Overhead lens Triplet 78 / 2.8. Review from the reader Radozhiva

Review of the Triplet 78 / 2.8 lens for Radozhiva prepared Rodion Eshmakov.

This is a review of the Triplet 78 / 2,8 overhead lens, which differs from previous TRIPLET Triplet 2.8 / 78 its frame, it is slightly different optically, and also has the features of transplanting to modern cameras.

Triplett 78 2.8

Triplett 78 2.8


Lens specifications:
Structure:  three lenses in three groups (Triplet Cook, a relative of the famous Meyer Trioplan scheme)
Format: medium (covers), APS (used)
Viewing angle: 53 degrees on the SF
Maximum Aperture: F / 2.8
Resolution: (center / edge) - 80/40 lines / mm (projection), 28/20 (photographic, in comparison with Industar-29 - quite a bit sharper in the center).
Features: does not have a focuser and aperture. It has many brothers from different factories in different frames (for example, a lens in a frame for a Svityaz projector <link but an overview of the past Triplet>), but the quality (resolution and drawing) floats.
Period: It was produced from the middle of the last century until the 1990s.

Design and adaptation features

This lens was in a plastic frame with a focus rail, obviously for an inexpensive Soviet projector.
The peculiarities of this frame - the depth of the rear lens inward, the large diameter and flimsy do not allow using such a lens unit in its almost original form (as with the previous Triplet from Svityaz).
Therefore, the frame must be destroyed (sawing it for a long time, dusty and dirty; the simplest thing is to cut it with a red-hot knife without unnecessary effort - this is an effective barbarism) and get the lens unit, which looks like this:

Triplett 78 2.8

The spoiled lens block of the Triplet 78 / 2,8, similar to the surveyed one, in its original form, but removed from the plastic frame of the projector.

It would seem - that's it, happiness! The lens unit is small and can be easily inserted into the focuser ... But it is not.
These frames have lens blocks at the back, in contrast to the metal frame for the Svityaz projector, not just a molded bottom, but a nut holding the lenses. And since there is a nut, there is also a thread for it, which protrudes very strongly.
All these features make it difficult to transplant the lens into the same Helios-44M body: the rear of the lens is very thick (greater wall thickness), and the nut with the rest of the thread rests on the mechanics of the G-44M diaphragm ...
Summary - lenses in special plastic frames cannot be easily transplanted into a focuser! - This is the most important note that everyone who purchases such a lens should remember.

Vega-5U ass disassembled, on which a detail crawling along the groove is clearly visible

Vega-5U ass disassembled, on which a detail crawling along the groove is clearly visible

But can it still be adapted? - Sure you may. I apologize in advance for the lack of explanatory photos, but instructions for disassembling the Helios-44M can always be found on the Web.

Let us describe the procedures required for the simplest and most complete lens conversion - using Helios-44M as a focuser.

  1. The Triplet lens block is disassembled, the ends of the lenses are blackened at least with a marker, and the lens inserts - with anything matte black. Then everything is assembled neatly. At this stage, the main thing is to put the middle negative lens on the right side. Otherwise it will turn out like here.
  2.  The rear lens is protected with masking tape (or by God alone - who relies on what ...), the nut and the remnants of the thread are grinded at the back as much as possible (if only to hold). Why twisted assembled? Then will it really be possible to twist something ...
  3.  The damaged insides are removed from the Helios-44M (we take the optically "killed" Helios-44M - a good lens for such a thing cannot be broken categorically. They say that people who break working lenses take homemade products worse)) - the rear and front lens blocks are removed. The inner slotted nut is removed from the diaphragm mechanism (from the front, do not touch the back). The ring with M52 * 0,75 thread is also removed.
  4. The next is the most interesting. We try on the triplet lens unit inside the G-44M and try it on the camera - we make sure that there is no infinity. What to do? Use the reserves of the 44th. Take off. jumper shank with M42 thread. Separate the lens unit housing with the diaphragm - unscrew the three screws on the inner part of the helicoid (it is also the helicoid screw). Then we completely unscrew the helicoid screw. And we sort out the threads of the multi-start thread so that it is possible to deepen the lens unit as much as possible (you need to remember the initial thread and the initial position). Looking through the turns, you also need to check the possibility of screwing the case with a diaphragm backwards - this does not always work out.
  5.   When the torment seemed to be behind us, we try to extend the focuser to infinity and fix the shank back. Most likely - nothing will come of it - something will rest against something. Now you will love the USSR forever!
  6. We remove the shank again, remove everything that touches the jump rope, except for the shift lever. Set the F / 2 aperture control ring and open the diaphragm with your hands (move the long stem to the extreme position). This stem must be fixed tightly in this position (if only the value set by the ring corresponds to the real one - at F / 2, the stem must keep the aperture open completely). For this I used cold welding - it couldn't be easier.
  7.   Trying to reinforce the shank again. Yeah, now this stock can also interfere with the fact that it sticks out. If this happens, carefully make a cut for him with a triangular file in the host (seen in the photo below). Now he does not interfere. Happy, we twist the shank, make sure that there is infinity when trying on (Nikonists may not be convinced - they, I'm afraid, need to change the shank on Nikon F at Helios).
  8.  The focuser stroke of the Helios-44M can be easily increased to make the MDF smaller. To do this, unscrew the focus ring screws and remove it. Notice a ledge on the bottom of it? Remove. Clean. Now we attach it back. Remove the shank. The part that walks along the guide is just the same as here: Under this part (one of them, any) we place something like a washer (I put a regular washer) 1-1,5 mm thick and screw it into place. that on MDF the focuser runs away strongly beyond the prescribed 0,55 m, but does not stand up tightly (this will be the case if the part is not lifted with a washer) and works normally. This gives us a 360-degree focusing ring - super! This modification can be carried out with any Helios-44M and M-x.

