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Thread: Converter lenses- a little pointer

  1. #1
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    Default Converter lenses- a little pointer

    What a minefield this area is. You know the things, bits of glass we screw to the front of our fixed lens consumer cams to extend the focal length at either end of the scale.

    There may well be a guide here somewhere about them, but that's not quite my point in this post. I want to talk to you about three particular lenses, and how they've worked for me.

    I've mentioned here enough times already that I'm building a time slice rig, so I've bought twelve used cameras, choosing the Olympus E-10 and E-20's as being the right quality at a price I wanted to pay. My point is that some of these cameras came as kits with accessory lenses, always the same lenses, and with some simple fiddling fitting these to my video cameras has been something of a revelation, because of the price!

    I would say that as a long time still photographer it becomes clear pretty quickly that the lens is everything. The fancy body of an SLR does nothing other than time the shutter release, hold the film in the right place, house a light meter which may or may not be useful, give you a way of viewing the subject through the 'taking' lens, and give you something to hold on to.

    The fact is that if you buy the latest all singing all dancing digital do-wacka-do SLR and put the end of a beer bottle in front of it your are wasting your time.

    When it comes to this firmly amateur end of the video camera world it strikes me that there is a surprising under emphasis on the still present need for decent glass up front. I can recall some twenty years ago a pro videographer showing me his cameras which had plastic lenses! Accompanied by the statement that 'it's just not the same league as still cameras'. That might have been true in the old Video8 or Hi8 formats, but these days the cameras are on a par with quality medium range still cameras in resolution, so now more than ever quality optics need to be the order of the day.

    When I bought my first digital8 cameras a few years back I immediately went on the hunt for accessory lenses, particularly wide angle ones. I went through about six of them before it became apparent that, quite rightly, you're going to have to part with serious money to get something that will not degrade the image at all. The best I ended up with was a Sony VCL HD model, that cost me half the price of the camera. Now that's not unusual, in the old days parting with two grand for a telephoto lens for one of my Nikons was normal. But when it comes to video gear there's something of a sinking feeling when that 'quality' Sony lens has your image vignetted at minimum focal length settings. What?!!

    In an effort to remove this problem I lashed out on a century x0.7 WA converter. A nice piece of glass, that's heavier than the camera . So now I had a result. A focal length that didn't bend the image too much, stays sharp to the very edge, and allows the prime lens to zoom through it to infinity without losing the ability to focus, in case I should ever need such a thing.

    So one day I'm sitting amongst my ever increasing pile of these accessory lenses intended for the Olympus E-10's, and me being me I dug around for some step-up rings to allow the 37mm filter thread on my cameras to take the 62mm they had, and lo and behold the quailty is indistinguishable from the Century! And they are lighter! But the best bit is that the smaller two of this range go in mint condition second hand for around 35!

    So what are they all about?

    Well, the Olympus E-10's in their day were considered to be a 'Pro' quality camera, they were about a grand when new. But the odd thing that distinguished them from others was that they have fixed lenses. No idea why that should be, I can say that it's proven to be a bonus in many ways, but without the ability to swap lenses Olympus had to do something special to extend the available focal lengths. And so the camera's from day one had three add-on lenses made for them which are optically matched, i.e damn good!

    The 'shortest' is the WCON-08B. A phenominal piece of glass, fully coated on all sides, as they all are in the range, with a huge front element bearing a filter thread size of 105mm. This lens is so big it does not reduce the light entering your prime lens at all. It modifies your prime lens focal length by a factor of X0.8, and no vignetting.

    There's a pic of one here, this is a lo res image: WCON-08B

    Next in line is the short Tele version, the TCON-14B. Muliplying the prime lens focal length by, you've guessed it, 1.4, it also does this without any loss of light, which is remarkable. The image of the 08B above was taken with one of these lenses, here's one fitted to one of my Sony video Cams (in this instance with a Tamron lens hood, and the stuff on the LCD screen is a home made screen hood and magnifier):



    Those two I can recommend whole heartedly, but if you want to push the boat out the next in line is the rather odd TCON-300B. This one needs some more application to make it fit a video camera, as it's so big that it comes with a special mount for the E-10. So I had to make up a fairly simple, but nonetheless accurate mounting plate setup to accomodate this lens. I don't think I can paste another image, but search google images for it and it will come up like a rash. This does stop the lens down a little bit, changing the E-10's prime lens of f2.4 on full zoom to f2.8. But that's still remarkable, to achieve that in regular interchangeable lenses you're talking telephone number prices. Yet again this lens is utterly superb, there is a faintest hint of chromatic abberation, but manageable. The down side of this particular one is that they tend to go for between 80 and 100 used, even more sometimes, I think this one seems more attractive to folk and they've kept their price better. I believe they were about 600 when new.

