In article <s88ieu$phf$1@dont-email.me>, Incubus
<incubus9536612@gmail.com> wrote:

> >> > ir pass filters block visible light for true ir photography, although
> >> > they are incompatible with slrs.
> >> I understand the practice with SLRs (D or otherwise) is to frame the shot,
> >> take a
> >> light reading and then attach the filter and increase the shutter speed by
> >> a
> >> set number of stops.
> >
> > if you know what you are doing you can use the+/- compensation dial that
> > most camers have.
>
> Exposure compensation is often +/- three stops. From memory, you need to
> increase your expsosure by at least four for IR. You have to do it manually
> anyway; with a filter attached, don't expect the light meter to function as
> intended.

the meters are calibrated for visible light.

what they do with infrared will vary, depending on the camera. same for
flashes.

On Friday, 21 May 2021 at 14:22:09 UTC+1, nospam wrote:
> In article <84df94f9-84f8-4f1c...@googlegroups.com>,
> Whisky-dave <whisk...@gmail.com> wrote:
>
> > > > Yes I know and you can get UV & IR filters too as I bought some that go
> > > > on
> > > > the front of the lens,
> > > uv filters are a scam. they are extremely high profit margin items that
> > > camera stores (when they existed) would push on uninformed customers.
> >
> > Not if you bought them to protect the lens.
> that's what a lens cap is for, and it even comes with the lens. no need
> to buy anything extra.

But it's not see through.

> in the event you need a replacement, they're cheap.

yes I have a few spare and some body caps too.

> > There were also skylight1A & 1B also pretty unnecessary as less you bought
> > them primary to
> > protect the lens, a bit like a transparent lens cap.
> > Otherwose you could claim less caps are a waste of time too.
> skylight filters were a bigger waste of money.

Depends on why you buy it.

> > > the glass in the lens blocks uv. there is no need for an additional uv
> > > filter.
> >
> > So how to full spectrum cameras record UV ?
> with quartz lenses.

Not if there's UV is on your sensor you can't.

> > > those who want to protect the front element of the lens from dirt or
> > > scratches can get a clear glass filter, but that will have a small
> > > effect on image quality. stay away from the cheap shit, which has a
> > > much bigger effect on image quality.
> >
> > Not seen any clear glass filters, unless you mean Zero ND.
> they are widely available, in varying levels of quality.

SO what is the purpose of them the ND 0 type ?

can you link to someone that is selling these ?

> > > it's quite amusing when people will spend thousands of dollars on a
> > > lens and then put a shitty $5 filter to protect it.
> >
> > Well, in the UK the filters suggested are usualy quite expensive as are
> > adition lens caps
> > for the more expensive lenes the more expensive the accessories.
> of course what they suggest is expensive. more profit for the store.
> > > ir filters come in two variants, blocking and pass.
> >
> > Yes I know but filters tend to block some type of light and pass others
> > anyway.
> > It;s the wavelenght of light that is important .
> whoosh.

yes it's gone obver your head not mine.

As I understand that there;s no such thing as the colour of light, it's an iillusion.
It's just a wavelengh of electromagnetic radiation.

> > > ir blocking filters, aka hot mirror, restore the ir blocking that is no
> > > longer done on the sensor, making the camera 'normal' again.
> > >
> > > ir pass filters block visible light for true ir photography, although
> > > they are incompatible with slrs.
> >
> > why are they incompatable with slrs ?
> with an slr, you are looking through the lens, so if you attach a
> filter to the lens that blocks all visible light, then you won't be
> seeing anything unless you are an alien life form that can see
> infrared.

Or you have a suitable film in yuor camera, which is the general idea of it.

> > and there's no such thing as true IR light is a wavelengh not a band as such.
> false.

True.

On Friday, 21 May 2021 at 16:09:23 UTC+1, Incubus wrote:
> On 2021-05-21, Whisky-dave <whisk...@gmail.com> wrote:
> > On Tuesday, 18 May 2021 at 17:58:27 UTC+1, Incubus wrote:
> >> On 2021-05-18, nospam <nos...@nospam.invalid> wrote:
> >> > In article <f32b51ef-e308-41d5...@googlegroups.com>,
> >> > Whisky-dave <whisk...@gmail.com> wrote:
> >> >
> >> >>
> >> >> Yes I know and you can get UV & IR filters too as I bought some that go on
> >> >> the front of the lens,
> >> >
> >> > uv filters are a scam. they are extremely high profit margin items that
> >> > camera stores (when they existed) would push on uninformed customers.
> >> >
> >> > the glass in the lens blocks uv. there is no need for an additional uv
> >> > filter.
> >> I thought about 75% of UVA passes through glass. This was a problem with older
> >> film but not really an issue for modern film or digital photography. UVB is
> >> completely blocked.
> >> > those who want to protect the front element of the lens from dirt or
> >> > scratches can get a clear glass filter, but that will have a small
> >> > effect on image quality. stay away from the cheap shit, which has a
> >> > much bigger effect on image quality.
> >> >
> >> > it's quite amusing when people will spend thousands of dollars on a
> >> > lens and then put a shitty $5 filter to protect it.
> >> >
> >> > ir filters come in two variants, blocking and pass.
> >> >
> >> > ir blocking filters, aka hot mirror, restore the ir blocking that is no
> >> > longer done on the sensor, making the camera 'normal' again.
> >> >
> >> > ir pass filters block visible light for true ir photography, although
> >> > they are incompatible with slrs.
> >> I understand the practice with SLRs (D or otherwise) is to frame the shot, take a
> >> light reading and then attach the filter and increase the shutter speed by a
> >> set number of stops.
> >
> > if you know what you are doing you can use the+/- compensation dial that most camers have.
> Exposure compensation is often +/- three stops. From memory, you need to
> increase your expsosure by at least four for IR. You have to do it manually
> anyway; with a filter attached, don't expect the light meter to function as
> intended.

Well as intended that depends on your intention and experience and the subject area being photographed.