012 6:22 pm

I just spoke with Meade customer service. The person there said the following:
1. The 1.25" diagonal with the new BF30 is NOT needed for operation. It is included as a convenience. The red filter in it is for contrast, and isn't part of the blocking filter.
2. The coatings on the blocking filter in the 2" BF30 unit itself have been changed, and that is why they look different than the old BF30 blocking filter.

I told the Meade person that the reason this has come up is that the casual view through the BF30 only is no longer reddish, like the old BF30s. He said he understood this, and the coating change explains it. I pressed him very hard on this issue, and on the need or not for the 1.25" diagonal. He was firm and without doubt in his statement that there is no need to use the 1.25" diagonal, unless you prefer the use of a 90degree diagonal rather than straight through.
I will test my unit hopefully this afternoon, sun willing.
Mark

markmanner · Post by **markmanner** » Tue Sep 04, 2012 7:25 pm

[quote]Mark,
.....The blocking filter that came with my Solarscope SF-100:

(a) looks like blue/green glass when viewed from the objective side

(b) has a peach coloured reflective coating on the eyepiece side

(c) obviously consists of multiple elements which are tilted, presumably to move reflections out of the field of view

(d) has a total thickness from the front of the first element to the rear of the last element of around one inch

(e) acts as a pale blue filter if looked through on its own. Transmission is quite high, my CdS photo exposure meter says 2.3 stops = approx. 20% over the visual band.]

Brian, this is a good description of the BF30--pale blue filter looked through on its own, with pretty high transmission. It seems that Coronado's BF30 is now being made similarly to the Solarscope blocking filter. I had my friend at Vanderbilt pull their Solarscope blocking filter out, and look through it alone, and he reports it looks pale blue as well. So, apparently the BF30 coatings/assembly is different from the BF15/10/5 units that are out there (and the older BF30s).

rsfoto · Post by **rsfoto** » Tue Sep 04, 2012 7:50 pm

I just spoke with Meade customer service. The person there said the following:
1. The 1.25" diagonal with the new BF30 is NOT needed for operation. It is included as a convenience. The red filter in it is for contrast, and isn't part of the blocking filter.
2. The coatings on the blocking filter in the 2" BF30 unit itself have been changed, and that is why they look different than the old BF30 blocking filter.

I told the Meade person that the reason this has come up is that the casual view through the BF30 only is no longer reddish, like the old BF30s. He said he understood this, and the coating change explains it. I pressed him very hard on this issue, and on the need or not for the 1.25" diagonal. He was firm and without doubt in his statement that there is no need to use the 1.25" diagonal, unless you prefer the use of a 90degree diagonal rather than straight through.
I will test my unit hopefully this afternoon, sun willing.
Mark

Hi Mark,

Thanks for your efforts in talking to the MEADE people.

You forgot to ask :whistle: why does the New BF30 need 4x more exposure times then the old one :silly: and more then 5x when adding the red filter of the diagonal ...

Look at my posting http://solarchat.solarastronomy.org/ind ... s-new-bf30

where I depicted some images as well as copies of the Log file produced by Lucam Recorder software.

markmanner · Post by **markmanner** » Tue Sep 04, 2012 9:05 pm

Mark

Hi Mark,

Thanks for your efforts in talking to the MEADE people.

You forgot to ask :whistle: why does the New BF30 need 4x more exposure times then the old one :silly: and more then 5x when adding the red filter of the diagonal ...
.

Yes, I did! I suspect the answer is the changed coatings they are using. It definitely now seems to be similar to the Solarscope blocking filters, based on Brian's and my friend at Vanderbilt U. today.

colinsk · Post by **colinsk** » Wed Sep 05, 2012 1:07 am

He said he understood this, and the coating change explains it. I pressed him very hard on this issue, and on the need or not for the 1.25" diagonal. He was firm and without doubt in his statement that there is no need to use the 1.25" diagonal, unless you prefer the use of a 90degree diagonal rather than straight through.

