105mmf3.8 Xpres - surprising coverage

[IanG]

I picked up a Ross 105mm f3.8 Xpres in a Trikon shutter about 3 weeks ago at a camera fair for £3 ($4.80) with a flange. Actually it's un-named but the shutter is made by Ross and it's coated and is identical to the Xpres on my Ross Ensign Selfix 820

Yesterday I put it on a spare lens board to check the coverage and was very surprised to find that it covers 5x4 and allows some movements. This version of the Xpres is front cell focussing, I tried it set to infinity. Some claim that the Xpres is a Tessar design, however the original Xpres is a derivative with 5 element. There's 5 reflective surfaces so it's not a Tessar type.

The Trikon shutter has flash synch and as the name suggests 3 shutter speeds 100, 50 and 25 plus B & T, it's Compur #0 compatible. Next I need to see how sharp the lens is with 5x4, the one on my Selfix is excellent.

Ian

[dave_whatever]

Interesting Ian - I once had an old 105mm Symmar (intended for 6x9) that "lit up" the full 4x5 ground glass but wasn't sharp out to the edges. You could just about get away with a 2x5" pano though - I wonder if your lens will show a similar thing?

[IanG]

It's the edge & corner sharpness that I'll be looking at, I guess I'll probably use it on a smaller camera though - maybe my Busch Pressman or my Houghton Victo ¼ plate camera. I made a roll-film back adaptor for the Victo - slips in like a Plate holder but olds a Graflex 67 roll film back instead.

Ian

[Dan Fromm]

Ian, the 105/3.8 Xpres on my Selfix 820 is a tessar type. I can see four strong, no weak, reflections from the front cell and two strong, one weak (and hard to discern) from the rear cell. According to the VM early Xpreses had a cemented triplet in the rear, supposedly (I can't verify) to get around the Tessar patent. A cemented triplet will show two strong and two weak reflections, and the weak reflections may be very hard to see. The 105/3.8 Xpres is post-WW II, not early. Count reflections carefully and tell us what you discern.

As for the 105/3.8 Xpres fitted to my Selfix, it is a considerable disappointment. I've never got a satisfactorily sharp image from that camera at any distance, not even far away with the lens set to infinity. I've checked, it seems to be properly collimated to the body.

As for a 105 fast tessar type covering 4x5, well, perhaps if you interpret cover as illuminate. If you interpret cover as put sharp image in the corner, there's never been a 105 tessar that covered 4x5.

I'm a little surprised that Ross put a premium lens in a bottom-of-the line shutter, but I suppose its possible.

[IanG]

I'm a little surprised that Ross put a premium lens in a bottom-of-the line shutter, but I suppose its possible.

So was I, but the seller was a 7 year old lad (+/- a year) so knew nothing about the lens, his dad gives him a box of oddments sell :D This was a stall at a camera fair where I bought close to mint Zorki C for £5 ($8) and paid the same for a good post WWII Ikonta.

I think the 105mm Xpres in the Trikon is probably off an Ensign Ranger II camera, the combination isn't listed in any of the BJPA's but a few do show up for sale with this lens/shutter combination. I've come across a few oddities for instance 3 & 4 speed Epsilon shutters, the same shutter was previously called an Ensign, prior to that the older Ensign 3 speed shutter was a Trichro.

Dan, at this stage I'm referring to the circle of ilumination of this Xpres which is much larger than I'd expect from a 105mm lens like a Tessar. I'm not expecting great sharpness towards the edges but it'll be interesting to see what it's really capable of. Checking the reflections today I get 4 strong from the front and 2 from the rear, I can't make out any weak reflections. My other Xpres is a good sharp lens so I gues you've been unlucky.

Ian

[tommfy]

I think the 105mm Xpres in the Trikon is probably off an Ensign Ranger II camera, the combination isn't listed in any of the BJPA's but a few do show up for sale with this lens/shutter combination.

Ian

Just to drag up an old thread, I indeed have an Ensign Ranger II with a Ross Xpres 105mm f3.8 in a TRIKON shutter!



Dan, at this stage I'm referring to the circle of ilumination of this Xpres which is much larger than I'd expect from a 105mm lens like a Tessar. I'm not expecting great sharpness towards the edges but it'll be interesting to see what it's really capable of. Checking the reflections today I get 4 strong from the front and 2 from the rear, I can't make out any weak reflections. My other Xpres is a good sharp lens so I gues you've been unlucky.

Ian

After viewing this thread I thought I'd put the 4x5 coverage to the test with a handheld shot on my DIY 4x5. As you can see by the attached image in the corners it's pretty sharp, not great but a lot better than I was expecting (I was focused on the pebbles of the beach) :)


155071155072

[Dan Fromm]

Arrgh! There's no detail in the subject near the corners. How can we conclude anything about image quality near the corners from your test shot?