    You can screw the TCON-14B on to the front of the TCON-300B with suitable step up rings, but the resulting image is not so good, lots of chromatic aberration and less sharp than each lens on their own.

    Now I could show you some footage shot with these, in fact I already have in the thread about steady mounts for an aeroplane, but with compression being what it is, and with me still learning how to reduce file sizes in the best quality there's little point tbh. All I can say is that if the opportunity arises, have a go on one of the first two at least. You will not be disapointed. And if anyone wants to see how I mounted the big one let me know and I'll post a pic.
    Last edited by Jerry Hill; 09-03-2008 at 11:35 PM.

  2. #2
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    Hi Jerry. I have the HDR HC7 Sony which looks very similar to your camera. Would love a more detailed description/sketch of your LCD screen viewer. It looks quite professional, down to the Sony box and clip arrangement. Any details you could supply would be much appreciated.

    I recently tried to buy a simple lens hood for my camera and apparently the 37 mm size is not well catered for in Australia. When you say you made your own adapter for larger lenses, could you be more specific, or do you have a lathe and skills to make such things yourself?

    Thanks.

  3. #3

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    Hmm yes that monitor hood looks interesting... where did yo get that one from?

  4. #4
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    Builder,

    I am in fact a fitter/turner by trade, one of few things I am actually qualified in , but that's academic here.

    The adaptors used to mount the lenses are simple 'step-up' rings. In this case to mount these lenses two steps are needed, I used 37-58, and a 58-62. But I also use a 37-52/52-62 with the same effect. Available on Ebay from China Hong Kong etc. The TCON 300 also needs the rings, but it doesn't actually screw to them. I'll expand on that if needed.

    These rings are available in all sorts of size ranges, and it'll be a solution for you to use a simple hood intended for an SLR camera, you just have to account for the fact that the bigger the diameter of the hood, the longer it needs to be to provide full protection.

    Builder/MarkOneMusic,

    The screen hood shown is home made, the only 'found parts' are a rubber eyecup, and a magnifying glass. I'm a bit stacked for time right now, but I've taken some pics and put them on a web page to save space and multiple links here, just the pictures for you to puruse for now. Please allow time for the page to load, once I'm clear I'll give you an explanation of how it was made, it's a work in progress, with two things to do, but easy to explain those when the time comes. Suffice to say that it's a simple build, no special tools needed apart from a bench grinder, but I'll get to that.

    DIY Screen Lens Hood
    Last edited by Jerry Hill; 09-04-2008 at 01:05 AM.

  5. #5
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    You know to make a simple lens hood you could always go the plant pot route, lol!:



    Right, the screen hood.

    I made this because I think commercial ones are too costly, especially magnified ones.

    The screen hood is made form a material known well to sign makers, PVC Foam Board. It’s best described as a medium/soft plastic board, which has been aerated when made, making it light and easy to cut. In this case 3mm board is used for everything. PVC Solvent Cement, like plumbers use for PVC pipe is used to glue the parts together, the glue is a solvent, so in essence the joins are ‘welded’, making a very strong joint.

    Basically what we have here are two simple box structures. The hood itself has a top section which nestles on to the top edge of the screen, two sides, and there are two struts across the bottom. On the HC5 there’s a touch screen monitor, so to be able to access the screen an elastic curtain, consisting of two sections overlapping each other will allow a finger to be poked in, and it will self close when your finger is removed. It’s bound to be a bit fiddly, but not too bad from trials. This is one of the outstanding things yet to be done to my hood. I don’t use the screen mounted stop/or zoom controls, so I’ve no problem covering them up

    The hood is lined with baize (like a pool table) to stop internal reflections, and this overlaps around the screen ends of the box to provide scratch free contact. Frankly matt black paint would do for just a hood, but I use the baize for a reason to come.

    The hood is held on with simple elastic bands, I put string ‘pigtails’ on to the pulling end, and heatshrink tubing over that, this gives something firm to grab hold of, but it’s not necessary.


    The magnifying element is a five sided box, made to be a sliding fit in the hood, which is why the baize is good as it gives a nice fit and sufficient friction, the sliding action is simply there to allow focussing, you could fix the focus if wanted. Inside the box is a magnifying lens, taken from a ‘Helping Hand Magnifier’, those devices which consist of a little stand, a couple of articulated crocodile clips, and an articulated magnifying glass, these are intended to provide a means of hold two parts together whilst some other operation is going on, I use them a lot for soldering circuit boards etc. The lens was ground to a suitable rectangular shape using a bench grinder. In fact I used a grinding wheel intended for tungsten carbide tools for lathes, but an ordinary aluminium oxide one will do, just be careful of heat build up, as this will force the glass to ‘shell off’ at the edges if you’re over zealous with it. Once the lens fits inside the box for the magnifier, some fiddling is needed to get it into the right position, once established two PVC foam board ‘stops’ with concave curved edges to match the lens shape are glued in on the screen side of the lens.

