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Author Topic: I'm a lucky fella!  (Read 2667 times)

Justan

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I'm a lucky fella!
« on: December 02, 2010, 10:12:12 am »


I carry my camera gear in and a good sized backpack which sits in the back of whatever vehicle I'm using. I've never been one to carefully package my camera stuff when not in use. Recently I was moving a bunch of stuff around in my suv to make room for something. Due to this I lifted my pack out. As I did, my Sigma 17-70 mm macro in it’s cloth case popped out of an open compartment in the pack and went tumbling end over end. I watched in horror as it exited the pack and arced downward towards the concrete floor of the garage. It hit the floor with a dull thunk and rolled a ways before coming to a stop next to a tire. There was nothing for it and I resigned myself to be paying for a repair bill or a new lens.

I didn’t want to look so I put the lens back in the pack and continued with what I was doing.

A few days later I took the lens out of the case and there was no physical damage! I used the lenses adjustments and there was no sign of miss alignment or unusual resistance to any moving parts!! I did a bunch of test snaps and amazingly the lens appears sharp and can focus from about inches away (or less) to infinity at every focal length I tried.

So here’s the question: Are there any standard tests I can use to measure sharpness at various focal lengths and distances? I'm beginning to think I got away clean on this accident but want to test the lens before I put it back in service.

Gary Brown

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Re: I'm a lucky fella!
« Reply #1 on: December 02, 2010, 10:32:14 am »

Are there any standard tests I can use to measure sharpness at various focal lengths and distances? I'm beginning to think I got away clean on this accident but want to test the lens before I put it back in service.

This might be useful as a general guide: How to test a lens.
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Rob C

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Re: I'm a lucky fella!
« Reply #2 on: December 04, 2010, 10:36:45 am »

I did a bunch of test snaps and amazingly the lens appears sharp and can focus from about inches away (or less) to infinity at every focal length I tried.

So here’s the question: Are there any standard tests I can use to measure sharpness at various focal lengths and distances? I'm beginning to think I got away clean on this accident but want to test the lens before I put it back in service.



Forget the checks: if your lens suddenly gives you that amazing new depth of field at all lengths, why worry? Be thankful for the ill wind that blew good!

;-)

Rob C

bill t.

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Re: I'm a lucky fella!
« Reply #3 on: December 05, 2010, 12:52:02 pm »

I didn’t want to look so I put the lens back in the pack and continued with what I was doing.
You are half way to being a pro.  When you can put the lens immediately back in the pack without not wanting to look, or even caring very much, you are there!

I dropped a 150mm Hassy Sonar from a cherry picker platform 40 feet in the air.  That's a pretty big lens.  It landed in dirt not too far from the model below.  Aside from a few marks on the focus ring, it was fine...which was not the case for the model.  That was the last cherry picker job I ever did.
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Rob C

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Re: I'm a lucky fella!
« Reply #4 on: December 06, 2010, 04:13:40 am »

You are half way to being a pro.  When you can put the lens immediately back in the pack without not wanting to look, or even caring very much, you are there!

I dropped a 150mm Hassy Sonar from a cherry picker platform 40 feet in the air.  That's a pretty big lens.  It landed in dirt not too far from the model below.  Aside from a few marks on the focus ring, it was fine...which was not the case for the model.  That was the last cherry picker job I ever did.


Not wanting to look means you are not a pro, but a wealthy dentist who just doesn't feel pain at little bites - all that freely available Novocain or whatever.

Dropping your 150mm Zeiss and not caring means you dropped it on purpose because you really wanted a 180mm and, better, are well insured and about to achieve your wish.

You must be that chap who makes insurance expensive.

;-)

Rob C

Justan

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Re: I'm a lucky fella!
« Reply #5 on: December 06, 2010, 10:26:44 am »

This might be useful as a general guide: How to test a lens.


Thanks for the link!  It was very educational! The part of the article that I found the most educational was the part regarding longitudinal color shift. From the article:

“One other thing to check with a wide aperture lens is spherochromatism (also called secondary longitudinal chromatic aberration or longitudinal color shift). Spherochromatism occurs in many wide aperture lenses because while the lens is corrected for chromatic aberration in the in-focus area, the out-of-focus areas in front of and behind the plane of focus can’t be corrected and will have magenta or green tints. There’s nothing to be done about it, but its good to know how severe it is. In problem lenses you can avoid large white areas if the foreground or background when framing your shot.”

I will definitely investigate to see if this has changed. Otherwise i havent had the free time to do any formal testing so will follow this guide when i have a free hour or so.

Justan

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Re: I'm a lucky fella!
« Reply #6 on: December 06, 2010, 10:47:58 am »

You are half way to being a pro.  When you can put the lens immediately back in the pack without not wanting to look, or even caring very much, you are there!

I dropped a 150mm Hassy Sonar from a cherry picker platform 40 feet in the air.  That's a pretty big lens.  It landed in dirt not too far from the model below.  Aside from a few marks on the focus ring, it was fine...which was not the case for the model.  That was the last cherry picker job I ever did.

Was it the last one for the model too?  :D
 
I found that dropping things from above someone so that it startles the bystander without hitting them is one of the most amusing ways to test reaction times and how easy some can be rattled.

It always appears that nearly eternity passes before most will even notice the item crashing to the ground at their feet (reaction time), and then, typically they will almost jump out of their skin (easy to rattle). I remember once that the target, er, bystander actually caught the item. THAT was impressive, but almost expected as the guy was an Olympic athlete.

Your test was similar and shows remarkable resourcefulness for selecting such a heavy yet surprisingly durable object as the test implement!

I've found that camera equipment is extremely well built so never saw the need to package it excessively. This event and the one you mentioned seems clear cases on point.

Riaan van Wyk

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Re: I'm a lucky fella!
« Reply #7 on: December 06, 2010, 01:30:52 pm »

It seems that you are a lucky one indeed Justan. What I find interesting about your post is that there is no reference to the "robustness" of the make of lens that happened to be dropped, merely a question of how to check if it is ok. Be it most other places on the www it would have read as a glowing report on the supreme qualities of said/ mentioned lens and the resultant three pages of useless namecalling so common these days. Sanity, it seems, does prevail on LULA. 

Over to the "luck" part, any chance of helping me find an almost brand new Italian made tripod that I left standing on a secluded beach in Mozambique?

Justan

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Re: I'm a lucky fella!
« Reply #8 on: December 06, 2010, 02:10:38 pm »

Heh, I lost a small tripod a couple of years back during a bike ride along a forest service trail. I posted an inquiry on my neighborhood web site and one of my neighbors said they found it about 6 miles back on the road I had traveled. So barring a trip to Mozambique, posting on a local to the area web site might help, if it wasn’t too long ago.

I saw a video article on how they make Canon telephoto lenses. I thought the article was very informative. When assembling the lens, they pretty much plop the individual elements into their place holders within the lens barrel. The lens barrel bears 99% of the responsibility for correct placement and alignment of the lenses. The other 1% comes from the lens elements being the correct size. Due to this, it is pretty clear that unless there is a significant trauma to the lens barrel, it will probably survive.

Still, my bread definitely landed butter side up this time, or at least it seems so. I still have to ttttest…..
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