Film speed of digital cameras

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Dave R Smith
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I understand digital cameras still have a film speed (or atleast a setting to emulate it).

So if you have 2 cameras, one digital, one 'film' same lens same f-stop and shutter speed, in poorish light with no flash, will image quality be about the same?
Lets assume for this question cameraman has a pocket full of real film of all speeeds/asa so the cameraman has a choice, the same as the digital counterpart where the film speed can presumably been changed at will.

If quality of results are similar - is this co-incidence or a reflection of the current state of digital technology? Is it still down to how many mega pixels a chip is, or like video cameras, can they perform reasonably well(or better) in low light provided the contrast range isn't too wide?

Or put another way, apart from the number of megapixels argument, is it likely that digital cameras will perform better in low light than their 'film' counterparts.
Is one digital cameras' chip light sensitivity the same as the next, if lens aspects etc otherwise being equal?

Alan Roberts
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The speed ratings accord with ASA (and ISO) rules, just like film. They aren't shooting at particular film stocks. The only thing that changes in a digital camera when you change the "film speed" is the signal gain; changing from, say 100ASA to 200ASA will require the camera to add 6dB of gain, and therefore you get 6dB more noise, which sort-of resembles grain. Some cameras do this better than others, using spatial filters to soften the image at high-speed to reduce the noise amplitude and spread it out to look more like big grain.

There are no rules, except that when you select a "speed", any external light meter will agree with the exposure settings (give or take a gnat's). But they aren't aiming to emulate specific film stocks.

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Alan Craven
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Compact digital cameras tend to have a small range of apertures, so you can use a change in "film speed" to exercise some control over shutter speed and/or aperture - at the expense of noise if you up the rating as Alan R says.

Dave R Smith
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Hi Alan * 2,
I realise that ASA in a digital context is slightly false, but serves as a reference point in using light meters and experience in judging f-top and shuuter speed.
My expectation is that as technology improves, digital images can be taken in low light conditions, that turn out better - or with less grain, than their 'film' counterparts.
I wasn't sure if my expectation was here now - or if it is still some date in the future.

When we are indoors we can see each other perfectly well, yet photography without flash would normally result in dark/awful results. If we use a video camera in such an indoors environment, it would be quite happy and would not appear dark, though admittedly be low resolution. I would expect the same to be true of digital 'stills' cameras in x years.

The implication from your replies are that digital versus non-digital in this context are currently comparable - though achieved using different methods.

In terms of gain and spatial filters, this suggests improvements are currently done by using software/firmware to improve the look of the source data provided by the chip. So the future hasn't yet arrived!

Alan Roberts
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Dave, I specifically made the point that the "speed" ratings are genuine, not false. Whether the pictures taken at any set speed rating are better or worse than film is largely down to implementation in the camera, and the referenced film stock. And those are not under our control.

Get my test cards document, and cards for 625, 525, 720 and 1080. Thanks to Gavin Gration for hosting them.
Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.

Alan Craven
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Sorry Alan - I think I caused this by putting "film speed" in my post - I had not appreciated the ambiguity.

Even though we have changed the image capture medium, the old concept of Exposure Value that my 1960s Weston Master used to determine the aprropriate shutter speed and aperture for a given film speed still applies. That uses three concentric rings to enable the calculation to be made - it uses the original German DIN speed rating.

Despite the passage of time, it is still as accurate as any means of determining exposure - and it uses no batteries.

Dave R Smith
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Alan Roberts wrote:
Dave, I specifically made the point that the "speed" ratings are genuine, not false. Whether the pictures taken at any set speed rating are better or worse than film is largely down to implementation in the camera, and the referenced film stock. And those are not under our control.

My question is about 'where is is stills technology today', rather than about how we as photographers control that technology.
So, when you say ' ..largely down to implementation in the camera', I take this to mean roughly comparable with film cameras. Do you concur?

This statement also implies that the CCD's sensitivity is a constant, but how that data is interpreted is variable.

Also, would you agree with my expectation for the future?:
'My expectation is that as technology improves, digital images can be taken in low light conditions, that turn out better - or with less grain, than their 'film' counterparts.'

