I have been trying to synth a fort (inside and out) The most amount of pictures (without reducing the size) has been just over 1000. I see that EdLee has been able to get near 1500! (By reducing the pictures size)
I now have over 2500 pictures of the fort! Way too many so I have tried to  be more selective.
 I still run out of memory though (1700 pictures and the resolution is now half of the originals)

PSWebClient version 2.0.1519.16
Target: x86 OMP
Running on Windows 6.1.7000 
Wow64: yes
Processor: architecture 9 family 6 model 15 stepping 11
Number of processors: 4
Memory available: physical 8189 MB virtual 4095 MB

The end of the test

06:38:12 VtApp: Upload finished
07:18:47 VtApp: PredictImages time: 3356.5
08:30:47 VtApp: ChoosePairs+MatchPairs time: 4319.3
08:30:54 VtApp: Total feature matching time: 7682.8
08:31:00 HR test fail <>\ReconstructionState.cpp(666) hr(8007000e)
08:31:00 HR test fail <>\ReconstructionState.cpp(450) hr(800700

What is the limit?

Hi LostinTheTriangle, my highest count to synth successfully was 1,499 photos -- although may not be 100% synthy; and even if 100% synthy, may not have zero disjointed point clouds. Photosynth had run out of memory, crashed, or failed even at under 1,470 photos. (All the above at 640x480 resolution.) Does 'Wow64' mean 64-bit Vista?

Edlee, wow64=64-bitVista, or in this case 64 bit beta windows7
So far this version of windows has refused to crash hard on me! I like it in that respect. 
Getting back to the synthing. I have even tried to reduce the resolution of the pictures. I tried again last night with around 1655 photos (down from 2500!) I have plenty of ram (8 gigs) and most of the pictures I believe are on the server. 
I would really like to get the inside and outside photosynthed together.

What does the RAM use peak at? 
8007000e means out of memory so I guess we either need a 64-bit client or a way to merge synths together

A 64 bit client would be great, but then I think storage would be a problem for the huge synths :)

I tried a 620 image synth last night and got 'out of memory'. I kept an eye on RAM (3GB) and it peaked at about 2.2gb. Funnily enough, the 'out of memory' came when the system was at 50% physical memory usage. HD = 200gb free. OS = Vista 32.

32bit machine will sometimes run into out of memory problem when the synther tries to allocate large memory block for reconstructing a really large scene/data set. Our new release yesterday (Apr 20th) made much improment on the memory usage for the reconstruction, which should relieve many of the "out of memory" issue. But synthing over 1500 images on a 32bit machine is still probably having a hard time to get it through.

houdan, are you saying I can try to synth "THE REALLY REALLY BIG ONE!" .............. (windows7-64, 8 gigs ram, etc, etc............

Also a question: Does running hyper threading help, or is it better to turn off?

you could give it a try. but keep in mind that more than 500 images generally don't give you very good navigation experience.

you could leave hyper threading on and the synther will try as many virtual cores as it can in image conversion, feature extraction and matching to speed things up. But the reconstruction is still single threaded now.

Thanks houdan, that answers a few questions. most synths do not need thousands of pictures, but the problem I found when trying to put the martello tower together was that it is so small inside I needed to shoot a lot of pictures to keep it together. My last attempt came out to 1077 pictures but some of the transitions and exterior details where lost. 

I think if I could add another 200 - 300 pictures it would improve. But then the performance (cloud point and picture lading times) would suffer. I will try again though.

Thanks again for a great program.

This is getting really frustrating now. I've just attempted a synth using 378 images of a 500 image synth that worked two weeks ago. I added about 20 different images in to make 398 (on new synth). 0x8007000E 'out of memory' message popped up even though only 50% of RAM was being used at the time. Running vista, 2.2ghz x2, 3Gb RAM & 180GB free on HD. Log below: 

20:55:31 HR test fail \PSReconstructionState.cpp(265) hr(8007000e)
20:55:31 HR test fail \PSReconstruction.cpp(223) hr(8007000e)
20:55:31 HR test fail \PSReconstruction.cpp(41) hr(8007000e)
20:55:31 HR test fail \Registration.cpp(673) hr(8007000e)
20:55:31 HR test fail \Registration.cpp(770) hr(8007000e)
exception SynthPipeline.cpp(293) hr(0x8007000E)
exception CollectionUploader.cpp(368) hr(0x80004004)
20:55:32 VtApp: FAILED: 0x8007000E

I'm having a similar problem. It seems almost that photosynth is having a hard time putting together a quarter of the number of pictures it used to....