Hello PZners,
As already motioned in several treads I have bought Tamron 70-300 VC EF mount.
It is my first telephoto lens and even more It is my first IS/VC lens.
The new focal length opens the new photographic opportunity.
After few weeks of learning I can make some decent shoots. Not toppers but just good enough for beginner.
But I have one technical problem with this Tamron 70-300 VC.
1. I cannot take pin-sharp images handheld with VC enabled. Even at S= 1/200sec
2. I can make pin-sharp images handheld with VC disabled and speed S=1/200sec
I examine the images the RAW images from my 50d at 100%view.
The images with VC are sharp but I have blur = less than 1 pixel in any direction. It worns me that this is VC blur. The handheld blur at S=1/200 must be only in one direction.
I have several technical questions.
1. Is it normal that I cannot take an even one single image with VC, that is as sharp as image taken at tripod + MLU? - Keep in mind that I can take some pin-sharp images handheld with VC-off.
2. What are the tolerances for motion blur introduced by VC/ IS?
3. In which situation I have to switch off the VC?
- Tripod is one of them.
- what about monopod?
- what about holding the lens with hand against three or wall?
- what about holding the lens on top of your backpack or ground.
…………
4. Do I need to switch the VC at higher shooter speeds e.g S=1/1000sec?
Thanks in advance,
Miro
[quote name='miro' timestamp='1298043880' post='6225']
Hello PZners,
As already motioned in several treads I have bought Tamron 70-300 VC EF mount.
It is my first telephoto lens and even more It is my first IS/VC lens.
The new focal length opens the new photographic opportunity.
After few weeks of learning I can make some decent shoots. Not toppers but just good enough for beginner.
But I have one technical problem with this Tamron 70-300 VC.
1. I cannot take pin-sharp images handheld with VC enabled. Even at S= 1/200sec
2. I can make pin-sharp images handheld with VC disabled and speed S=1/200sec
I examine the images the RAW images from my 50d at 100%view.
The images with VC are sharp but I have blur = less than 1 pixel in any direction. It worns me that this is VC blur. The handheld blur at S=1/200 must be only in one direction.
I have several technical questions.
1. Is it normal that I cannot take an even one single image with VC, that is as sharp as image taken at tripod + MLU? - Keep in mind that I can take some pin-sharp images handheld with VC-off.
2. What are the tolerances for motion blur introduced by VC/ IS?
3. In which situation I have to switch off the VC?
- Tripod is one of them.
- what about monopod?
- what about holding the lens with hand against three or wall?
- what about holding the lens on top of your backpack or ground.
…………
4. Do I need to switch the VC at higher shooter speeds e.g S=1/1000sec?
Thanks in advance,
Miro
[/quote]
It is normal to NOT take photos with VC/IS enabled on tripods. Unless the lens has tripod detection that will turn off the image stabilization, you will get nasty effects from the VC feeding back to itself, and if I understand you correctly, this is your problem.
So.. VC is only for handheld. Monopod might work, try. Handheld with you leaning against something should be ok. Lens on top of something, also turn off VC.
You just only need VC when handheld, and then only when the exposuretimes get to be too long. On tripod, turn it off.
Are you focusing and exposing all in one go? From what I've heard, Tamron's VC takes half a second to stabilize. Half-press the shutter button to focus, set exposure, and engage the VC. Then wait half a second for the VC to stabilize while half-pressing the shutter button. Once stabilized, press all the way and expose.
I hope that helps! Arie
[quote name='backcountryskier' timestamp='1298044438' post='6228']
Are you focusing and exposing all in one go? From what I've heard, Tamron's VC takes half a second to stabilize. Half-press the shutter button to focus, set exposure, and engage the VC. Then wait half a second for the VC to stabilize while half-pressing the shutter button. Once stabilized, press all the way and expose.
I hope that helps! Arie
[/quote]
Hello Arie,
I heard the same news about Tamron VC and required settle time of about 1/2 sec. I'll try it this weekend.
If it is true I wonder why i have VC. For 1 sec I can recompose and shoot with Ball Head and nonVC lens I need VC only for grabbing shoot of my children but for 1/2 second they are moving to the next corner. Maybe I have to play with AI servo mode just to keep the moving subject in track - bird, animal or kid.
