Lightdow f/6.3 MF 500mm Mirror Lens. Brief overview of the reflex lens

Lightdow f / 6.3 MF 500mm Mirror Lens material especially for Radozhiva prepared Rodion Eshmakov.

Lightdow 500/6.3 lens. increase.

Lightdow f / 6.3 MF 500mm Mirror Lens, aka “500 mm 1: 6.3DG Mirror Lens” is a telephoto reflex lens of the Chinese ultra-budget brand Lightdow (hereinafter I will call it “Lightdow 500 / 6.3”). In essence, this is another version of the controversial Samyang 500 / 6.3 reflex lens, reviewed and compared with the new LZOS Rubinar 500/5.6 is already on Radozhiv. This short article highlights the main differences between lenses under the Korean brand Samyang and under the Chinese brand Lightdow.

Specifications Lightdow 500/6.3:

Optical design - 7 elements (2 mirrors, 5 lenses) in 6 groups, identical to the Samyang 500/6.3 lens;

Optical design Samyang 500/6.3.

Focal length - 500 mm;
Field of view angle (on the frame 36×24 mm) – 5°;
Relative aperture - 1:6.3 (excluding central shielding);
The minimum focusing distance is 2 m;
Filter fastening thread (front) - М95×1;
Filter fastening thread (rear) - M34x0.5;
Camera mount - T2 thread (M42x0.75);
Lens weight - 651 g;
Features - constant aperture without the possibility of change.

Photo of the lens box. Some of the written things look rather strange.

Differences between Lightdow 500/6.3 and Samyang 500/6.3
Lightdow 500 / 6.3 is structurally no different from Samyang 500 / 6.3, but at the same time, the difference in the performance of the "Korean" and "Chinese" versions is clearly visible:

• Lightdow 500/6.3 does not have any branding on the case.
• On the "Chinese" lens it says "500mm 1: 6.3DG", on the "Korean" - "500 mm 1: 6.3 DX". What these DG and DX mean is anyone's guess.
• The Lightdow 500/6.3 does not have the "Made in Korea" label on the case.
• The attachment of the secondary mirror for lenses differs slightly in appearance.
• The Lightdow 500/6.3 distance scale looks rough and sloppy.
• From the inside, it can be seen that oil oozes abundantly from the helicoid (see photo).
• The interior surfaces of the Lightdow 500/6.3 are more "glossy" compared to the Samyang 500/6.3.
• The screws that secure the plastic shank are not blackened like on the Samyang 500/6.3.
• The plastic part of the shank has strange drop-like streaks on the surface.

Optical properties Lightdow 500/6.3

The lens has below average image quality, with quality fluctuating with focusing distance and limited mostly by strong on-axis astigmatism, which is visible even in the bokeh, even in the viewfinder. This indicates a significant decentering of the elements of the optical system, that is, a violation of the lens assembly technology. I don't remember this problem being so acute with a lens Samyang 500 / 6.3. In addition to axial astigmatism, the image generated by the Lightdow 500 / 6.3 is also affected by spherical aberration ("soft"), chromatic aberration (what an irony), field curvature and pincushion distortion.

Moreover, the lens is really not capable of thermal stabilization in the cold, like the Samyang 500 / 6.3 - when trying to take a few shots while walking at -5 ° C, it was stated that it was completely impossible to focus. The astigmatism was so strong that even the bokeh bagels were asymmetrical.

It was an attempt to focus on a car at -5°C.

The image contrast is also quite low, the photos require post-processing.

Like other reflex lenses, the Lightdow 500/6.3 produces a remarkable "donut" bokeh that can be used as an artistic technique.

Below are sample photos on a full frame camera Sony A7s.

Conclusions

The Lightow 500/6.3 actually turned out to be a cheaper (where else?) version of the Samyang 500/6.3 lens with a rougher and lower quality performance. Problems with optical quality are even more pronounced than in Samyang 500/6.3. I wouldn't recommend Lightdow 500/6.3 even "to try". Despite the extremely low cost (<$100), it is still more productive to use serviced Soviet reflex lenses (ZM-5A 500/8, ZM-6A 500/6.3, Rubinar 500/8 and 500/5.6).

You will find more reviews from readers of Radozhiva here.