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Possible alternative to barlows/teleconverters (1 Viewer)
- Thread starter Paul Corfield
- Start date
Paul Corfield
Well-known member
With your Max DSLR or CNC Prime Focus Adapter on the camera I would put the baffle ring inside the 2" nose piece.
Paul.
JGobeil
Nature Photographer
Paul,
Please excuse my English but, what is the "nose piece". My setup is:
Camera - CNC 2" adapter - 80mm extension tube - focuser tube.
I sometimes install a TN between the camera and the CNC adapter but it is already baffled.
Regards
J
Tord
Well-known member
Paul,
That sounds interesting.
What is a nose piece? Is that the same as the 2" port, i.e. the part that is screwed to the focuser and with a 2" connection towards camera? What material have you used/thought of? Semi-rigid plastic? Soft metal e.g. aluminum? (Of course painted or covered with flocking tape). Would you also baffle the extension tube, and what end? (I guess further away from sensor is better).
Sorry if my questions are stupid.
Tord
Well-known member
I use exactly the same connection method, and happened to type the question while Jules was uploading it...
Paul Corfield
Well-known member
I tend to talk in astronomy terms. Before the invention of one piece camera adapters like those from CNC supplies you would have the T-ring and screw a 2" or 1.25" dia nose piece into that. That's where I put my baffle and it saves having to put one on individual Tn's, plus as the series of pigeon photos showed it works well without a TN. I used to have one on the front of my 50-75mm extension tube and I think I had one inside the scope on the end of the focuser tube too.
If you plan on having a series of them through the various tubes then start with the furthest away one first to check vignetting at each stage.
Paul.
If you plan on having a series of them through the various tubes then start with the furthest away one first to check vignetting at each stage.
Paul.
Paul Corfield
Well-known member
My Elicar MACRONET-Telecon 3x teleconverter arrived today. The 3X TC part of it works ok. I got this one though with a view to adapting it for TN's so after studying the design I decided I could strip the whole thing down and still be able to use it with the original 3x TC part should I wish. For now I have unscrewed the TC bit and stripped out all the insides. All that's left is a circular disc shaped part that moves in and out with the helical action. The middle of the disc has around a 10mm hole that is threaded for the original 3X TC. This disc travels around 35mm from front to back and provides enough movement to give a decent variation in magnification with a TN. With a 1.5X TN I'm guessing it will give a range of around 1.5X to 2.5X. I will test it out tomorrow as best I can but the forecast is for rain.
Paul.
Paul.
doublespinss
Well-known member
Paul, sorry for being awkward, but I just want to thank you for your patience and willingness to share your innovations. You make this forum great.
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JGobeil
Nature Photographer
Thanks - Got it now !
Paul Corfield
Well-known member
After a couple of days testing with various TN's I've settled on mounting the Canon FD 100-200mm TN inside the Elicar Macronet TC housing. There's two types of TN in the Canon FD 100-200mm and it depends on whether you have the non S.C. version or the S.C. version. The one I'm using here is from the non S.C. version of the lens. I've stripped everything out of the housing except the helical movement and this leaves plenty of room to mount any type of TN.
There's 35mm of travel in the helical movement and from the two photos I took at min/max travel there is a 35% difference in size. So basically every 1mm of travel gives a 1% increase in mag with the Canon TN. It's probably not enough to make the project worthwhile with a low power TN as you could quite easily do the same thing with cropping. What we really need is a lens that increases mag rapidly over a short distance and that can be achieved with small C-mount extenders, basically small TC's for CCTV lenses. They give the biggest difference in mag between the min/max travel on the Elicar. A 2X C-mount extender gives about 3X, maybe a little more when mounted to a dslr with a 1.6X crop sensor. At the max travel on the Elicar it's getting up around 5x and keeping everything steady can be troublesome. The nice thing is that the C-mount extenders screw into the Elicar to make mounting easy. The threads aren't exactly the same pitch but you can get about half a turn which is enough to give a firm fitting. I have a Pentax and a Fuji extender in C-mount,the Pentax one works the best of the two.
