Bolex Lens Conversion to Elmo GP Deluxe!

[Shane C. Collins]

I recently bought a Elmo GP Deluxe dual 8 projector from the early 70's. Being a fuss button about lenses, and sharpness I decided to do a conversion. I used a previous conversion done by Leon Norris back in 2019. I decided to do the same as he did then. A retro fit of the Bolex prime 1.3 15mm lens used on the first series of Bolex 18-5's. As Leon needed to do back in 2019 I used an Elmo 1.3 zoom lens. I took the lens apart, as the only part I needed was the back portion which contains the metal pin that rotates in the focus assembly. As Leon did, I filed down the rear portion until the Bolex lens slid back far enough to get focus. When this was accomplished, the Bolex lens fit perfectly inside the rear assembly of the Elmo lens. I installed the lens back in the projector, and ran a film. It took a few adjustments to find the proper distance between the lens and the film plane. Once I did, I had perfectly sharp images from the left to right frame. I forgot just how sharp those Bolex "hifi" prime lenses were on screen! The Elmo GP Deluxe uses a 150 watt EJM halogen which is plenty bright for my current Ektachrome home movies. Keep in mind the Elmo GP Series of projectors use the same lenses from the later Elmo GS 1200 machines. This is a great upgrade for anyone that has a spare Elmo zoom laying around. Below are some photos of my upgrade. Please note the large Super 8 sticker on the flip down cover was placed there by me!

[Paul Adsett]

Well done Shane, looks like a great conversion and a very neat job. You just cannot beat a prime lens for the very best projected image quality. I use my Prime Ektar lens all the time on all my Eumig projectors. Just wish I could fit it into my GS1200!

[Shane C. Collins]

Well done Shane, looks like a great conversion and a very neat job. You just cannot beat a prime lens for the very best projected image quality. I use my Prime Ektar lens all the time on all my Eumig projectors. Just wish I could fit it into my GS1200!

Thanks Paul for the kind words! It really is night and day between a zoom lens, and a prime! The only zoom I like is the Eumig Suprovar 1.0, which I'm sure you've heard me talk about constantly, LOL. Anyways, I would love to get my hands on one of those prime Ektar lenses. Too bad it can't fit inside the rear sleeve of an Elmo zoom lens. But, I assume the Ektar lenses diameter is closer to 32.5 mm?

[Paul Adsett]

Shane you might want to keep an eye open for an old Kodak M100 Super 8 sound projector. It was Kodak's flagship super 8 projector when super 8 was first introduced as a new film. They clearly made this lens to be the very best quality to show off the new guage. As far as I know it was only available on the old M100. So if you see an M100 on ebay - GRAB IT! just for the lens!
Note that I had to have the Ektar barrell machined down a bit to fit the Eumig 32mm lens holder.

[Shane C. Collins]

[QUOTE=Paul Adsett;n108093]Shane you might want to keep an eye open for an old Kodak M100 Super 8 sound projector. It was Kodak's flagship super 8 projector when super 8 was first introduced as a new film. They clearly made this lens to be the very best quality to show off the new guage. As far as I know it was only available on the old M100. So if you see an M100 on ebay - GRAB IT! just for the lens!
Note that I had to have the Ektar barrell machined down a bit to fit the Eumig 32mm lens holder.

Thanks Paul! A few years ago I think I may have come across one of these lenses. It was being sold by itself on eBay. After clicking the listing, I cross referenced the lens to make sure it was the correct one. I came to the conclusion it was, but decided not to put in a bid. Looking back I probably should have. Not sure what machine I would even be able to use it in?

[Brian Harrington]

Note that I had to have the Ektar barrell machined down a bit to fit the Eumig 32mm lens holder.

I assume you had easy access to someone who could do that. Was it CNC-machined? Did you remove all the glass first?

