Ross Xpress 10" f4,5

I got this lens recently - is there anybody having info about this?

 

Sharpnes/contrast - image circle<div></div>

Its an f/4.5 Tessar. That says it all. Covers 11", should be sharp and contrasty in the center, softer in the corners.

As Dan says the Ross Xpres was a Tessar type lens and will have the usual Tesar characteristics. The serial number according to the Vade Mecum is about mid 1950's. I had a 14inch Xpress of this type which was an impressive lump of glass but a bit soft at full aperture.

Thanks - a Tessar type is just fine for me (especially at 20$)

Five elements in three groups. Similar to a tessar, not identical.

Dave, you're right about early Xpres lenses, wrong about the one we're discussing. Per P-H Pont's chronology, it was made around 1947.

 

The original Xpres was as you described, with a cemented triplet behind the diaphragm, to evade Zeiss patent. Later ones have a cemented doublet behind the diaphragm, like the Tessar. The lens under discussion is, um, later.

In both world wars, Germany lost all their patents and copyrights prior to the end of the war. When we call a lens "tessar type" or "plasmat type" usually in lower case where it is a description rather than a proper.

 

Tessar type lenses typically are 56 degrees, very high contrast, slightly more astigmatism than other designs, and very rarely with an f ratio of more than 3.5, and more often that, even lower f ratios.

 

That type lens is great as an illustrators optic and if the focal length is right, very good for landscapes.

 

Lynn

Never heard of P H Poot. Kingslake describes as five elements/three groups.

Les chiffres cles, PH Pont<BR><BR>ISBN 2906840068<BR><BR>

Tessars that are F2.8 are more common in 8mm and 16mm cine lenses. The Rollei A110 had a killer 23mm F2.8 Zeiss Tessar. <BR><BR>Optical literature is riddled with errors.<BR><BR>Is the lens in question the Ross Xpress 10" f4,5 a lens for a still camera; or a barrel lens for an enlarger or copy camera?

Kelly, it is a taking lens.

 

Sims, I'm sorry that you don't know everything. When I was a small child I thought I should try to learn everything. Went to the library, measured, concluded that I couldn't read fast enough to learn everything that was known at the time before I died of old age, also that I couldn't keep up with new additions to knowledge. So much for childish ambitions ... Anyway, Sims, you really ought to try to learn more. Here are a few suggestions:

 

You might want to acquire a copy of A Lens Collector's Vade Mecum. It is, as everyone says, full of errors and incomplete but its the best thing of its kind going. Kingslake's History is much less comprehensive and his use of English is, um, idiosyncratic. In addition, for some reason he slights most of his classmates at Imperial College and is very weak on modern lenses.

 

The VM stands out from books on optics with lists of lenses appended because it reports on how well they shoot. This is much more useful than knowing their designs.

 

There is a third edition of Les Chiffres Cles, ISBN 2-912848-14-8. IIRC, I got mine from FNAC.

Dan, Dan, remain calm. (Remember what Nurse said!)

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I couldn't agree with you more. Kingslake's a completely unreliable source-- real <A HREF="http://spie.org/x3073.xml">second-rate intellect</A>, that guy was. And photo.net's a fount of <A HREF="http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00KGTC">accurate information</A>-- no pseudoscience and BS here!

Sins, I don't know what your problem is, but it seems that you don't know everything yet. Good luck in your studies.

Daffy, I've been thinking about your response. Its irrelevant.

 

Rudolph Kingslake was a well-educated very bright person who had a wonderful career. He didn't know everything -- no one knows everything -- and his popular works are not free of errors. In this they are like every compilation of lens designs I've ever seen <I> except </I> those published by manufacturers that include only the maker's own lenses. And even these are often incomplete.

 

I don't see the point of your other link at all, except perhaps that you and I don't agree on much. You're still mistaken and off-topic.

 

The OP asked about a Ross Xpres made in the late '40s, and we've been discussing its design. Since Xpres, like Ektar, a trade name and not a design type, the question is empirical and can be answered only by looking at the lens in question or its brother. By an odd coincidence, I have a 105/3.8 Xpres made in the early '50s. It is a tessar type, i.e., the rear group is a cemented doublet, not a cemented triplet. This is not conclusive, but it casts doubt on the information you got from one of Kingslake's books.

 

Good luck in your studies.

There is alot of info in Optical texts that at first seems rigid; then later thru experience one finds errors and ommisons. There are errors in most all books ever written; and most maps too. Thus some folks and texts have said that an Ektar is a Tessar. Most are; but three are triplets, ones with 5, 6, and 7 elements too. <BR><BR>Experts and books is like the mid 1970's bet I had about "all Buicks have holes in their sides". My buddy believed this myth; its was in his several of his grand books written by experts. His dad owned Buicks and was a Buick expert. Except I lived in Detroit in the 1960's; most all neighbors worked in the auto industry. I produced a photo of a Buick Skylark with no fender holes to my Buddy. He still today cannot admit the bet was lost. His comment is still' "Buick Skylarks were not REALLY Buicks"!<BR><BR>As Dan mentioned; one should look and measure the lens in question. If its a Tessar the coverage will roughly be its focal length. The lens can also be a variant for closeups or an enlarger too; sometimes they do this but just spacing the elements different and making a optimizing the design for a closer working ratio. Its probably not; but sometimes Xenars variants were made like this.

<p>I will concur with Dan.  I have an early 1950's Ross Express f4.5 and it is a lovely Tessar design and a great shooter.  Sadly the aperture is missing so it only comes out when f4.5 is appropriate.  Mine was originally coated and some muldoon rubbed the coating about 2/3 off.  It's ghastly to look at.  You think it would have no contrast at all.  Yet it makes the most lovely images. <br>

<img style="vertical-align: middle;" src="http://tonopahpictures.0catch.com/English_Kodak_65X85/daisys7512Ross.jpg" alt="" width="472" height="619" /><br>

I doubt mine would fetch the $20 yours did, but, it ain't for sale.</p>

<p><img src="H:\Colin\Photos\Ross%20Xpres" alt="" /><img src="H:\Colin\Photos\Ross%20Xpres" alt="" />I'm reinstating this discussion because I have a 12" version of this lens. I am also curious what design it is. Two sets of three reflections from a light above me are apparent with one of the reflections having a blue colour cast. One reflection in the back set is so faint it is barely visible. When I close down the aperture blades there are two sets of two reflections with the single blue cast still there. The serial number might give an indication but I can't find any literature.</p>

<p>Regards</p>

<p>Colin</p><div></div>