Alan Roberts
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I reckon all your assumptions are about right. The current state of sensor technology can capture around 11 stops of contrast range, maybe a little more with a good lens and good electronics. That's in the same ball-park as film. I don't expect to see great improvements in that, we're already at a quantum efficiency of around 75% (i.e. 75% of photons that hit the sensor become electrons), so any improvements have to come from clever processing tricks, of which there are plenty.

However, there are great strides to be made in terms of colour accuracy, there are some fundamentals that aren't really being fixed yet.

Get my test cards document, and cards for 625, 525, 720 and 1080. Thanks to Gavin Gration for hosting them.
Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.

Dave R Smith
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Thank you for your informed opinion Alan (Roberts).
Thank-you too, to Alan Craven for your feedback.
I reckon in another 40 years we'll be on batteries.:eek:

red
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Canon EOS 1D MKIIN

I can only tell you the results we get in the field.

With the above camera, the on demand ISO settings are a blessing and it's so responsive to conditions on the day it's unbelievable.
Many a time this camera surprises me with the quality it gives out under the worst conditions imaginable.
Digital is the only way to go in low light conditions, if you need that versatility to adapt on the hoof.
Technical arguments aside, next time you look on the T.V. at a football match, presentation, or awards event, take a look at the digital camera's the pro's are using. Film is very close to having it's day if it's not happened already.
I've just sold all my film camera's while they're still worth something!

Alan Craven
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red wrote:
I've just sold all my film camera's while they're still worth something!

Me too! I got good prices for specialist items e.g. Micro-nikkor lenses, but relatively little for modern Nikon bodies and standard lenses.

The days when the world and his wife went around with an SLR complete with 50mm lens are long gone!

infocus
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Dave R Smith wrote:
So if you have 2 cameras, one digital, one 'film' same lens same f-stop and shutter speed, in poorish light with no flash, will image quality be about the same?

Whilst agreeing with all that's gone before, I'm not sure it answers the question as asked. And in short - it depends upon the digital camera referred to. This is perhaps one of the biggest difference between a small pocketable consumer digital camera, and a digital SLR. On my small pocket Canon, ISO400 produces poor results (though excellant at ISO100), whilst on the EOS20D ISO1600 is accepatable, though with some noise. Generally I'd say modern DSLRs outperform 35mm film SLRs nowadays.

I suppose the same may be said about film. Under given conditions a particular film speed may be judged too grainy as a 35mm negative, but OK if used in a medium format camera.

Alan Craven
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infocus wrote:
.

I suppose the same may be said about film. Under given conditions a particular film speed may be judged too grainy as a 35mm negative, but OK if used in a medium format camera.

Yes, but largely because the MF negative requires less enlargement for a given size print! The difficulty with all digital imaging cameras is the small size of their imaging device and hence the enlargement needed for the finished image.

Did not someone once assert that Kodachrome 25 was effectively 20+ megapixels? My Nikon Coolscan produces 55 MB tiff files from these 35mm slides; my 5 megapixel Olympus produces 15 MB tiffs at most. A fair indication of the relative "quality".

Alan Roberts
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Yes, indeed, Kodachrome25 is effectively around 25Mpixels, but that's only the film itself. Project it and you've got the projection lens involved, and so on. The change from, say 5Mpixels to 25Mpixels isn't 25:5 (i.e. 5:1), it's the square root of that (about 2.23:1) in each direction. Plus, figures like these are grossly misleading as well, since the modern digita; camera talks of total pixels, and that has a Bayer pattern (or similar) that delivers resolution up to about 2/3 of the linear pixel count, so a 5Mpixel camera with an image of say 2,300 square, actually delivers resolution up to around 1,700 pixels square because of the interpolation to extract RGB. But fiolm doesn't get it that easy either, because the colour layers don't have the same resolutions as each other, blue is far sharper than red (by at least 4:1).

Once you lift the lid on this can, the worms don't stay still.

Get my test cards document, and cards for 625, 525, 720 and 1080. Thanks to Gavin Gration for hosting them.
Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.

Alan Craven
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Right then Alan, as for me the lid is superglued, nailed and screwed down tight!