[Brian Harrington]

I recently bought a Elmo GP Deluxe dual 8 projector from the early 70's. Being a fuss button about lenses, and sharpness I decided to do a conversion. I used a previous conversion done by Leon Norris back in 2019. I decided to do the same as he did then. A retro fit of the Bolex prime 1.3 15mm lens used on the first series of Bolex 18-5's. As Leon needed to do back in 2019 I used an Elmo 1.3 zoom lens. I took the lens apart, as the only part I needed was the back portion which contains the metal pin that rotates in the focus assembly. As Leon did, I filed down the rear portion until the Bolex lens slid back far enough to get focus.

When this was accomplished, the Bolex lens fit perfectly inside the rear assembly of the Elmo lens. I installed the lens back in the projector, and ran a film. It took a few adjustments to find the proper distance between the lens and the film plane. Once I did, I had perfectly sharp images from the left to right frame.

I forgot just how sharp those Bolex "hifi" prime lenses were on screen! The Elmo GP Deluxe uses a 150 watt EJM halogen which is plenty bright for my current Ektachrome home movies.

I'm curious when you get your Elmo 1.1 lens to hear which is better on that machine.

What were those final adjustments that you had to make? The distance between the lens and the film plane is what focusing does -- or am I mis-understanding something? When side-to-side focus is "off", there are small screws to adjust -- is that what you meant? Same as on the Elmo ST-1200 models.

thnx

[Paul Adsett]

I assume you had easy access to someone who could do that. Was it CNC-machined? Did you remove all the glass first?

Yes I was able to "bootleg" the job through the machine shop of the aerospace company where I worked. The glass was not removed, but protective covers were placed over each end of the lens. The lens was clamped into a collet of a manual lathe. The guy who did the job was a very skilled machinist who knew exactly what he had to do to ensure no damage to the lens. The lens was machined down to 32mm diameter over a 35mm length from the original stepped down edge ( shiny surface as shown in the photo) .
It is now an exact fit for all my Eumig 800 series and 900 series projectors.
Focusing is done by twisting and sliding the lens in the projector lens mount, which seems to work well , and much better than engaging the clunky focusing knob arrangement on the projector.

[Brian Harrington]

Nice. I wonder what other projectors it would fit in as-is with no mods. Not that it is an easy lens to get anyway.

If you think about it, all projectors should be able to run film smoothly and safely. Setting aside sound and reel capacity for the moment, the lens and the lamp are what sets apart one projector from the other. So if lens barrel sizes were standard, all you would need is a long-play unit. Everything modular. Piece together a system to your liking the way audiophiles do. You buy the basic projector to transport your film. (Auto-thread models, manual threaders, sprocketless, with sprockets, super 8, 8mm, dual-8, speed control, whatever.) Different levels with different features. Buy the lens you want. But a long-play unit. You're done! The perfect projector for you!

Maybe that's the way it works in a parallel universe!

[Shane C. Collins]

I'm curious when you get your Elmo 1.1 lens to hear which is better on that machine.

What were those final adjustments that you had to make? The distance between the lens and the film plane is what focusing does -- or am I mis-understanding something? When side-to-side focus is "off", there are small screws to adjust -- is that what you meant? Same as on the Elmo ST-1200 models.

thnx

Hi Brian, The Elmo 1.1 zoom came in a few days ago. I was able to screen a print with it, and overall I liked what I saw! I still hold steadfast, that my favorite and sharpest zoom, is that Eumig Suprovar 1.0 I can't seem to stop talking about! That zoom really is that good! Anyways, I'm going off topic again as usual!

The adjustments I needed to make, were basically to make sure the Bolex prime fit far enough back to gain focus. The Elmo zoom was disassembled, as I mentioned, only needing the rear portion. That part of the lens contains the rear glass element that is screwed to the rear plastic part of the lens, and the focusing pin. Once the glass was unscrewed the plastic lens casing was empty. Then I needed to file down the rear opening so the Bolex prime slid further back. As it stood the Bolex prime only went as far as the rear portion of the lens tube, but not far enough to stick out the back. I simply used a metal file to shave off more plastic in the rear portion of the lens tube. It took some time until I was able to push the Bolex prime all the way through. I then set the lens, and assembled it into the Elmo GP Deluxe. After threading a movie, I only slightly moved the Bolex prime back and forth until the focusing knob was able to bring the image into focus!