A couple of images showing min/max mag difference with the Canon TN.
Paul.
There's 35mm of travel in the helical movement and from the two photos I took at min/max travel there is a 35% difference in size. So basically every 1mm of travel gives a 1% increase in mag with the Canon TN. It's probably not enough to make the project worthwhile with a low power TN as you could quite easily do the same thing with cropping. What we really need is a lens that increases mag rapidly over a short distance and that can be achieved with small C-mount extenders, basically small TC's for CCTV lenses. They give the biggest difference in mag between the min/max travel on the Elicar. A 2X C-mount extender gives about 3X, maybe a little more when mounted to a dslr with a 1.6X crop sensor. At the max travel on the Elicar it's getting up around 5x and keeping everything steady can be troublesome. The nice thing is that the C-mount extenders screw into the Elicar to make mounting easy. The threads aren't exactly the same pitch but you can get about half a turn which is enough to give a firm fitting. I have a Pentax and a Fuji extender in C-mount,the Pentax one works the best of the two.
A couple of images showing min/max mag difference with the Canon TN.
Paul.
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Paul Corfield
Well-known member
Mounting the Fuji 2X C-mount extender into the Elicar Macronet TC housing gives 4.5X magnification. At the full 35mm helical travel it goes up to 6X but it's really pushing the small optics of the Fuji TC a bit too far.
Here's a photo of a Blue Tit from around 10m and it's at 4.5X uncropped (2700mm before crop factor or 4320mm with Nikon 1.6X crop factor). You can see even at this mag the optics are slightly struggling with the tiny bugs in the birds mouth. They aren't nice and clear like they would be in real life and they have the appearance of being magnified. The rest of the bird isn't too bad though. For long distance the tell tale signs of magnification are less apparent in the photos, so that's probably where this style of TC is best used.
I'd like to get hold of a C-mount 1.5X TC just to see if it's a better option.
Paul.
Here's a photo of a Blue Tit from around 10m and it's at 4.5X uncropped (2700mm before crop factor or 4320mm with Nikon 1.6X crop factor). You can see even at this mag the optics are slightly struggling with the tiny bugs in the birds mouth. They aren't nice and clear like they would be in real life and they have the appearance of being magnified. The rest of the bird isn't too bad though. For long distance the tell tale signs of magnification are less apparent in the photos, so that's probably where this style of TC is best used.
I'd like to get hold of a C-mount 1.5X TC just to see if it's a better option.
Paul.
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Paul Corfield
Well-known member
I won a Vivitar 100-200mm today for £1, it's not a lens I've had before and as it was so cheap I took a punt.
After this one I'm going to start taking a look at certain prime lenses. Looking at online lens diagrams it looks like some primes have telenegative type lens groups in them just behind the objective. A lot of primes are very basic and don't contain a TN and it may be a while till I can get an old damaged one cheap enough to strip down.
Also some of the primes along with zooms that have built in image stabilization have what looks like a telenegative group as the part that does the stabilizing. Have a look at this Canon 70-200mm zoom, the stabilizer lens group looks just like most of my 3 element TN's. Plus it also has the regular TN group just behind the front objective. The TN in this Canon is a 4 element design with one lens being made of UD glass (ultra low dispersion glass) which is Canon's own synthetic fluorite.
Paul.
After this one I'm going to start taking a look at certain prime lenses. Looking at online lens diagrams it looks like some primes have telenegative type lens groups in them just behind the objective. A lot of primes are very basic and don't contain a TN and it may be a while till I can get an old damaged one cheap enough to strip down.
Also some of the primes along with zooms that have built in image stabilization have what looks like a telenegative group as the part that does the stabilizing. Have a look at this Canon 70-200mm zoom, the stabilizer lens group looks just like most of my 3 element TN's. Plus it also has the regular TN group just behind the front objective. The TN in this Canon is a 4 element design with one lens being made of UD glass (ultra low dispersion glass) which is Canon's own synthetic fluorite.
Paul.
