Focus Masks

Discuss any astro equipment that does not have its own forum, such as focusers, finders, chairs, etc.
User avatar
Gazbo
Earth Ambassador
Articles: 0
Offline
Posts: 21
Joined: Sat Jun 22, 2019 8:42 am
4
Location: England
Status:
Offline

Re: Focus Masks

#21

Post by Gazbo »


Done ! glued last night. sprayed this morning. screws fitted just now. test fitted to scope. they fit fine, but will they work ? looks like a long wait for some clear sky ! (The pics are maybe not in order, but they give an idea. I couldn't hope to hack these from card - freehand ! at least not to that accuracy !

I promise to let you know if they work, and which is best. Maybe a long wait though - after all...this is England you know !
Attachments
DSC_0230 (2).jpg
DSC_0224 (2).jpg
DSC_0221 (2).jpg
Prime member of the "Home for the Terminally Stupid"
Meade ETX80 (original) various accessories to suit. Some home-made.
User avatar
seer
Saturn Ambassador
Articles: 0
Offline
Posts: 372
Joined: Sun Jun 02, 2019 1:24 am
4
Location: Johnstown, Pennsylvania, USA
Status:
Offline

Re: Focus Masks

#22

Post by seer »


Looks like you've done GREAT Gary :D
I can't wait to read how well they work for you.
Donald
Tasco BRK Essentials Model: 169735 7x35, Celestron Cometron 7x50, Bushnell 10x50 Legacy WP, Oberwerk 15x70 LW, Meade Infinity 60mm AZ Refractor, Bushnell Deep Space 3 inch Reflector, Meade Polaris 80mm EQ Refractor, Meade Polaris 114mm Reflector.
User avatar
Gazbo
Earth Ambassador
Articles: 0
Offline
Posts: 21
Joined: Sat Jun 22, 2019 8:42 am
4
Location: England
Status:
Offline

Re: Focus Masks

#23

Post by Gazbo »


Gazbo wrote: Sun Jul 07, 2019 1:58 pm Last week I made a Hartmann, from an Indian Take-away tub - (Well Washed !) plastic lid. fitted 3 nylon m4 screws through at about 120 degrees apart, to fit down the outside of the tube (ETX80). Craft hole cutter cut 2 holes on horizontal centre line, leaving about a hole's worth of material in the centre looked about right. , and sprayed the whole thing with Halfords satin black, on the outer side only. Works a treat. But then I realised, I have a Mk 1 Silhouette Cameo vinyl cutter, which cuts vinyl and card, so I grabbed an image of a Bahtinov, and a Carey, and A 3 hole Hatmann type. Loaded into the silhouette program, re-sized, to fit just inside the inner lip of those lids, and cut 2 copies of each, from cereal box card. They came out far neater than any hand- cut items. Glued the pairs, back to back, with PVA. They are presently weighted flat down on the garage bench, until dry. I have now cut the middles out of 3 further lids, with the same circle cutter, leaving enough landing, to glue the finished cards to. Then these will be fitted with screws, a la original, and sprayed again with same black stuff. I'm interested to experiment with all 4 masks, to see what works best with what. (my Mk 1 eyeball ain't what it used to be !)

If the image does show, it is simply a screendump of the various types of mask, from my Silhouette program, ready to cut. fingers crossed, will post pics if they are a success.
UPDATE :
As I still don't know how to use forums very well, My masks are now finished. that post (With images) is on page 2 of this topic - for those remotely interested.
Prime member of the "Home for the Terminally Stupid"
Meade ETX80 (original) various accessories to suit. Some home-made.
User avatar
Gazbo
Earth Ambassador
Articles: 0
Offline
Posts: 21
Joined: Sat Jun 22, 2019 8:42 am
4
Location: England
Status:
Offline

Re: Focus Masks

#24

Post by Gazbo »


Still no clear skies ! found this on wiki. shows Bahtinov in action. Thought it might be useful for the "Uninitiated" lot (Me - included !)

https://en.wikipedia.org/wiki/File:Simu ... cusing.gif
Prime member of the "Home for the Terminally Stupid"
Meade ETX80 (original) various accessories to suit. Some home-made.
User avatar
Gazbo
Earth Ambassador
Articles: 0
Offline
Posts: 21
Joined: Sat Jun 22, 2019 8:42 am
4
Location: England
Status:
Offline

Re: Focus Masks

#25

Post by Gazbo »


Gazbo wrote: Mon Jul 08, 2019 10:07 am Done ! glued last night. sprayed this morning. screws fitted just now. test fitted to scope. they fit fine, but will they work ? looks like a long wait for some clear sky ! (The pics are maybe not in order, but they give an idea. I couldn't hope to hack these from card - freehand ! at least not to that accuracy !