Alan Roberts
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I'm happy to lift the lid, but it's a mighty big subject that takes a lot of explaining (I've been doing this professionally for several years now, and I'm starting to get it right :))

Get my test cards document, and cards for 625, 525, 720 and 1080. Thanks to Gavin Gration for hosting them.
Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.

JimBird
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Hi,

I remember reading about a landscape photographer who used his digital camera first to check out the result on his camera’s display before committing the same settings and image to his film camera (TACHIHARA 4X5 FIELD CAMERA).

He said, “This was the best use of a digital format camera”.

Jim Bird.

Alan Roberts
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I can understand that. It's the same approach as using a Polaroid back on a plate camera.

Get my test cards document, and cards for 625, 525, 720 and 1080. Thanks to Gavin Gration for hosting them.
Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.

Dave R Smith
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Red, I checked out your camera, £2500 plus - and thats without the lens.
My question was really in context of 'low light conditions' where consensus seems to be
each can slightly out perform, but the difference isn't a hands down winner on either side.

I'm sure red will be please to know he has a £2.5k light-meter if Jim's landscape man is to be followed.

The discussion seems to be widening from 'low light' context ..
When red points to
> 'at a football match, presentation, or awards event, take a look at the digital camera's >the pro's are using. ',
this may be true, but they are also good examples where other factors dictate medium - such as ftp'ing results quickly to newspaper, tv company etc and 'time' needs to be taken out of the equation.

Would wildlife be on this list? here you have dark / contrasty backgrounds, often shot on mega big lens, so largish aperture. Time is not an issue.

red
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Agreed, time is not an issue

Hi Dave

There are many reviews about the Canon 1D MkII and 'N' on the web. A lot of them are from wildlife photographers who wouldn't use anything else having first been 'educated' by the 1D then MKII then MKIIN, it really is a groundbreaking camera.

http://www.andyrouse.co.uk/gear.asp

I take your point, you do not spend that type of money on a camera and more on a lens unless you use it professionally and your income depends on it. I just thought you'd like to know an opinion from someone who uses this type of camera every day.

For me it's not practical to carry several different formats about all day and compare.
You either go digital or you don't.The 1D MKII and 'N' does the business, time is irrelevant, quality sells, it gives you so much adaptability whatever your circumstance I personally would not dream of taking a film camera on a professional shoot.

To answer the lowlight question, as I said in previous post, it amaze me with the results, even when you think your on a hopeless cause the final image can surprise you with it's clarity.
If the difference is minimal then there's only one way to go, I've made my decision, what will yours be?

Alan Roberts
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I think you're both making the same point, indirectly.

A photographer takes pictures. Period. The technology isn't relevant unless it restricts the funtion. Digital cameras have now reached that stage, so personal preference comes into it, but is often clouded with prejudice.

Get my test cards document, and cards for 625, 525, 720 and 1080. Thanks to Gavin Gration for hosting them.
Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.

Dave R Smith
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Hi Red,
My question wasn't a prelude to purchase (or not), but an understanding of where the technology is (regardless of price) - and where it's going.
A video camera take a perfectly well exposed picture in an unlit room and not seen to be lacking. My expectation is that 'stills' cameras will be able to do this (without flash) - and better - it's just a question of whether it is next month, next year or next decade.

So, while you 'are amazed a the results' , 'and difference is minimal' I would take this as meaning 5 to 30% better than film alternatives, whereas the possibility is 200 or 500% better or more.

I was surprised at the price as video HD cameras are about this price, with more gizmos.
But yes, it is good to know from you what can be done at 'the top end', as this quality will no doubt trickle down to lesser cameras over 6 /18/ ? months.

I realise there are many other advantages of digital, so thats why I tried to keep my question tight/specific. With HD development in video (my business) I am obliged to invest here, wheras photography is a hobby.

So, given our respective trades, we have the same reasoning.

Alan Roberts
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Remember that the biggest HD video format is 1920x1080, although in practice only 1440x1080 is recorded (unless you go to HDCAM-SR or hard-drives), so the images are 1.5Megabytes/colour. At best, that's 4.5Mpixel in stills terms. Stills cameras have far more than that these days, although they're not capable of filling the available bandwidth with content because of the interpolation needed to extract RGB from the Bayer pattern, but they're getting close.

