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Convert Telephoto adapter to Macro focus
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PostPosted: Fri Feb 14, 2025 3:34 pm    Post subject: Convert Telephoto adapter to Macro focus Reply with quote
I've just bought a Helios 3x auto teleconverter from that most popular auction site. It was sold as spares or repairs, so it was very cheap.

It appears to be in excellent condition, except for its ability to focus...I initially thought it was broken as I tried taking a picture of the view from my lounge window and it was just a blurry mess but then I realised that it happily focuses at a close distance, so I was wondering whether it had been modified to become a macro focusing adapter.

Is that possible and if so, how do I go about restoring it to be a normal teleconverter again? Is it a point of putting the glass in the other way round?

How easy are these teleconverters to strip down?

Does anyone have a link to where I can buy decent lens repair tools? They don't have to be the most expensive, they just have to do their job well.


PostPosted: Fri Feb 14, 2025 4:52 pm    Post subject: Reply with quote
I'm not familiar with the lens in question. Could you post a photo? As to repair kits there are options on "that popular auction site". You will likely need a set of small screwdrivers, a set of rubber lens wrenches, and an adjustable spanner wrench.

Two types of spanner wrenches, rubber lens wrenches, and a small screwdriver kit with a multitude of different interchangeable bits.



The rubber wrench set and the spanners were from ebay at Japan Toy and Hobby. The screwdriver set I got locally at a woodworking specialty store. They no longer have them and I have tried unsuccessfully to locate that same kit online. Similar kits should be available online though.


PostPosted: Fri Feb 14, 2025 9:02 pm    Post subject: Reply with quote
I may have put this in the wrong section....apologies

It's actually a teleconverter, although i suppose that's a lens...of sorts

It's a very common one but here's a pic all the same
#1


I was rather hoping for a link to the necessary tools...preferably from someone who's bought them and can verify they're good


PostPosted: Sat Feb 15, 2025 11:44 am    Post subject: Re: Convert Telephoto adapter to Macro focus Reply with quote
Bololoco wrote:

It appears to be in excellent condition, except for its ability to focus...I initially thought it was broken as I tried taking a picture of the view from my lounge window and it was just a blurry mess but then I realised that it happily focuses at a close distance, so I was wondering whether it had been modified to become a macro focusing adapter.


The only thing a teleconverter is supposed to focus on is the image from the lens to which it is attached and which it magnifies. It looks like it requires a threaded lens, M42?

Although I can't quote anything, x3 converters were generally thought to be of inferior quality to x2 ones.


PostPosted: Sat Feb 15, 2025 4:30 pm    Post subject: Re: Convert Telephoto adapter to Macro focus Reply with quote
e6filmuser wrote:
The only thing a teleconverter is supposed to focus on is the image from the lens to which it is attached and which it magnifies. It looks like it requires a threaded lens, M42?

Although I can't quote anything, x3 converters were generally thought to be of inferior quality to x2 ones.


To be honest, the mirror lens is soft AF already, so I lowering the quality isn't really too much of an issue. I just want it to work.

And yes it is an M42 but that's not important.

So i'll ask the question again since I haven't had an answer yet...

can you turn a telephoto lens into a macro focusing lens by reversing the glass? This telephoto only seems to manage to focus on close objects, not distant horizons, so I was wondering whether it had been altered and could I turn it back into a telephoto lens again?


PostPosted: Sat Feb 15, 2025 5:27 pm    Post subject: Reply with quote
mmm a teleconverter is just a compound negative lens, I would have thought most of them would be optically similar reversed - looking through a tamron 2x tc one way and then the other, virtually no difference. However the spacing of the elements from one end vs the other is very different so that could certainly produce big focus differences if it was used the other way round by swapping the male and female mounts on the ends, or if the optical block had been remounted in the shell the other way round.
But to echo previous comment, these 3x tc's are optical junk tbh
Take the optics out and use it as an extension tube.


PostPosted: Sat Feb 15, 2025 6:51 pm    Post subject: Reply with quote
This looks longer than my variable M42 TC (which switches between 2x & 3x by changing the order of it's two parks).

I have several macro TCs & they all have a helicoid section, so I don't think it was intended to work as it now does.

Is there any sign that a previous owner has 'serviced' it? If so they might have put it back together wrong (elements reversed or perhaps swapped).

In any event the optical quality will be disappointing on digital, I'd expect cropping to give a better result


PostPosted: Sat Feb 15, 2025 7:02 pm    Post subject: Reply with quote
DConvert wrote:
This looks longer than my variable M42 TC (which switches between 2x & 3x by changing the order of it's two parks).

I have several macro TCs & they all have a helicoid section, so I don't think it was intended to work as it now does.