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Johnlantransj
Active member
Very interesting idea about TNs of prime lenses, Paul. I heard that some prime lenses have TN like zoom lenses, but when I tried to look for prime lens diagrams, I could not find any diagrams on the internet. Do you have any examples that I can look at? What advantages do these prime lens TNs have over the zoom TNs? Lots of old prime lenses are very cheap, especially the slower primes (135/3.5; even 135/2.8; or 200/5.6; 200/4).
I am stopping buying lenses because I am happy with the Vivitar 2x Macro TC (which is very convenient and has some helical extension) and the Pentax 75-150 TN (or a combination of these two when more magnification is needed). I have three other TNs that I need test more (Minolta 100-200; Vivitar 70-150; canon 100-200).
Thanks for all the ideas and hard work
John
I am stopping buying lenses because I am happy with the Vivitar 2x Macro TC (which is very convenient and has some helical extension) and the Pentax 75-150 TN (or a combination of these two when more magnification is needed). I have three other TNs that I need test more (Minolta 100-200; Vivitar 70-150; canon 100-200).
Thanks for all the ideas and hard work
John
Paul Corfield
Well-known member
I doubt the prime lens TN's will behave any better and there's so many lenses that don't have one in, especially the older lenses. It's hard to find lens diagrams and it will be a bit of guess work in the beginning. With me it's a bit of an addiction and I have a very inquiring mind. I like to experiment a lot, it's how I stumbled across the idea of using TN's in the first place. I can't help but take stuff apart and try it on the scope and when I don't have anything to take apart I can't help but start looking on ebay. 
The Teleplus/Vivitar 2X macro TC is very good. I have mine on the camera a lot at the moment, it's very sharp and I like the smooth focusing that it provides.
Paul.
The Teleplus/Vivitar 2X macro TC is very good. I have mine on the camera a lot at the moment, it's very sharp and I like the smooth focusing that it provides.
Paul.
Paul Corfield
Well-known member
My Vivitar 100-200mm 1:4 Close Focusing Auto Zoom lens arrived today. The serial number starts with a 28 and this shows it's made by Komine. Komine are sought after for their excellent glass and having tried out the TN I can see why. I stripped the lens down and took out the TN. Straight away I could see it was a really nice 3 element design and I couldn't wait to try it out on the scope. With this lens you can't unscrew the TN from the front, you have to strip it down further and undo two screws that hold the TN from the side. Once it's out it really is a beauty.
Mounting it as close as I could to the camera it gives 2.4X magnification.
A few images, all uncropped from around 10m range (33 feet). With the Blue Tits constantly feeding their young I get plenty of photo opportunities.
The second image shows a stray reflection as a slightly orange spot on the bird. I messed around with baffles but couldn't get rid of it. Reversing the lens and mounting it back to front cures this problem. It's something I've had to do with other TN's and it makes no difference to sharpness but it can stop stray reflections.
Paul.
Mounting it as close as I could to the camera it gives 2.4X magnification.
A few images, all uncropped from around 10m range (33 feet). With the Blue Tits constantly feeding their young I get plenty of photo opportunities.
The second image shows a stray reflection as a slightly orange spot on the bird. I messed around with baffles but couldn't get rid of it. Reversing the lens and mounting it back to front cures this problem. It's something I've had to do with other TN's and it makes no difference to sharpness but it can stop stray reflections.
Paul.
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Tord
Well-known member
I butchered two lenses tonight.
Started with Clubman 80-200. It was quite easy to dismantle, starting from rear and working forward just by using precision screwdrivers (PH 00/PH 000 and 1.2/1.8 mm flat). Out came four groups of optical elements, a bunch of tiny screws, springs and tubes. I think I figured out which is the TN. Glass looks clear. The TN is quite small in diameter and is mounted on a tube that I think is made of steel, which length fits in the longest of the extension tubes. For radial fit I needed 19 or 20 wraps of electical tape. A quick test (in poor artificial light) indicates magnification somewhere between 2.5 - 3.0
Zuiko 100-200. Same here, was easiest to dismantle starting from the rear. Two screws had jammed, and had to be drilled out, but apat from that it was easy. Four optical groups came out, what I think is the TN is mounted in a tube that fits almost perfectly inside the extension tube, just needed a few strips of office tape for perfect radial fit. So I took the metal saw and cut a tube segment that matches the shortest extension tube. Quick test indicates approx. 1.5 magnification. The rear lens group has fungus, the TN was quite dirty so I had to clean it, spectacle cleaning liquid seemed to do the trick. Hard to tell in artificial light, though.
