Camera Testing Suit

Lens Projector

Ok so only my boss would go and blow £20 k ish on a projector that can’t even show the rugby on a big screen let alone my old 35mm slides, I know he’s crazy but this seems excessive even for him.

I’ve had a look at our latest toy and tried to get my head around what it is and why it cost quite so much for what essentially seems to be a rather nice torch. Now I’m dipping my toe into the techie world of lens testing and maintenance and that’s difficult when you wear steel toe capped boots like me but here goes.

For those of you in the know it’s probably sufficient just to say we now have a dedicated testing bay for our snazzy new Chrosziel LED TP-7 lens projector and its available for crews wishing to check lenses prior to shoots and obviously for us to inspect and maintain our own extensive collection of glassware. If you know what I mean then you can skip to the end of the blog and save yourself five mins. For the rest of us let me try and explain what a lens projector is and why you should be impressed that we have one and that its available for you to use.

So, as I say the LED TP-7 is a very nice torch, it’s a techy looking black box with a LED inside and a mount to attach lenses to the front. So, it projects light through the lens from the back to the front and out onto a nice white wall. The thinking behind this is that enables you to see any lens defects or flaws and to inspect and compare lens characteristics. Lenses don’t care what end light comes into I’ve tried this by flipping the odd DSLR lens round to make a Heath Robinson macro lens back in the day so it makes sense to me that any issues with the lens will be highlighted and easier to spot with this arrangement. As most lenses reduce the size of the image to fit onto the camera sensor then projecting light backwards through the lens would make the image larger and hence make anything naughty easier to spot.

With me so far?

So, the lens to be tested is set up on the front of the TP-7, the lights are dimmed to make it more romantic and the 5000 k LED light is turned on. This projects a 60mm circle of light into the rear of the lens. This is then projected onto the wall or a lens testing chart through a reticle*.

The lens can then be focused, zoomed and so on to test for geometric distortions, chromatic aberrations, sharpness, fall off, internal barrel flare and any breathing issues and so on.

This means we can test our kit to ensure its performing at optimum levels before it ends up on your shoot, you can double check this and compare different lenses to find what best matches your specific requirements and then we can do it all over again when you give it back and tell us that you didn’t really drop it, well not very hard anyway.

It’s all about accuracy when we are talking about lenses especially when testing and this is why a projector that only projects light is quite so expensive. The TP-7 is about as accurate as you can get with tolerances down to below 5 microns* (that’s quite small in fact the same as the length of a typical human spermatozoon’s head or half as long as a typical bacterium)

Here is a pic of a 6 Micron thick carbon filament resting on a human hair to give you an idea (note I spared us all a pic of a spermatozoon (that’s a singular spermatozoa))

Sorry I can’t resist here is a pic of Mr Woody Allen who presumably has a head that’s only 5 microns in size.

The TP-7 has some rather nice features, as I said it projects an evenly lit 60mm image circle so it can simulate camera sensors up to KPL format. Also a 3x3 glass filter insert is present between the lens mount and the reticle to allow for simulating glass in specific cameras up to 7mm thick and another between the light engine and the reticle to allow for colour correction filters up to 4.6mm. It even has a little LED work light so you can see what your doing.

below is a grab from the Chrosziel website as they explain it all much better than I can but if you have any questions just give us a call and I’ll get one of the tech guys to bore you to death for an hour or two.

Ok I can’t give this a very high rating on my Brucie coolness scale I’m afraid, yes it’s a very very nice example of what it is but that’s the trouble, it’s a back room sort of thing, something we have to have but not something we would choose to buy if we didn’t need it a new lens or light would be far more fun so I’m going for a 5/10 BCR. What is cool is that we have one and we will even let you use it, yes YOU, now that is cool 10/10 cool in fact. Our lenses will continue to be tip top (not that they were ever anything else) and you can now see that for yourselves!

Please be aware we do require you to book the testing facility so we can ensure all the lenses you want to test are at hand on the day.

Cheers BB

*Reticle, a series of fine lines or fibres in the eyepiece of an optical device, such as a telescope or microscope, or on the screen of an oscilloscope, used as a measuring scale or an aid in locating objects.  (Well I didn’t know that may be useful if you play scrabble.)

*Micron, or Micrometer is one millionth of a metre or one thousandth of a millimetre, in other words its really rather small.