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Home: Video University Forums: Digital Photography for Videographers:
adjustments to lens

Shadow
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Dec 9, 2006, 10:38 PM

Post #1 of 10 (689 views)
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adjustments to lens	Can't Post

A while back I mentioned I was having problems with sharpness and some bright soul said that lenses can be .... (forgive my lack of technical knowledge/terms here)... out of allignment or need tweeking.

Anyway, I've kept this in the back of my mind and did some tests with a new lens and indeed I think this is true! It just isn't as sharp, but is by far a much better lens than the new one.

Has anyone ever had to get a lens adjusted? I'm curious about this. I did a quick google but didn't turn up much, I'll try again but thought I'd ask here.

Anyone know about this?

Cheers
H

RustyB
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Dec 10, 2006, 12:23 AM

Post #2 of 10 (681 views)
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Re: [Shadow] adjustments to lens [In reply to]	Can't Post

Maybe a backfocus issue? I don't know much about DSLR, aren't you using a Canon? If your other lenses work fine, maybe it's an issue with that particular lens...did you get it at a good price off eBay? Tongue

I don't know if DSLR lenses can be adjusted for backfocus, but there may be a firmware miracle. Might try googling the lens for backfocus problems, and see if you get lucky.

Could also be a focus point issue, if you're using multiple focus points?

Good luck!

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Shadow
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Dec 10, 2006, 9:16 AM

Post #3 of 10 (670 views)
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Re: [RustyB] adjustments to lens [In reply to]	Can't Post

Thanks Rusty for the ideas.

From my google search I found that you can get lenses adjusted, although I am not sure what that means or how. I'll have to wait until i have time next weekend to go into the camera store.
I have a shoot today so I really wanted that lens. :( I'll have to use my other one.

I took the same shot with both lenses and one was sharp and one was not, centre metering on both. I had always wondered as my shots just weren't crisp enough, they're fine and some people I show can't see any difference, but I can.

I bought the lens at the camera store but think it only had a couple of months warranty on because it was used. It was in really good condition though, didn't look used.

Frown

Dieps
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Dec 10, 2006, 11:36 AM

Post #4 of 10 (661 views)
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Re: [Shadow] adjustments to lens [In reply to]	Can't Post

There are a number of posts on photo web sites, like fredmiranda.com, that mention a lens might be a good copy or a bad copy. Camera lenses are like autos, cameras, televisions or anything else...you can get a good one or you can get a lemon. There is also a possibility your lens might have been dropped or bumped hard enought to misalign some of the elements. The manucaturer can turn it up to return it to factory specs but I have no idea what the cost might be.

Zoom lenses have a larger chance of soft focus or becoming misaligned because they have more elements and more moving parts than primes. That's why many photographers prefer primes; they simply feel primes are more reliable and produce a better image. On the other, I own three zooms and think the images they produce are sharp more than adequate for my purposes.

Jim

PD-170, VX-2000 (2), TRV-900
Sony Wireless, iRiver, Mini Discs, other stuff
Canon 20D with some lenses

DarrenS
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Dec 10, 2006, 2:19 PM

Post #5 of 10 (652 views)
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Re: [Shadow] adjustments to lens [In reply to]	Can't Post

Some lenses especially the less-expensive ones just aren't sharp, even in perfect non-lemon condition. It's why I'm so amazed with the 18-70DX Nikkor...it's sharp as a tack and it shouldn't be for $250.

Also, I'm not sure what lens you're talking about but if it has a big aperture the issue can sometimes be shallow depth of field. Wide open some lenses are quite difficult to get focused properly. It takes lotsa practice. The 85/1.4D was a challenge at first, but once you 'get it' the results are absolutely stunning. Never seen a lens so sharp in my life.

Shadow
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Dec 10, 2006, 4:59 PM

Post #6 of 10 (634 views)
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Re: [DarrenS] adjustments to lens [In reply to]	Can't Post

:) thanks
It for sure isn't a depth of feild problem, I had thought that at first too.
I dont know what it is. The lens was $450 so I'm assuming it is better than the others I had purchased at around $200.

