Dust (1 Viewer)

[Tord]

Has anyone come up with a clever solution how to reduce the amount of dust coming into the tube, some of it eventually landing on the lens? I guess it comes in through the gap in the focuser. Would some sort of felt filling the gap help?

 

[JGobeil]

Has anyone come up with a clever solution how to reduce the amount of dust coming into the tube, some of it eventually landing on the lens? I guess it comes in through the gap in the focuser. Would some sort of felt filling the gap help?

I guess this is a lost cause. When using a TN, there are 4 joints that are far from hermetically sealed between the camera and the main tube. Add to this that the focusing knobs assembly is not sealed - on the SW80, there are 4 O-rings that prevent it from touching the focuser, leaving a gap in between. Finally, the focuser back and forth movements act like a pump to attract dust inside.

Also, I don't know about you, but I often move the camera body between the scope and the 100-300mm lens when in the field. Even if I keep a cap on the adapter when I don't use the scope, those are all perfect occasions for dust entry.

 

[Tord]

Jules,
I realize that achieving a fully hermetically sealed scope is not feasible. I was more thinking of ways to reduce dust.

I have taped the flange of my camera adapters, eliminating play and also serving as a barrier against dust entering in proximity of the camera. I used regular office tape or electrical tape depending on what is needed for perfect fit. Touch wood, I haven't experienced dust sticking on my Olympus sensors...

I tend not to un-mount the camera and switch between lenses. I bring a second camera with me in the rucksack, should I want to also take pictures with regular lens.

I was more thinking of making it difficult for dust to pass through the gap in the focuser (several mm wide), this should by far be the largest opening in the system. Some sort of ring-formed elastic part that is somehow fixed to the fixed part of the focuser, has a good fit and and slides on the moving part without friction to speak of. Maybe neoprene (e.g. cut from a discarded glove) on which some sort of textile (trapping the dust) is glued would work.

Speaking of textile, I have noticed that the self-adhesive flocking tape that I have used in my extension tubes is a great dust trap. Anyone else?

 

[JGobeil]

You are right, I forgot about the gap caused by the long track on the focuser tube...

If I may, I would suggest you stay away from electrical tape because, after some time, it will leave sticky glue on the contact surface. I use masking tape to lock the IS switch on my 100-300mm lens and it performs well without leaving any residue.

Personnaly, I'm not too worried about small dust particules on a lens because they can't be seen on the photo most of the time. Also, they are quite easy to remove if they bother me. Same for the scope, both inside out.

 

[rferrieri]

Tord

What about using a sleeve gauntlet to enclose the scope and camera leaving the front optics open--such things are worn by folks working in class 100 clean rooms. Check out Fisher Scientific they may have something. Rich

 

[Tord]

You are right, I forgot about the gap caused by the long track on the focuser tube...

If I may, I would suggest you stay away from electrical tape because, after some time, it will leave sticky glue on the contact surface. I use masking tape to lock the IS switch on my 100-300mm lens and it performs well without leaving any residue.

Personnaly, I'm not too worried about small dust particules on a lens because they can't be seen on the photo most of the time. Also, they are quite easy to remove if they bother me. Same for the scope, both inside out.

The thing is - while the lens on the SW80 is easy to clean, the TS102 is not. The lens cannot be unmounted without having to adjust the collimation, and is difficult to wipe from the inside due to the length of the tube. Maybe vacuum cleaner...?

 

[Paul Corfield]

I used to use a long rod with a soft paint brush taped to the end. Around the paint brush I would wrap/tape a good quality glass cleaning cloth. That was my method with the SW80ED up until I eventually got the lens cell to unscrew.

Paul.

 

[JGobeil]

The thing is - while the lens on the SW80 is easy to clean, the TS102 is not. The lens cannot be unmounted without having to adjust the collimation, and is difficult to wipe from the inside due to the length of the tube. Maybe vacuum cleaner...?

Tord

I didn't know that. Now I understand your concern. I hope you will find a fix.

If it were mine, I would try this:

1. Use camo tape over the fixed joints. The type that extends and sticks only to itself.
2. Try a rubber balloon cut as a cylinder over the moving joint of the focuser. It may just work...

Good Luck
Jules

 

[doublespinss]

You could always set up an air pump and filter and keep the scope at positive pressure XD

 

[Tord]

Tord

I didn't know that. Now I understand your concern. I hope you will find a fix.

If it were mine, I would try this:

1. Use camo tape over the fixed joints. The type that extends and sticks only to itself.
2. Try a rubber balloon cut as a cylinder over the moving joint of the focuser. It may just work...

Good Luck
Jules

Jules,
Thanks for the tips. I already have camo tape over most of scope including the fixed joints. Can certainly add more, round the focuser wheels, several layers means less dust.

The balloon might be a solution. I previously tried with a cylinder cut out of a discarded neoprene glove and it almost worked, fitting and sliding nicely on the focuser. The challenge was how to secure it to the fixed part.

I'll keep you posted of progress.

 

[Tord]

Jules,

I tried the balloon thing and it does not work, the material is too weak and will not resist scratches.

What I did instead was to cut a cylinder from a discarded neoprene glove, secured it with duct tape and wrapped the duct tape in camo tape. Looks quite OK and seems to to the job. Had it on during a full day session and as far as I can see no dust entered the scope (I had the lens blowed and cleaned prior start). So I will leave it on for some time and run a long term field test. "Spring force" is however increasing when focusing towards full contracted focuser (which contracts the cylinder) and when reaching the last cm or two the spring force is higher than the focuser friction will withstand. However on my TLAPO804 + CNC prime focus adapter + 80mm extension tube I reach infinity with the focuser extracted about 2 cm so it is not an issue as such.

Possibly a dish washing glove would work, should be more resistant to scratches than thin ballons. Will try that on the TS102 (it has a 3" focuser so need a larger diameter). Or maybe use a cylinder cut out from a discarded neoprene wet suit or something like that.

 

[JGobeil]

Jules,

I tried the balloon thing and it does not work, the material is too weak and will not resist scratches.

What I did instead was to cut a cylinder from a discarded neoprene glove, secured it with duct tape and wrapped the duct tape in camo tape. Looks quite OK and seems to to the job. Had it on during a full day session and as far as I can see no dust entered the scope (I had the lens blowed and cleaned prior start). So I will leave it on for some time and run a long term field test. "Spring force" is however increasing when focusing towards full contracted focuser (which contracts the cylinder) and when reaching the last cm or two the spring force is higher than the focuser friction will withstand. However on my TLAPO804 + CNC prime focus adapter + 80mm extension tube I reach infinity with the focuser extracted about 2 cm so it is not an issue as such.

Possibly a dish washing glove would work, should be more resistant to scratches than thin ballons. Will try that on the TS102 (it has a 3" focuser so need a larger diameter). Or maybe use a cylinder cut out from a discarded neoprene wet suit or something like that.

You're getting there ! Since dust is a problem with your scope, it is worth experimenting.

Neoprene and similar plastic foams are interesting. It is available in all thicknesses and can be glued easily. I make all sorts of cases and utilities with 1 cm foam from exercise mats. I use LEPAGE solvent free Contact Cement. If you search a little, you will find some in the thickness you require.

Good luck with your project.
Jules