I promise to let you know if they work, and which is best. Maybe a long wait though - after all...this is England you know !

Helpful links for those who have not yet tried these :

https://en.wikipedia.org/wiki/Carey_mask - this shows how the Carey mask operates.

and.....

https://en.wikipedia.org/wiki/Bahtinov_mask - this shows how the Bahtinov Mask operates

:Clap:


Prime member of the "Home for the Terminally Stupid"
Meade ETX80 (original) various accessories to suit. Some home-made.
User avatar
Gazbo
Earth Ambassador
Articles: 0
Offline
Posts: 21
Joined: Sat Jun 22, 2019 8:42 am
4
Location: England
Status:
Offline

Re: Focus Masks

#26

Post by Gazbo »


Don Quixote wrote: Wed Jun 26, 2019 9:13 pm
seer wrote: Wed Jun 26, 2019 8:01 pm
Don Quixote wrote: Wed Jun 26, 2019 7:13 pm Ok.
I is a ignorant flatlander... :-)

What are these ones with the two holes used for.
I know the bahtinov but I am not familiar, Donald, with the other ones.
They are all used for focusing. I am very new to all of these. From what I am gathering some of the designs predate the others and might have been bought over from other areas of optics. Some are suppose to do a more precise job then the others. I am guessing the Bahtinov is best for stars but I wondering if one of the others might do better with the moon. These are some of the things on my to do list.
I think the Hartman, the two hole one, would be very good for the moon focusing.
Attachments
post-23525-0-03812300-1355491464.jpg
Prime member of the "Home for the Terminally Stupid"
Meade ETX80 (original) various accessories to suit. Some home-made.
User avatar
seer
Saturn Ambassador
Articles: 0
Offline
Posts: 372
Joined: Sun Jun 02, 2019 1:24 am
4
Location: Johnstown, Pennsylvania, USA
Status:
Offline

Re: Focus Masks

#27

Post by seer »


I was just out with my 76mm reflector and the focus mask that I made for it. I tried it with the moon and Jupiter. It seem to me to be superfluous. I think I actually did better with out it.
The feature on the moon that stood out to me the most this time was the rim of Archimedes crater and how built up it is on the inside and outside.
Donald
Tasco BRK Essentials Model: 169735 7x35, Celestron Cometron 7x50, Bushnell 10x50 Legacy WP, Oberwerk 15x70 LW, Meade Infinity 60mm AZ Refractor, Bushnell Deep Space 3 inch Reflector, Meade Polaris 80mm EQ Refractor, Meade Polaris 114mm Reflector.
User avatar
seer
Saturn Ambassador
Articles: 0
Offline
Posts: 372
Joined: Sun Jun 02, 2019 1:24 am
4
Location: Johnstown, Pennsylvania, USA
Status:
Offline

Re: Focus Masks

#28

Post by seer »


I think that I read one time long ago that focus masks really come into play with astrophotography. It is supposedly more difficult to focus with a camera attached and looking through it.
Donald
Tasco BRK Essentials Model: 169735 7x35, Celestron Cometron 7x50, Bushnell 10x50 Legacy WP, Oberwerk 15x70 LW, Meade Infinity 60mm AZ Refractor, Bushnell Deep Space 3 inch Reflector, Meade Polaris 80mm EQ Refractor, Meade Polaris 114mm Reflector.
User avatar
JayTee United States of America
Universal Ambassador
Articles: 2
Offline
Posts: 5619
Joined: Thu Apr 25, 2019 3:23 am
4
Location: Idaho, USA
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: Focus Masks

#29

Post by JayTee »


seer wrote: Wed Jul 10, 2019 12:02 pm I think that I read one time long ago that focus masks really come into play with astrophotography. It is supposedly more difficult to focus with a camera attached and looking through it.
That is exactly right. Your eye through the EP can do as good (sometimes better) than the focusing mask. The Bahtinov was originally devised for imaging purposes. That doesn't mean you can't use it for visual observing but it typically doesn't gain you anything.

When I do planetary imaging, I don't use the Bahtinov for that either. The image on my computer screen is bright enough that my eye does at least as well as the Bahtinov plus, for me, it's faster to not use the Bahtinov for focusing.

