Narrow dew heater needed

[Andy56]

Hi,

I'm using vintage lenses on a 600d and have had issues with condensation. I have two COOWOO heaters but they're are 45mm wide and the lens is 30mm long so I could get vignetting. It's a 28mm Pentax M SMC.

I've had a hunt around the net and can't find any narrow ones, ie about 25 to 30mm, Ideally something about 10-15mm wide would be ideal so it can go round the focus ring and run off a USB power pack.

Do they exist?

Cheers

Andy

Edit: typos and bad grammer.

Edited February 28 by Andy56

[Clarkey]

You could make one from a ring of resistors in a sleeve. That's how I have made a couple of mine for secondary mirrors. Plenty of guides on line.

[Stuart1971]

5 hours ago, Andy56 said:

Hi,

I'm using vintage lenses on a 600d and have had issues with condensation. I have two COOWOO heaters but they're are 45mm wide and the lens is 30mm long so I could get vignetting. It's a 28mm Pentax M SMC.

I've had a hunt around the net and can't find any narrow ones, ie about 25 to 30mm, Ideally something about 10-15mm wide would be ideal so it can go round the focus ring and run off a USB power pack.

Do they exist?

Cheers

Andy

Edit: typos and bad grammer.

I have an old Orion dew zapper 12v one which is 20mm wide, but it’s pretty long as it was for an 8” SCT

if of any interest DM me…👍🏻

 

Edited February 28 by Stuart1971

[Andy56]

Clarkey: Good plan. I'll look for these.

Stuart: Many thanks but a bit big I think compared to the lens

 

Cheers

Andy

Edit: I had a look for DIY heaters, looks like some Nichrome wire will be coming my way

Edited February 29 by Andy56
After thought!

[TiffsAndAstro]

I think I have the same dew heater band.

On my 50mm pentax I like to think of it as a free lens hood.

If I'm careful.

At 28mm no chance

[Mick J]

This may help,  http://test.blackwaterskies.co.uk/2013/05/making-your-own-nichrome-dew-heater.html

[Clarkey]

I have made nichrome dew heaters and although they are effective, for a small lens heater I would still suggest the resistor option. Nichrome is a pain to solder effectively and quite expensive to buy for a single use. Of course, it will work.

[Andy56]

Hi,

Thanks for your ideas and thoughts.

I'm slightly concerned that using resistors may give a problem of the copper wire becoming work hardened over time and breaking whereas I understand that Nichrome/KANTHAL is much more resilient.

If I use Nichrome/KANTHAL I would crimp the ends to connect the power wires. Something like a JST connector crimp and then solder the power wire to that.

Cost: KANTHAL wire seems to be very popular for foam cutting and Vaping coils and is very cheap £6.95/50m

I think this is the way to go.

Blackwaterskies (thanks for the link) suggest 0.3w/cm for a telescope but to lower this for camera lenses. So I my plan it to design for a max on 0.3w/cm and use the COOWOO controllers.

Fun ahead!

Cheers

Andy