The last lens is a Sigma 100-200. Will dismantle it later this weekend and test the lot outdoors, it's supposed to be good light.
By the way - are there any other potentially useful parts worth saving, or can I discard them?
Started with Clubman 80-200. It was quite easy to dismantle, starting from rear and working forward just by using precision screwdrivers (PH 00/PH 000 and 1.2/1.8 mm flat). Out came four groups of optical elements, a bunch of tiny screws, springs and tubes. I think I figured out which is the TN. Glass looks clear. The TN is quite small in diameter and is mounted on a tube that I think is made of steel, which length fits in the longest of the extension tubes. For radial fit I needed 19 or 20 wraps of electical tape. A quick test (in poor artificial light) indicates magnification somewhere between 2.5 - 3.0
Zuiko 100-200. Same here, was easiest to dismantle starting from the rear. Two screws had jammed, and had to be drilled out, but apat from that it was easy. Four optical groups came out, what I think is the TN is mounted in a tube that fits almost perfectly inside the extension tube, just needed a few strips of office tape for perfect radial fit. So I took the metal saw and cut a tube segment that matches the shortest extension tube. Quick test indicates approx. 1.5 magnification. The rear lens group has fungus, the TN was quite dirty so I had to clean it, spectacle cleaning liquid seemed to do the trick. Hard to tell in artificial light, though.
The last lens is a Sigma 100-200. Will dismantle it later this weekend and test the lot outdoors, it's supposed to be good light.
By the way - are there any other potentially useful parts worth saving, or can I discard them?
Johnlantransj
Active member
Tord,
Do you have some ideas in mind? With the lens barrels, I tried to modify them to be used as a extension tubes but some were too long while others too big and heavy. I liked the barrel of the Canon 100-200 because it consisted mainly of two tubes that you could push/pull to make a "zoom extension tube." I bought a 52mm reverse macro ring to reverse mount it on the EM5 and I intended to modify the other end with an m42 tube. The parts were purchased from China but they won't be here until 2 more weeks.
As for the optics, Paul said that the front objective could be as diopters for macro work. I tried some of them but they were very strong (my guess was that they were between +5 to +10 diopter range). They also worked as focal reducers but I found them to be too big to fit inside my various adapters for the EM5. I discovered that some elements of the back groups could also be used as focal reducers and they fitted better in my adapters because they were smaller. Out of the six lenses that I had, I found three of these but only one seemed to work decently, but I would have to do more testing.
Please keep us updated with these TNs.
John
Johnlantransj
Active member
With me it's a bit of an addiction and I have a very inquiring mind. I like to experiment a lot, it's how I stumbled across the idea of using TN's in the first place. I can't help but take stuff apart and try it on the scope and when I don't have anything to take apart I can't help but start looking on ebay.
Paul,
I also love taking things apart and testing and learning. Right now, though, I want to spend more time doing photography because spring is beautiful here. Having said that, I am collecting stuffs to test over the winter when there is not much to do.
Take care
John
Paul Corfield
Well-known member
Some of the front objectives can be mounted inside macro tubes and used as focal reducers. They don't all produce a flat field, I think only one of mine does, but even the bad ones are only a little soft in the corners. My one takes the 600mm SW80ED down to around 360mm. I don't notice any loss in sharpness with them.
Some of the rear groups make good close up magnifiers.
Some of the elements can be paired up with similar ones from other lenses and can make really good quality Plossle type eyepieces.
Paul.
