• Ultraviolet Photography
  •  

Assessment of the Meritar 50mm f/2.9

Lens
2 replies to this topic

#1 Bernard Foot

    Bernard Foot

  • Members+G
  • 722 posts
  • Location: UK

Posted 31 March 2021 - 17:33

Lenses used in this test:
  • E.Ludwig 50/2.9 Meritar
  • Leitz Wetzlar 50/4.5 Focotar-2
  • Meyer Optic Görlitz 50/2.9 Trioplan
  • Steinheil München 50/2.8 Cassar S


In these 2 posts Reed Curry was praising the Ludwig Meritar 50mm f/2.9 as a good UV-friendly lens:

https://www.ultravio...h__1#entry42711

https://www.ultravio...__fromsearch__1

Andrea and Timber have also sung its praises. As they are relatively inexpensive I thought I’d get one to compare with my other 50mm UV-friendlies.

About the Meritar 50mm f/2.9

There were Meritars in existence pre-WW2, but I’ve only seen longer focal length versions. Post-WW2, Ernst Ludwig found itself in the tender embraces of the East German state. Meritars started being made again in 1949 but only the 50mm f/2.9 version. It succeeded the Victar 50mm f/2.9, and may just have been a rebranding.

The Meritar triplet was an entry-level lens, sitting below the 4-element Tessars and the various 6-element up-market lenses.

Three versions were introduced, all in M42 and Exakta mounts (although the M42 mount was discontinued in 1959 – perhaps too much competition), and also as non-interchangeable lenses:
1. Simple manual diaphragm, unpainted aluminium with a slightly conical shape.
2. Pre-set diaphragm, unpainted aluminium with a slightly bulbous shape. My copy, and I believe those of Reed and Andrea, are of this model. My copy has the M42 mount.
3. Pre-set diaphragm, beehive shape, unpainted aluminium but with black and silver focus and aperture rings. This seems to be the most common version.

Production ceased in 1968.

Assessing the Meritar

I compared the Meritar with my other UV-friendly 50mm lenses:
  • Focotar-2 50mm f/4.5 (from 1975)
  • Cassar S 50mm f/2.8 (from about 1957)
  • Trioplan 50mm f/2.9 (from about 1937)
UV-Reach

UV reach was assessed by comparing exposure factors using 380BP20, 345BP25, and 315BP20 filters.

The Meritar performs well at 345nm, similarly to the Cassar S and Trioplan (although none of them are as good as the Focotar-2). However, by 320nm it was very poor – just a faint smudge of an image, whereas the other three lenses are all capable of producing good images.

So the Meritar is fine for general-purpose filters like the Baader U, but does not have the UV reach for applications such as TriColour.

Image Quality - Resolution

In visible and UV light at f/8, the Meritar is not as sharp as the Cassar S in the centre but outperforms it at the edges. In fact at f/8 there is very little drop-off in resolution between the centre and the corners (APS-C sensor).

The measurements in visible light were quite different depending on whether a full-frame or APS-C camera was used. As mentioned in another post, this may be due to the lower pixel density on the full-frame camera. Real photographs on the full-frame camera showed the Cassar S was sharper than the Meritar, in line with these numbers.

In IR, the centre sharpness is about the same as for the Cassar S, but performance at the corners is far better.

The Focotar-2 is sharper than both the Cassar S and the Meritar.

Attached Image: Resolution LoRes.jpg

Whole frame showing crop area:

Attached Image: Cassar f8 (1) Frame.JPG

Crops from whole image, Cassar S on right and Meritar on left (both at f/8):

Attached Image: Cassar f8 (1) Crop.JPG Attached Image: Meritar f8 (1) Crop.JPG


Image Quality – Aberrations

Attached Image: Aberrations.jpg

Summary

For UV photography through a broadband filter like the Baader U or a filter sandwich like the U340 + S8612, the Meritar works well. Image quality overall is better than the Cassar S, although the Cassar S has a slightly better peak performance.

Bearing in mind the stupidly high prices being demanded for the Cassar S, the Meritar is a good alternative.

However, if you need deep UV reach (e.g. for TriColour work), then the Meritar is not the lens for you.

The Focotar remains the best of the 50mm lenses, but it is difficult to find and expensive.
Bernard Foot

#2 UlfW

    Ulf W

  • Members+G
  • 1,830 posts
  • Location: Sweden, Malmö

Posted 01 April 2021 - 05:57

This is an excellent evaluation Bernhard.

I would expect that on a full frame sensor these older lenses would be quite fuzzy too and that a Focotar would be dramatically better.
Ulf Wilhelmson
Curious and trying to see the invisible.

#3 Reed F. Curry

    Member

  • Members
  • 401 posts
  • Location: New Hampshire, USA

Posted 17 June 2021 - 00:21

Bernard,

I have two other E. Ludwig lenses, the Peronar 50/2.9, and the Victar 50/2.9. They are both Exakta mount triplets. Performance is the same as the Meritar.
Thanks.
Best regards,
Reed
http://www.uvroptics.com