Quark - Baader UV/IR Cut-Filter VS Baader H-alpha 35nm CCD Filter

[DRT]

10 minutes ago, Toxophilus said:

I can see where you are coming from as there is not a 100% clear statement of requirement and it is open to interpretation for simple air spaced type refractors. Perhaps some clarification from Daystar is required on this by asking them directly. However I think the advice at the bottom of the article sums up the best approach:

"In general, if a telescope owner is uncertain or uncomfortable with the application of UV/IR cut filters on the rear of the telescope, then it is best to revert to the standard DayStar Colored glass front mount Energy Rejection pre-filter."

Personally, if I was ro run a 80+mm scope with a quark I would use a front mounted ERF as I would rather not take the chance, but as I'm using an ST80 and ED80 I use an internal IR/UV cut filter.

I understand where you are coming from. My choice to use the UV/IR Cut filter is based on two things: (1) the generally accepted view seems to be that energy rejection is required to protect the Quark (not my eyesight) and (2) given that the risk associated with the UV/IR Cut filter relates to potential damage to the OTA I am happy not to spend twice the price of the OTA on a front-mounted 150mm ERF.

As I said at the beginning of all of this, I have been using this set-up for some time and have never noticed any problem with heat in either the OTA or the diagonal. I'm happy with the set-up and I get great views so my intention is to stick with what works.

[spaceboy]

@DRT in my mind the fact Daystar had a configuration wizard http://www.daystarfilters.com/Wizard/ would strongly suggest to me there is an upper limit to the use of a 2" UV/IR filter before an ERF is required. If you do contact them it would be interesting to get some clarification on this.

[spaceboy]

4 minutes ago, DRT said:

I understand where you are coming from. My choice to use the UV/IR Cut filter is based on two things: (1) the generally accepted view seems to be that energy rejection is required to protect the Quark (not my eyesight) and (2) given that the risk associated with the UV/IR Cut filter relates to potential damage to the OTA I am happy not to spend twice the price of the OTA on a front-mounted 150mm ERF.

As I said at the beginning of all of this, I have been using this set-up for some time and have never noticed any problem with heat in either the OTA or the diagonal. I'm happy with the set-up and I get great views so my intention is to stick with what works.

Did you not recently have issues with your quark? Maybe this is a result of your erf combination ??

 

As you say thought if your happy.

[DRT]

14 minutes ago, spaceboy said:

Did you not recently have issues with your quark? Maybe this is a result of your erf combination ??

 

As you say thought if your happy.

I did, and it has been replaced, but the problem was with the exit window just before the eyepiece and Daystar declared it to be "a known issue" rather than damage from mis-use. I suppose I'll know if the new one develops the same problem but I suspect if Daystar thought that was the issue they would not have replaced it.

I think the key to this is the diagonal, which never gets even remotely warm and suggests to me that harmful UV and IR rays are not getting past the filter. If it isn't reaching the diagonal, it can't reach the Quark.

Edited August 16, 2017 by DRT

[jetstream]

1 hour ago, spaceboy said:

I don't always think "people can do what ever they want" is the best advice!

Some make choices and hopefully they are informed ones....

A few have tried the reflective filters but the con to this is the reflected light- I wouldn't want to inadvertently look at a D-ERF while its tracking the sun.

BTW there are more choices for the full  aperture ERF and not all are reflective I believe.

[ngwillym]

I went through this loop a few months ago - having cracked a filter in front of my Quark - I suspected that the UV/IR filter was 'dodgy' - of dubious quality from a well known auction site - caveat emptor.

 

However, I contacted Daystar directly - in April this year-  after seeing a couple of threads on CloudyNights:-

My question to them was:-

I was just checking with you for confirmation that it is possible to use a Quark Chromosphere on a 127mm f7.5air spaced Apochromatic refractor with just a 2" UV/IR cut filter - i.e. without the need for any other type energy rejection filter -  as per the  discussion on CloudyNights forum - https://www.cloudynights.com/topic/527861-good-news-from-daystar-about-using-quark-ep-with-uvir/

Their response:-

Yes, the UV/IR cut filter is a sufficient energy rejection blocking filter with your 127mm Refractor

 

and to be doubly sure I contacted Rupert @Astrograph - who supplied my Quark - and asked about the 35nm Halpha filter - here's his reponse:-

The UV/IR cut is often recommended as a simple ERF for systems. We have found however that there is quite a variation between brands. We have had most success with the Astronomik UV/IR and also Daystars own (I am not sure who makes that). Although it does not have the ‘hole’ in the Calcium H/K area as the other two have, the Baader UV/IR resulted in a burnt filter that was placed between it and a Quark (this is what happened to me), so we do not recommend that. In experiments we found that a 2” UV/IR was effective up to 100mm aperture but even with this you could feel heat in the beam that passed through it. While the Quark has a blocking filter in its nose which should kill any residual energy, We elected not to recommend use of a UV/IR above 100mm.

