Enna Tele-Ennalyt -whats the correct lens arrangement?

[l_n_h]

Ive just acquired an Enna Tele-Ennalyt 1:2.8/135mm lens (made West Germany). But the previous owner cleaned one of the inner 23mm lenses and I think he might have put one or both of them back in the wrong way. There are two of these separated by a plastic spacer tube, and both have a convex face and a flat face. They are currently aligned as follows:

49mm Front lens / Shutter etc / CI /spacer tube/ CI / Camera body.

where 'CI' represents the convex side facing left and 'D' would represent the convex side facing right.

Note both lenses currently face the same way. I haven't seen the resulting pics developed yet but the microrasters on the Praktica camera viewfinder I screwed the Enna onto dont completely disappear as they normally do, which suggests imperfect focussing.
Does anyone know the correct positioning of these small lenses? I can try all the combinations but it would be time consuming and I have to dismantle the Enna each time, so your time-saving advice is welcome!

 

[JHutchins]

Well down the page there's a description (in german) of the Tele-Ennalyt 2.8/135 with a diagram but it doesn't really match what you're describing.

http://photobutmore.de/exakta/objektive/enna/

 

[l_n_h]

Lenses inside a lens -is there a general rule?

Lenses inside a lens -is there a general rule?

We are talking here about the lenses that are removable and fit onto the camera body. Is there a general rule how such lenses are constructed? For example, I have an 1:2.8/135mm lens, which is made up like this-

Front lens / Shutter & mechanism / CI /spacer tube/ D /// Camera Body
(49mm)

where 'CI' and 'D' are small lenses which are flat on one side and convex on the left and right side respectively (and are separated by a small plastic spacer tube).

Would this be a correct arrangement for the small lenses? I presume these small lenses could be acting as a composite double-sided convex lens separated by the tube, but it requires somebody who knows optics or is familiar with cameras generally to know the answer.

The reason I ask? Because when I got this item I found that the small lenses (measuring 23mm each) had been removed for cleaning and may have been replaced wrongly -they were in a 'CI /tube/ CI' position. If anyone knows the correct positioning do let me know, since the lens logically cannot function unless it is set up right. Presumably most cameras would use the same lens arrangement.

 

[sevo]

That is a relatively rare arrangement. Indeed I am stumped as to what camera system it might belong - I am not aware of a single 135/2.8 triplet lens with lens side leaf shutter. Large format lenses are pretty generally slower, more symmetric and usually are four or more element.

You would have to research the formula of the lens in question to figure out the proper arrangement of elements - sometimes the lens name is related to the formula (Zeiss named by type, Leitz named by speed), and often the original product literature has some drawing of the lens schematics.

 

[David Hughes]

Hi,

Could the mechanism be the aperture? That would make sense.

Make and exact model/spec. might help.

Regards, David

 

[radi(c)al_cam]

Could the mechanism be the aperture? That would make sense.

Make and exact model/spec. might help.

Dear David,

I suppose it's this one:

Enna Tele-Ennalyt -whats the correct lens arrangement?

 

[David Hughes]

Hmmm, we seem to be going round and round in circles, and it's not a Tuesday ;-)

But there's only a few variations on the alignment and if the suspects are just 2 lenses then that's just 3 more to check...

Regards, David

 

[sevo]

Given that the Tele-Ennalyt 135/3.5 already is a five element lens, this will have at least as many elements, so what you are looking at are three groups, or more probably one solitary element and two groups. Is the rear group a very big block, almost as long as wide? If so, it will be a Sonnar type.

 

[radi(c)al_cam]

Given that the Tele-Ennalyt 135/3.5 already is a five element lens, this will have at least as many elements, so what you are looking at are three groups, or more probably one solitary element and two groups. Is the rear group a very big block, almost as long as wide? If so, it will be a Sonnar type.

cf. http://photobutmore.de/exakta/objektive/enna/

5linsiges Tele-Ennalyt 2,8/135 mm (Nr. 3 203 171)

Rastblende 2,8-22, Bildwinkel 18°, Fokus ab 1,5 m, Filtergewinde ES52.

 

[l_n_h]

Youve got it. Its an Enna Tele-Ennalyt 1:2.8/135mm, but I didnt want to say the brand name on this forum because its not supposed to be for individual lenses. Yes it was that Enna lens posted on the other forum. Sorry I posted on here but my original posting got moved and I couldnt find it so thought it had been deleted.

That info sheet printed in German could have the answer so Ill have to have a go at decoding it.

But do note that there may be a whole range of lenses between the outer 49mm lens and the first 23mm 'CI' half-convex lens. I excluded any others to simplify the diagram so you knew which lenses I was talking about. Any other lenses are almost certainly in situ.

