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Docter Deltrintem 8x30 - First impressions (1 Viewer)

Etiennef

Well-known member
I have always been keen on acquiring one of the proper "classics" in the binocular world, and the 75 years or so production run of the Deltrintem 8x30 is of course on of the major standouts. The most recent reincarnation of this binocular under the Docter brand has been the one I have been on the lookout for. Partially because it is not so common (I'm always drawn to the more odd ones out), and also because it comes with rubber eyecups that I anticipated would be way more comfortable than the hard plastic ones on the previous Zeiss-versions. I have also a couple of times in the past been very pleased with warranty service from Docter (now Noblex), and all initial Docter products are still under a 30-year warranty.

From what I could read online, this model was produced by Docter for only about 3-4 years, so in practice, that means that all Docter Deltrintems are from the first half of the 1990s. This is probably the major reason why there is very little information about this specific version of the Deltrintem, and also why I felt the urge to write something about it. |8(|

Anyhow, I eventually found a Docter Deltrintem in decent condition on eBay and bought it. Prices are usually at a somewhat higher price point than the typical Zeiss-Deltrintems, placing them more towards the 100 EUR mark. I also bought a new Docter-branded case for a reasonable sum to match the binoculars. The leather case it came in was decent but does not really feel modern or match the style of the binocular. The binocular originally came with leather straps it seems, but attached was a (Japanese) nylon strap of OK quality.

On to some historic details; To my knowledge, the Docter version differs visually from the last decades of Zeiss Jena Deltrintems primarily by the oculars. The shape is very different, and as mentioned before; the eyecups are made from soft rubber. I have however seen a Zeiss-marked Deltrintem with such oculars on eBay. But I also read that early items rolling off the Docter production line did, in fact, have still the old Zeiss Jena logo. It could also be some sort of "hybrid" based on old stock, or just a repair with newer parts. What is more definitive is that Docter initially kept the Zeiss Jena serial numbering scheme (Perhaps starting clean at around 7300000, since Zeiss production apparently ended at mid-72xxxxx).

There are also claims on some sites that the Docter version has improved coatings, and that they have a greenish tint. The coatings may be improved, but being greenish is however not the case with the Deltrintem I have. I would describe the coatings as red/orange/amber/deep purplish. In fact, I have not seen any greenish coatings on any of the other Docter Deltrintems I could find on various pages on the Internet. Even the original box from Docter shows a reddish reflection... Perhaps really late samples have green coatings, or this claim is simply not accurate.

The optical design seems to be the same nevertheless, or at least very similar. I recently looked through a mid-1970's non-multi coated Jenoptem 8x30 (the production-optimized twin of the Deltrintem). The general "feel" is the same, although the old Zeiss immediately gave the impression of a muted picture compared to more modern items (not unexpected considering the age and early coatings). A commonality independent of this is, of course, the very concentrated sharp area in the center. Sharpness drops, or more specifically; focus shifts, very fast from the central 1/3 of the image circle.

I took a couple of pictures through the Docter to illustrate this. I know that photographing through a binocular with good results is tricky. Especially when it comes to the corners. Pictures actually look slightly worse than real life (probably due to the eyes focus accommodation), but the general principle still applies. Nevertheless; were not looking at details here, just an example of the focus shift. What I did was essentially put the binoculars on a pile of books, aimed it at some distant tree and rooftops, and took some pictures with my Sony A7 mounted on a tripod and paired with the Zeiss FE 35/2,8. With good centering, I can just avoid vignetting in the corners.

I know this is a bit sloppy and it is, of course, possible to do it much better, but with a three-year-old running around there is usually not much time available for undisturbed "precision" work... Sorry, but that's the best I can offer.

In the first picture, the focus is on the trees in the center. Also, the top row of bricks on the roof are in really acceptable focus in the center, but everything comes crashing down as one move to the sides. On the second picture, the focus is on the far right chimney-corner, which also puts the sharpness at decent levels on bricks on the far left side. The center section is, however, a blurry blob at this point.

This effect is, of course, common, to some degree, for practically all optics. However, in most quality optics this is not really distracting when not deliberately looking for it. But in the case of the Deltrintem(/Jenomptem) I do actually find this effect so pronounced that it is constantly apparent when looking through the binocular.

I would like to add that the image in the center region, when focused correctly, is very sharp. I did some comparisons between some other binoculars I have here; more specifically a Leica Trinovid 8x20 dating circa 2000 (with phase coating) and an old Leitz Trinovid 8x32 from the early 1970s.

Some key observations during a brief comparison based on looking out the window from time to time across a few days:

  • Ignoring the stated differences like format and objective diameter, and the obvious consequence of this in low light, the Leica Trinovid wins in terms of overall sharpness and focus shift towards the edges. It, of course, has a much smaller AFOV which has to be taken into consideration. The very center sharpness is, during practical observation without support, to my eyes nearly the same.
  • The Leitz also has significantly less focus shift than the Docter, but the very center is definitely less sharp in the Leitz. The Leitz does, however, provide the most comfortable and relaxed view of all the three.
  • The Docter displays remarkably little color fringing, while the Leitz is definitely the worst. Although, I would not consider any of the binoculars bad in this sense.
  • In terms of color saturation and contrast, both the Docter and the Trinovid are far ahead of the Leitz.
  • Due to the porro-construction of the Docter, the "3D"-effect is of course much more prominent than in the other two roof prism binoculars.

I took a few photos to illustrate the center sharpness. For the same reasons as stated earlier, this is really a quasi-scientific approach, but I still think it gets the point across. I took these photos early in the morning, and the camera is set to ISO 100, f2,8 and 1/100th shutter speed for all photos. They are all processed from RAW files with the same settings, like white balance, etc. What you see is the center portion of the image. The pictures are taken through the following binoculars from left to right: Docter Deltrintem 8x30 – Leica Trinovid 8x20 – Leitz Trinovid 8x32.

The level of light in each photo is very different. Partially this can be due to moving clouds, but I presume the primary difference is the objective diameter, which seems to correlate fairly well with the brightness of the pictures.

As a last experiment, I took the same pictures but focused on the very center portion. I then did some quick adjustments to the RAW files to compensate for the variations in brightness, color tone, and saturation. The idea was that this would give a good picture of the "on-axis" sharpness of each binocular – eliminating all other parameters.

The Sony A7 has a pretty decent dynamic range in the RAW files. But you can see that in this more or less 100% pixel crop from a 24 Mpix image, the picture through the Leica Trinovid starts to display some noise after the adjustments. It is still however in my eyes the binocular that offers best "on-axis" sharpness amongst the three. However, as stated earlier, in practical viewing conditions I find the difference hard to notice. The Leitz is clearly the one with the lowest result, but for "leisure" viewing it is definitely sharp enough for a good viewing experience.

There are of course a gazillion other things you could talk about and test between these, and other, binoculars. But I hope at least these thoughts, summary and test and is of interest to some of you. |=)|
 

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jring

Well-known member
Hi,

this is indeed a very nice test - especially the second and third image could be used for explaining field curvature...

Enjoy your classic porros!

Joachim
 

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