ERF questions
ERF questions
Hi Guys,
I am going to organise a couple of large ERFs. I will buy Schott RG630 glass and will give it for polishing. It will have at least 1/4 lambda surface accuracy.
The questions are:
1. How important is to coat AR coatings, what hapens if I don't have it on ERF?
2. Is IR-cut coating needed if I will use 2" Baader UV/IR-cut filter in diagonal?
3. Will BelOptic UV/IR-cut be better than Baader in viewing and imaging? Oliver's filter has lower transmission ir h-alpha (75%) than Baader (over 90%). In the other hand IR is cut very far (to 5000nm)
I am going to organise a couple of large ERFs. I will buy Schott RG630 glass and will give it for polishing. It will have at least 1/4 lambda surface accuracy.
The questions are:
1. How important is to coat AR coatings, what hapens if I don't have it on ERF?
2. Is IR-cut coating needed if I will use 2" Baader UV/IR-cut filter in diagonal?
3. Will BelOptic UV/IR-cut be better than Baader in viewing and imaging? Oliver's filter has lower transmission ir h-alpha (75%) than Baader (over 90%). In the other hand IR is cut very far (to 5000nm)
- marktownley
- Librarian
- Posts: 42272
- Joined: Tue Oct 18, 2011 5:27 pm
- Location: Brierley Hills, UK
- Has thanked: 20440 times
- Been thanked: 10246 times
- Contact:
Re: ERF questions
Hi there.
Without an AR coating you will get reflections / ghosts. To answer questions 2 & 3 what aperture are you planning to work at here?
Without an AR coating you will get reflections / ghosts. To answer questions 2 & 3 what aperture are you planning to work at here?
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
- swisswalter
- Way More Fun to Share It!!
- Posts: 17948
- Joined: Thu Feb 06, 2014 4:28 am
- Location: Switzerland
- Been thanked: 1 time
- Contact:
Re: ERF questions
Hi Pawel
my dream is a 8" triband like filter
my dream is a 8" triband like filter
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
- pedro
- Way More Fun to Share It!!
- Posts: 12256
- Joined: Sun May 01, 2016 8:26 pm
- Location: Portugal
- Has thanked: 14 times
- Been thanked: 6577 times
- Contact:
Re: ERF questions
There is one for sale in UK B&S (85mm)
http://www.astrobuysell.com/uk/propview.php?view=80336
- Diameter 85mm (82mm free aperture)
- Thickness 8.25mm
- Schott N-BK7
- Triple bandpass coating (transmission in Ca, Continuum and Ha)
- Substrate precise polished
- New and unused without cell
- Made in Germany
http://www.astrobuysell.com/uk/propview.php?view=80336
- Diameter 85mm (82mm free aperture)
- Thickness 8.25mm
- Schott N-BK7
- Triple bandpass coating (transmission in Ca, Continuum and Ha)
- Substrate precise polished
- New and unused without cell
- Made in Germany
Pedro Re'
https://pedroreastrophotography.com/
https://pedroreastrophotography.com/
Re: ERF questions
Hello,
Mark, I plan to buy 165x165mm glass and cut it to maximal diameter - probably 150-160mm. ERF will work with 100-150mm refractors.
Walter, no chance at this time, sorry...
Thanks Pedro, but I am buying more than 5pcs of glass to make ERFs for me and my friends. If anybody wants to join me with the project, please let me know
Mark, I plan to buy 165x165mm glass and cut it to maximal diameter - probably 150-160mm. ERF will work with 100-150mm refractors.
Walter, no chance at this time, sorry...
Thanks Pedro, but I am buying more than 5pcs of glass to make ERFs for me and my friends. If anybody wants to join me with the project, please let me know
- swisswalter
- Way More Fun to Share It!!
- Posts: 17948
- Joined: Thu Feb 06, 2014 4:28 am
- Location: Switzerland
- Been thanked: 1 time
- Contact:
Re: ERF questions
Hi Pedro
thank you very much. I have an 85 mm, I wish a 200 mm
thank you very much. I have an 85 mm, I wish a 200 mm
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
- Valery
- Way More Fun to Share It!!
- Posts: 4059
- Joined: Sun Nov 18, 2012 3:13 pm
- Has thanked: 156 times
- Been thanked: 893 times
Re: ERF questions
Walter, what is the telescope you will use such 200mm filter with?swisswalter wrote:Hi Pedro
thank you very much. I have an 85 mm, I wish a 200 mm
We can make such filters, but better to have 5 or more persons who want one.
Valery.
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
- swisswalter
- Way More Fun to Share It!!
- Posts: 17948
- Joined: Thu Feb 06, 2014 4:28 am
- Location: Switzerland
- Been thanked: 1 time
- Contact:
Re: ERF questions
Hi Valery
the filter should work with my TMB203/1800
the filter should work with my TMB203/1800
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
- marktownley
- Librarian
- Posts: 42272
- Joined: Tue Oct 18, 2011 5:27 pm
- Location: Brierley Hills, UK
- Has thanked: 20440 times
- Been thanked: 10246 times
- Contact:
Re: ERF questions
Regards question 2&3 I guess you just got to try it an see!
