Infinity (and beyond)
Posted 10/09/2010 - 09:12
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I don't understand, infinity is infinity how do you go infinity+1?
Barrie - Too Old To Die Young
https://pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/
https://pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/
Posted 10/09/2010 - 09:38
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Do old MF lenses stop at infinity? The only MF lenses I regularly use at infinity are both long mirror lenses, and both focus considerably past infinity (annoyingly so). I guess that may be a special case because they are mirror lenses though.
Tim
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
Posted 10/09/2010 - 09:38
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Just nipped outside and did these very unscientific demonstrations with the DA* 50-135 @50mm, looking at a house about 50m away - a DoF calculator has the near point at 23.5m which is about the end of my garden.
- Only cropped for 1:1, no sharpening or any PP
Infinity :
Beyond Infinity :
- Only cropped for 1:1, no sharpening or any PP
Infinity :
Beyond Infinity :
Still shooting in the dark (literally and metaphorically)...
Posted 10/09/2010 - 10:05 - Helpful Comment
Link
Most lenses now use plastic material in their construction, and they go "beyond" infinity to allow for plastic components thermal expansion. Even long lenses made of metal will suffer thermal expansion, too.
Yves (another one of those crazy Canucks)
Posted 10/09/2010 - 10:11
Link
Won't it be because of the AF adjustment on the camera. They probably set infinity on a camera that was on the limit for being out of adjustment.
Some Vivitar lenses such as the Series 1 28-105mm let you adjust infinity by rotating the front element.
Some Vivitar lenses such as the Series 1 28-105mm let you adjust infinity by rotating the front element.
Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
Pentax K-1 + K-5 and some other stuff
Algi
Posted 10/09/2010 - 10:27
Link
Tim wrote
I think that answers bforbes
"Two lines that meet at infinity"
But how far away is that?
Geoff
Quote:
The only MF lenses I regularly use at infinity are both long mirror lenses, and both focus considerably past infinity (annoyingly so). I guess that may be a special case because they are mirror lenses though.
And so does my mirror lens. But I suspect that what Tim and I (and others) mean is that one can turn the focus ring so that the infinity mark has gone beyond the index mark. The only MF lenses I regularly use at infinity are both long mirror lenses, and both focus considerably past infinity (annoyingly so). I guess that may be a special case because they are mirror lenses though.
I think that answers bforbes
Quote:
I don't understand, infinity is infinity how do you go infinity+1?
It's a bit like the definition of parallel lines:I don't understand, infinity is infinity how do you go infinity+1?
"Two lines that meet at infinity"
But how far away is that?
Geoff
Water can wear away a stone - but it can't cook lunch
X-5
istDS
K2000
P50.
Lenses Digital: 50-200, 18-55 KAF: 28-80.
Lenses KA & K: SMC-KA f2.0, SMC-K f1.4, SMC-K f1.7 Tokina KA 28-70 , SMC Pentax 70-210 F4, Sigma KA 75-300 , Hanimex 500mm Mirror, and the Tamron Adaptall-2 stuff.
and then there's all the M42 kit, and the accessories ...
X-5
istDS
K2000
P50.
Lenses Digital: 50-200, 18-55 KAF: 28-80.
Lenses KA & K: SMC-KA f2.0, SMC-K f1.4, SMC-K f1.7 Tokina KA 28-70 , SMC Pentax 70-210 F4, Sigma KA 75-300 , Hanimex 500mm Mirror, and the Tamron Adaptall-2 stuff.
and then there's all the M42 kit, and the accessories ...
Posted 10/09/2010 - 11:05
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I've never been entirely sure how far away infinity should be anyway - I recently spent some time trying to get an old K 28-50mm adjusted by the simple approach of attaching it to my Super A (which has a split focus screen), putting it on a tripod, then lining up on a ridge line which I would guess to be about five or six miles distant. Hopefully that was far enough!
Matt
Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.
Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.
Posted 10/09/2010 - 11:52
Link
Dangermouse wrote:
I've never been entirely sure how far away infinity should be anyway - I recently spent some time trying to get an old K 28-50mm adjusted by the simple approach of attaching it to my Super A (which has a split focus screen), putting it on a tripod, then lining up on a ridge line which I would guess to be about five or six miles distant. Hopefully that was far enough!
Should be. The moon would probably be better I've never been entirely sure how far away infinity should be anyway - I recently spent some time trying to get an old K 28-50mm adjusted by the simple approach of attaching it to my Super A (which has a split focus screen), putting it on a tripod, then lining up on a ridge line which I would guess to be about five or six miles distant. Hopefully that was far enough!
There is a method where another camera with a lens known to focus on infinity accurately can be used as a collimator to set up a 2nd camera and lens to infinity. See here
Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
Pentax K-1 + K-5 and some other stuff
Algi
Posted 10/09/2010 - 14:07
Link
It is all about the focus point changing as the lens expands and contracts. This becomes relevant with big telephoto lenses in particular.
Best regards, John
Posted 10/09/2010 - 14:58
Link
Who could resist a little buzz?
Tim
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
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