[Brian Harrington]

Thanks -- it does seem to be a lot of intricate work to get it right. It seems to me if the filing isn't 100% even, then the lens wouldn't sit exactly right to get an even side to side focus. It wouldn't be worth it to me since I'm very satisfied with the Elmo 1.1 lens.

One thing that Lipton points out is that the f numbers are sorta just a "potential", and that's why one 1.3 lens may let through more light than another 1.3 lens. I was surprised to read that -- to me, a spec is a spec is a spec. Anyway, I guess that's why a prime 1.3 lens, for example, is brighter than a zoom 1.3 lens.

I've also read that the Elmo 1.0 lens isn't as sharp as the Elmo 1.1 lens. Part of the reason is the difficulty of keeping the 1.0 in focus throughout a reel.

Anyway, for me, the Elmo 1.1 was a big upgrade from the Elmo 1.3. I noticed it right away when I got it over 25 years ago. The bonus is that I get to use it for both Standard 8mm and Super 8 due to the Elmo GP projector. So for all my longing for better lenses for my other projectors, in fact I'm really all set for both gauges, for both silent and sound.

What I really need is a 38mm lens for my Eiki 16mm machine since the 50mm one doesn't cut it. I do have an Elmo 16CL with a 38mm lens, though. But that's a topic for the 16mm sub-forum.

[Shane C. Collins]

Thanks -- it does seem to be a lot of intricate work to get it right. It seems to me if the filing isn't 100% even, then the lens wouldn't sit exactly right to get an even side to side focus. It wouldn't be worth it to me since I'm very satisfied with the Elmo 1.1 lens.

One thing that Lipton points out is that the f numbers are sorta just a "potential", and that's why one 1.3 lens may let through more light than another 1.3 lens. I was surprised to read that -- to me, a spec is a spec is a spec. Anyway, I guess that's why a prime 1.3 lens, for example, is brighter than a zoom 1.3 lens.

I've also read that the Elmo 1.0 lens isn't as sharp as the Elmo 1.1 lens. Part of the reason is the difficulty of keeping the 1.0 in focus throughout a reel.

Anyway, for me, the Elmo 1.1 was a big upgrade from the Elmo 1.3. I noticed it right away when I got it over 25 years ago. The bonus is that I get to use it for both Standard 8mm and Super 8 due to the Elmo GP projector. So for all my longing for better lenses for my other projectors, in fact I'm really all set for both gauges, for both silent and sound.

What I really need is a 38mm lens for my Eiki 16mm machine since the 50mm one doesn't cut it. I do have an Elmo 16CL with a 38mm lens, though. But that's a topic for the 16mm sub-forum.

Hi Brian, some good information here in your post, thanks for sharing! I also like the Elmo 1.1 zoom, it's a nice solid performer! I agree it's a major upgrade from the 1.3 zoom. Last night I decided to watch a few current home movies, shot on modern Super 8 Ektachrome. For this I used the Bolex "hifi" 1.3 prime, wow is all I have to say! Being this prime is a 15 mm I didn't need to be very far from the tripod silver screen. The first thing I noticed was the sparkle from the grain, as well as nice contrast and super sharp! That lens was worth the upgrade in every way! The other big difference was how in focus it was for the entire Super 8 frame. I also didn't need to readjust the focus once it was set. That is sometimes a much harder thing to do with a zoom. Then again it really does depend on the type of focusing mechanism one is using. The GP Deluxe, as you know, is the rotary dial focus. I usually only achieve this while using the Eumig 709 with twist-to-focus. So, I have learned something, not all rotary dial focus mechanisms are necessarily hard to keep focus. I've long been advocating for using twist-to-focus, and shunning rotary style focus, I concur.

