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aly324
7-Jul-2019, 16:06
Do the Xenotar 150mm f/2.8 projector lenses share the same optical design with the ones meant for large format photography?

Greg
7-Jul-2019, 17:38
Thank you for posting this. Have come across quite a few large aperture projection lenses and always wondered about their projected images. FYI: Buhl large aperture projection lenses in no way project images anywheres near that of a Xenotar. The old comparing apples to oranges saying but optically speaking.

Corran
7-Jul-2019, 18:35
Are you talking about those Xenotar lenses sold years ago on eBay that were used for scientific testing? Or something like the Rollei 150mm f/2.8 projection lens or similar?

LabRat
7-Jul-2019, 21:02
Remember that many/most projection lenses (despite longer FL's) were designed with a central sharp area, usually for smaller format projection that is critically sharp, but sharpness falls off quickly in the IC... The trick is to find a lens with a good transition in between these areas...

I recommend older lenses, as they were not critically as sharp as newer ones, as the older ones blend better...

Steve K

aly324
8-Jul-2019, 01:59
I mean this lens (and variants)
https://www.bhphotovideo.com/c/product/43842-REG/Rollei_66876_150mm_f_2_8_AV_Xenotar_Projection.html

Just out of idle curiosity really. I assume they aren’t the same because otherwise someone would’ve adapted the optical cells already for photography, seeing how expensive the “real” Xenotar 150’s are.

Greg
8-Jul-2019, 04:59
I believe the lens was also marketed as a 150mm f/2.8 S-Heidosmat P66 projector lens for Rollei P66 slide projector. Projector was for projecting 2 1/4" square slides. So coverage probably around 84mm in diameter. Probably a bit less at infinity. Same formula as the "real" Xenotar 150? I'd guess yes. Possibly Bob can shed some light on this projector lens since this/my post is more of educated guesses in nature.

Corran
8-Jul-2019, 05:50
Looks the same as the Rollei Greg mentioned, but that is definitely not the same lens as the Xenotar. I have a Xenotar and my friend has a Rollei 150mm f/2.8, and they are clearly different. The Rollei definitely has less usable image circle before distortion (swirl). I assume the Rollei is closer to a Petzval design, not double-Gauss.

Dan Fromm
8-Jul-2019, 06:14
Looking at the picture of the lens in the B&H link in post #5 above makes me wonder about a purely mechanical issue. The projector lens is fixed aperture, its barrel is plastic. Is the lens made up of two cells that screw into the barrel and so might be screwed into a shutter or are the glasses mounted individually in the barrel? I've seen fixed aperture lenses whose elements were mounted individually in the barrel. Not knowing better, I've opened one. The elements all fell out.

Bob Salomon
8-Jul-2019, 08:53
Looking at the picture of the lens in the B&H link in post #5 above makes me wonder about a purely mechanical issue. The projector lens is fixed aperture, its barrel is plastic. Is the lens made up of two cells that screw into the barrel and so might be screwed into a shutter or are the glasses mounted individually in the barrel? I've seen fixed aperture lenses whose elements were mounted individually in the barrel. Not knowing better, I've opened one. The elements all fell out.

Most of the 150 Xenotars for the Rollei P66, P66S and Dual had a metal barrel, they were quite heavy. The economy lens for these projectors were a 3.5 and had a plastic barrel.

Dan Fromm
8-Jul-2019, 08:55
Bob, thanks for the correction.

Bob Salomon
8-Jul-2019, 09:19
Bob, thanks for the correction.

I was the US Product Manager back in the early 70s when the P66 was going to be produced. This was when Rollei had opened their factory in Singapore.

The first production prototype arrived just before we were going to introduce it at the PMA show in Chicago. The President, the Sales Manager, the PR Manager, the Marketing Manager and I gathered around the table where we unpacked it, set it up (special instruction was that you must not push the lens into the lens mount as this was an autofocus projector, the first for 6x6, instead you just placed the lens against the roller just inside the lens mount and the AF system would then position the lens).
We carefully did this and watched as the projector pulled the lens into the projector by itself. It then pushed the lens out until it fell out of the projector and onto the floor!

We did not introduce the projector itself, showed pictures of it at the show, along with the non functioning first SLX and a wooden model of the SL2000 with a rubber band making the shutter sound!

Corran
8-Jul-2019, 09:24
And so, is the projector lens in question the same design as a traditional Schneider 150mm f/2.8 Xenotar lens designed for 4x5 cameras??

Bob Salomon
8-Jul-2019, 09:27
And so, is the projector lens in question the same design as a traditional Schneider 150mm f/2.8 Xenotar lens designed for 4x5 cameras??

