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

Triplet 78 / 2.8 Lens Review 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: It does not have a focuser or aperture. He has many brothers from different factories in different frames (for example, a lens in the frame for the 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 bar, obviously - for an inexpensive Soviet projector.
The features of this frame - the depth of the rear lens inward, the large diameter and flaccidity do not allow the use of such a lens unit in almost pristine 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 efforts - such barbarism is effective) and get a lens block that 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 - here it is, happiness! The lens block is small and can be easily inserted into the focuser ... But this is not so.
Such lens frames on the back, in contrast to the metal frames for the Svityaz projector, are not just molded, but a nut holding the lenses. And if there is a nut, there is a thread for it, which sticks out very strongly.
All these features make it difficult to transplant the lens into the same Helios-44M body: the lens rear 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 can not just be easily transplanted into a focuser! - This is the most important point that everyone who acquires 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 still it can 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.

We describe the procedures necessary for the simplest and most complete alteration of the lens - using Helios-44M as a focuser.

  1. The triplet lens block is disassembled, the ends of the lenses are blackened with at least a marker, and the inter-lens inserts are matte black. Then everything is carefully assembled. 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 by masking tape (or by one god - who relies on what ...), the back and the thread thread are maximally (if only held on) the back. Why the assembled curled? Then will it really be something to spin already ...
  3. Damaged insides are removed from Helios-44M (we take Helios-44M “killed” optically - it’s absolutely impossible to break this lens. They say that people who break working lenses remove homemade products worse)) - the rear and front lens units are removed. The internal spline nut is removed at the diaphragm mechanism (from the front, do not touch from the back). A ring with a M52 * 0,75 thread is also removed.
  4. Then the most interesting. We try on the lens block of the triplet inside the G-44M and try it on the camera - we make sure that there is no infinity. What to do? Use reserves of the 44th. Take off. shank with a jump rope and M42 thread. Separate the lens block housing with the diaphragm - unscrew the three screws on the inside of the helicoid (it is also the helicoid screw). Then we completely unscrew the screw of the helicoid. And we sort out the turns of multi-threading so that you can deepen the lens block as much as possible (you need to remember the initial turn and the initial position). Going through the turns, you still need to check the possibility of screwing back to the body with the diaphragm - this does not always come out.
  5. When the torment seemed to be behind, 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 forever the USSR!
  6. Remove the shank again, remove everything related to the skipping rope, except the shift lever. We expose the F / 2 aperture control ring and open the aperture with our hands (move the long stem to the extreme position). This rod must be fixed tightly in this position (if only the value set by the ring corresponds to the real one - at F / 2 the rod should keep the aperture fully open). For this I used cold welding - nowhere is easier.
  7. Again, try to strengthen the shank. Yeah, now this stock can also interfere with the fact that it sticks out. If this happens, we carefully cut it with a triangular file in the host (it can be 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 sure - they, I am afraid, need to change the shank for Nikon F with Helios).
  8. The focus of the focuser at Helios-44M can be easily increased so that the MDF is smaller. To do this, unscrew the screws of the focus ring and remove it. Did you notice a ledge on it from below? To remove. Completely. Now fasten back. Remove the shank. The part that follows the guide, like this one: Under this part (one of them, any) we put something like a washer (I put the usual washer) 1-1,5 mm thick and fasten it in place. that on the MDF, the focuser runs a lot behind the set 0,55 m, but doesn’t get up tight (this will happen if you do not raise the part with the washer) and it works fine. So we get the focus ring stroke at 360 degrees - super! Such a modification can be carried out with any Helios-44M and Mx.

    photo of the back of the lens assembly

    photo of the back of the lens assembly

  9. Finish the triplet’s lens block to the desired diameter (the diameter of a Helios-44M glass) - it is best to use epoxy-impregnated paper (“nukemall getinax”). So you can evenly make the part of the desired diameter.
  10. Finding exactly infinity is better - without overrun, according to Live View, and fix the lens block in this position (even with the same epoxy, but carefully - do not seal the diaphragm! There is no escape from the EHP if it froze)
  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 projector “Svityaz”

In terms of bokeh, the lenses are almost indistinguishable:

T-78-1

from Svityaz

T-78-2

on monitored

Both are able to give a point 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, judging strictly - they are both unsharp) This is such a scheme.
When shooting, it also seemed to me that the “pea” lens from this review gives somewhat 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 software. There is no distortion.

A lot of distortion falls on the edge - there is coma and astigmatism ... In short, on an open aperture, the lens is suitable as a soft portraiture, it will not appeal to lovers of 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 bit “watercolor” and “airy”, as some photographers and amateurs put it.

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

The lens is distinguished by the plasticity of the picture - on 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 of the lens is good, but you can still catch hares or “sunny rain” 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 adaptation for adaptation of the available overhead projector Triplet 78 / 2,8. But although the alteration is significantly complicated in comparison with the obv from the Svityaz projector, this does not prevent Triplet 78 / 2,8 from being a pleasant portrait lens with an unusual design.

Thank you for attention. Eshmakov Rodion.

Add a comment:

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(

Add a comment

Copyright © Radojuva.com. Blog Author - Photographer in Kiev Arkady Shapoval. 2009-2020

English-version of this article https://radojuva.com/en/2016/03/triplet-78-2-8/