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1880s Brass: Taylor, Taylor & Hobson - Rapid Rectilinear
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PostPosted: Fri Jul 16, 2010 2:24 pm    Post subject: Reply with quote

It's very difficult for me to guess because I don't own any of your lenses so I don't have any idea of how they would look.
Just based on the contrast I would attempt to say that the old rapid rectilinear (which obviously can not have any coating) should not be #2 whose contrast seems to suggest at least a coating of some kind.


PostPosted: Fri Jul 16, 2010 4:14 pm    Post subject: Reply with quote

I would agree with Orio except B is overexposed a bit; I think the TTH RR would glow a little more with overexposure. So, I'm guessing A is TTH RR, based on low contrast. I've no clue about B & C; I like C rendering best of all three.


PostPosted: Fri Jul 16, 2010 6:50 pm    Post subject: Reply with quote

I think it's C, only because C's image seems to be a little more soft on the edges than the other two (although A is close to C in this regard), and I suspect that a lens such as the subject one was probably not great in corner to corner sharpness.

Still, I also find C to be the most dramatic of the three, so if this is the one, then I'd say you've got a real winner. Although it appears that all three lenses did a good job.


PostPosted: Sat Jul 17, 2010 1:22 am    Post subject: Reply with quote

I probably should have adjusted the settings to balance the perceived exposures... keeping the exposure settings the same makes it easier to see how the lenses differ, but I suppose it doesn't necessarily show them at equivalent "image reproductions". Wink

Nobody has any guesses for the competition? Very Happy


Here are the histograms for the three samples:

Sample A:



Sample B:



Sample C:


PostPosted: Sat Jul 17, 2010 4:41 am    Post subject: Reply with quote

Scheimpflug wrote:

Nobody has any guesses for the competition? Very Happy


Sorry. Hard to say. I'm figuring you probably used the 500mm f/6.3 preset tele for one of them, but it would be hard to say which one. Maybe A. I still think C is the TTH RR


PostPosted: Mon Jul 19, 2010 7:20 am    Post subject: Reply with quote

You guys are good! Cool

Both A and C are the TTH RR. Very Happy Sample B comes from my Aetna Rokunar 300/5.6, a lens which really surprised me with its performance. The Aetna is sharper at 100%, although part of it could have been my focusing. CA is very similar- I can see just the tiniest touch on the Aetna, and none on the TTH RR. Shocked Bokeh appears to be slightly smoother on the Aetna, although I will need to try some night shots with bright point light sources to confirm.

So why two shots with the TTH RR? Since this is a large format lens, I knew that the tiny lens hood would not be adequate. Therefore, Sample A is with the factory brass lens hood, and Sample C is with an improvised hood of my own design. Cool cooltouch picked up on C having softer edges (something I can't see myself Embarassed), which probably indicates that my hood was a bit too aggressive. Wink

Either way, this quote sums it up:
cooltouch wrote:
Still, I also find C to be the most dramatic of the three, so if this is the one, then I'd say you've got a real winner.

Cool

Pretty impressive performance, I would say, especially given that its competition is larger, heavier, and at least 80 years newer. Shocked



Oh, and also, I still need to clean the rear element. Since it is so far down in the tube, it probably hasn't been cleaned in decades. Shocked


Anyone have any ideas how to do this? Question


PostPosted: Mon Jul 19, 2010 4:32 pm    Post subject: Reply with quote

Scheimpflug wrote:
cooltouch picked up on C having softer edges (something I can't see myself Embarassed), which probably indicates that my hood was a bit too aggressive.


Well, it wasn't easy to see, especially at the picture size posted, but careful examination of details at the edges compared to details closer toward the center suggested a slight softening. No more than a hint, really, but it's all I had to go on, so I gave it a shot. Glad to find out I was right, and it also explains why I saw similar softening with A.

If that rear element has a slotted retainer ring, you can probably remove it with a lens spanner. Is it deeply recessed?


PostPosted: Mon Jul 19, 2010 8:33 pm    Post subject: Reply with quote

cooltouch wrote:
If that rear element has a slotted retainer ring, you can probably remove it with a lens spanner. Is it deeply recessed?


Yep, very deeply recessed. The carrier for the rear elements is the part which is soldered to the tube, so while I can clean one side, the other is all the way at the end of this black tube:


No threaded retainer rings here... appears to be hammered over brass that retains the lens elements. Wink


PostPosted: Mon Jul 19, 2010 8:49 pm    Post subject: Reply with quote

1. Blow out all you can with compressed air.

2. Use an artists brush to loosen some more dirt, blow againg.

3. Tape q-tips to a barbeque stick/chopstick, dampen with alcohol, wipe glass.

4. Wipe some more with dry q-tips