Is there any sign that a previous owner has 'serviced' it? If so they might have put it back together wrong (elements reversed or perhaps swapped).

In any event the optical quality will be disappointing on digital, I'd expect cropping to give a better result


I can't see anything untoward. It's fairly pristine but that doesn't mean it hasn't be tampered with. It's just weird that it's acting as a macro focusing unit and that i'm unable to focus on anything distant.

I think i'll have to take it apart anyway and see if I can alter things around inside. If not, i'll use it as is and get myself another one. They're not rare and are often found for a couple of quid.

Thanks for the help though.


PostPosted: Sat Feb 15, 2025 7:16 pm    Post subject: Reply with quote
marcusBMG wrote:
mmm a teleconverter is just a compound negative lens, I would have thought most of them would be optically similar reversed - looking through a tamron 2x tc one way and then the other, virtually no difference. However the spacing of the elements from one end vs the other is very different so that could certainly produce big focus differences if it was used the other way round by swapping the male and female mounts on the ends, or if the optical block had been remounted in the shell the other way round.
But to echo previous comment, these 3x tc's are optical junk tbh
Take the optics out and use it as an extension tube.


Thanks for the info. I'm not that knowledgable on lens optics, although I do remember doing a bit of that in school Physics....over 40 years ago.

I'll be taking it apart some point soon to see what I can do about it, although I took my previous TC apart last week and lost some of the screws...they're blinking tiny and although I had a table top prepared for the job, they still managed to disappear.

As for the quality...yes, I know they're pretty bad but i'm after the huge range.

I'll upload a picture to the digital mf gallery i took of a building 0.8 miles away with 2200mm of lens (4400mm if you include the crop factor)....it's suprisingly good if not a bit soft as long as you don't do any pixel peeping

Update....site under maintenance...it won't let me upload this pic


PostPosted: Sat Feb 15, 2025 8:46 pm    Post subject: Reply with quote
With the lenses reversed it becomes a (poorly corrected) "speed booster" if I am not mistaken.


PostPosted: Sat Feb 15, 2025 9:33 pm    Post subject: Reply with quote
jamaeolus wrote:
With the lenses reversed it becomes a (poorly corrected) "speed booster" if I am not mistaken.


Ok, so do you have any idea what has turned it into a macro focusing lens?

It's confounding me.


PostPosted: Sat Feb 15, 2025 11:01 pm    Post subject: Reply with quote
Well...I am not familiar with this precise lens but is it possible that one of the elements has been put in upside down? How are the elements fitted into position? Most lenses have a mounting ring that screws into a base ring (sometimes even a stack of these rings) and sandwiches the element between and holds it in a precise position. Sometimes the lenses may have elements that look pretty much symmetrical are not actually perfectly biconvex or biconcave. If it then gets put in upside down it might change the optical path. Just a guess though. They are generally tightened with a spanner lens similar to the ones I showed. Other designers sometimes use a flange held down with screws around the orbit of the lens.


PostPosted: Sat Feb 15, 2025 11:26 pm    Post subject: Reply with quote
Jar lids, are useful to hold smallbits when you dismantal anything


PostPosted: Sat Feb 15, 2025 11:49 pm    Post subject: Reply with quote
Ok. I checked google images. The lenses appear to be held in with a ring fitted with round holes for the spanner to push. You will find them on the flat portion of the lens hold down ring. I'm not sure what kind of financial position you are in but for me on an inexpensive lens like this I would not hesitate to try home made tools. For example, an old fashioned compass might be just enough to fit in the holes and give just enough torque to loosen the hold down ring. Or you could buy a different sample of the lens.


PostPosted: Sun Feb 16, 2025 12:30 am    Post subject: Reply with quote
Slalom wrote:
Jar lids, are useful to hold smallbits when you dismantal anything


I bought myself one of those latex soldering mats with indentations for all the screws....it worked perfectly until I had to put the screws back and they almost literally disappeared in front of my eyes. I have 2 left out of the 5 needed to put it back together properly.

Does anyone know where I can buy such screws? They're absolutely tiny.


PostPosted: Sun Feb 16, 2025 12:38 am    Post subject: Reply with quote
jamaeolus wrote:
Ok. I checked google images. The lenses appear to be held in with a ring fitted with round holes for the spanner to push. You will find them on the flat portion of the lens hold down ring. I'm not sure what kind of financial position you are in but for me on an inexpensive lens like this I would not hesitate to try home made tools. For example, an old fashioned compass might be just enough to fit in the holes and give just enough torque to loosen the hold down ring. Or you could buy a different sample of the lens.


I'm somewhere between poor and not poor. I'm a self employed gardener, so really need to pull my finger out this summer.