Stills cameras, at the top end, are far better at delivering detail than HD is. But exposure range (contrast handling) is very similar. All the decent sensors will now capture around 11 stops, slightly more when clever processing's allowed. So, while not as wide-range as film yet, digits are delivering all that can be used in a single picture (i.e. not allowing the dodging and shading that I messed around with 30 years ago).

Get my test cards document, and cards for 625, 525, 720 and 1080. Thanks to Gavin Gration for hosting them.
Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.

JimBird
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Have a look at this URL and see what you think.

http://www.kenrockwell.com/tech/meters-digicam.htm

Jim

foxvideo
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Have to say I take a lot of what Ken Rockwell says with a pinch of salt, this is the guy that advocates jpeg over RAW. The LCD on the back of the camera is not reliable enough to use for any sort of exposure in critical conditions, the histogram, yes and this is standard practice recommended for all pro shooters - see the shoot guidelines on Sports Illustrated Photo here

Not sure why you want to use a digital camera as an exposure meter anyway, if you're shooting digital - fine, if you're shooting film - fine, but to use one to meter for the other - the guy's off his trolly!

There still is only one way to get "correct" exposure - incident light - read the light actually falling on the subject, it then can't be influenced by light or dark objects. This is the method you'll see most wedding photographers use as the bride wears white and the groom black, it's also the method you'll see film cameramen using to get exposure correct.

Dave Farrants Fox Video Editing

Willow
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I have not got involved previously, as Alan R had adequately answered this thread.

I have to agree with Dave or Sue F, You should read histograms for correct exposure, with it being centred. It does not mean the cameras settings are wrong, if they read to the right or left.

For a shadow (or night) scene the histogram will read to the left, for a bright scene, say a beach or snow, with lots of reflected or backlit light it will read to the right.
This can be got around by setting the camera to bracket the shot, then manipulating (layering) both the over / under exposed sections in photoshop, to re-create a “perfect image”.

Whilst saying that, I recognise it is better to get it correct in the first place – but this is not always an option.
Also bracketing uses more memory, sometimes unnecessarily.

I often wander around after dark, taking “handheld” shots only using the available light, NO flash, as I want to capture the background too, admittedly this is with a IS lens and no filters to obscure the light going to the lens further, so this gives me a extra bit of room for shutter speeds etc.
Using a tripod I can get longer exposures BUT at the cost of the subject (people) moving (blurring), or others coming into the frame.

Dave S, possibly you can claim the camera costs back against tax? (then, deprecation the following 2 years) and the VAT if you are registered. As a legitimate business expense – I have previously claimed for, and got, some outrageous things offset against tax.
Sometimes you must be asked to produce stills, surely?

Willow

Dave R Smith
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Hi Willow,
Good point about offsetting cost versus taxman.
When asked to do photos I always explain it is my hobby as to justify charging you need current/pro gear which I don' have.
I sometimes take pictures of a video shoot for my own PR as well as for client as a freeby with my 'film' SLR.
In winter I get involved in web design, where digital camera would be handy.

I'm currently costing HD set-up, and extra mike, so 'nice to haves' are taking a back seat
and selling 'spare' XM1 tol help finance.
http://forums.dvdoctor.net/showthread.php?t=37644

rbarry
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Having recently come back from holiday with one camera less than I went out with, I am in the market for a compact digital camera. Whilst most replies in this thread reference pro/semi-pro Digital slrs, the question of low light performance is still relevant to compacts.

I am looking at replacing my stolen digital compact with something like the Fuji finepix F11 ,or if I wait a little while longer, the F30. Having spent some time looking at review sites and user ratings, the F11 looks like a great little camera. This could be that I am biased toward Fuji as I was very pleased with my now missing Fuji Finepix A303.

The article link below about the Finepix F30 is sub titled: "FinePix F30 Zoom: a low light landmark"
http://www.dpreview.com/news/0602/06021403fujif30.asp#specs

What are your thoughts or suggestions, and have any members experience of a Fuji Finepix F11?

Rick.

Dave R Smith
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I'm really sorry you had your camera nicked. I've had camera gear stolen on holiday, so know the feeling - just hope you didn't lose too many prize-winning photos.