Have a nice weekend,
Miro
[quote name='Brightcolours' timestamp='1298044328' post='6227']
It is normal to NOT take photos with VC/IS enabled on tripods. Unless the lens has tripod detection that will turn off the image stabilization, you will get nasty effects from the VC feeding back to itself, and if I understand you correctly, this is your problem.
So.. VC is only for handheld. Monopod might work, try. Handheld with you leaning against something should be ok. Lens on top of something, also turn off VC.
You just only need VC when handheld, and then only when the exposuretimes get to be too long. On tripod, turn it off.
[/quote]
Thanks for the quick response.
My experiance at F=300mm is
1. handheld images bellow s=1/320sec are sharper with VC-off.
2. At monopod, backback or holded agians three the border is S=1/100sec.
3. For tripod I have NEVER EVER tried to use VC. I know that theoretical is impossible to make high performance handhold VC that can work on stable tripod. I can prove that with mathematical equation.
Do you know what is the rule to switch off the VC?
Is there some rule like 1/F or 1/(2*F)?
Greetings
Miro
[quote name='miro' timestamp='1298043880' post='6225']
Hello PZners,
As already motioned in several treads I have bought Tamron 70-300 VC EF mount.
It is my first telephoto lens and even more It is my first IS/VC lens.
The new focal length opens the new photographic opportunity.
After few weeks of learning I can make some decent shoots. Not toppers but just good enough for beginner.
But I have one technical problem with this Tamron 70-300 VC.
1. I cannot take pin-sharp images handheld with VC enabled. Even at S= 1/200sec
2. I can make pin-sharp images handheld with VC disabled and speed S=1/200sec
I examine the images the RAW images from my 50d at 100%view.
The images with VC are sharp but I have blur = less than 1 pixel in any direction. It worns me that this is VC blur. The handheld blur at S=1/200 must be only in one direction.
I have several technical questions.
1. Is it normal that I cannot take an even one single image with VC, that is as sharp as image taken at tripod + MLU? - Keep in mind that I can take some pin-sharp images handheld with VC-off.
2. What are the tolerances for motion blur introduced by VC/ IS?
3. In which situation I have to switch off the VC?
- Tripod is one of them.
- what about monopod?
- what about holding the lens with hand against three or wall?
- what about holding the lens on top of your backpack or ground.
…………
4. Do I need to switch the VC at higher shooter speeds e.g S=1/1000sec?
Thanks in advance,
Miro
[/quote]
Hello Miro,
1. It is not normal to take blurry images all the time with VC on. If you have a steady hands the VC will create a blur (like on tripod). If S-1/200 can freeze the motion of your object why not compensate for your little hand movement. Have you tried the VC with even slower shooter speeds? and do you use singe focus point in your testing?
4. Basically if the shooter speed exceeds the sampling rate of your VC sensor you don't need VC on. For VR system it sampling is rate 500Hz, so I don't think the VC is much different here.
I hope this is helpful
Kind regard,
Boris
The lens should be able to deliver sharp images with VC on, handheld. Without crops one can't judge much, but it sounds as if there is something a bit wrong with the lens' VC system?
Thanks for all your comments.
It seems that If I slow down the moment between Half and fully pressed shooter the images are pin-sharp.
It is not as bad as I expected. The wait time is less that 1/2sec.
I’m still happy with this lens. Unfortunately now it comes the most difficult part – Exercise, exercise and again exercise.
Many thanks,
Miro.
genotypewriter
Unregistered
[quote name='borisbg' timestamp='1298107332' post='6239']
4. Basically if the shooter speed exceeds the sampling rate of your VC sensor you don't need VC on. For VR system it sampling is rate 500Hz, so I don't think the VC is much different here.
[/quote]
Hmm I don't know about the VR sampling rate but the actual VR reaction speed should be effective to less than 50Hz... just imagine what it would be like if you were vibrating at anything near 50/60Hz (like AC current)! <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />
GTW
It look like that Tamrons control loop is running at 500..1000Hz sample rate.
GTW: In control techniqiue there are several perameters. I'll tell few of them
1. Sample rate
2. Controller bandwidth
3. Settle time
4. Max. error.
As far as i understand you, you are mixing either sample rate with controller bandwidth or sample time with settle time.
