All gone wrong

[arith]

I bought a new secondhand lens part exchanged against my old camera but I haven't been able to take a decent pic with it yet. I got sick of waiting until I could buy a decent L type because in the current climate second hand ones go for only a few pounds less than new.

But now I wonder because AF only seems to work for close up and I accidently left image stabilisation on whilst doing a HDR and got shifts of 80 pixels.

So I superimposed the sky in this which still doesn't look the sharpest but that might be my processing, and I can still see CA although this is pointing directly into sun, the CA on this lens is supposed to better than the L type.



Or am I expecting too much.

[carregwen]

What lens is it?

Try this test. Find a big brick wall with a smallish print sign on it (that will give you lots of fine detail). Take a variety of shots at different focal lengths (if it's a zoom) and at different distances from the wall. Shoot them in RAW so the camera doesn't sharpen them. Compare the results.

[Colin Southern]

Hi Steve,

Not sure what lens you're using, but if it's a Canon then this is one occasion where you really need to turn IS off when tripod mounted. All later generation IS units have tripod detection, but they only go into standby mode and are not mechanically locked as they are with IS turned off ... and it's quite normal for them to shift the image around; not a problem for a single frame, but with multi-frame for HDR this could well be an issue.

[Colin Southern]

PS: Just had a quick play with the image -- two biggest issues were incorrect black clipping point and lack of sharpening ... how does this look to you?



(If the image now looks too dark then you probably have a monitor calibration / profile issue).

Hope this helps!

PPS: The lens itself seems fine based on what I've seen here.

[arith]

What lens is it?

Try this test. Find a big brick wall with a smallish print sign on it (that will give you lots of fine detail). Take a variety of shots at different focal lengths (if it's a zoom) and at different distances from the wall. Shoot them in RAW so the camera doesn't sharpen them. Compare the results.

It is this one

http://www.photozone.de/canon-eos/48...750_28vc_canon

I already did similar using a net curtain and it looks ok, I also used stability hand held down to 1/3 seconds but I can sometimes get a 50mm sharp down to 1/8 seconds without stability.

It is the AF that has me worried, if the object is close it is quick but anything further than the hyperfocal distance will not lock, but obviously I could just use manual since I got over £200 off new price part exchange and it might just be a problem with the type of lens. The review states AF is so so, but the numbers are near 2200 LW/PH over all focal lengths and CA insignificant. The CA swung it as well as the price. Ef-s 17-55 f2.8 IS £850 ef 17-40mm f4 L £650 ef 16-35mm f2.8 L £1350

[arith]

PS: Just had a quick play with the image -- two biggest issues were incorrect black clipping point and lack of sharpening ... how does this look to you?



(If the image now looks too dark then you probably have a monitor calibration / profile issue).

Hope this helps!

PPS: The lens itself seems fine based on what I've seen here.

I think it is just my eyes Colin, yours as always looks better

[arith]

I just took this to check sharpness at all focal lengths here at f7.1 and they are all sharper than this; it is the AF that is a problem plus the stupid giant hood and I accidently dropped the cap in the centre and dragged it across the front of the lens; I can't see any damage though. I like my little primes.



Sharpness is only an issue at extreme edges of 17mm at f2.8

[rpcrowe]

Arith,

What lens is it that seems to be causing the problems.

Most older IS lenses like the 28-135mm f/3.5-5.6 cause problems when shot on a tripod with the IS turned on. the IS seems to search for image motion to stabilize and when none is found, causes a sharpness problem.

Some Canon lenses are not very good, especially wide open. The 75-300mm (not the 70-300mm) IS is one that immediately comes to mind. This lens seems to do better stopped down a coupple of stops and shot at around f/8.

[arith]

It is the one refered to in post #5, I thought it was quite new. I have never had image stabilisation but aleady knew it was suppose to be switched off on a tripod and I forgot. Never mind I will get it right one day.

Just found out it came out in October 2009 in the USA, so it has been out around 6 months here.