The filing I did was not so the Bolex prime fit in the lens, but to make sure it stuck out the back far enough to achieve focus. The Bolex prime fits right in, and is snug enough to stay put. So actually the filing down of the rear opening in the Elmo zoom assembly is quite easy, just takes a bit of time to get it right. I would say it took maybe 15 minutes from start to finish, and the lens slid right it! I was a happy camper it went so well, LOL. But, using Leon's instructions was a big help. Without his post I would have never thought to do this upgrade!

Paul Adsett's upgrade to the ever elusive Ektar 1.0 was my original inspiration to start using prime lenses. Now I don't know how the Bolex 1.3 prime compares to the Ektar, but I would imagine these two lenses have some things in common. The Ektar being brighter, and maybe sharper, but I've never used one so I don't know for sure! But, I would assume the Bolex primes are in the same league or very close? I've liked them for many years now.

The other big plus for anyone wanting to do this upgrade, is the fact the original Bolex 'hifi" prime will work in all the Elmo GP's, SP's, and the GS 1200 line of sound machines! They all use the same European standard size zoom lenses. Now whether they all come a part the same way I am not sure, but assume they do?

[Paul Adsett]

I've also read that the Elmo 1.0 lens isn't as sharp as the Elmo 1.1 lens. Part of the reason is the difficulty of keeping the 1.0 in focus throughout a reel.

Well I'm sure that due to manufacturing tolerances there has to be some variation in lens quality. I have the Elmo f1.3 zoom, the Elmo f1.1 zoom, and the Elmo f1.0 zoom. I have found that the Elmo f1.0 zoom is noticeably brighter (theoretically 21% brighter) and slightly sharper and better contrast than the 1.1 lens, and it does not seem more difficult to focus. It is an exceptional quality lens, so good that I never use my 1.1 lens anymore. As would be expected, the 1.3 lens is dim, dull, and soft in comparison with the other two. I think the only lens that would beat the Elmo f1.0 zoom would be the Ektar 1.0 22mm prime.

[Shane C. Collins]

Well I'm sure that due to manufacturing tolerances there has to be some variation in lens quality. I have the Elmo f1.3 zoom, the Elmo f1.1 zoom, and the Elmo f1.0 zoom. I have found that the Elmo f1.0 zoom is noticeably brighter (theoretically 21% brighter) and slightly sharper and better contrast than the 1.1 lens, and it does not seem more difficult to focus. It is an exceptional quality lens, so good that I never use my 1.1 lens anymore. As would be expected, the 1.3 lens is dim, dull, and soft in comparison with the other two. I think the only lens that would beat the Elmo f1.0 zoom would be the Ektar 1.0 22mm prime.

Thanks Paul for your input on these Elmo lenses! I did find the Elmo 1.1 to be brighter and sharper than the stock 1.3. What's interesting, the Bolex 1.3 prime is just as bright as the 1.1 zoom. I'd imagine the prime, having less glass, has something to do with this? And of course that lens is also 15 mm, so I don't need to be very far from the screen. I'm projecting a 3' by 3' image in the living room. Primes are becoming my favorite lens after what I saw last night! I also have a Eumig 1.1 prime that's a twist-to-focus, that can be used in my 709. However, I think the Bolex is sharper. I guess Bolex just used better glass in this regard!

[Brian Harrington]

I also have a Eumig 1.1 prime that's a twist-to-focus, that can be used in my 709.

I just saw one listed for sale today -- from Australia. If it wasn't twist-to-focus I may have been interested.

What confuses me is that a 1.3 prime can be just as bright as a 1.1 zoom. I know what Lipton wrote about "potential", but I don't care about "potential", I care about execution up to that potential.

Anyway, like most things, the only way to know for sure is to try something. So I believe you when you say they are about the same brightness.