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04/07/2006 12:47:32 PM · #26 |
Originally posted by MadMan2k:
The thread size of the 50 1.8 should be 52mm. B&H has that info on the lenses they carry, which is most current ones. |
Those are still usable for digital cameras arnt they? |
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04/07/2006 01:14:11 PM · #27 |
My dear BowerR64,
One can take anything apart....if you have the right tools. The problem is never taking things apart but rather "putting them back together in working order".
- Saj |
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04/07/2006 01:15:21 PM · #28 |
Does make me wonder what would happen if you stacked a couple of f/1.8 50mm lenses atop of each other though.
*ponders*
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04/07/2006 01:25:19 PM · #29 |
I don't think that type of lens will work/focus properly without all of the elements in place.
Why not just buy a magnifying glass, some cardboard tubing and duck tape and experiment? |
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04/07/2006 03:53:44 PM · #30 |
| how many elements do you think they have? |
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04/07/2006 03:55:21 PM · #31 |
Originally posted by theSaj:
Does make me wonder what would happen if you stacked a couple of f/1.8 50mm lenses atop of each other though.
*ponders* |
a 100mm with focus issues?
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04/07/2006 04:42:27 PM · #32 |
Something simple like a canon 50 f1.8 has 6 lenses, in 5 groups.
The more complex zooms have around 21 lenses in 15 groups or so.
Message edited by author 2006-04-07 16:43:23. |
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04/07/2006 05:25:55 PM · #33 |
Originally posted by Gordon:
Something simple like a canon 50 f1.8 has 6 lenses, in 5 groups.
The more complex zooms have around 21 lenses in 15 groups or so. |
So if i got one of those, i could take out 1 lens at a time and try it eventualy i would have a badass lens right? lol
Say i take 10 of em out
Man i cant believe 21 lenses?!?! and they look that good? woah!
How many do the prime lenses have? |
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04/07/2006 05:26:15 PM · #34 |
If you have too much time, I rather suggest to put together a pinhole camera. You can find very nice cardboard cut-off patterns, just look it up with google.
What about a Dirkon? You can download it from HERE... ;-)
You see, I am sick of the idea of taking apart any lenses. Unless they are not useable anymore. |
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04/08/2006 11:14:58 AM · #35 |
Im probobly not thinking of how this works right.
Say the lens is like a telescope, (know thats a bad way to look at it because the lenses are probobly all different)
The telescope has the eye piece section of lenses and then it has the outter lenses that magnify that. I figure the set of lenses near the sensor is like the eye piece section and as you get further down the barrel of the lens the glass gets larger and these are the lenses that are still good and they might be the ones that would work with mine.
I figure i would need somthing near the same total lenght as what i can get out of the S2 with the 2X converter. So say i add the 2X converter and i get a total focal lenght of like 650mm i would want somthing in that same area. maybe?
The S2 is like 430mm stock If i add a 1.5X teleconverter it bumps it up to just over 600mm so if i start with a 650mm SLR lens and slowly remove some of the lenses i figured i would eventualy get to the lenses that would be similar to what the adapter uses, only better quality.
Maybe im not looking at it right? |
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04/08/2006 11:30:09 AM · #36 |
Ha. Funny this should pop up.
I'm right in the process of opening up a S-M-C Takumar 50/1.4 to clean out the fungus.
And yeah. It's the reassembling, that's hard. |
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04/08/2006 11:34:16 AM · #37 |
Mike,
UIf you really want to try this, none of us can stop you. You seem pretty intent upon this course of action.
I suggest simply that (even being someone with a lot of time) that there are things that your time can be better spent upon.
If you really feel the need to do this, find a chapo zoom from like Phoenix or something, and then do it is all.
Maybe your experiments will help you in the long run with understanding about this. IMO, just read a book about optics instead. I doubt without advanced electonics engineering degrees or experience, that you'll get anything out of this that work any time soon.
But what do I know, you could be a Stephen Hawking type super genius and looking at this post with derision and scorn.
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04/09/2006 12:38:49 PM · #38 |
What about one like this? does it have the appature parts?
