Search results for 'back focus' - page 2789
Macro on the cheap (and suggestions for focus rail, please)
Whatever you do be careful if you are using two lenses coupled front to front. I pulled the front off a K7 when the weight of the lenses pulled the quick release from the tripod, only looked away for a second :shock: Heck, I've only just learnt to cope with one lens. Wouldn't know where to start wit...
Posted by milamber on 26/02/2012 - 19:58
Macro on the cheap (and suggestions for focus rail, please)
be very careful because it becomes incredibly addictive if you aren't careful. Too late:D Thanks for the link.
Posted by milamber on 26/02/2012 - 20:01
Macro on the cheap (and suggestions for focus rail, please)
The magnification depends not only on the focal length of the lens and the length of the tubes, but also how close the lens will focus in the first place. If you have a 100mm lens that focuses to 1.0m and a 100mm lens that focuses to 0.8m without tubes, then the one that focuses to 0.8m will produc...
Posted by George Lazarette on 26/02/2012 - 20:12
Macro on the cheap (and suggestions for focus rail, please)
The magnification depends not only on the focal length of the lens and the length of the tubes, but also how close the lens will focus in the first place. If you have a 100mm lens that focuses to 1.0m and a 100mm lens that focuses to 0.8m without tubes, then the one that focuses to 0.8m will produc...
Posted by milamber on 26/02/2012 - 20:19
Macro on the cheap (and suggestions for focus rail, please)
No. Now I have confused things! :oops: David was talking about lenses of the same focal length, so that is what I was commenting on. The only purpose of tubes is to enable you to focus closer to the subject. Macro lenses are simply sharp lenses, generally with a fairly flat plane of focus, ...
Posted by George Lazarette on 26/02/2012 - 20:29
Macro on the cheap (and suggestions for focus rail, please)
What I was meaning was that a lens which focusses closer without a tube will also focus closer with a tube. So, assuming you have two lenses and one focusses closer than the other, using an identical extension tube length, the closer focussing lens will give you the biggest magnification! Hope t...
Posted by davidstorm on 26/02/2012 - 20:55
Macro on the cheap (and suggestions for focus rail, please)
If the creature is venomous don't poke it with a stick. From the book "There are more things that can kill you in Austrailia than anywhere else on the planet" :lol:
Posted by tyronet2000 on 26/02/2012 - 22:09
Macro on the cheap (and suggestions for focus rail, please)
So, in really simple terms that even I can understand, because I'm still struggling. I've tried the 50mm tube with the 135mm lens and, whilst it allowed closer focussing and some magnification, it was nowhere near as much magnification as the 50mm lens with the 50mm tube. What length of tubes ...
Posted by milamber on 26/02/2012 - 22:19
Macro on the cheap (and suggestions for focus rail, please)
I have no idea how many tubes you would need with your 135mm lens. Picking upon David's point, it all depends how close the lens will focus to start with. If you don't already have one, you should buy a set of tubes. They come in an assortment of lengths so that you can choose a combination tha...
Posted by George Lazarette on 26/02/2012 - 22:47
Macro on the cheap (and suggestions for focus rail, please)
If both the 50mm & 135mm are set at infinity then adding 135mm extension to the 135 will give the same magnification as 50mm extension on the 50. (life size reproduction) When the lenses focusing is adjusted that (effectively) includes some extra internal extension, and so complicates matters. In m...
Posted by petrochemist on 26/02/2012 - 22:53
Macro on the cheap (and suggestions for focus rail, please)
Basically the calculations (based on simple lens theory) are :- 1/U + 1/V = 1/F M = U/V where F = focal length of lens U = combined distance of extension + focal length (assuming lens is focused on infinity) V = object distance so for a 50mm lens focused on infinity the inmage distanc...
Posted by Frogherder on 26/02/2012 - 22:57
Macro on the cheap (and suggestions for focus rail, please)
I find that with a standard 50mm (mine is a Chinon F1.9), the depth of field is absolutely minute, whereas with my Sigma 50mm Macro, there's a bit more depth to play with. Is that just a perception or is it real? I would have thought that any 50mm lens in an identical set up to take a photograph wou...
Posted by JAK on 26/02/2012 - 23:02
Macro on the cheap (and suggestions for focus rail, please)
What I'd like is the same magnification and potential quality as I got from the 50mm lens and tube, but from a little further away so I don't poke the subject in the eye......or is this simply not possible on a budget? Is this what a macro teleconverter is for? All the help appreciated - apologie...
Posted by davidstorm on 26/02/2012 - 23:09
Macro on the cheap (and suggestions for focus rail, please)
Having gone back & read the posts I'd missed at the bottom of the first page... Yes, longer focal lengths give you a longer working distance, though require more work to get the same magnification. If the macro teleconverter is similar to my two, (I have both 2x PK & 3x PKA versions) it's a us...
Posted by petrochemist on 26/02/2012 - 23:12
Macro on the cheap (and suggestions for focus rail, please)
I've no idea why but when mixing extension tubes and x2 converters I found that :- Camera - x2 - tube - lens gave a different distance from camera to subject than Camera - tube - x2 - lens I've not been able to rationalise the maths though Incidentally in my previous comment I forgot to...
Posted by Frogherder on 26/02/2012 - 23:17
Macro on the cheap (and suggestions for focus rail, please)
Thank you all. I think I'm beginning to understand - it's obviously not as straightforward as simply adding a set number of tubes. It sounds like the best bet is simply to play around with different combinations of tubes and lenses which is hardly a chore..... I just have one tube at the momen...
Posted by milamber on 27/02/2012 - 07:43
Macro on the cheap (and suggestions for focus rail, please)
I've no idea why but when mixing extension tubes and x2 converters I found that :- Camera - x2 - tube - lens gave a different distance from camera to subject than Camera - tube - x2 - lens I've not been able to rationalise the maths though regards Bernard The two set ups are actually qui...
Posted by petrochemist on 27/02/2012 - 07:46
Macro on the cheap (and suggestions for focus rail, please)
This is my contribution :) Will probably be shot down in flames :oops:
Posted by tyronet2000 on 27/02/2012 - 09:10
Macro on the cheap (and suggestions for focus rail, please)
This is my contribution :) Will probably be shot down in flames :oops: Don't see why - that's really helpful. Shows just how hard it is to focus even when playing with a generous 1.07mm as I was yesterday! Thanks
Posted by milamber on 27/02/2012 - 09:18
Macro on the cheap (and suggestions for focus rail, please)
It reinforces in our minds how critical macro focusing is. Tripod and manual focus still remains the best option I think.
Posted by johnriley on 27/02/2012 - 09:22