[arith]

I read on another forum where a chap set his camera to the lens; so I thought I would give it a go but before I did checked AF and I couldn't get it to fail. For no good reason it has just started working.


So how do you check out IS on this lens called VC; this is 1/3 sec on f2.8 and looks soft or isn't it possible to check IS?

[Sahil]

Errr... I don't get this.. There are times when we need to turn IS/VR off??? Why & when?

[arith]

Errr... I don't get this.. There are times when we need to turn IS/VR off??? Why & when?

On some lenses you need to turn IS VR VC off when using a tripod, which is easy to forget. :embarrassed:

[Sahil]

Thanks for replying, Arith.

But what do we lose if we leave it on? Any trade offs?

[arith]

I think you lose sharpness; yep definitely sharpness gone and you can't do panning with it on unless you have a panning IS button.

[arith]

I have found out that infinity isn't set as far round as the ring will go, and it is out of focus past this point, and you can micro adjust for lenses but how do you do it? It locks in AI servo but will not lock but hunts for points if they are greater than the hyperfocal distance in normal mode.

[arith]

Found the method.

Choose wide open and longest focal length.

Set the camera at 50x the focal length away from your lcd screen computer, on a tripod trying to keep focal planes in square. Also set IS/VR/VC off

Choose lowest iso.

Have pattern on screen got from http://www.northlight-images.co.uk/a...djustment.html

In live mode and manual set focus.

Choose normal mode and auto focus, press shutter half way watching focus ring. If it doesn't move and the camera beeps you are done. If it does move make a note of how much and which way.

Micro-adjust in steps, say +5 or -5.

Start again. In live view focus in manual and go through all the steps until the focus ring doesn't move.

Turns out to be -5 on mine.

Made absolutely no difference to my locking on distant objects though.

[Dave Humphries]

Thanks for replying, Arith.

But what do we lose if we leave it on? Any trade offs?

Hi Sahil,

I tend to agree it makes more sense to turn off VR on a tripod, although since I so rarely use one, I'm even more likely to forget than Steve.

FWIW, panning shouldn't be an issue with Nikon VR, the book it says it senses and copes with panning automatically.

The book also says when to use Normal and Active modes - Normal most times when handheld, only use Active if you and the camera are in a vibration situation; e.g. shooting from a moving car, train, plane or helicopter.

One other thing I was surprised to see as a Tip of the Month on Nikon's website yesterday was a suggestion to turn off VR when the shutter speed is fast (> 1/500s was stated). Not sure I buy into this, but I may check it out. Personally, I still find the VR helpful for accurately placing the focus point at 300mm on a small subject and I don't care if I am using 1/2000s!

Cheers,

[Colin Southern]

I just took this to check sharpness at all focal lengths here at f7.1 and they are all sharper than this; it is the AF that is a problem plus the stupid giant hood and I accidently dropped the cap in the centre and dragged it across the front of the lens; I can't see any damage though. I like my little primes.

Hi Steve,

Be sure to apply capture sharpening of 300% @ 0.3 pixels to all RAW images before evaluating sharpness.

[Colin Southern]

I have never had image stabilisation but aleady knew it was suppose to be switched off on a tripod and I forgot.

Don't worry about switching it off if you're not planning to stack images. You can do, but it probably won't make any difference either way. Canon used to mention it in the manual, but that was more on "battery drain" grounds (not sure what their current manuals say through). I eMailed Canon's tech guru Chuck Westfall about the issue a few years ago and that's when he explained the difference between being switched off and in "standby" mode. Switched off is definately "best practice", but in practive it can be more theory than practice. In fact I got a call from a pro-photograper who'd just returned from an overseas assignment just the other day ... he'd left IS on whilst on a tripod, and was concerned about a sharpness issue. When I looked at some of the problem images there was - perhaps - a small deterioration which was easily compensated for by slightly more agressive capture sharpening (I think I used 300% @ 0.5 pixels) ... he went away happy

[Colin Southern]

and you can't do panning with it on unless you have a panning IS button.

Wanna bet?