    The eyepiece of the magnifier is another box which fits inside the other, the end plate though is the outside profile of the main box. The inside ends of the sides of this section are also curved to trap the eye side of the lens. This part is held in place by a couple of screws on the side. I did this to allow the lens to be removed for thorough cleaning, as I have a real thing about dirty lenses, wherever they are.

    The eyepiece is simply an old eyecup off a pair of trashy binoculars. I cut out rings of varying size to provide a lip for the cup to fit over, and between the rubber eyecup and on the outside of the eyepiece hole there’s a cut down microscope glass slide, this is held in place by the eyecup itself, and obviously is there to stop dust getting inside the assembly. Again cleaning can be done properly by just popping off the eyecup to release the glass slide.

    The other thing that needs doing is to provide a support, this assembly is heavy enough to overcome the friction on the LCD screen, but as I always use tripods, it’ll be easy to rig a simple adjustable support for allow full positioning of the hood magnifier. It's fine with just the hood and no magnifier, it's the lens that adds most of the weight.

    I’ve just done a quick drawing of the hood alone, no dims, but to scale. It’s here:

    Screen Hood Drawing

    The parts were finished using simple auto paints in aerosols, a ‘Clear over Base’ two part metallic system, readily available at auto shops. The decals are a bit of tarting I did for fun really, I do that sort of crap a lot, dunno why. My wife owns a small sign making business, so the stuff to make these decals is to hand. It’s self adhesive brushed aluminium, applied to the finished article, then the whole thing given another coat of lacquer. None of that finishing stuff is necessary, but for me, being a former custom motorcycle painter, it’s just as simple to do this as fiddle with brushes etc.

    Anyway, not a definitive set of instructions, but if you need to know more, let me know.
    Last edited by Jerry Hill; 09-06-2008 at 12:07 AM.

  6. #6
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    Thanks Jerry. Great photos. So the screen hood box needs magnification? I just need to shield it from the sun myself. I reckon I can make one of those, so I'll give it a go. Appreciate the details.

    I think the viewfinder on the Sony is the only thing that lets it down. I have the larger battery pack, and my nose hits the battery before my eye hits the viewfinder.

    As for the lens conversions, what kind of filming do they allow? I have been experimenting with the macro capabilities of the Sony, and the depth of field is pretty reasonable so far.

    Once again, thanks for your help.

  7. #7
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    Ahh, good point, I should have made the magnification thing clear in the first place .

    No, the magnification is not a requirement, I just liked using the eyefinder's on the cams before this one for telephoto work, largely because for my subject I'll be setting up real low to the ground, all of my decent tripods allow this, it's why I bought the ones I have, so the screen would be pointing upwards to be able to see it otherwise I'd be on the ground like a sniper, a screen pointing upwards is no good for reflections, hood or no hood. My previous cams have an eyefinder which extended rearwards, and could flip up, so my low mounted cameras were looked into from above a bit, at about 30 degrees, which was nice and comfortable. I also like the visual isolation eyefinders give, I use the screens for steady cam work, but that's about it. I have both eyes open when using the eyefinder, for both safety and subject awareness. You can't actually do that with an LCD screen, as the natural act of the eyes independently focussing correctly on the cameras view and the actual scene doesn't work if the camera eye sees the scene in peripheral vision. With an LCD screen alone both eyes are focussing on that.

    Not only does the HC5 eyefinder not flip up, it's just plain rubbish! The image is far too small to be of use, so checking for focus etc is just not a happening thing, so I made this eyefinder to regain the facility, and to be honest, it's better than ever, big, and in colour of course.

    I'm guessing that the LCD screen has simply taken over from eyefinders for most hobby users, but it's clear that as you go up the camera quality range eyefinders become increasingly better quality and take more prominence too, so I guess I'm not alone.

    EDIT:

    I've recalled this image. The tripod bag is in the way a bit, but it shows a typical setup of mine, tripod legs splayed right out, camera lens about 18" off the ground.

    And yes, I do have to wear Hi Vis gear, and a helmet. This stuff can be dangerous!



    EDIT EDIT:

    Sorry, the lenses. The wide angle converter allows full zooming and focussing to infinity, which many don't, I've not tried any close up stuff with it, but naturally the minimum focal distance will reduce by the same factor, 0.8X, so it has to be an improvement, I'll take a still off my cam later to see what it can do. Needless to say it does not vignette at all, as it's such a huge piece of glass!

    The 1.4x converter does vignette at full wide zoom setting, you need to go forward about 10% to prevent that, but all telephoto converters do that but not as little as this one, and in spite of what I'd said above, using a teleconverter on a wide angle setting is a bit silly really so it'll never become a problem.

