Now that would provide a great marketing shot! Just in time too, the current crop on the theme of 'just come out of the freezer' are looking a bit old hat.

I thought magnesium would be heavier than plastic (in similar amounts that is) ??

Thats the dealbreaker then

I looks like we may be talking about similar things. If the funtion is to 'wipe back' an effect already applied, and not erase pixels, then that sounds the same.

We are all very fortunate that there are a variety of high quality editing products avalaible to us. You mention auto mask for colour selection, and these newer sort of tools offer in many ways a quicker and more direct way to target elements in an image - an alternative to the traditional Photoshop method of selections.

Sagelight uses radio buttons on the filter dialogues (such as 'undo brush') eg 'select colour', 'avoid colour', 'highs', 'mids' etc. After activating the button you click on the image to define the specific element to be selected. In the background, unseen on the image, the programme provides a mask to allow the tool to do its stuff only where required.

I accept the things that have been said here about glass ND filters and their continuing necessity. But the choice to use them can be limited depending on the type of scene. I was out photogaphing recently and was framing the view under some tree cover, so the top of my shot was very dark, then the bright sky was in the middle, and then the ground below darker again. So I couldn't use a filter. I shot different exposures for the sky and foligae - now I've got the job of blending them on the computer.

Are you sure that 'Erase', at least in Adobe terms, is really the same as 'Undo Brush' in Sagelight? As we all know, I'm not a Lightroom user and you're not a Sagelight user, so its good to share this knowledge.

AFAIK 'Erase' in Adobe terms refers to the process of 'rubbing out' pixels, for example on an upper layer to reveal whats on a layer underneath.

The Sagelight 'Undo Brush' is not 'rubbing out' pixels, it is 'rolling back' the previously applied adjustment, but precisely under the control of the brush movements with a specific sized brush, and with an exact strength of 'rolling back' in percentage units.

Hey, if you're able to say that LR's Erase tool is exactly like this, well then we've both learnt something!

Wow, quite a list! As I said above ... 'Clearly these software Grad filters are hugely more flexible than on-camera glass filters.

I guess most of this type of software is able to apply its various effects to any selected area, but I listed the most significant features of a software Grad specifically - namely the strength of effect, angle of application, and the fade distance (the grad bit).

But there's still strong support here for on-camera ND glass. People are saying is best to balance the components when shooting.

By the way, Sagelight 4 has an 'undo brush' feature, allowing you to erase any previously applied adjustment from any part of the shot, and apply the strength of erasure in 1% increments.....

OK, thanks David and Alan. Its good to have such clear views on it. What I was wondering though, with digital capture and the ability to assess exposures on the LCD and using a histogram, is there a significant difference (in quality or output terms) between shooting a single frame with the glass ND in place, or shooting separate frames exposed individually for the sky & ground?

Obviously by this second method the blending and transition would have to be done in processing, whereas with the physical filter you would choose a suitable grad and precisely place it when shooting. I can see the advantage of being able to see the effect immediately though.

The key part of my question really was whether the metered exposure would lock during the timer countdown in self-timer operation, or whether the ev setting could be altered during timer countdown by light entering the VF. As Smeggy has said, this can be tested for, and I'm going to try and test it - I'll reportback on that.

The same question occurred to me during while using the remote control, as I was raising the mirror with the first press, then moving away (allowing light into the VF) before pressing the remote again to fire the shutter. Obviously in this scenario the mirror is raised.

Would it be fair to assume that might be because you find with the very large exposure difference that when the software filters are 'cranked up' then the quality suffers?

I've read that the introduction of Graduated ND filters (and other colours too) into ACR (was it 3 or so years ago) really made it easier for landscape photographers to balance their shots in software - previously you had to use the far more complicated 'Gradient' dialogues. I've tried these in Elements, and its not for the fainthearted!

But I've seen screenshots of the PS CS ACR Grads in use, and they are clearly very flexible, with full exposure control fine-tunable in 1% units, and the ability to precisely fade the grad line and also tilt the effect to match an angled horizon.

Sagelight 4 also implements similar functionality in a fairly simple filter dialogue - I probably should make more use of it instead of HDR at times!

Clearly these software Grad filters are hugely more flexible than on-camera glass filters. It raises the question of whether the physical items are really still needed (unless you're not into computer editing).