Rexatar 135mm f1:2.8 Pentax M42Mount
WHat is M42 mount? is that 42mm threads? |
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04/09/2006 01:11:49 PM · #39 |
| M42 is an older mounting specification for lenses/cameras, manual focus only I believe. Has nothing to do with thread size, you could email the seller and ask them though. A lot of lenses say the thread size on the front or somewhere. Should be a circle with a line through it and then a number. |
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04/09/2006 01:14:45 PM · #40 |
| Why don't you try and get an old manual lens and take it apart? You can buy the whole damn camera for under $100 anymore. It seems like you'd be able to get the lenses for fairly cheap. |
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04/09/2006 02:06:44 PM · #41 |
Originally posted by ragamuffingirl:
Why don't you try and get an old manual lens and take it apart? You can buy the whole damn camera for under $100 anymore. It seems like you'd be able to get the lenses for fairly cheap. |
I thought thats what this one was? it looks so open i didnt think it had anything in it but the lenses. |
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04/09/2006 03:55:05 PM · #42 |
Having an interest in astronomy and telescopes means that I have spent plenty time trying to figure out how the primary lens aperture and the eyepiece work together with the focal lengths of both to produce certain magnifications. And also the effects that start happening when you play around with these lenses;
When the limits of optical diffraction set in, and what it looks like (No matter how good the glass, there's a physical limitation to the resolution you can achieve at high magnification)
How the light gathering power is affected by the aperture - things get very dark very quickly if the lenses aren't matched up
The focus plane. This is the most frustrating piece. I've played around with barlows, eyepieces, extenders, and webcams. But if you 'lose' the focal plane, it's very difficult to correct.
All in all, playing around with optics is a great experiment. And it really helped me to understand why there are so many different lenses and different types of glass that go into a telescope eyepiece, or a camera lens. And why the manufacturer has to be so exact about the alignment and distances between each.
Optics *is* rocket science! :) |
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04/09/2006 04:44:28 PM · #43 |
If can get a lens like this (and for this price) I think it would be a great lens for you to take apart and experiment with. It is a manual-focus lens so there is no focusing motor to complicate it. It is also a prime lens (not a zoom) so the only thing in it other than the lenses will be the iris which controls the aperture. When you get it apart you will have two or more separate glass lenses. You can then experiment with them in front of your current camera lens.
You should NOT expect to get a combination that works with excellent quality. As jhonan said "Optics *is* rocket science! :)" All lenses have faults and part of what a lens designer does is use combinations of lenses that have the opposite faults so they cancel out.
But you can get some very interesting effects. Some distortions can look really cool. I'd also suggest that you try using some ordinary magnifying glasses. A few years ago I was in a workshop where we had an assignment that required us to use a disposable camera. I put a magnifying glass in front of the lens and got some shots that were certainly different from everyone else's.
The important thing is to have fun and learn a lot.
--DanW |
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04/09/2006 05:37:59 PM · #44 |
Thats what i want to do, have fun and try and learn somthing. I know it sounds like i jsut want to tear somthing apart but thats not it at all.
I do what to see what is in an SLR lens what the lenses and stuff look like but i also want to try and make it work on somthing other then an older SLR film camera.
Ive already taken apart my dads old 400mm telescope and cleaned all the lenses on it it only has 4 but he got it in the 60s made by jason.
Then i took apart that 2.0X starD lens because it had mould between the 2 lenses. Now im ready for bigger and better things :D
Message edited by author 2006-04-09 17:38:44. |
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04/09/2006 05:47:05 PM · #45 |
Here's what you do with your lens after you take it apart ...
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04/09/2006 06:52:40 PM · #46 |
I dropped my 50mm 1.8 on the ground and something broke inside the lense. I decided to take it apart and, not to disagree with anyone about the difficulty of reassembly, but had the hardest time getting the thing apart without damaging it. The focus ring on the 50mm 1.8 actually doubles as a retaining ring, and it is simply press-fit into the lens housing. While attempting to get the focus ring off, I gouged it pretty bad and made a mostly useless lens a piece of trash.
But I think if the 50mm were manufactured better, it would have been much easier to take apart. Older lenses often are built like aircraft machinery, so that would be a good start. |
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04/09/2006 11:15:01 PM · #47 |
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04/10/2006 09:45:21 PM · #48 |
Man the more i fool around with these cheap teleconverters, im starting to think this idea isnt going to work.
Im starting to think the curvature of the lens is a little more important then i thought.
