Monday, January 28, 2019

Fast Lens Test - Kodak EA178, Schneider Xenotar 150 2.8 and Voigtlander Petzval


   Recently I was lucky enough to acquire a famed Schneider Xenotar 150mm 2.8 as part of a deal I could not pass up.  This lens has been touted as one of the best by a lot of lens junkies whose chatter I see online.  For a while though, I’ve already had another lens coveted and highly regarded by many others – the 178mm 2.5 Aero Ektar (AE178).  Having these two at hand I wondered which one would be sharper wide open and how would their field of focus act under more or less stringent test conditions.  To make things a bit more interesting, I decided to include in the test one of my personal favorite lenses, a Voigtlander Petzval 7in (so 178mm as well) f3.2.  The point of including it was two-fold.  One reason for inclusion was of course to see how it’s sharpness would compare, but I also wanted to see how brightness of exposure with it would compare to the two others, because Xenotar has excellent new coatings on the lens and AE178 is also single coated, on top of that my AE178 suffers from relatively minor yellowing due to aging of the thorium element and there’s also a fair amount of condensation in it, to which I can’t get for the life of me, those darn set screws are super tight… See a picture at very bottom of the actual condition of my AE178.  The other two lenses tested are as close to mint as you’ll find with Voigtlander is showing only extremely small amount of surface cleaning marks and the Schneider is like new.

Lenses tested 


  With above said – you see that this is a fairly loose personal test, I wouldn’t be surprised if someone else out there has a very clean AE178 that may give better contrast and sharpness because it’s not all fogged up. For what it’s worth, here’s how I conducted the test and results.

  Test was made with Zone VI camera, with ¼ plate sized plates (3.25inx4.25in), using same collodion of unknown formula (whatever batch was closest in my fridge, I don’t label them, just look at color).  I used strobes to eliminate any chance of moving and before firing it I discharged the pack and gave it same 20sec to recharge, to eliminate possible differences in flash power, I also used a focusing loupe to make sure the center of my sharpness target, which I placed in the center of the frame, was in perfect focus on ground glass.  Developer temperature was controlled between plates by keeping the bottle refrigerated up until 15sec prior to pouring over the plate, and development time was carried out according to a timer for 30sec on each plate. KCN was used for fix and time in it was also restricted to 15sec exactly.
  Afterwards, plates were copied while still wet, using Canon 5DII with 24-105 lens at f11.  Standard amount of sharpening was applied in Photoshop, no other adjustments were made. 

  Here are images of full ¼ plates and then crops from them. First is Xenotar, second Voigtlander, and lastly AE178.
  Please note – Voigtlander focus is a little off.  I’m not sure if this is due to me missing it somehow even with the loupe, or chemical focus, which would be super weird because I’ve never ever noticed that issue with any Voigtlander Petzvals, so I’m inclined to assume that it was either me missing the focus, or something moving somehow on the camera…


 Xenotar 150 2.8

Voigtlander Petzval 7in 3.2

Kodak Aero Ektar 178mm 2.5

 Xenotar 150 2.8

Voigtlander Petzval 7in 3.2

Kodak Aero Ektar 178mm 2.5

For reference - this is the scene I shot

My Aero Ektar 178mm - yellowing and condensation...

  I’m not going to draw any conclusions, I’d rather let the viewers decide for themselves what they are looking at, and what appeals to them most.

  Cheers,
Anton


Wednesday, December 19, 2018

Wet Plate Collodion 11x14 Petzval 3-Lens Test


Dallmeyer 3A 16in f4.0, Wollensak Vitax #5 16in f3.8, Dallmeyer 4B 17in f3.7

  Having very recently completed the adapter for my Century #2 11x14 camera to have a spring back for standard plate holders, I thought I’d make this post for the sake of posterity.  There’s a lot of talk nowadays about Petzvals and a lot of folks I see are looking for proper ones for their 11x14 cameras.  It’s not often that above three lenses find themselves in each other’s company, and so I have never seen a real side by comparison done in controlled environment.

  Very briefly, I must state that technically for a ‘large head’ cropping as seen below, on 11x14 camera a truly correct lens to use would be of at least 20in focal length to avoid possible distortion of the nose when shooting this close.  17in is a ‘normal’ focal length for 11x14 format, of course as you rack it out your plate sees less and sell from its angle of coverage, so the lens becomes de facto ‘longer’, but 17in is still not enough.  In old times of proper photography, 24+in lenses were recommended for 11x14 format, but I can’t blame folks for shooting round 17in on 11x14 since any Petzval of 20in focal length and above is going to cost about as much as some new cars today…  
These plates were shot at 1:1 ratio, so head of model on plate is same as in real life.   I'm not going to go into how effective aperture changes with bellows draw, that's for another time.
Fred the neighbor was as always kind enough to sit in for the sake of art and science.
Oh…  On the plate made with the Vitax I think I forgot to turn one of the light back toward Fred, so lighting is a bit different there, but that doesn’t really affect what we’re looking at to much.

  Controls for the test were as follows.  Lighting was provided by flash to eliminate possibility or motion blur.  To keep the focal plane right on the eye between final check of focus and exposure, an International Head Brace was used, these things are great whether you’re shooting continuous light or flash and I rarely go without it.  Collodion and developer formulas matter little, as does the fact that I barely cleaned the glass after pulling it out of the box, just dusted it off and that’s it.  This isn’t a test of how clean of a plate yours truly can pour, and I used glass so I can erase these images later…  Development was carried out by visual inspection. Plates were copied on a Polaroid MP4 copy stand via Canon 5DII and 24-105L lens at f11.  Equal amount of sharpening was given in Photoshop as standard procedure (100% at 1 pixel radius and 0 tolerance).

  In interest of full disclosure – the glass on both 3A and Vitax is as good as it can be for 100+ year old lenses, while the 4A I have actually suffers from previous mistreatment, leaving it with a few significant scratches on back element and separation around the edge of front pair…  I think the below results do show that, despite the flaws in glass, the image from it suffers very little if any at all.

Full 11x14 plates

Dallmeyer 4B

Dallmeyer 3A

Vitax #5


Closeups of same plates
(copy camera lowered)

Dallmeyer 4B

Dallmeyer 3A

Vitax #5

Left eye from all three plates
(shot in macro range and cropped again in PS)

   Personally I can barely tell them apart.  Dallmeyers seem to have a tiny bit of softness to then, which is really nice for skin smoothness. Vitax though seems to have more contrast, and I like that in my plates (though that can really be due to me switching lighting to higher ratio).  Above copies will likely appear much larger on your screen than in real life, so I would encourage you to think about that as you’re thinking about this – in reality, the eye in last photo is same as your eye size, so shrink the picture down to until that is the case and then think if you’d be able to tell the difference in sharpness at that scale.  Pretty sure that in competent hands any one of these lenses is able to wow customers and viewers if one is not picking apart details and doesn’t have another plate of same subject made with a different lens…    

Anton