No idea, question never came up. But we sold the same lens for the Liesegang 66 projector and Kindermann also sold it. That question should be directed to the manufacturer, but there is probably no one there from back then.

Corran
8-Jul-2019, 09:32
I am pretty sure they are using Xenotar as a trade name, not indicative of design or heritage. I could be wrong.

Bob Salomon
8-Jul-2019, 11:00
I am pretty sure they are using Xenotar as a trade name, not indicative of design or heritage. I could be wrong.

Bare in mind, for several years Rollei was owned by Schneider before they sold Rollei to Samsung.

Corran
8-Jul-2019, 11:09
A quick look online shows Rollei was purchased by Schneider Kreuznach in 1987. The Schneider 150mm f/2.8 Xenotar was designed and made several decades earlier IIRC. It seems very likely that the Rollei Heidosmat 150mm f/2.8 was rebranded to AV-Xenotar when owned by Schneider. I've seen plenty of Heidosmat lenses online for sale and in person, but never seen a Schneider-branded one - likely because as you say, the company was resold less than a decade later to Samsung.

All this to say, again, it's very likely to have no similarity to the actual classic 150mm f/2.8 Xenotar from Schneider.

Bob Salomon
8-Jul-2019, 11:43
A quick look online shows Rollei was purchased by Schneider Kreuznach in 1987. The Schneider 150mm f/2.8 Xenotar was designed and made several decades earlier IIRC. It seems very likely that the Rollei Heidosmat 150mm f/2.8 was rebranded to AV-Xenotar when owned by Schneider. I've seen plenty of Heidosmat lenses online for sale and in person, but never seen a Schneider-branded one - likely because as you say, the company was resold less than a decade later to Samsung.

All this to say, again, it's very likely to have no similarity to the actual classic 150mm f/2.8 Xenotar from Schneider.

Now you have:

https://www.bhphotovideo.com/c/product/43842-REG/Rollei_66876_150mm_f_2_8_AV_Xenotar_Projection.html

Corran
8-Jul-2019, 11:46
No Longer Available. That was already linked earlier. It's clearly not in production, or has been re-rebranded.

Regardless, are you saying this lens is the same as a double-Gauss Schneider 150mm f/2.8 Xenotar? If not, I'm not sure what we are talking about and why.

Bob Salomon
8-Jul-2019, 12:14
No Longer Available. That was already linked earlier. It's clearly not in production, or has been re-rebranded.

Regardless, are you saying this lens is the same as a double-Gauss Schneider 150mm f/2.8 Xenotar? If not, I'm not sure what we are talking about and why.

I said to ask Schneider what it was. Schneider had a very large business, at one time, manufacturing projector lenses. What formulas they used was something we never looked into, nor did it ever come up at any Rollei factory meetings.

Tracy Storer
8-Jul-2019, 13:09
I have one of these Rollei 150 2.8 AV Xenotars, there is a long tube on the back (for focusing it in the projector body) which will vignette on formats larger than medium format, but it can be cut off. I am planning on trying it on my 3.25"x4.25 Graflex SLR when I can get time to work on the project.

aly324
9-Jul-2019, 11:21
I have one of these Rollei 150 2.8 AV Xenotars, there is a long tube on the back (for focusing it in the projector body) which will vignette on formats larger than medium format, but it can be cut off. I am planning on trying it on my 3.25"x4.25 Graflex SLR when I can get time to work on the project.

Tracy, looking forward to your findings!

Xifoideus
10-Jul-2020, 22:19
It's possible to make a Av-xenotar 150mm 2.8 fit in a copal 3s shutter. I know becouse I have made one. The lens formula is not that of a xenotar, it is more like an altered sonnar. The image circle is about 127mm at infinity. So no 4x5. For portraits however, you do get the 4x5 coverage.
Waiting for some last parts to ad a filter thread to the lens and then selling it. Fantastic lens. Also good for close-up/macro photography (with the aperture behind the 4th element)
Ask me anything if you have a question about this lens.

Tracy Storer
29-Jun-2023, 17:43
I realize I never updated the forum on this. I shortened the tube on the back of the lens, and it seems like it will cover 3.25" x 4.25", but can't be used on the Graflex (nor on my Plaubel Makiflex) as the back focus is too short, something like 3.75" from the rear element to the focal plane at infinity. It COULD be adapted to a Pentax 67, I suppose. I will probably eventually mount it on one of my 3.25 x 4.25 Speed Graphics.


I have one of these Rollei 150 2.8 AV Xenotars, there is a long tube on the back (for focusing it in the projector body) which will vignette on formats larger than medium format, but it can be cut off. I am planning on trying it on my 3.25"x4.25 Graflex SLR when I can get time to work on the project.