Mark

Mark,

Can you supply your contacts name? I have not been able to find a person at Meade knowledgeable about H-Alpha systems. The last time I tried I was given the email address of an ex-employee that likely could have answered my questions. Not surprisingly he never replied.

markmanner · Post by **markmanner** » Wed Sep 05, 2012 1:51 am

Mark,
..........
Does it actually work??
.............??

Regarding Merlin's question, at the end of the day I got a bit of sun. Seeing was bad, but I got a couple of images through the BF30. It definitely works, see pics below:

markmanner · Post by **markmanner** » Wed Sep 05, 2012 1:55 am

[quote]He said he understood this, and the coating change explains it. I pressed him very hard on this issue, and on the need or not for the 1.25" diagonal. He was firm and without doubt in his statement that there is no need to use the 1.25" diagonal, unless you prefer the use of a 90degree diagonal rather than straight through.

Mark

Mark,

Can you supply your contacts name? I have not been able to find a person at Meade knowledgeable about H-Alpha systems. The last time I tried I was given the email address of an ex-employee that likely could have answered my questions. Not surprisingly he never replied.

Colin, I asked for someone who knew about Ha filters. He did give me his name, but for some reason I neglected to write it down, and I had to go into a meeting right after the call, and by the time I got out, I had forgotten it. Sorry!

Post by **Merlin66** » Wed Sep 05, 2012 2:04 am

OK, it seems to work!
Does this mean a shift in technology? Will all the future BF's (Lunt and Coronado) be based on a similar ITF design?
Interesting days..

Rainer, I'd love to see the transmission spectrum of a BF15 v's the new BF30...

rsfoto · Post by **rsfoto** » Wed Sep 05, 2012 2:05 pm

Mark

Hi Mark,

Thanks for your efforts in talking to the MEADE people.

You forgot to ask :whistle: why does the New BF30 need 4x more exposure times then the old one :silly: and more then 5x when adding the red filter of the diagonal ...
.

Yes, I did! I suspect the answer is the changed coatings they are using. It definitely now seems to be similar to the Solarscope blocking filters, based on Brian's and my friend at Vanderbilt U. today.

Hi Mark,

Thanks. Well that is bad as 4x more exposure time is really unacceptable ...

rsfoto · Post by **rsfoto** » Wed Sep 05, 2012 2:09 pm

OK, it seems to work!
Does this mean a shift in technology? Will all the future BF's (Lunt and Coronado) be based on a similar ITF design?
Interesting days..

Rainer, I'd love to see the transmission spectrum of a BF15 v's the new BF30...

Hi Ken,

As I already wrote before that is bad as 4x longer exposure time is quite unacceptable ...

My tests already showed that the results are the same comparing the Old BF30 with the New BF30 without the red filter and as written the red filter even makes the exposure longer by about 3-4ms additionally.

http://solarchat.solarastronomy.org/ind ... s-new-bf30

I have no BF15 and I am waiting to get back the BF10 I bought for tests in July :whistle:

markmanner · Post by **markmanner** » Wed Sep 05, 2012 2:11 pm

Rainer, I am sorry, my reply was confusing. I meant that I did forget to ask about exposure time. However, I don't think that I see a 4x difference in exposure time between my BF15 and the BF30. I will test it and confirm it one way or the other.

rsfoto · Post by **rsfoto** » Wed Sep 05, 2012 2:30 pm

Rainer, I am sorry, my reply was confusing. I meant that I did forget to ask about exposure time. However, I don't think that I see a 4x difference in exposure time between my BF15 and the BF30. I will test it and confirm it one way or the other.

Hi Mark,

I am not saying that there is a difference of exposure time between a BF15 and a BF30.

I am saying that there IS a 4x exposure time difference between an Old BF30 and a New BF30 (NO red filter added). The New BF30 with red filter added is even worse :blink: 16ms comparded to 12.7ms. Now imagine what that means when I add a 4x barlow and use the New BF30 ... Just unacceptable exposure times.

I have used the Old BF30 with 4x barlow and get exposure times of around 55 to 70ms (still 12frames per second). Now that would mean that with the New BF30 I get exposure times of 220 to 280ms and so ridiculous 3-4 frames per second which for Sun imaging is just unacceptable at all.

Look at the posted message link :woohoo: