Your Camera Equipment

[Sir Stiggington]

I'm seeing some pretty good prices for lenses on ebay. Just wanted to know if it's a good idea to buy your stuff there, or if it's a big no-no...

Anyone done it?

[evoWALO]

Camera: Canon EOS 5D Mark II
Exposure: 0.1 sec (1/10)
Aperture: f/2.0
Focal Length: 200 mm
ISO Speed: 4000
Exposure Bias: 0 EV
Support: Handheld

Got this last 31st from HK. Landed cost is $100 lower than what is available online.

[47]

mmm, carbon

How does that perform, I mean being so light? I thought tripods are suposed to be nice and stable.
Heavier seems like a better option. And I've held a CF Gitzo, and daaamn that's light!

[sifu]

thats what sandbags are for..

[47]

Originally Posted by sifu

thats what sandbags are for..

*googles sandbags*

oh, I see...

[matt2000]

Originally Posted by Sir Stiggington

I'm seeing some pretty good prices for lenses on ebay. Just wanted to know if it's a good idea to buy your stuff there, or if it's a big no-no...

Anyone done it?

I bought a used Nikkor 55-200mm VR on there last year, was the best buy I've ever made. Think I got it for something like £130, when the RRP is still £250 now.

Shop around, there are some great deals on there, but I would only but lenses that have everything with them (if the owner hasn't taken the care to include the box/soft case, then how much care have the taken with the lens?)

I need a new tripod because the head on my cheapy one broke off (don't ask how, I have no idea). Looking for something solid below £40, suggestions welcomed.

[evoWALO]

Originally Posted by 47

mmm, carbon

How does that perform, I mean being so light? I thought tripods are suposed to be nice and stable.
Heavier seems like a better option. And I've held a CF Gitzo, and daaamn that's light!

I don't think 6.5lbs is light. It can handle 55 lbs of gear. Recommended for any focal length from 14mm to 1200mm. Stability is related to torsional rigidity strength. You can also add weight be it sandbags or your camera bag via the screw-in hook under the tripod base.

Before the Gitzo I had a 1.7kg Manfrotto CF tripod that can handle 8kg. Boy did it vibrate from the wind and I was loading it with 8kg of gear. Vibration worsens when I start shooting as the tripod cannot dampen my movements. The Gitzo doesn't suffer from this deficiency.

The difference between the two is like night and day. I now appreciate why Gitzo charges a premium. Now I'm going to reassign the Manfrotto 055CXPRO4 to the ballhead I ordered and use it with the 300/2.8L IS and shorter lenses. Though indirectly based on Gitzo's studies an 8kg tripod is ideal for 200mm or shorter lenses.

The lighter the gear the better in my book. Now I have to lug around 14kg.

[BerserkerCatSplat]

Originally Posted by evoWALO

Stability is related to torsional rigidity strength.

What on your tripod is undergoing torsional stress? Flexural rigidity I can see, but torsional?

[evoWALO]

Originally Posted by BerserkerCatSplat

What on your tripod is undergoing torsional stress? Flexural rigidity I can see, but torsional?

I'm glad you asked that.

The torsional stress is related to how stable your camera + tripod is when acted upon by an outside force like the photographer using the camera, wind blowing, etc. In other words will having a tripod be a help or a hindrance in how low of a shutter speed can I use with the camera mounted on the tripod before camera shake becomes evident and will my camera topple over into the drink or to hard concrete if a gentle breeze will nudge it a bit.

Ideally the tripod’s torsion angle should always be lower to the view angle of the longest focal length lens you intend to use. Before learning such things I bought a 8kg max capacity Manfrotto 055CXPRO4 tripod for my 800mm lens as the camera + lens + plate + gimbal head was 8kg and my assumption was buy to max weight and did not factor in Newton's 3rd Law of Motion. But my experience at the beach taught me otherwise as I was suffering from lower than normal keeper rate as compared to shooting in my backyard and the wind was really shaking up the tripod even when I am not touching it.

It is like filling a glass full of water until the brim and expecting no spill when moving it normally from the tap to your mouth. You need a certain amount of allowance to not get wet. It is a bad analogy but it should serve its purpose.

Now on a handheld 35mm full frame body with a 200mm lens without any form of stabilization should use a shutter speed of 1/200 to avoid camera shake. This isn't always the rule as some can hold it for longer or shorter than that but that's the generally accepted convention. With 5 stops of IS or VR you could go slower than that. The photo of the tripod was taken at 1/10 with 5 stops of IS handheld. With a good tripod I bet I could go lower than that.

Going back I was expecting my gear to increase to 10kg by December so I started looking for a replacement for it. I was looking at a 18kg capacity tripod but was discouraged because of the length of my lens so I went with what 99% of owners recommended which is the 25kg capacity Gitzo tripod.

For those interested Gitzo did some tests using popular DSLR lenses and came out with recommendation on which Gitzo tripod Series to get. Seeming Gitzo nor anyone for that matter gave a measure on torsional stress capacity I am instead basing what tripod is appropriate on max load capacity.