    The TCON 300, 3.0x, vignettes hugely at wide angle setting as you'd expect, down to a tiny circle in the middle of the screen, but that's actually useful to align the lens, as this one does not actually fix to the filter thread, and is only really useful say between 80-100% of the zoom range. Minimum focus on this one shifts accordingly, but the image quality is awesome, this is from a 4mp still from my HC5, says it all I think.

    Last edited by Jerry Hill; 09-05-2008 at 04:51 PM.

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    Sadly the daylight here has been, well, rubbish! It's was heavily overcast and not much use for photography. So for DOF trials I'm not able to show anything at the moment, but I would like to know what you mean by 'depth of field is pretty reasonable so far', are you looking for great depth, or shallow depth of field?

    For now though I've taken these stills on a Sony HC5 to show at least something. By way of statutory cop out these are rushed images using a flash, both flash and camera hand held, because I had to use a slave flash because the lens obscures the on camera flash completely! I claim no artistic merit for these! LoL! Believe me I don't need to be told about the lack of contrast because of the lighting, the blown out highlights da-da da-da da-da! Naturally they are resized and heavily compressed for the forum too, a mere shadow of the originals.


    In this first one, the standard camera lens is set to minimum zoom, the slave flash had to be behind the flower (a Moth Orchid btw) as the light path was still obscured by the lens even on this off camera flash unit! There's enough transparency in the petals to throw some light on to the visible side of the flower. Image is full frame. For reference the distance across the main yellow fringed petals in the middle of the flower is 25mm.




    In this one the TCON 08B is fitted, the camera is on the same zoom setting, but physically closer to the subject due to the reduced minimum focussing distance. In fact this lens is so close it's touching the flower, you can see the two tendril things at the bottom are now bent up!

    Significantly though you can clearly see how the perspective has changed, by looking at those two yellow fringed petals you can see that we are further inside them as it were. Again the image is full frame




    This final picture was a different approach, TCON 08B fitted, and the lens was zoomed out, enough so that I could squeeze the flash between the lens and the flower, and the image has been cropped down to emphasise the capturing of detail, for what that's worth in a so heavily compressed image.





    EDIT:

    For the record, here's a 600 pixel wide crop from the full size image, i.e. no size reduction, but still heavily compressed. The width across the spotted section of the actual flower is 7mm.





    Anyway, if you could let me know the target you have for DOF, I'll see if there's a chance of testing that over the weekend.
    Last edited by Jerry Hill; 09-05-2008 at 10:41 PM.

  9. #9
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    Thanks for the useful info, Jerry.

    As for your question:
    Sadly the daylight here has been, well, rubbish! It's was heavily overcast and not much use for photography. So for DOF trials I'm not able to show anything at the moment, but I would like to know what you mean by 'depth of field is pretty reasonable so far', are you looking for great depth, or shallow depth of field?
    The macro thing is a throwback to my days of still photography, and my interest in nature on a macro scale. Subjects like spiders making webs, for example, mostly because they don't fly away. The macro option in the camera menu really brings you in close, but any movement of the zoom button cancels the macro automatically, which is why I'm interested in a lens that allows fine focusing while in macro, rather than using the camera's inbuilt macro feature.

    Shallow depth of field is expected in macro, and sometimes useful, but stretching the depth to a little more than the thickness of a pane of glass would also be a help, depending on the motion of the subject/s. I have a short film of an amazing little spider, with a bright orange carapace that looks like a sheild on his back. The start of the film is just out of focus, and so is the end, so being able to slightly refocus while in macro mode, by adjusting the camera lens, rather than the zoom button, would be handy to me.

    Nice pics, btw. I have some great flower shots myself, but I'm using internet cafes at the moment, awaiting a new computer for film editing.

    Oh, and the flower-pot lens hood would be better than a sheet of paper, or my hand. Seems I always need an extra hand when filming.
    Last edited by builder; 09-09-2008 at 06:36 AM.

  10. #10
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    Hmm, I'm not sure any trial, which I'll have a go at again this weekend, will help really as I don't have control over apetures on my cams.

    I'm hoping to run some more tests for a gun review video this weekend, and I have a tracking shot in mind which is real close to the rifle, moving along its length. These crappy test videos (hand held), were shot ages ago and made to highlight the issues, though not made using these lenses and with my old cameras. In this one the cam is perpendicular to the gun, but I want to angle the cam more, like a starcruiser going past, so it may be a way of seeing how the DOF appears. I've tried to make it smaller for your netcafe viewing:

    Rifle cam test 1

    This one is at the desired angle in places on a different gun, but more general faffing around trying things:

    Rifle cam test 2


    I'll try these tests again, with some better dolly work and my better camera with the TCON08B, if able.

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