Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_globular_clusters_winners.thumb.jpg.13b743f39f721323cb5d76f07724c489.jpg

Rusted

Lacerta 2" + ND3 safe enough with a 7" refractor?

Recommended Posts

Hi

My shiny new Lacerta 2" LAC2S wedge is waiting to be used for the first time but want to be absolutely certain about safety.
The model I bought has a rotating [polarizing filter] adapter and contains a fitted 2" ND3 as standard.
I have fitted a 2" Baader polarizing filter in the rotator ready for visual dimming.


The problem [?] is that I am intending to use this setup on my 7" [180mm] f/12 refractor.
Lacerta mentions using a 2" UV/IR blocking filter with larger refractors.
Their Optolong KG3/IFIRUV2 filter recommendation costs another whopping 120 Euros! Eek!


I will be using a Baader 1.25" Solar Continuum filter in my eyepieces as standard.
I decided I couldn't afford the 2" SC to fit permanently inside the wedge at the moment.
This just means I have to remember to refit the green filter when I change eyepieces.


Question: Is the Baader SC considered a true [safe] UV/IR blocking filter in its own right?
Or should I really invest in a separate 2" UV/IR blocker to be really safe? The 2" Baader costs 100 Euros.
Or, should I stop down the 7" to [say] 120mm? Optimum aperture for average seeing conditions, etc?

Thanks

Share this post


Link to post
Share on other sites

The Herschel wedge with a ND3 filter is considered safe for all apertures.

Addition filters - Continuum may improve the contrast.

 

  • Like 1

Share this post


Link to post
Share on other sites

The Continuum filter does let through quite some near IR, I noticed when using with CMOS camera. If you have any doubts, you could always use a 1.25" UV/IR block filter on the EP, or get a cheaper UV/IR block filter at 2". I have had no issues with Teleskop Service filters for visual, and the 2" just sets you back 59 euro.

  • Like 2

Share this post


Link to post
Share on other sites

Thanks for your helpful responses. The TS filter sounds much more affordable.
I suddenly developed safety doubts after shining a torch and a laser pointer through the bare prism.
Even the 8% reflection is fiercely bright. As is the second reflection off the back of the wedge.
Though shining beams through the ND3 and polariser alone greatly reduce the brightness, I had no real idea of their passband.
A separate UV/IR blocker would give me the option of not having to use the SC. [green] Allowing me to make simple visual comparisons.
A 2" filter can be left permanently in place. Offering an increased safety margin when changing eyepieces.
It was the very high price of the alternatives [at 2"] which put me off.

 

 

Share this post


Link to post
Share on other sites

I would have purchased the 1.25" Lacerta HW and used the smaller filters. The 1.25" Lacerta is about the size of most other 2" models.   🙂

  • Like 1

Share this post


Link to post
Share on other sites

Thanks, Peter.
I went with the larger model for its increased acreage of heat sink to cope with my 7" aperture.
The feeling on the groups and Lacerta's advice is that a 2" is best with larger instruments.
It also gives me more clear aperture for a full screen DSLR.  If only!  :icon_rolleyes:

  • Like 1

Share this post


Link to post
Share on other sites

An update: My M48>T2 adapter and1.25 EP holder have arrived.

The Lacerta 2" prism is an instant improvement over the Baader solar foil!

I'm seeing surface texture on the disk near the eastern "ramp" prom as shown in H-a on GONG! 😎

Heat sink temperature peaked at 38C, 100F after 3 hours. NO noticeable heat out of bottom window.

 

P1360640 rsz 500.JPG

P1360651 rsz 600.JPG

P1360653 rsz 600.JPG

Edited by Rusted
images attached

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.