Cheers,
JT
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°

Searching the skies since 1966. "I never met a scope I didn't want to keep."

Image
User avatar
Gazbo
Earth Ambassador
Articles: 0
Offline
Posts: 21
Joined: Sat Jun 22, 2019 8:42 am
4
Location: England
Status:
Offline

Re: Focus Masks

#30

Post by Gazbo »


I agree with the above points. I tried my 2 hole version first in daylight, trying the church flagpole, around a half mile away. Yes - it did giive a double image, which merged when focussing. But it semed incredibly difficult to tell when I was on the money, however, I have since realised, the smaller the object is, the more accurate the filter mask will be, as larger objects have too much "EDGE" to work with, for the mk 1 eyeball to be able to decypher. Obviously, if ( unlike me) you have good 20-20 vision, then the masks may not be of much use. The great "unblind" amongst us will just tell when it is bang-on. My eyes do need that last bit of help.Still awaiting a clear night to test, but I'm still hopeful these masks may help. No harm in trying, after all, mine only cost me my time.
Prime member of the "Home for the Terminally Stupid"
Meade ETX80 (original) various accessories to suit. Some home-made.
User avatar
Gazbo
Earth Ambassador
Articles: 0
Offline
Posts: 21
Joined: Sat Jun 22, 2019 8:42 am
4
Location: England
Status:
Offline

Re: Focus Masks

#31

Post by Gazbo »


I now post a general query. Bearing in mind I am still new to all things asto- telescope, correct me if I'm wrong, but at the distances we are talking about, is not a certain "in focus" setting , going to be the same for all areas of the sky( as would be "infinity" on a camera lens)? If that is indeed the case, then once focussed, you could then leave the focus alone ? This was the theory behind making my masks. Use once at the beginning of the evening, then put them away for the duration.
Prime member of the "Home for the Terminally Stupid"
Meade ETX80 (original) various accessories to suit. Some home-made.
Don Quixote
Articles: 0

Re: Focus Masks

#32

Post by Don Quixote »


Gazbo wrote: Sat Jul 13, 2019 9:37 am I now post a general query. Bearing in mind I am still new to all things asto- telescope, correct me if I'm wrong, but at the distances we are talking about, is not a certain "in focus" setting , going to be the same for all areas of the sky( as would be "infinity" on a camera lens)? If that is indeed the case, then once focussed, you could then leave the focus alone ? This was the theory behind making my masks. Use once at the beginning of the evening, then put them away for the duration.
My experience has been that this once focused idea is pretty good, I am speaking for visual, but I still may have to tweak a bit after a while.
It could be due to temperature change over the time of my session causing this necessity. I am not sure about this.
User avatar
Gazbo
Earth Ambassador
Articles: 0
Offline
Posts: 21
Joined: Sat Jun 22, 2019 8:42 am
4
Location: England
Status:
Offline

Re: Focus Masks

#33

Post by Gazbo »


Thanks Don. I did think that would be the case. It always was for photographic lenses at any rate.understand the temperature fluctuation thing. I just seemed to get the impression people were maybe re-fitting their masks to re-focus on each new object, which I didn't think would be necessary.
Prime member of the "Home for the Terminally Stupid"
Meade ETX80 (original) various accessories to suit. Some home-made.
User avatar
JayTee United States of America
Universal Ambassador
Articles: 2
Offline
Posts: 5619
Joined: Thu Apr 25, 2019 3:23 am
4
Location: Idaho, USA
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: Focus Masks

#34

Post by JayTee »


Gazbo wrote: Sun Jul 14, 2019 9:20 am Thanks Don. I did think that would be the case. It always was for photographic lenses at any rate.understand the temperature fluctuation thing. I just seemed to get the impression people were maybe re-fitting their masks to re-focus on each new object, which I didn't think would be necessary.
Most APers refocus (or at least check focus) every 30 to 60 minutes. Focusing is THE most important job when imaging. Forgetting or screwing up this single act is a sure fire way to ruin three hours or more of valuable imaging time. For AP, set and forget focusing is just not done.

Cheers,
JT
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°

Searching the skies since 1966. "I never met a scope I didn't want to keep."

Image
Post Reply

Create an account or sign in to join the discussion

You need to be a member in order to post a reply

Create an account

Not a member? register to join our community
Members can start their own topics & subscribe to topics
It’s free and only takes a minute

Register

Sign in

Return to “Other Accessories”