For holidays I always take a fuji throwaway underwater camera (fuji's beat competition for u/w use) to supplement SLR. Handy for canoeing/snorkeling and environments where you may damage your posh camera.

However I recently saw an underwater compatible compact digital camera - which I though would be a useful choice. Sorry - can't remember make/model.

rbarry
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Hi Dave, thanks for the reply.
Possibly the Sealife DC500, as featured recently on channal 5's "The gadget show".
The Show likes the Fuji F11 anyway, and featured it in the underwater tests it conducted recently with an underwater housing. Others tested were the Pentax Optio W10 which is water-resistant as it is, without a special housing, but can only safely be used at 1.5 metres and only for a limited time of 1/2 an hour. handy all purpose compact to have though.

The more I read about the Fuji F30, the more I want one!

Rick.

Chris.
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FWIW Looking at my portfolio you'd be hard pushed to say which pictures were taken with a budget DSLR (300D), a mid-range (10D) and my main camera (1DMkII). They all have similar CMOS sensors producing silky smooth images even at high ISOs. The difference is that the 1D is far more programmable, can shoot at a much quicker fps, autofocuses faster, is far more robust and weather sealed etc etc. One DSLR might be six times the price of another, but the pictures are most definitely not six times the quality.

rbarry
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Hi Chris,
what do you use to create your panoramic images? Some people use phtotshop, but there are dedicated programs that do just this, and I was wondering if you use such a program. I have used a piece of software in the past called panorama factory with great results.

Rick.

Chris.
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Hi Rick

I used to use a program whose name I forget, but I'm sure it had "Vista" in it somewhere, then I free-trialed a few different programs with various results.

However, I've found what works best for me amazingly is the freebie Canon PhotoStitch that Canon bundle with many of their cams! The interface is a bit Toys'R'Us / AOL - if you know what I mean - but the results are fantastic. I'm not sure if it only works with images produced with Canon's own cameras, I do know that it reads the EXIF data from the JPEGs which might stop it working for other brands.

If you can get hold of a copy and get it to work, give it a try, it's very, very fast and very accurate.

rbarry
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Cheers Chris,
If the panoramic examples on your images website used Canon Photostitch to create them, it must be a great bit of software. Obviously some thought has to go into taking the pictures in the first place, but you can tell when the software is good at its' job when the stitching of the photos blends the images together without any banding. Thanks for the reply.
Rick.

Chris.
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Joined: Nov 5 2000

Rick
Those website ones are done with Canon PhotoStitch, I have had banding before, but I've learnt to always use manual exposure for images intended for stitching, which unless the light changes dramatically between shots (eg sun goes behind cloud) seems to cure any banding in Canon PhotoStitch anyway, some other programs are a bit overzealous, trying to match exposure across images, getting it totally wrong so you get dark blue sky in one, light blue in another and banding where they join.

Have you any of your Panorama Factory generated panoramas on the www so I could have a look?

tom hardwick
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A big problem with stitching is the very evident vignetting that occurs across each shot when the camera's used to frame at wide apertures and wide angles. So if you plan to stitch later, avoid the two widest apertures and go for a medium telephoto focal length - that way you'll avoid the perspective and barrel distortion that's so evident in a lot of happy-cheepie lenses these days.

tom.

rbarry
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I haven't done any in the last couple of years. I did have some on my pc of my favourite place in Cornwall, but can't find them right now. However, in 2003 I posted one on the photosig website located here:
http://www.photosig.com/go/photos/view?id=1005755&forward=user
This was done using Panorama factory.

Rick.

Chris.
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The buggers at photoSIG won't let me see the picture unless I open an account with them, tsk.

rbarry
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Basic membership is free, I can't remember what the limit per day/week is for uploading photos, but if it's free what the heck! There are loads of similar sites like Photosig on the web, but I quite like it as it is fairly comprehensive and enables you to browse by searching many different categories; by camera make and model being most useful.

Rick.

Chris.
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Joined: Nov 5 2000

Hi Rick

Been off the net a little bit (well back on dial up for a while). I dumped Pipex and am now using TalkTalk's free bb (so far so good btw).

Anyway, created an account at photoSIG and can now see your cornwall panorama properly. Panorama Factory seems to do a decent job, it's a nice shot too.