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Fixing Baader-U with crack

9 replies to this topic

#1 Johan

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Posted 27 September 2018 - 19:11

So I just bought a 2" Baader-U with a crack for £35 which I am rather pleased with CONSIDERING THE BLOODY THINGS COST NORTH OF £250 NEW! Shout over :)

So it has the tiniest of tiny cracks, barely visible in this (terrible phone) photo:

Posted Image

So I'm wondering, it's a hairline crack, I think I can probably get away with a very thin accurate slice of gorilla tape over both sides.

But curious if anyone has tried this/found a more cost effective solution OR indeed if the filter will degrade because of exposure to air?

Thanks
My new extreme-macro.co.uk site, macro from 1:1 to 10:1 and beyond. Your comments and input there would be gratefully appreciated.

#2 Cadmium

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Posted 27 September 2018 - 21:10

Remove it from the ring, glue it with some kind of glue, preferably something that is black to UV.
Tape is fine, don't worry about the substraight degrading. it will only do it very little on the broken edges, which is no good for anything now anyway.
If you glue it, that may seal the edge. You could use optical cement, such as Norland 63, UV curing. That would seal the edges, but would be clear to UV, so a leak, so the crack would need to be taped over or such.

Edited by Cadmium, 27 September 2018 - 21:11.


#3 UlfW

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Posted 28 September 2018 - 06:06

I would not remove the glass from the ring as the ring might be keeping it together. Beside the mechanical aspects of a crack there is some risk of light leakage into and through the filter. I would try to cover the crack with something opaque, preferably black. A thin strip of insulation tape might do or a line of black paint applied with a very thin brush.

With some luck it might work well and the loss of active filter surface will not be that big, impacting much on exposure times.

This mending technique is similar to filling local nicks or short scratches in lens surfaces with black paint.
Such actions can improve performance very much if the damaged area is small compared to the total lens area.
Ulf Wilhelmson
Curious and trying to see the invisible.

#4 Johan

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Posted 28 September 2018 - 08:30

Great, thanks guys, appreciated
My new extreme-macro.co.uk site, macro from 1:1 to 10:1 and beyond. Your comments and input there would be gratefully appreciated.

#5 dabateman

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Posted 09 October 2018 - 10:43

Have you had any luck with the fix?
What did you end up doing?

I am now faced with this issue as I dropped mine on my concrete floor this morning while imaging. From my filter tests I only need about 25mm central circle to avoid all vignetting.

I have a crack, that I can tilt and see through. I have black epoxy from JB weld, for plastics and metal. I also have gorilla tape which I know is uv black. Not sure which to test. The aluminum frame is holding the pieces together. So I will not move it around.

Edited by dabateman, 09 October 2018 - 10:46.


#6 dabateman

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Posted 12 October 2018 - 06:05

I fixed my Baader venus using 3M brand Scott black cold weather electrical tape. The Cat reference number on the back is 16736NA I first ran a light test and a single layer of this thin tape does not let any UV/vis/IR light through. Which is great, as it is not bumpy and really thin.

I layed a strip down on metal surface, then cut thin strips using fresh razor blade. I had to go a little thick as I had chipping on the back of the filter. Then using Tweezers lined up the cut sections over the cracks. I worked quite well.

Image of Franken filter:
Attached Image: Baader_tape.jpg

Image with largest aperture lens I have the Nikon 50mm F1.2 at F1.2 on Full spectrum EM1, No vignetting:
Attached Image: Baader_50_12.jpg

#7 Cadmium

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Posted 12 October 2018 - 08:35

Start mounting those with O-rings. I do that with 1mm thick glass sometimes, cushions the glass. 1mm glass is very thin and easy to break.
I don't have my Baader U mounted in the original ring, which is another thing to point out, not that it pertains to this issue at all, just full disclosure, so to speak.
I hate the Baader frames, well not as much as 'Kuri Clones with no real name' (of course, wink), but the Baader frames are too deep and the wrong mm for me.
You have all seen my adaptation I think. This is just a 52mm to 48mm step down ring, with the Baader U filter glass sandwiched between two 48mm retaining rings (one in front, and one in back, of the Baader U filter glass).
It is a slim design, and has since been adjusted to provide ample front thread for step up rings and hoods. I love it, works great, been using it for many years now, fully recommend it.
This uses no O-rings however, I didn't start using those until years later, but this has longevity nonetheless.
People seem to be scared to do this, I don't know why, the Baader U is no big deal, you can easily remove it from the ring, without harming it, and install it in some other ring.
Attached Image: baader_U_step_down.jpg

Edited by Cadmium, 12 October 2018 - 08:38.


#8 dabateman

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Posted 12 October 2018 - 10:52

Interesting,
I almost placed my Baader venus in a 49mm filter housing once. I have only standardized to 25mm, 52mm and 72mm filters in the last 2 years with an explosion of filter purchases. Previously I was keeping everything 58mm.
I found, at least for me though that the very large Baader filter housing acts as a mini hood. I rarely needed to add a hood. I just recently got a step up ring, as you can see in the photo to 52mm, to add filters or a hood in front.

Just thinking, I never needed a slim design as I have been using 43rds cameras. First an Olympus E510 and now Em1 full spectrum. That maybe why I haven't needed to go slim with my filters.

Edited by dabateman, 12 October 2018 - 10:55.


#9 JCDowdy

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Posted 12 October 2018 - 14:35

I am a big fan of step rings, here is a site that has a lot of options. Depending on the remaining clear aperture you might be able to mask the crack with a step-down ring. You might have to add a ring of black felt to make it light tight. You can also stack some combination of both step down and step up rings to sandwich the larger remains of a more severely broken filter. Our fellow member Enrico Savazzi has a nice tutorial on making step ring stacks incorporating hoods that may inspire a solution.

#10 Andrea B.

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Posted 12 October 2018 - 15:42

Using a full frame camera, I get a lot of corner vignetting with my BaaderU on a 52-48 step ring. So Cadmium's solution looks very appealing if it helps prevent that.
Andrea G. Blum
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