Crows feet in telescopes

[Jeffkop (Jeff)]

This is most likely a stupid question ... but as Ive never seen it discussed on the this forum nor has any of the literature supplied with my telescopes mentioned it I thought Ide ask it.

Do telescopes suffer from the growth on the lens that a camera lens does if it doesnt have light pass thru it for a long time ???

[torana68 (Roger)]

mould? yep

[AndyK (Andy)]

The "crows feet" which can afflict lenses is actually a fungal growth. It can be common in warm, humid environments.
I've even had a friend have the sensor in their digital SLR camera ruined by fungal growth ... mind you they live in Cairns.

The fungus actually grows in the lens coating so uncoated lenses won't be affected and neither will uncoated mirrors.
Many eyepieces do have coating though, and could potentially be affected.

I keep all my telescope eyepieces as well as camera lenses in sealed cases, with a few sachets of silica gel thrown in for good measure.

Cases like THESE are available in various sizes at a number of places.
Bunnings sometimes has them as do leading Edge Electronics.

[brian nordstrom (As avatar)]

yep we have that problem here in Darwin , what I do during the wet is put some small pieces of rags soaked in bleach ( janlola ) in small plastic bags left open in the dew shield with the cap on and placed in storage , that kills any fungi or spores and stops them growing .
it smells a bit when after 5-6 months but that soon dissapates , and no crows feet .
Brian.

[Jeffkop (Jeff)]

Originally Posted by torana68

mould? yep

Originally Posted by AndyK

The "crows feet" which can afflict lenses is actually a fungal growth. It can be common in warm, humid environments.
I've even had a friend have the sensor in their digital SLR camera ruined by fungal growth ... mind you they live in Cairns.

The fungus actually grows in the lens coating so uncoated lenses won't be affected and neither will uncoated mirrors.
Many eyepieces do have coating though, and could potentially be affected.

I keep all my telescope eyepieces as well as camera lenses in sealed cases, with a few sachets of silica gel thrown in for good measure.

Cases like THESE are available in various sizes at a number of places.
Bunnings sometimes has them as do leading Edge Electronics.

Originally Posted by brian nordstrom

yep we have that problem here in Darwin , what I do during the wet is put some small pieces of rags soaked in bleach ( janlola ) in small plastic bags left open in the dew shield with the cap on and placed in storage , that kills any fungi or spores and stops them growing .
it smells a bit when after 5-6 months but that soon dissapates , and no crows feet .
Brian.

Thanks very much for the replys .. I had an idea that this may be the case .. hmmm better check the reflector scope as well by the look of it
Once again .. thanks

[MLyons (Martin)]

Originally Posted by brian nordstrom

yep we have that problem here in Darwin , what I do during the wet is put some small pieces of rags soaked in bleach ( janlola ) in small plastic bags left open in the dew shield with the cap on and placed in storage , that kills any fungi or spores and stops them growing .
it smells a bit when after 5-6 months but that soon dissapates , and no crows feet .
Brian.

Wow! I would've thought that bleach (Chlorine - or Sodium Hypochlorite, the active ingredient) anywhere near Aluminium such as mirrors would be an absolute no-no.

Can you confirm that the Chlorine has no effect on the coatings?
I realise most commercially coated mirrors have a protective SiO coating, but that always has tiny pinholes through which a corrosive gas could penetrate and, over time, corrode the Aluminium under the SiO

I'd be inteested to see long term effects, if any.

Martin

[DavidU (Dave)]

A good read here.......
http://throughavintagelens.com/2010/06/lens-fungus/

[brian nordstrom (As avatar)]

Na I dont think so , I've been doing it for years , all my scopes are refractors with good fully multi coatings . A good point though, Martin .Brian.

Originally Posted by MLyons

Wow! I would've thought that bleach (Chlorine - or Sodium Hypochlorite, the active ingredient) anywhere near Aluminium such as mirrors would be an absolute no-no.

Can you confirm that the Chlorine has no effect on the coatings?
I realise most commercially coated mirrors have a protective SiO coating, but that always has tiny pinholes through which a corrosive gas could penetrate and, over time, corrode the Aluminium under the SiO

I'd be inteested to see long term effects, if any.

Martin