Helios-44M model doesn’t differ much from the models of the same series. Some significant differences are only in the lens control methods, resolution and in the number of aperture leaves. The represented sample was released at the optical-mechanical plant «Jupiter» in the town of Valdai. You can note some remarkable features of this model compared to Helios-44, which has a unique 13-leaf aperture (there are also models with a 7-leaf aperture), compared to that very Helios-44M which has only 8 leaves. As for minor differences you can pay attention to the differences in the color of the frames, as Helios-44 has a traditional white frame, and Helios-44M has a black frame. As for aperture features, Helios-44M has a bouncing aperture, unlike Helios-44 which has only manual control by means of a preset ring. However, Helios-44M has an ability to switch aperture control modes, there is a clear resemblance to the model Zenitar-M 50 1.7.
Differences in the pilot thread can play a major role when you choose a matching camera and lens. So Helios-44 has a pilot M39 thread, and in H-44M-M42 this difference is the most important in comparing these two models. Front optical filters have a diameter of 49mm (H-44) and 52mm (H-44M).
If we compare pictures, they are all of good quality. Helios-44M focus is quite good; using F2.0 we don’t see a simple operation of the aperture. The drawback of this lens is unsatisfactory performance of the lens switch of the automatic and manual control. The quality of the switch mounting structure is not of a high quality either. Zenitar-M 50 1.7 lens has the same problem.
When using Helios-44M with Nikon D200 camera pictures are pretty good, you can use CP-42/H adapter on this camera. This lens model may be appropriate for different cameras, this is because M42 thread is widely spread.