    photo of the back of the lens assembly

    photo of the back of the lens assembly

  9.  Finish the Triplet lens block to the required diameter (the diameter of the Helios-44M glass) - best of all with epoxy-impregnated paper (“getinax” from nukemall). So it will be possible to uniformly make a part of the desired diameter.
  10.  Find infinity for sure, better - without overrunning, using Live View, and fix the lens unit in this position (even with the same epoxy, but carefully - do not seal the diaphragm! There is no salvation from the EDP if it is frozen)
  11.  When everything is ready, we find that the front of the lens does not look very good. Fix two rings M49 (or M52) * 0,75 from the filter on the face. Until I figured out how beautiful it is to make a limb with a name for the lens and just inserted a cardboard circle :). Well, we did a great job! Now you can catch your breath. Our lens is ready to go. Let's see how much he differs from his first brother.

Comparison with the lens from the Svityaz projector

In terms of bokeh, the lenses are almost indistinguishable:

T-78-1

from Svityaz

T-78-2

on monitored

Both are capable of giving a dot in a circle - peas, both give a bright border.
And the sharpness of the lenses are similar. However, as it seemed to me from a test around the world, the lens from this review is somewhat sharper than the glass from Svityaz:

T-78-1 2

T-78-1 2

 

T-78-2 2

T-78-2 2

Well, if you judge strictly - they are both blurry) Such is the scheme.
It also seemed to me when shooting that the "pea" lens from this review gives a little less than the previous one.

IMG_7852

Optical properties

From tests, let's move on to real photos. Triplet 78 / 2,8, as a typical fast aperture Triplet, forms a soft image, with under-corrected spherical aberrations.

Chromatism is not noticed - it is masked by the software. There is no distortion.

A lot of distortions fall on the edge - there is coma and astigmatism ... In a word, at an open aperture the lens is suitable as a soft-portrait lens, it will not appeal to those who like sharpness.

However, the lens is just valuable for its distortions - the software allows you to unobtrusively hide skin imperfections without plastic retouching, makes the picture a little “watercolor” and “airy”, as some photographers and amateurs say.

Due to spherical aberrations, the lens has a unique bokeh with “bubbles”, which is enhanced by the twisting effect (due to transplantation into the G-44M body, where the diaphragm shields part of the rear lens). The only thing is that the blur of the prefocal lens is very sharp - with strong ghosting and bagels.

The lens is distinguished by the plasticity of the picture - at F / 5,6 (on the Helios-44M scale, i.e. in reality - ~ F / 8) the software leaves, the picture acquires the best sharpness.

The contrast after blackening is good at the lens, but rabbits or “sunny rain” can only rarely be caught if you try hard.

The color rendition is not bad, but nevertheless, the lens is a little yellow when viewed through. Overall, the lens is very good for its purpose.

IMG_7851

IMG_7850

conclusions
This lens is not the best modification of the available Triplet 78 / 2,8 overhead projection lens for adaptation. But although the alteration is noticeably complicated in comparison with the lens from the Svityaz projector, this does not prevent the Triplet 78 / 2,8 from being a pleasant portrait lens with an unusual pattern.

Thank you for attention. Eshmakov Rodion.

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Commentary on the subject: Triple projection lens Triplet 78 / 2.8. Review from the reader Radozhiva

  • Vladimir

    thanks. You can optical lens circuit. I use such a lens on a dpi projector. there is a problem(

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