GS400 lens hood?
 

I've been searching for a lens hood for my GS400 but i can't find one! Does anyone know where to buy one or maybe just the name of a model that works?

thanks!

Is this what you're looking for

http://www.bhphotovideo.com/bnh/cont...ughType=search

Jim

I don't know if the GS250 filter size is the same as that on the GS150,
but here is what I just mounted on my GS250.


http://www.bhphotovideo.com/bnh/cont...ughType=search

Hama 49mm Snap-on Rectangular Plastic Wide Angle Lens Hood with Cap

Also, you'll need a 43-49 step up ring. Without the step up ring, I don't
even see how the hood would attach to the GS250.

For the GS400, there are a number of hoods that work. I recommend 55mm clip ons like Hama or the Konica 28mm hood. Examples of hoods are (click) here.

Wow, that is a great page on snap-on hoods, complete with pictures.
Thanks, Guy. Though, note that an addtional filter ring must be

I just bought a Hama hood that appears to be for the 16:9 apect ratio.
Since I shoot in 4:3, will I have better flare protection with a 4:3 or 1:1
hood ?

Also, the Kama wider hood partially obstructs the reception of the IR remote control signals.

The optimum hood is one that has the same shape as the CCD.

Check out this auction: http://cgi.ebay.com/58mm-lens-hood-U...QQcmdZViewItem . When I had GS400, I bought that hood and it fits the cam perfectly. Before they were selling it separately, but now they seem to be pushing the filter together with it. Note that you will need some stepup rings, for example 43-52 and 52-58.

What about when one has a wide-angle adapter (eg. I have the Raynox .66x with a 72mm thread)?

No idea as I haven't tested with an extra lens. I guess the hood needs to go when you are filming with additional adapters :(

I ended up making one. There were none available in the size and 16:9 profile that I was looking for.

You can check out the Cinetatics Matteblox or the Kenko RCH085 85mm wide angle hood.

Actually, I was thinking that making one is a very good option. I guess the question is what shape it should be.

I presume that it should be some kind of petal shape on the sides if one wants to maxmise shading without incurring vignetting, but how to actually get the best shape must be a matter of trial and error. Advice welcome...

Thinking about it, it should be possible to calculate mathematically the shape. Perhaps I'll have a go at that.

So probably best to prototype something in cardboard and then build the real thing from some kind of durable plastic before spraying with the mattest of black paint to prevent internal reflections?

Later: Of course the petal shape only applies for parallel-sided hoods. The way to go here is a pyramid fustrum shape which should be easily calculable.

The ideal shape for 16:9 is a rectangular hood in those proportions. Bigger is better. You don't need math (although I did use Visio for my templates). You can use paper to create a mockup to check for vignetting at full wide. In my case, I used mouse pad material with ballistic nylon glued to it (fabric spray glue). The hood is sewn on the seams with velcro being used so it can be collapsed. Stiff plastic is inserted along the outer rectangle to keep it stiff. I have a 72mm UV filter with velcro crazy glued on its rim to keep the hood in place. The Cinetactics hood was my inspiration. Works great.

Thanks - sounds good! I've no idea what "velcro crazy" is, but I'm sure I can improvise something....

Let me rephrase, "Crazy glue was used to apply a strip of velcro on the rim of a 72mm UV filter." :-)

Out of interest, does a UV filter help the image in any way? I do like the idea of some glass to protect the (expensive) WA adaptor

They say it does in some conditions, but I didn't notice it at all when I used one on my GS400 and it more like messed up the video, because when powerful light like sun entered the lens from appropriate angle, the picture got a big reflection of the UV filter. I'm now trying to skip the filter with my VX2100 and am using it only in conditions where the lens could get dirty for some reason. Instead I apply lens cap whenever I don't film.

Pics

Templates

If you save the jpgs to your hard drive and print them full page, they'll be to scale.

Alex - I'll say it again - a 72 mm filter costing £11 won't be coated at all, believe me. You go to your Panasonic shop and hand over £1200 for your new cam. The salesman smiles and tells you matter of factly that the front element of this fine 12x zoom lens is completely uncoated. How do you feel now? Would you still buy this model when the fully multi-coated version cost just £13 more? No you would not, and for very good reason.

I have a test I show people. I have two VX2ks. One has an uncoated UV and the other has a Hoya S-HMC UV. In less than 3 minutes I would have you skimming your £11 UV out over the lake, and you'd be smiling as you did it.

Ignore the UV side of things as all glass absorbs UV. The mechanical insurance protection offered by another slab of glass in front of the lens has to be weighed against the disadvantage of adding two more (dust-attracting) surfaces and the fact that converter lenses require you to take the filter off. Don't filter the front of the Raynox - the threads are there for attaching a hood. The massive DOF means however clean your filter, it's never clean enough.

Use the aspect ratio hood that came with your cam and dispense with the filter. This is my recommendation.

tom.

Thanks for the reply, Tom, and sorry to be dense, but I don't understand what you are advocating!

What is the purpose of coating?

BTW - I didn't get any hood with my cam, and I'm mostly worried about a hood for WA adaptor use.

You're not dense Alex, you're learning. Nothing wrong with being a student, and the brightest ones are the ones who ask all the questions.

Lenses are coated to increase the amount of light that is passed through the glass. There's also coatings to harden the surface of plastic elements, but we'll ignore those.

If you take a sheet of ordinary glass and shine a light at it, about 8% gets reflected back and doesn't pass through. This 8% comes off the front surface (entry) of the glass as well as the second (exit) surface. If lenses are coated - or better yet multi-coated, this reflection is reduced to about 0.5%, meaning that now 99.5% of the light gets through. The very best coatings (Zeiss T*) pass 99.9% of the light.

We're not overly concerned with losing 8% of the light - it's almost impossible to spot in an A/B test. But your average 12x zoom will have 13 or so elements making up the zoom, and you can imagine what would happen if each element reflected back 8% of the light that struck it. If the windows of your house comprised 13 panes of glass the outside world would be take on a nasty dim green colour.

The problem with uncoated optics is the reflection causes the light to 'bounce around' inside the lens cylinder, and this ends up washing over the image and causing what's known as veiling flare. The very best coatings are delicate, so spectacle wearers have to settle for 2nd best just to allow them to survive without scratching.

Do get a hood for your cam, and especially for the w'angle Raynox. That lens (to save money) only has a single coating, and a hood is a real necessity I find.

tom.

Thanks for that, Tom.

I presume that what you've left unsaid (as an exercise to the reader!) is that some of the problems of lack of coating can be significantly reduced through use of a lens hood.

Perfectly correct, star pupil.

What you want to avoid is non image-forming light hitting the front element. Once it hits it gets ducted into the lens, bouncing around and degrading your image. Sometimes this can be used to effect, and Photoshop, PSP etc include this 'failure' filter simply because modern coatings are so good.

So first off, ensure to the best of your ability that this doesn't happen. Use a hood (aspect ratio shadowed ones are best, petal hoods are good, cylindrical ones are better than nothing as is your hand held up, or ensuring the front element is held in a tree's shadow or something).

It takes but a few extra seconds to look down at your shadow when shooting into the light. You might only have to move a couple of feet to shadow the front element, and look - much better image quality at a stroke. Not only that but hoods that come fitted to zooms are only efficient at the wide-angle end. They're horribly inefficient at telephoto.

Pop over to www.cavision.com. They do a few good hoods and flags and matt boxes.

And lastly, remember this. Any imperfection in the lens coating will negate its effect almost entirely. One single fingerprint (greasy by its very nature) will allow light to enter the lens element, even if it's T* coated.

And point two. A lens hood is the cheapest, lightest, simplest way to improve your picture quality. The next accessory up - the tripod - is many times dearer.

tom.

Alex, the Raynox .66's 72mm face just loves to introduce flare of several types into your images...some of it not obvious like the veiling Tom refers to. In my opinion, this lens absolutely requires the largest hood you can find or make. If you look at my design you'll see that it is fairly large, and it observes a 16:9 ratio of width:height. Quite frankly, a french flag should be added on. Don't bother with a screw on plastic hood. None of them will be big enough to be worth buying.

I regulary use a 72mm Tiffen .6ND, and a Tiffen 72mm circular polarizer on this lens. The filters were not cheap! You do need to keep things clean, but getting the GS400 into the F5 range pays off when you examine your images. If you are using auto mode in bright conditions, the camera will peak at F16 and 1/60s so you must either add the filters, or switch to manual and crank your shutter speed. If you check out the pics and clip here you will see the lens flare fire up as the crane'd GS400 with .66 WA turns toward the sun, even with my large hood attached.

OK, so what's your latest mad invention?!!!

I see that was back in January - are there any other new clips around showing use of the crane?

Chuckles quietly to himself ... Here's the latest.

Nice rig Dennis, and good to see you're using a 16:9 hood - and I presume you're then shooting 16:9?

Just a reminder that your Panasonic may well indicate f/16 while recording and on replay later, but this is just an extrapolation of the figures of course. The automatic internal ND filters won't allow apertures as small as this as the diffraction losses would be quite unacceptable in a camcorder with such tiny chips. It's much more likely that you're shooting at f/4 or f/4.8, and the internal ND is soaking 4 stops of light.

tom.

Yep, pretty much 100% 16:9. I've done a fair bit of testing on the cam in auto and manual mode, and judging from the blown out footage in bright snow, it just maxes at F16 then overexposes in auto mode. Although the internal ND filters have been documented in Panasonic's PV953, I've yet to see anything in official print on the GS400...although it is assumed they are there. Have you found anything on this?

I did some carefull analysis on the GS400 at F8 vs F16 (using a .6ND and CP) and did observe noticeable image degradation at F16. Ever since then I've tried pretty hard to stay in the F5 to F8 range.

Manufacturers are very coy about their automatic internal ND filtration. My MX300 has a ND attached to the lower aperture blade and at small apertures this comes on axis automatically. Stupid thing is that at full telephoto there's ALWAYS ND in place, so making the camera even worse in low light if you use any tele at all. No wonder they keep quiet.

I tested the Sony PDX10 for Computer Video magazine here in the UK, and found (completely undocumented) that it contained 3 ND filters. These are slotted into the light path one after another as soon as the aperture blades hit f/4.8. But the PDX10 doesn't give aperture readouts (and this is supposed to be a pro camera?) and on replay the display figures are just wrong. This is a polite way of saying Sony lies to us.

The MX350 and 500 both give made-up figures for aperture values - going as far as f22. Nonsense of course, but the punters feel happier to read figures on rec and replay. I'm betting the GS400 uses exactly the same technology, but I've yet to see it for myself. I write not a word till I've seen it for myself.

Sony's TRV900 insisted you inserted the ND manually, but folk would often forget and the camera would then have to up the shutter speed to compensate. But even so, using f/9.5 (when the higher shutter speeds were brought into play) would still give soft images at wide-angle. This is because very short focal lengths are much more susceptible to diffraction losses.

So yes, do try and shoot at f/4 or wider with a 1/5" chipped camcorder, and certainly with a 1/6" camcorder consider f/4 as the smallest aperture you should ever use.

Not too that the C-Mos chips of Sony's new A1 don't require internal NDs.

tom.

You raise some interesting points Tom. It makes sense though that the cam would report a "virtual" F stop as opposed to a physical correlation with the iris blades. The stinker on the GS400 is that in auto mode, it does not deviate from 1/60s shutter. This means in bright conditions you must switch to manual and up shutter speeds, add filters, or use one of the AE program modes that actually will change the shutter speed. I discovered this very quickly shooting ski stuff...same problem on the water.

You got me thinking so I strapped on my LED headlamp, put the cam in manual, zoomed to 50% so I could watch the iris and here's what I observed.

At OPEN (F1.6) the iris is fully open (diamond shaped).

F2.8 it closes a bit.

Now from F2.8 to F8, a square ND filter (looks to be one piece, but darker part way down) starts to slowly advance across the iris. Each time you increase F/stop, the ND filter moves up slightly. The iris itself does not appear to move at all.

From F8 to F16, the ND filter is fully deployed, and I can only assume that the iris then physicaly closes. At F2.8, it is still almost fully open.

Here's a pic posted up "the guru" Guy Bruner

Because the internal NDs are slivers of uncoated gelatin they have to be placed at an angle to avoid introducing lots of nasty reflections. Not only that but there are many times when you're shooting through the edge of the filter - a nasty solution but workable simply because the filter is so well out of focus.

By far the best way - for a photographer - is to have manually introduced fiilters (TRV900, DVX100, VX2100, GL/XL Canons) - that way you're in control. When you select f/8 for it's depth of field you know you're getting f/8 - modern cams shoot nearly everything at f/4.8 with greater or lesser amounts of ND to make up the difference.

The diamond shape you observed Dennis is due the the Leica lens only having a two bladed diaphragm - like the very simplest Super-8 cameras of 30 years ago. Herr Leica would be turning in his grave if he knew. The TRV900 has a beautiful (but far more expensive) 6 bladed diaphragm, and this of course is more efficient (it opens to a perfect circle at maximum aperture) and gives much nicer 6 point highlights on sparkly water.

I must say I don't like hidden ND filters, but I have to admit that they do work well, especially for the millions out there who want their cam to work indoors under a single lamp and out on the ski slopes imn blazing sunshine. In the latter regard I'm very surprised to hear that the GS400 doesn't up the shutter speed automatically. How do you know this? Are you believing the readout when you hit 'display' later? Are you also believing the f/11 readout? Big grin.

tom.

Tom, I'd can certainly see how the F/stop is a calculated value, particularly after looking at the ND filter's operation. What I can accept though is that the shutter speed value is not changing in auto mode. We've done experiments on shutter timing and CCD charge times corelated with NTSC field timing (done by filming a marked disc spinning at 3450 rpm) and I can tell you that when this cam indicates 1/60s it is...at least under the shoot conditions in the experiment.

Also in very bright environments the picture is blown out in auto mode. Switching to manual shows the cam at its "virtual" F16, 1/60s and zebra bars everywhere. Once the shutter speed is upped sometimes as high as 1/250s, then the zebras disappear. The difference in the footage with these speeds is fairly obvious too. I've found auto mode with the GS400 useless on open ski hills with direct sunlight.

I'm interested in your thoughts though as I really haven't considered the shutter speed to be extrapolated.

EDIT: Sorry that experiment was done at 1/500s...and the CCD charge times were indeed 1/500s.

I also remember GS400 not changing shutter speed automatically. VX2100, for example, has a special setting in the menu called AUTO SHUTTER which probably makes it able to change the speed automatically.

Quite correct Georg, and I have it switched off at all times. For any filming of movement even doubling the shutter speed to 1/100th sec (I'm a PAL man) gives a most noticeable staccato effect, and of course spoils any chance for making fluid slow motion later. Not only that but you've only soaked a stop, not much when an ND8 can easily soak 3 stops.

Interesting to hear that the GS doesn't up the shutter speed Dennis. The TRV900 does it, but the PDX10 does indeed choose smaller apertures if the light gets too bright for the three internal NDs and f/4.8. Of course this degrades the very fine picture quality, but going the other route (aperture priority automation) gives some very strange effects.

I've seen PDX10 footage where propeller aircraft have their propellers come to a standstill as they lift into the sky and then go round in reverse. Of course this is just the propeller blades strobing with the camera's shutter, but it doesn't half look strange.

High shutter speeds can look pretty good sometimes (think battle scenes in Ryan, Brothers, etc) but in small, mega-chipped camcorders CCD smear gets to be a real problem, and the PDX10 is unusable above 1/300th sec in my view. Camcorders with bigger 1/3" chips (VX2100) are much better in this regard.


tom.

Nice information, Tom.

I have the auto shutter currently switched on and it works quite well. I've also noticed that with higher shutter speeds the motion is not fluid and it might be disturbing sometimes.

I was a bit surprised on the shutter speed behaviour in auto too. Several of the program AE modes, however, will increase shutter speed. "Portrait" mode for example attempts to maintain a low f-stop (for what little DOF there is) by upping the shutter speed.