8mm Forum: Scope Lens Question

This is topic Scope Lens Question - RCA 416 in forum 16mm Forum at 8mm Forum.

To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=5;t=000735

Posted by Chris Fries (Member # 2719) on January 19, 2012, 05:10 AM:

Hello everybody,

I have an RCA 416 from the 1950's. Can anyone tell me if there is a 'scope lens that will work for this model?

Thanks,

Chris

Posted by Leon Thomas Jones (Member # 2731) on January 19, 2012, 06:03 AM:

Hi,as far as I know you can use any scope lens ,as long as you have a free stand scope holder.You can buy them from Classic movie in u.k
thanks
Leon

Posted by Chris Fries (Member # 2719) on November 25, 2013, 08:40 PM:

I have a 'scope film arriving soon. My first. I still need an anamorphic lens for the RCA. Leon mentioned Classic from the U.K but does anyone know where I might find one in the U.S.? Reasonably priced, perhaps? They sometimes pop up on eBay but when they do they're really expensive.

If it makes a difference, the throw is about 22 feet.

Chris

Posted by Gerald Santana (Member # 2362) on November 25, 2013, 09:03 PM:

Hi Chris,

It looks like a Bauch and lomb Cinemascope 2" lens might fit. Can you measure the barrel of the lens the RCA is equipped with?

[ November 25, 2013, 10:38 PM: Message edited by: Gerald Santana ]

Posted by Maurice Leakey (Member # 916) on November 26, 2013, 04:34 AM:

Chris
Be very careful what you buy. eBay is littered with 'scope lenses removed from 35mm cinema projection. They seem a reasonable price until you realise they are not suitable for home use as they do not focus down enough.
Most cinema "throws" were between 75 feet and 200 feet.
Anamorphics for home use are at a premium price, as you can learn from other postings on this Forum.

Posted by Chris Fries (Member # 2719) on November 26, 2013, 09:04 AM:

Thank you for the info, Maurice.

Gerald,

The RCA has a Somtar 2 inch f/1.6 lens.

I just found this.

http://www.ebay.com/itm/310792471171?_trksid=m570.p5508 .l4763&_trkparms=ga1m%3DT10%26ga2m%3DT37%26ga3m%3DT0%26ga4m%3DT3

Is that a good price?

Will it work? Will it keep focus or does the throw need to be longer?

Thanks again,
Chris

Posted by Maurice Leakey (Member # 916) on November 26, 2013, 10:04 AM:

Chris
This is more suitable for you, it appears to focus down to 6 feet.
http://www.ebay.com/itm/Rare-SUN-Anamorphic-Cinemascope-Lens-/200994139377?pt=Camera_Lenses&hash=item2ecc2f2cf1

Posted by Chris Fries (Member # 2719) on November 26, 2013, 10:33 AM:

Maurice,

That is a nice lens but how do I mount it on my projector? The housing is 2 inches.

Posted by Maurice Leakey (Member # 916) on November 26, 2013, 11:31 AM:

Lightweight 'scope lenses like this are usually attached to a prime lens by means of a double sided step-up/step-down threaded adapter ring.

Your projector lens and the 'scope lens probably have standard sizes in millimetres.

Sample shown here:-
http://www.digitaltoyshop.co.uk/Accessories_Lens_Holders_and_Adapter_Rings_t991

Posted by Chris Fries (Member # 2719) on November 26, 2013, 12:18 PM:

Maurice,

Here is my lens. The full diameter of the largest part of the casing is 32mm.

Can I use an adapter for this Somtar lens or do I have do buy a new prime lens in addition to an anamorphic lens?

If an adapter will work for the Somtar, does it attach at the widest end or does it slip over the narrower middle part of the casing?

Or is this my prime lens and the adapter attaches here?

Posted by Maurice Leakey (Member # 916) on November 26, 2013, 12:46 PM:

I assume your prime projector lens has a screwed thread around the inside of the front of the lens. Most lenses have. The adapter then screws into the lens.

The anamorphic should also have a threaded lens ring. This is then screwed to the front ring of your adapter.

You need an adapter that has a thread on one side for the projector lens and the other side (either smaller diameter or larger diameter) to screw into the anamorphic.

This is the beauty of these small lightweight lenses; they do not need a mounting bracket like a larger (and heavier) lens would need.

I am sure that there are stores in the US who sell adapter rings, all you need to know is the diameter of each ring in millimetres.