The Beloptik UV/IR cut is on a KG3 substrate so this will offer IR protection to OD2.5 all the way up to 2500nm, I think this is the one I would go for. However KG3 blocks by absorption and my only concern is a 6" lens, even with RG630 infront may pass too much IR and may thermally overload the KG3 causing it to crack / shatter - but like I said before, this is just a 'maybe' - all uncharted territory!
The Beloptik UV/IR cut is on a KG3 substrate so this will offer IR protection to OD2.5 all the way up to 2500nm, I think this is the one I would go for. However KG3 blocks by absorption and my only concern is a 6" lens, even with RG630 infront may pass too much IR and may thermally overload the KG3 causing it to crack / shatter - but like I said before, this is just a 'maybe' - all uncharted territory!
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
- Valery
- Way More Fun to Share It!!
- Posts: 4059
- Joined: Sun Nov 18, 2012 3:13 pm
- Has thanked: 156 times
- Been thanked: 893 times
Re: ERF questions
Heh heh! When have you bought such a beast?swisswalter wrote:Hi Valery
the filter should work with my TMB203/1800
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
Re: ERF questions
Mark, looking at Lunt LS152 and internal ERF size (ca.50-70mm) it should be ok if placed as near to the objective as possible to make more effective aperture work/absorb.
What do you think?
What do you think?
- swisswalter
- Way More Fun to Share It!!
- Posts: 17948
- Joined: Thu Feb 06, 2014 4:28 am
- Location: Switzerland
- Been thanked: 1 time
- Contact:
Re: ERF questions
Hi ValeryValery wrote:Heh heh! When have you bought such a beast?swisswalter wrote:Hi Valery
the filter should work with my TMB203/1800
a long time ago. It is very seldom used
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
- Valery
- Way More Fun to Share It!!
- Posts: 4059
- Joined: Sun Nov 18, 2012 3:13 pm
- Has thanked: 156 times
- Been thanked: 893 times
Re: ERF questions
Internal filters must be properly installed. Mark know well this problem with his CaK complicated rig.Pablito wrote:Mark, looking at Lunt LS152 and internal ERF size (ca.50-70mm) it should be ok if placed as near to the objective as possible to make more effective aperture work/absorb.
What do you think?
Shortly, an internal flat glass filter should have some inclination to escape the reflections. However each such inclination will introduce an astigmatism in the final image.
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
- Valery
- Way More Fun to Share It!!
- Posts: 4059
- Joined: Sun Nov 18, 2012 3:13 pm
- Has thanked: 156 times
- Been thanked: 893 times
Re: ERF questions
How this is possible? To have such a great refractor and keep it in it's box???? I can't understand this.swisswalter wrote: It is very seldom used
I can only imagine a high resolution photos you can make with such a telescope, especially in CaK!!!
Walter, give it a full use!
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
- swisswalter
- Way More Fun to Share It!!
- Posts: 17948
- Joined: Thu Feb 06, 2014 4:28 am
- Location: Switzerland
- Been thanked: 1 time
- Contact:
Re: ERF questions
Valery wrote:How this is possible? To have such a great refractor and keep it in it's box???? I can't understand this.swisswalter wrote: It is very seldom used
I can only imagine a high resolution photos you can make with such a telescope, especially in CaK!!!
Walter, give it a full use!
Hi Valery
time, sunshine and a good seeing are required. Not very often all 3 fall together
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
- Valery
- Way More Fun to Share It!!
- Posts: 4059
- Joined: Sun Nov 18, 2012 3:13 pm
- Has thanked: 156 times
- Been thanked: 893 times
Re: ERF questions
Hi Walter,swisswalter wrote:Valery wrote:How this is possible? To have such a great refractor and keep it in it's box???? I can't understand this.swisswalter wrote: It is very seldom used
I can only imagine a high resolution photos you can make with such a telescope, especially in CaK!!!
Walter, give it a full use!
Hi Valery
time, sunshine and a good seeing are required. Not very often all 3 fall together
In the case of permanent installation (dome, roof-off) you will have enough time, sunshine and starry sky at nights. This is a key - the possibility to use the instrument any time you wish/can.
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
Re: ERF questions
Hi Valery,
As far as I remember, you use LS50 in your 150mm system without additional ERF, right? If so, 2" IR on KG3 used in conjuction with front RG630, should be enough.
Can you please comment?
As far as I remember, you use LS50 in your 150mm system without additional ERF, right? If so, 2" IR on KG3 used in conjuction with front RG630, should be enough.
Can you please comment?
- Valery
- Way More Fun to Share It!!
- Posts: 4059
- Joined: Sun Nov 18, 2012 3:13 pm
- Has thanked: 156 times
- Been thanked: 893 times
Re: ERF questions
The ERF in my system is on the first lens component. First (front) surface is visible spectrum filter (allows CaK and Ha) and the back surface is IR cut filter. No front mounted ERF as I said.Pablito wrote:Hi Valery,
As far as I remember, you use LS50 in your 150mm system without additional ERF, right? If so, 2" IR on KG3 used in conjuction with front RG630, should be enough.
Can you please comment?
Valery.
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.