TheSkySearchers

I have read Gabby's post on baffles and the various links provided. I have a general idea on what they do, but would like to ask some basic questions.

What are they made of?

How do they attach to the tube?

How large are they?

What is their shape?

Do they encircle the whole tube?

Thanks very much for your help.

Michael

Hello Michael.

In a refractor tube the baffles could be like paper thin donuts of the same outer diameter as the inner diameter of the tube with gradually smaller and smaller donut holes but the same outer diameter. These donut shaped wafers attached to the inside of the telescope tube with the largest donut hole closest to the front of the telescope and gradually getting smaller as you move toward the back of the telescope.
I suppose you could make them out of anything from cardboard to metal. They could be attached with glue or spot welded or several other fastenments.

Which telescope are you going to baffle?

Michael131313 wrote: ↑Fri Oct 04, 2019 11:10 pm I have read Gabby's post on baffles and the various links provided. I have a general idea on what they do, but would like to ask some basic questions.

What are they made of?

How do they attach to the tube?

How large are they?

What is their shape?

Do they encircle the whole tube?

Thanks very much for your help.

Michael

They are made of anything convenient and attached in some stable way. Depends on what you’re wanting to do.

They are as large as possible without shadowing the field of view. Gabby treated a good method for sizing.

They are cylindrically symmetric, encircling the tube inside. They can be annular rings.

The most important part aside from geometry is flat black finish.

If you are wanting to place new baffles in your telescope I would recommend drawing it out full size so placement can be worked out accurately.
I have made baffles out of metal and even stiff poster paper.
I can post an image of what a baffle looks like and is held in place inside the tube as I was going to be removing the focuser from one tonight.

Repost of the link to the Berfield method:

http://www.berfield.com/baffles.html

This is minimal IMO. A couple more can only help.

Also another idea for building a complete baffle assembly which can be removed for maintenance if necessary.

http://mirrorworkshop.mtbparker.com/refractorStory.html

The spacings of the baffles are not like Berfield and so are not so recommendable. (I see considerable redundancy.) But I very much like the idea of a baffle assemblage that can be removed / replaced as a unit.

Thanks all for the info:

Don Q. I haven't decided if I want to place baffles in my ES AR102. It does not have any baffles. I did what John posted and looked down the tube at the objective to see how dark it was. I did this in the daylight. Unfortunately the sides of the tube are not at all dark. Now I realize what baffles do. I have never taken the scope apart, so I'm a little wary as to what might happen. I live in an area where there would be no help except for TSS.

n_FA. Thanks for the info and links. The baffle assembly is an interesting idea. How do you think it is attached?

Gabby. I would very much like to see the baffle. Thanks.

My idea would be to simply size the baffle assembly to slip into the tube to fit. Then should maintenance be necessary it can be easily removed.

Another thing you may consider in evaluating any light controlling upgrade is the focuser tube.

When I am evaluating my own kit, looking through the objective end in daylight can give some false flags because NOTHING captures ALL the light. You WILL see lighter areas and shadows depending on the angle of direct light entering the objective. I recommend making this observation with the objective pointed toward a uniform, neutral background, like a ceiling. Shining a flashlight down the tube may be overkill.
Comparing one scope to another of equal spec may reveal a difference between the two which could be meaningful as well.

One objective of controlling the light scatter with baffles is to optimize contrast.

But I also look through the focuser end with no diagonal installed. This can reveal light scatter in the focuser tube. It will show up as a lighter ring between the entry point of the focuser and the field stop of the objective.

I have treated this in my 2 inch and larger focuser by inserting a flocking material into the focuser tube. This can be slid forward and backward in the focuser tube to tune out these reflections.

I would add to my evaluation of the need of upgrading your 102 a look through the focuser end with no EP installed.

I have posted here, somewhere, my method for this focuser tube treatment. It has been effective for me.

viewtopic.php?f=18&t=3495

Here is a image of the rear factory baffle, you can see the folded over tabs that hold it in place. These are towards the focuser.
I usually make the tabs about 15mm.

When looking through the objective you should not be able to see the tube walls.

Just on a side line,

next to the baffles in the OTA tube, it is flocking of the zenit mirror house interior. The side walls on the budget zenit mirrors reflect the light rays, which are not trapped by the baffles in the OTA. Tomorrow I'll take a pic, need the day light for my photography.

Some people place an adjustable iris diaphragm in front of the zenit mirror/prism, I have for it an iris diaphragm form Leitz Diavert. It is at the moment in the socks drawer, should I believe to need it in future.

And last but not least is is an oversized lens hood on a refractor, protecting the lens and the OTA from the stray light sorces and from the sky glow.

When the refractor is correctly protected from the unwanted light, then a 6" rich field refractor will beat on contrast even the much larger Dobs, and it will show some faint fuzzies even at lower magnifications.

Best,
JG

Thanks everyone. When I look through the objective, no diagonal or EP, I just see black (no tube walls) except the light from the focuser opening. When I look through the focuser end, no diagonal or EP, the focuser tube is black, but the inside of the OTA tube is a light grey. (During daylight). Would this be a case for baffles?

For what it is worth...
These are images of the focuser end and the objective end on my 100mm Evostar Doublet.

This telescope has only three factory installed baffles.

First is Objective. One with flash. One with no flash. The next set is the focuser end. One with flash. One with no flash. Personally I would think three or four times before disassembling your 102 to add baffling.
Just my conservative opinion.

The flocking of areas mentioned by JG in post #10 above would also be good to consider.


Cheers.

Thank you everyone for the info and help. I have learned a lot.

Don Q. Thanks for the photos. I agree. My AR102 gives me very good views as is. I don't feel good about messing around with it right now.

Hello Michael,

it looks o.k. for me, I would do just nothing, leaving it as it is,

JG

Michael,
just not to forget, if you are using a zenit diagonal mirror, check out its inner life on spurious reflections.
Best,
JG

Thank you for your help JG.
I do not know what a "zenit" diagonal mirror is. The ES AR102 came with GSO (I think) 99% reflective 2 inch mirror diagonal. I will do as you say and check for stray light soon.
Michael

Michael131313 wrote: ↑Sun Oct 06, 2019 9:28 pm Thank you for your help JG.
I do not know what a "zenit" diagonal mirror is. The ES AR102 came with GSO (I think) 99% reflective 2 inch mirror diagonal. I will do as you say and check for stray light soon.
Michael

That's exactly a "zenit" mirror in German.

Got my German lesson today. Thanks n_FA.

"zenit(h) diagonal mirror"

It is an "unword", something like "make the right angle right" in the fun video.
Another unword is "zenit(h) prism diagonal",
https://www.baader-planetarium.com/en/a ... t-14).html

There are not many prisms without diagonal,
and the mirrors are just flat, concave, convex, dirty, ...

Best,
JG