The only problem is, I am semi allergic to soil, so would rather just take and edit photographs and walk my dog all day.

I have enough money for a few tools and I have almost 200 manual lenses, most of which need a deep clean, although only a handful are worth the effort but I suppose I could sell the ones I don't like after I've cleaned them.

I sort of think there's no such thing as a bad lens, they just need the right scene but I definitely have way too many.


PostPosted: Sun Feb 16, 2025 12:40 am    Post subject: Reply with quote
jamaeolus wrote:
Well...I am not familiar with this precise lens but is it possible that one of the elements has been put in upside down? How are the elements fitted into position? Most lenses have a mounting ring that screws into a base ring (sometimes even a stack of these rings) and sandwiches the element between and holds it in a precise position. Sometimes the lenses may have elements that look pretty much symmetrical are not actually perfectly biconvex or biconcave. If it then gets put in upside down it might change the optical path. Just a guess though. They are generally tightened with a spanner lens similar to the ones I showed. Other designers sometimes use a flange held down with screws around the orbit of the lens.


yes, I suppose that is definitely possible. I've yet to dismantle it to find out.....and manual teleconverters are relatively simple lenses, so hopefully it won't be difficult.


PostPosted: Sun Feb 16, 2025 5:06 pm    Post subject: Reply with quote
While the slotted bits may be fine, if you're working on anything Japanese, using those cross-head (Philips) bits are going to end in tears, since despite appearing similar, they don't have the correct tip angle to use on Japanese (JIS) screws and will strip them out. Incidentally, modern Chinese lenses also typically use the Japanese-style screws. Any driver set purchased in the U.S. is going to be Philips unless it explicitly indicates JIS.

A proper set of JIS screwdrivers/tips is the very first thing I recommend anyone getting into the hobby of lens repair to purchase, as it's the only critical tool for which there really is no off-the-shelf workaround.

jamaeolus wrote:
I'm not familiar with the lens in question. Could you post a photo? As to repair kits there are options on "that popular auction site". You will likely need a set of small screwdrivers, a set of rubber lens wrenches, and an adjustable spanner wrench.

Two types of spanner wrenches, rubber lens wrenches, and a small screwdriver kit with a multitude of different interchangeable bits.



The rubber wrench set and the spanners were from ebay at Japan Toy and Hobby. The screwdriver set I got locally at a woodworking specialty store. They no longer have them and I have tried unsuccessfully to locate that same kit online. Similar kits should be available online though.


PostPosted: Sun Feb 16, 2025 5:27 pm    Post subject: Reply with quote
BrianSVP, thanks for the tip on the philips lookalike drivers. I was completely unaware! Will definitely buy a set! You seem to be the best on this site for lens repair. I dabble on some of my less expensive examples but won't open any expensive things. Would you consider trading your skill for a lens of your choice? I have literally thousands of lenses but a a few really good ones I would like to have fixed. For example I have a Canon FL 300mm 2.8 with some hitches in the focus throw. You could name a few lenses you covet and I likely have a sample. Thanks.


PostPosted: Sun Feb 16, 2025 8:13 pm    Post subject: Reply with quote
Place mat in a tray -- tray sides catch screws. A strong magnet is useful for "finding" screws, parts, that have fallen to the floor (or dirt Smile).


PostPosted: Sun Feb 16, 2025 11:40 pm    Post subject: Reply with quote
This is where I got my JIS tools:

https://www.micro-tools.de/en/Screwdrivers/Kits/JIS-Type-S-Driver-Set-Pollicis.html

(pre-brexit, I can add).
I have a set of JIS micro screwdrives and also I acquired a starrett jewellers screwdriver off ebay and bought JIS bits for it.


PostPosted: Mon Feb 17, 2025 12:35 am    Post subject: Reply with quote
I have a few sets of JIS screw drivers, from amazon uk.plenty of feed back on sellers.


PostPosted: Mon Feb 17, 2025 10:28 am    Post subject: Reply with quote
These are JIS, from a reliable brand (Vessel), and available in the UK:

https://amzn.eu/d/2P9yzRb


PostPosted: Mon Feb 17, 2025 5:52 pm    Post subject: Reply with quote
Thanks for the screwdriver information and links. I've heard of JIS screwdrivers so will have to get myself a set.

I already have a powerful magnet (500lb pull) but that hasn't helped me find it.

Does anyone know where I can get replacement screws for a prinz galaxy auto teleconverter? It's a waste of glass having it sat in a bag just because of a few screws.


PostPosted: Mon Feb 17, 2025 10:24 pm    Post subject: Reply with quote
You can get non JIS screws that will work - you need to id the size (ie diameter: M1.8, M2..).
And I have a tc or two in my junk box that may well have compatible screws...
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