I found again today, with a different lens, that the pictures were good but still not super crisp.
I moved to centre metering and tried that too. They look nice but it bugs me.
Mad

DarrenS
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Dec 10, 2006, 5:23 PM

Post #7 of 10 (628 views)
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Re: [Shadow] adjustments to lens [In reply to]	Can't Post

Is it a zoom? Usually only the most expensive zooms are super crisp. Also, read user reviews on your lens on the net and see what aperture setting your lens is sharpest at. Only the very best lenses are really sharp at all apertures. The vast majority are not, particularily at big apertures (this goes for zooms and primes alike). You may get sharper results with a smaller aperture, usually between 6 and 9...in around there anyway.

Best thing to do is set the camera up on sticks and shoot a scene with detailed texture, taking your time to ensure focus is absolutely perfect. Then take a bunch of pictures, one at each f-stop making sure not to change anything else. See if you can see a difference between the various apertures (on your computer @ 100% magnification..don't rely on the camera lcd). I bet you will see a big difference.

The Nikkor 70-200/2.8 zoom is an expensive unit, like $1600 (I think). But the 200/2 prime is about 40% sharper than the expensive zoom at 200mm. Zooms simply cannot compete with primes. You trade off speed & sharpness for the convenience of having the zoom.

Shadow
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Dec 10, 2006, 5:40 PM

Post #8 of 10 (623 views)
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Re: [DarrenS] adjustments to lens [In reply to]	Can't Post

Thanks Darren
Yes, it is a zoom.

I had heard this about zoom vs. prime before but was one of those things that filtered through and my brain decided to let go. Thanks for the advice, I think maybe you've got it figured out.

I'll do the test shots. I think a lot of time I use 2.8 to about 5 or so for f-stops, perhaps the higher ones are what is better with that lens.
I noticed the cheaper zoom I used today (it was about $240) wasn't super crisp either and I was very careful with focus because of the problems I've had recently.

Maybe my next lens needs to be a prime lens. How many/what ones would you suggest?

Thanks
H

p.s. I find it funny that we live a few blocks away from each other and the only place we bump into each other is on the VU

DarrenS
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Dec 11, 2006, 4:39 AM

Post #9 of 10 (595 views)
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Re: [Shadow] adjustments to lens [In reply to]	Can't Post

For weddings I'd start with a fast 50mm because they're pretty cheap and useful for shooting singles, couples or even small groups with enough room. Then a wider one, then a longer one. Get a longer one last because they're less useful and way pricy (for the fast stuff). Also, check out Canon's 'tele extenders' and what lenses they're compatible with because they're a relatively inexpensive way of getting different focal lengths without buying and lugging more lenses. Example I have a 2x extender for use with the 200/2 when 200 isn't long enough; it turns it into a 400/4. Amazing for $400, plus you don't have to carry two lenses. 400mm is like a 600mm on a film body. A 600mm f4 lens is somewhere in around eight or nine grand I think!

I'm in fla for Jan, but one day in the ny we should hook up for Druxy's lunch at the Center or sumthin. Yak about shooting and wedding battle wounds. Smile

You have an open invitation to visit the studio in Port once it's totally done in Feb, too.

Shadow
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Dec 11, 2006, 3:45 PM

Post #10 of 10 (587 views)
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Re: [DarrenS] adjustments to lens [In reply to]	Can't Post

That's so awesome about your studio! I'm assuming you mean Port Perry not Port Hope? I really like your photos and know you're going to do so well with it. Funny, I've spent a lot of time in Port Hope lately and realized there is no photography studio there. With such an 'artsy' little community I am surprised. Maybe one day I"ll have enough money to set up something there in one of those funky old buildings downtown. Oh to dream...

Anyway, yeah we should hook up sometime in the new year and yack about photography.

Thanks for the lens advice, I didn't mean to turn the thread into one of the "what lens should I buy" posts. :)

I heard Santa bought me a bracket so I'm excited to try it out!