What made me think it was so easy is this third telephoto lens i got off e-bay. I got the first one was a "crystal optics" (cheapie)it kinda sucked. Then i got a canon DC58 it wasnt much better then i just picked one off e-bay and it looked really good. I just figured it was a little less important after that. That was the wrong way to think.
I got in 3 other ones today, they dont work either.
There is only 2 lenses in these converters and i think they need to match the lens on the camera. If they dont its going to look like those pictures up there. Focused in the center not on the edges. |
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04/10/2006 10:09:56 PM · #49 |
I onced repaired my mamiya 50mm1.4. In fact after that i have opened it many times. But i must admit for the first time putting it back back helluva work.
Originally posted by JayWalk:
Taking them apart is easy.... it's putting them back together that I haven't figured out! :/ |
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04/11/2006 10:45:27 AM · #50 |
Hey Bowerdude. I think you are definitely playing with a lot of open learning territory, but please, please, PLEASE, do NOT open or mess around with your S2 IS.
Please remember that you are NOT dealing with a 36-432mm lens. You are dealing with a 6-72mm lens. It is HIGHLY OPTIMIZED for the EXACT specific crop of your camera's sensor.
The aperture (ie f/1.8) is a RATIO number that relates to the physical dimensions of the lens (I believe it is the diameter of the aperture:the distance to the focal plane from the optical center of the lens). This are VERY high precision electronics and I SERIOUSLY doubt that you have come across anything like this in just about ANY telescope you have come across.
Telescopes are usually extremely simple with very few moving parts. Magnification is usually chosen by the use of different eyepeices which are effective 'cropping tools'.
In every telescope I have ever seen, the aperture is FIXED by the mere nature of the telescope itself; NOT controlled by any sort of servo or diaphragm.
Changing the aperture diaphragm is not something that is likely to even be possible across different formats of lenses.
You could learn something, but I believe that what you are actually attempting to do is physically impossible.
If you want to play at mounting the reversed lens for macro stuff, it works and it is lots of fun. If you want to boost your telephoto, be careful. If you go much beyond where you already are, you are likely to face SERIOUS degradation of image quality. The lens on the S2 IS is actually very good optically (considering the 12x zoom range) and is made up using ULD elements which again are customized to the camera and the unique needs of such an extreme crop factor.
Image quality is already pushing hard against the border of the physically impossible on the S2 (a fair bit is made up for already by in-camera sharpening).
To understand this better, take a sample picture from any DSLR. Of any quality.
Lets say the 20D which is a pretty decent camera.
It's shooting at 8.2MP. This is 3504x2336.
This is actually already 1.6x crop, so lets multiply by 1.6 to get a 1x crop equivalency.
3504x2336x1.6 = 5606x3737.6
If the pixel pitch was maintained, and the sensor of the 30D was FF, it would be 5606x3737 pixel sensor. The sensor as is is not that large, so the hypothetical edges have been 'sliced off' to get that 1.6x crop factor.
Now lets find out what the 30D would be like a 6x crop factor like the S2 IS. To do this, we need to divide by 6.
5606x3737/6 = 934x623.
So here's what you can do now. Take that 20D sample picture and crop a 934x623 pixel peice out and do whatever you like to upsize it to the resolution of the S2 IS (2592x1944).
This isn't intended to be a direct comparison of resolutions because the S2 actually has finer resolution.
What it's intended to show is the VAST difference between the two formats.
Resizing the images is a digital way to increase the size of it, but the S2 tries to do this same thing optically, and with a good, but still inferior lens compared to most of the glass that gets stuck on the front of a 20D. Now obviously, this picture doesn't look too good if you look close, but it probably looks half-way decent (if you took a nice sample pic). Now try to sharpen it so it looks good. Not so easy is it? Why? Because you started with insufficient information.
Now take a picture at the lowest sharpening setting in your camera.
Now you see what the camera is actually seeing. (or pretty close) And you see exactly how much the lens is actually NOT able to do as far as increasing resolution optically. The rest gets done digitally. Just as you were doing when you were trying to sharpen the upsized 20D crop.
The moral of the story then?
Switching apertures: Probably physically impossible.
Switching physical lenses: Probably impossible and likely a step downwards in quality even if you did manage it.
Try to stick to external lensing...
(PS. Not trying to be harsh, just trying to show you a different POV)
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