A question about filters and my "new" lens...

[Phil]

Hi,
As some may know, I've been attempting photos of stars...
I decided the best thing to do would be to buy a wide angle lens. I saw a Sigma 10-20mm f4 lens for a good price and bought it.
I know its not especially fast, but I have to work to a budget.
It turned up and was immaculate. It had also been fitted with a filter of the brand "camlink."

Now I've noticed two things.

First up, the lens. When taking regular photos in daylight, I have to have a very low shutter speed, when compared with my other lenses. Is this normal with a wide angle lens?

Second question which is specific to the filter.
Last weekend I went out at night and the front of the lens misted up over the filter. This has never happened for me before. (I usually use Hoya or Gobe filters.)

So do cheap filters (camlink) tend to mist up easily? Do better quality filters have some anti fog coating??

[Kennyeth]

Originally Posted by Phil

Hi,
As some may know, I've been attempting photos of stars...
I decided the best thing to do would be to buy a wide angle lens. I saw a Sigma 10-20mm f4 lens for a good price and bought it.
I know its not especially fast, but I have to work to a budget.
It turned up and was immaculate. It had also been fitted with a filter of the brand "camlink."

Now I've noticed two things.

First up, the lens. When taking regular photos in daylight, I have to have a very low shutter speed, when compared with my other lenses. Is this normal with a wide angle lens?

Second question which is specific to the filter.
Last weekend I went out at night and the front of the lens misted up over the filter. This has never happened for me before. (I usually use Hoya or Gobe filters.)

So do cheap filters (camlink) tend to mist up easily? Do better quality filters have some anti fog coating??

Hi, Jeff (coolcat) and Alan (clf) are the two I know of to ask.
I try to keep to Hoya filters, a bit more expensive but has very good reputation.
Ken.

[Phil]

Hi Ken,

Thank you, I too prefer Hoya, but still impressed with my Gobe ND filters.

I wouldn't have bought the camlink myself, but it was already fitted.

[Avulon]

Take the filter off ... and bin it. what type of filter is it anyway? if it's affecting daylight exposures by more than 1 stop there's something wrong unless it is an ND Being supplied with the lens I'd guess it would be a UV filter? A wide angle lens in daylight I'd expect to let in more light (than a longer lens) and so need less exposure - not more. Taking star shots It's not going to make any real difference to exposure - just capture more stars, making the starfield in shot look denser than with a zoomed in lens. Are you using a tracking mount? Found a great youtube vid here includes a diy tracker - https://www.youtube.com/watch?v=vg3a0I0duMI

[planenut]

If the ambient temperature is low then one is advised to expose the camera and lens and give it time to cool and adapt before use; that should reduce the misting.

[Phil]

Originally Posted by Avulon

Take the filter off ... and bin it. what type of filter is it anyway? if it's affecting daylight exposures by more than 1 stop there's something wrong unless it is an ND Being supplied with the lens I'd guess it would be a UV filter? A wide angle lens in daylight I'd expect to let in more light (than a longer lens) and so need less exposure - not more. Taking star shots It's not going to make any real difference to exposure - just capture more stars, making the starfield in shot look denser than with a zoomed in lens. Are you using a tracking mount? Found a great youtube vid here includes a diy tracker - https://www.youtube.com/watch?v=vg3a0I0duMI

Hi,
I'd already decided to replace the filter with a Hoya, which I ordered yesterday.
I didn't see any plus point regarding the filter when I bought the lens, other than this cheap filter had been fitted from new and had therefore probably protected the lens.
I have been quite unimpressed with the lens for day light shots and had kind of assumed it was down to the cheap filter.

For star photography I am quite pleased with the lens, just wish I didn't have to use such high ISO, which results in so much post processing...
I'm not using a tracking mount. I'm purely a novice and stare at the sky until I can see things!
I tend to use 3200 ISO and a 20 second exposure.

These are the two most recent results using my "new" lens, both taken with full moon which isn't ideal..

I will definitely check out the video you linked to tomorrow, but now I have to go to bed!
Stars over the Brecon beacons. Wales, UK. by Philip Davies, on Flickr
Stars over Ravensroost wood, WIltshire, England. by Philip Davies, on Flickr

Originally Posted by planenut

If the ambient temperature is low then one is advised to expose the camera and lens and give it time to cool and adapt before use; that should reduce the misting.

Hi, I understand that, I was out with my fiance and her camera was completely unaffected, only mine misted up. It wasn't cold out either.
I assumed that the cheap filter that came with the second hand lens was to blame. I wondered if the cheap filters weren't anti fog coated... (I have no idea if any filter has anti fog coating!)