 

[radi(c)al_cam]

Yes it was that Enna lens posted on the other forum. Sorry I posted on here but my original posting got moved and I couldnt find it so thought it had been deleted.

Use «Find More Posts by l_n_h», then you'll find it again 😉

 

[sevo]

Let's hope he mistook the front element plus group for "a lens", otherwise the thing might be missing a group...

 

[Rob-F]

Since it is identified as "tele" it presumably has telephoto construction; in which case the rear element ought to be concave, not convex.

I looked up the 135mm Enna Tele-Ennalyt in my copy of "Photographic Optics,"by Arthur Cox. It is listed there as an f/3.5, not an f/2.8. The schematic shows it as a five element lens in four groups, with the second lens being a cemented doublet. After that comes the diaphragm (no shutter) and then the third and fourth elements are shown as singlets with concave sides facing each other. So the flat side of the rear element should face outward and rearward. The diagrams are awfully small, and it is possible that the third element may have a convex side in addition to the concave side; in which case, the convex side faces the diaphragm.

 

[Rob-F]

I posted my answer to the original Enna-specific question, now under the camera repair forum. I looked it up in "Photographic Optics" by Cox, and saw a schematic almost the same as the one posted by Sevo, above. The concave surfaces of the last two elements should face each other, as shown.

 

[David Hughes]

Use «Find More Posts by l_n_h», then you'll find it again 😉

Hi,

Nothing like stating the obvious, put the cursor arrow on the name of the poster, that's you in this case, and do a left click with the mouse...

Regards, David

 

[l_n_h]

Many thanks everyone for showing me how to find the first post -you can always tell the new starters...

Sevo- 'Is the rear group a very big block -about as long as wide?' If you mean 'is the block the depth of the lens diameter?' well its quite hard to say. Ive shone a light in it, looked through a magnifying glass, and find it hard to see 3 lenses in a group at the 'big' end. I can only see 2 for sure -the surface marks give them away- though its possible there are three and Im looking right through the other one without knowing it. That leaves a possibility that the very front lens is missing. Look at the picture of it -the glass looks very far back in the casing. I estimate about 11 -12 mm inside. Plenty of room for there to have been another lens in front.

Rob-F -Thanks for your advice with 'concave'. I just did a test with a small plastic bead and was surprised to find the 23mm lens on the extreme right ('short' end of the unit) has a concave side and flat side -not convex as I thought. So the concave is now facing left as on the diagram used here. (The other 23mm lens I confirm is flat/convex. Im unsure from that diagram which way it should face so have made convex face right).

A quick test on the camera shows the split image focusing occurs now more in the middle rather than right at one end of the focus range -which is a promising sign -though I still cant get rid of those microrasters. But those MR's have been a problem before because sometimes even my quality zoom lens doesnt pair the two focus methods up and Ive then to choose between split screen OR microraster as to which will give the sharpest pic.

However the shutter mechanism keeps detaching at random moments so I dont know if Ive lost a spring somewhere with all this experimenting (it works again when I push the arm with a fine screwdriver so it might only be sticking on something).

Today my film was finished so will soon find the results of all this lens swapping and if any combination has worked (today's lens swap not included).

 

[sevo]

Sevo- 'Is the rear group a very big block -about as long as wide?' If you mean 'is the block the depth of the lens diameter?' well its quite hard to say.

After we've seen the schematics, that is settled. No, it cannot be a classic Sonnar.

Today my film was finished so will soon find the results of all this lens swapping and if any combination has worked (today's lens swap not included).

If you went by the schematics, you can't be wrong.

 

[l_n_h]

Right. Got back the film and the pics with the extreme right hand lens concave facing left are definitely better than the convex facing right. If we number the lenses or elements in the 5-piece diagram quoted above (left to right) then '5' is this small concave lens. Id say the colours this Enna unit produces could be slightly more accurate than the Cosinon unit Im comparing it with, though the focusing quality is still a bit dodgy in my opinion. (There seems to be an incredibly small depth of field -if you take a 3/4 view pic of say a bus, you can have the front not perfectly clear, the back not perfectly clear and the middle just right). So right now this wouldnt be my regular lens of choice. However before I put the matter to rest, one last question for you all. In the above diagram then, which way is the convex side facing on lens/element number '4' in your opinions?

On the diagram the left side looks slightly convex and the right side straight -but the right side is rounded off top and bottom -is that meant to mean its convex? The plastic bead test on the actual lens shows one side convex and the other side flat -theres definitely no concave quality here.