test chart for the new Hi-Def cams

[tom hardwick]

http://tinyurl.com/6evu5

[Chrome]

Why the hell are calibration charts so expensive? These ones seem to follow suit.

Sure I understand their creation is a precision job, working to very exacting tolerances (0.1mm being the finest it appears; not that small), ensuring that shades & paletts etc. are uniform and accurate...

But essentially once the work has been completed it's really just a poster. I presume the printing is in fairly high res possibly 1200 dpi+ and the printing machines have to me precisely calibrated as well, but it's still just a poster!

BTW - Though I work exclusively in video now, I have been a digital artist for quite a few years producing imagery and graphics for games/video/film & print, so I know a little bit about this subject.

[tom hardwick]

I think the people who use expensive test charts properly are the same people who buy big BMWs rather than little Nissans. Both cars will get you A to B, but the pleasure is in owning something that you know has been built (or printed) to tighter tolerances.

tom.

[Alan Roberts]

Don't knock test charts. They're very hard to get right. It's easy to make a cheap one, I do it all the time, but then you need to interpret it intelligently. The thing about the expensive ones is that they're totally accurate, and they get that by having a very small production yield.

That said, the zone plate chart I had at DVC was printed on a conventional Canon printer, but was drawn directly in Postscript.

[Chrome]

I wasn't trying to "knock" test charts Alan. I certainly know their worth; many years ago I used to use them to test/prove camera lenses for a photographic dealer. They based their 'new' stock lens cohices on the results; only the best at ech price range were stocked.

I just wanted to point out that they could be sold for say £50 and the manufacturer should still make a whopping profit. They would certainly sell many, many more surely? I would certainly buy one (or more) and affix it to my office wall in order to calibrate and test my cameras. As it is I find things like back-focus notoriously difficult to get 'precisely' correct, but I'm buggered if Im going to pay $800+ for a 'poster'.

[Alan Roberts]

The problem is yield. A Canadian company that does nice ones has a yield of less than 3% for it's best charts. That means not omly that 97% are thrown away, but someone has to check everything to decide which gets sold and which hits the bin.

All this can be solved by using simpler charts. The good/expensive charts test a lot of things and are worth every penny. But if all you want to do is set back focus, you can use a simple star chart (there's a Corel file for one in my set of test cards, posted on your site smile.gif )

[Chrome]

Ah I see... never really thought about 'error', 'inspection' and of course therefore 'yield'. Now I understand Alan, thanks.

[cstv]

but they can't just throw them away!!! :eek: i want one (or more) to stick on the wall! The one Alan had at DVC was beautiful! Test cards and tube maps - some of the bect posters ever made! :D

[Alan Roberts]

The EIA1956 chart is fine for many purposes. I got it as a Corel file from a web source, only 4:3, but I've expanded it to 16:9 and added resolution blocks that take it up to HD resolutions. I'll happily email it to anyone who wants it. You can print it on any good printer, but it needs at least 1440dpi on an inkjet for A4, and even then the highest frequency blocks can show aliasing.

The zone plate chart was created at BBC R&D, at my instigation. It exists as a Postscript file, the copy I had at DVC was the first prototype of it. The grey level isn't right yet, but it doesn't really matter if you know what you're doing. BBC R&D is negotiating with a distributor to see if they can make it available commercially. Until that's done, the best way to contact them is through me. I'll contact the R&D folk to see what progress is happening.

[timropp]

I'd love an email of that chart Alan...
email is tim at ropps dot net.

Thanks!

[DV_Ed]

Alan, I two would like one of these, if you would be so kind my email is ed at micra.org.uk

smile.gif

Ed

[tom hardwick]

And me too please Alan. Oh my, we're a sad lot, aren't we? Test charts instead of beautiful women.

[branny]

This saddo would like one too please.

[Alan Roberts]

OK guys, sending soon.

[tom hardwick]

We're feeling less sad at the thought, Alan.

[Alan Roberts]

The difference is you can print your own test cards, beautiful women are not so easy to come by.

[Stigg]

Perhaps a small collection could go on the next mag DVD?

[Alan Roberts]

I did a collection of video test cards (with explanatory notes) ages ago, they're still hosted in the CV mag site somewhere. I'd have no objection to them going on the DVD.

[branny]

Thanks for the image Alan. Unfortunately I dont have an image viewer for cdr files. Any chance of a Tiff, or is there a workaround?

[harlequin]

http://www.bealecorner.com/trv900/respat/
has them available in multiple formats including pdf.

i assume these are the same as the ones alan is talking about.

[Alan Roberts]

The whole point about using Corel Draw is that the file contains only vectors, no bitmap. The resolution isn't defined until you send it to your printer. A tif is a bitmap, so I have to know the rewsolution of your printer, and you get an enormous file that will work on only one printer. Anything else simply won't produce a test card that will make any sense, it'll have alias patterns already built in so you'll not be able to see exactly what the camera's doing. PDF has the same problem, it's a raster file, so the resolution's fixed. No good for text cards. That's why Beale offrers so many variations, because each is fixed at a resolution.

Have you tried importing it into Word? That has a viewer (not very good, but better than nothing).

[harlequin]

The pdf version i have just printed off on my epson 2100 looks as good as the ones that came with my sony dsr-370's.

[branny]

Originally posted by Alan Roberts:

Have you tried importing it into Word? That has a viewer (not very good, but better than nothing). [/QB]smile.gif
Thanks I'll try that.

[StevenBagley]

PDF has the same problem, it's a raster file, so the resolution's fixed. No good for text cards. PDF is vector I can assure you, it's just a compiled form of PostScript (also vector) with the loops removed. If someone supplies me with an EPS of the diagram I can convert it to a vector-based PDF.

Steven

[Alan Roberts]

Steven's just emailed me a pdf of the file, and it's fine. He's going to post it somewhere and tell you all the URL. I've kept a copy. I now have it as pdf, cdr, ai and pct, all are vector form.

[StevenBagley]

And the PDF version is at

http://homepage.mac.com/stevebagley/EIA1956wide.pdf

Steven