 

The Baader 35nm Ha filter has proven very effective as an ERF. I have used it successfully with scopes up to 152mm. The beam behind it is cool, even on a 152. For your 127 I would definitely recommend it.

 

For best results with an internal ERF, you should place it as far forward as possible. This is so it encounters the light beam when it is least concentrated. The filter is not stressed and will be more effective.. An internal ERF does cause some slight spherical aberration. However visually it is still better than a basic coloured glass front mounted ERF. The Baader front mount D-ERF is however far superior and offers a sharper image.

 

I've been using my Quark on my 127mm Apo with the Baader 35nm filter since that time, with no problems

hope this helps.

Neil

 

[jetstream]

7 minutes ago, ngwillym said:

"While the Quark has a blocking filter in its nose which should kill any residual energy"

Great post and I know this isn't quoting you Neil but I wanted to mention something.

This mention of the "blocking filter" in the nose of the Quark is misleading IMHO. This front filter is the induced transmission filter (ITF) which serves a completely different role than the blocking filter. As the etalon is a "comb" filter the actual blocking filter isolates one line for us to see or image.

To me this ITF is the fail safe energy reducing "broadband" filter and not the actual blocking filter.

I thought it might be worth mentioning this.

Edited August 16, 2017 by jetstream

[DRT]

12 minutes ago, ngwillym said:

The Baader 35nm Ha filter has proven very effective as an ERF. I have used it successfully with scopes up to 152mm. The beam behind it is cool, even on a 152.

Thanks for your post, Neil - very informative!

Can I ask how you are testing whether or not the beam behind the 35nm Ha filter is cool?

[ngwillym]

8 minutes ago, DRT said:

Thanks for your post, Neil - very informative!

Can I ask how you are testing whether or not the beam behind the 35nm Ha filter is cool?

To be honest I'm not doing too much testing - just touch at the edges of the quark nosepeice - nice and cool.

While I think of it, i might just fit the quark with its cover on and see if it melts next time :-)

 

[DRT]

7 minutes ago, ngwillym said:

To be honest I'm not doing too much testing - just touch at the edges of the quark nosepeice - nice and cool.

While I think of it, i might just fit the quark with its cover on and see if it melts next time :-)

 

I can confirm that the nose of my Quark is never hot when I finish a session but I can also confirm that I have burned a hole through the centre of the lens cap when I forgot to remove it  

I hope the sun comes out tomorrow as I'm itching to test some of this stuff  

[DRT]

PLEASE DO NOT REPEAT THIS UNLESS YOU KNOW EXACTLY WHAT YOU ARE DOING AND UNDER NO CIRCUMSTANCES LOOK INTO OR STAND BEHIND A TELESCOPE THAT IS POINTED AT THE SUN WITHOUT A PROPER SOLAR FILTER IN PLACE 

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I just tried a quick experiment with my TV Pronto and a 2" Baader UV/IR Cut filter.

First I set-up the scope with the filter in place on the nose of a 2" diagonal and placed a loosely fitting sheet of paper across the eyepiece end of the diagonal. I then pointed the scope at the sun and a small, very bright disk was projected onto the paper. I left it in place for a few minutes and then slewed the scope away from the sun and removed the sheet of paper. It wasn't remotely warm.

I then removed the UV/IR filter and repeated the experiment. 15 seconds in this happened...

I quickly ended the experiment  

My conclusion is that the UV/IR Cut filter certainly rejects a significant amount of energy/heat. That and Daystar's recommendation to use one is good enough for me  

Edited August 17, 2017 by DRT

[Peter Drew]

Practical is better than theory. 

[Toxophilus]

A picture says 1000 words. Nuff said.

[daslolo]

On 17/08/2017 at 05:09, DRT said:

2" Baader UV/IR Cut filter.

Is it this filter ? https://www.amazon.com/dp/B0028LSMR2/ref=cm_sw_em_r_mt_dp_U_TX7uEbC9EFJFF

has anyone tried that moon filter? It has a long leg past 1000nm

https://www.amazon.com/dp/B005POM8GU/ref=cm_sw_em_r_mt_dp_U_WC5uEb6ZR6CFJ

 

[skybadger]

I used a 50 mm filter screwed to the front of the quark , caused the view to lose clarity in my opinion.