Posted by Chris Fries (Member # 2719) on November 26, 2013, 02:20 PM:

Thank you again for all the info, Maurice.

So, if this is my primary lens (24mm),

this is the anamorphic lens from eBay,

and an adapter similar to this connects them,

what about the 2 inch space inside the lens housing?

It's like trying fit 10 lbs. of.... well, you get the idea.

Of course, I suppose there are adapters that are at least 2 inches long, right?

I'll keep looking.

Posted by Maurice Leakey (Member # 916) on November 26, 2013, 03:09 PM:

I don't think you understand what I am trying to say.
Your projector's primary lens is the silver coloured lens as shown mounted in the projector gate.
The adapter is just a ring about 4-5mm wide with screwed threads either side. It is used to connect the anamorphic directly onto the front of the silver coloured lens.
Do I assume you have unscrewed the lens?

Posted by David Guest (Member # 2791) on November 27, 2013, 08:25 AM:

I have a scope lens to fit your projecter also I have an adapter ring to also a scope bracket all in ex condition and all for sale if interested email me on dwgdodgems@hotmail.co.uk

Posted by Chris Fries (Member # 2719) on November 29, 2013, 10:24 AM:

David,

Please check your email.

Maurice,

Yes, the small black lens was unscrewed from the solid silver part. I understand now that they both make up the primary lens. The adapter screws on to the inside threads. Can it just clamp on or does it have to attach on the inside where the big lens is? Will the lens have to be re-positioned?

Thanks,
Chris

Posted by Maurice Leakey (Member # 916) on November 29, 2013, 11:16 AM:

Having now seen your lens in more detail it will not be suitable for an adapter ring. This is because the anamorphic needs to be rotated to give a picture with 90 degree corners.

On such projectors as the Bell & Howell later models the backing (prime) lens focusses by going backwards and forwards, thus the attached anamorphic itself does not rotate. The Bell & Howell lens can be rotated to ensure the whole assembly gives the correct ratio picture.

However, in the case of your RCA you will need a supporting bracket which will hold the anamorphic in front of the backing (prime) lens without actually being in contact.

In operation the prime backing lens is focussed correctly, then the anamorphic is placed in front, having first been set up by the markings on its focussing ring. A final slight refocus of each may be necessary when your film starts.

Posted by Chris Fries (Member # 2719) on November 29, 2013, 11:49 AM:

Maurice,

I'm waiting to see what David has to offer in the way of a lens and bracket. In the meantime, what about the lens I found on eBay?

I know it will fit in the RCA's housing but can I use it with a throw of only 22 feet and still keep focus? Are you familiar with this B&L Cinemascope Lens? If so, does the 2x Horizon Expansion part just make the projected image very large?

Posted by Maurice Leakey (Member # 916) on November 29, 2013, 02:13 PM:

Without knowing any more details of the lens, I cannot comment, other than saying that your projector uses a lens which has a screwed thread and the one which you show has a smooth barrel, as such, it's most unlikely to be of any use.
Most scope lenses have an expansion ratio of 2X, this makes the standard 16mm frame doubled in width which does make it seem quite an expanse of picture. But, I suppose that's what CinemaScope is for!
A 1.5X lens would look more like the ratio as shown in 35mm cinemas. I don't know if digital cinemas still retain this ratio.

Posted by Gerald Santana (Member # 2362) on November 29, 2013, 04:31 PM:

Hi Chris,

I have the adapter you will need so that the lens fits onto your projector. Send me $1 through paypal so I can print out the shipping label and you can have it. I use a different one that fits onto my Kodak Pageant.

Here's the information below on other models this lens will fit and a picture of the part if you decide to get the lens.

Posted by Chris Fries (Member # 2719) on November 29, 2013, 11:22 PM:

Thank you so much! Payment for postage sent. If I get the B&L lens, I'll have an adapter to secure it. Excellent!

Posted by Maurice Leakey (Member # 916) on November 30, 2013, 03:45 AM:

May I ask Gerald what the black adapter(?) is made of? Is it rubber which can expand and grip? What are the silver coloured sleeves for?

A further word to Chris. Even if the long lens which you are considering could be fitted onto the projector's prime lens I consider it to be unwise. This is because the long unsupported anamorphic would probably vibrate and cause an unsteady picture. Furthermore, Chris, don't consider the purchase of any anamorphic until you can establish it can focus down enough for use in your home.

UBB.classic^TM 6.3.1.2