400mm or longer 20-25kg capacity tripod
300-500mm 18kg capacity tripod
300mm below 9-12kg capacity tripod
200mm below 8kg capacity tripod
135mm below 5kg capacity tripod

Now I'm looking at a good ballhead to use with my now headless Manfrotto to be used with my lenses 300mm and below. I know it isn't recommended but at least it isn't maxing out the load capacity.

[BerserkerCatSplat]

I fully understand tripod weight standards, but I'm still not seeing where any part of your tripod would be undergoing torsional stress and why that would affect your buying decision. Flexural rigidity keeps the legs from bending longitudinally, which is a prime concern, and the leg angle affects the applied moment ratio between static load and applied overturn load, but there's nothing under any kind of normal operation that's going to induce torsion.

Are you just confusing torsion and longitudinal flex?

[evoWALO]

http://www.gitzo.com/webdav/site/git...TALOGUE_GB.pdf

page 10-11 should answer your question further.

[LeVeL]

[evoWALO]

Originally Posted by LeVeL

[BerserkerCatSplat]

Originally Posted by evoWALO

http://www.gitzo.com/webdav/site/git...TALOGUE_GB.pdf

page 10-11 should answer your question further.

Ah, they're using "torsional rigidity" as a sort of layman's term for the resistance to the applied moment of the whole assembly.

However, how you've described it as a tripod feature is quite inaccurate.

Originally Posted by evoWALO

I'm glad you asked that.

The torsional stress is related to how stable your camera + tripod is when acted upon by an outside force like the photographer using the camera, wind blowing, etc. In other words will having a tripod be a help or a hindrance in how low of a shutter speed can I use with the camera mounted on the tripod before camera shake becomes evident and will my camera topple over into the drink or to hard concrete if a gentle breeze will nudge it a bit.

No, not really. Gitzo's idea of "torsional rigidity" is its resistance to the tripod twisting while panning, rather than having anything to do with static stability. You could make your tripod out of a single piece of rigid carbon with perfect "torsional rigidity", and your toppling point will still only be based on leg splay, flexural rigidity, and mass distribution. A torsional force, even using Gitzo's definition, can only be applied in a plane parallel to the ground, hence how true torsion cannot possibly cause a tripod to tip over. An off-axis applied force that causes a moment about the center column could cause it to tip, but that's due to the offset force, not torsion.

The photo of the tripod was taken at 1/10 with 5 stops of IS handheld. With a good tripod I bet I could go lower than that.

I, er, would really hope that your tripod would allow you to use longer shutter speeds.

For those interested Gitzo did some tests using popular DSLR lenses and came out with recommendation on which Gitzo tripod Series to get. Seeming Gitzo nor anyone for that matter gave a measure on torsional stress capacity I am instead basing what tripod is appropriate on max load capacity.

400mm or longer 20-25kg capacity tripod
300-500mm 18kg capacity tripod
300mm below 9-12kg capacity tripod
200mm below 8kg capacity tripod
135mm below 5kg capacity tripod

Uh, OK? The "torsional rigidity" described by Gitzo has exactly nothing to do with weight capacity, and everything to do with the amount of slop in the leg joints, because that's all it is. If your leg joints (that are in bending and shear, not torsion) have play in them, then the tripod will twist when panning or under off-axis loads. The only other way to cause twist is for the legs themselves to bend - which is 100% determined by flexural rigidity, not torsional as the individual legs are never, ever put in torsion no matter what you do, short of removing the leg, putting one end in a vise, and twisting it.

[Ramseus]

Originally Posted by BerserkerCatSplat

the individual legs are never, ever put in torsion no matter what you do, short of removing the leg, putting one end in a vise, and twisting it.

oh... that's not the right way? I guess I'm doing it wrong then...

[evoWALO]

Originally Posted by Ramseus

oh... that's not the right way? I guess I'm doing it wrong then...

That makes the two of us.

[BerserkerCatSplat]

Well stop it then!

[evoWALO]

Without doing a Gitzo "torsional rigidity" test how do we know which tripod is appropriate for which focal length?

[BerserkerCatSplat]

Depends on what your application is. You'll find that having your legs angled properly or the tripod counter weighted will prevent it from overturning in the strongest of winds, and will give you the most effective stability in static shots. If you're doing a lot of panning with long lenses, I certainly agree that a higher-end Gitzo with tight joint spec couldn't hurt. However, you're far more likely to see benefit from a good low-drag head that imparts very little stress on the tripod itself, as that "torsion" can only be transmitted through friction via the head. I believe you have a full Wimberly head, no? That should be sufficient for the vast majority of applications.

[matt2000]

What's the general opinion of the Nikon 50mm AF-S f/1.4G lens? Looking at a couple of used ones on eBay (new ones are just too expensive) and from what I've read on Ken Rockwell's site and others it's one of the best lenses around for general photos.