Ambrotype - advice please about exposure and tonal range

Hello, I am a new wet plater in Tokyo. It took me two months for all the preparation, and finally, I got my first plates a week ago. Today I had some test shots and would like to know how I can improve my technique. I am asking this because I rarely had a chance to see real ambrotypes. The only time that I saw was when I took the workshop on wet plate photography.

If you can check my test result today (below), I’d greatly appreciate it.
https://photos.google.com/share/AF1...?key=QTgxeURnZDBZRlBUYlZONld1eVJWcmw0Tk1haDV3

#2 seems to be the best exposure, but to be honest, I was expecting to get a much nicer tonal range. The photos were shot using only natural light. All the developments were about 15sec. The size of the plate is 5x7in. Just so you know, I didn’t make any adjustments when I scanned them (the lid opened with reflection mode).

Although I highly appreciate any comments, I do have two questions:
1. What are very fine streaky lines going diagonally that are visible all over the plates? I circled a spot in red where the streaks are clearly visible although they are everywhere (much clearer on my original scan though). Please zoom in to see this problem.

2. Is it possible to get the highlights in the pictures a bit brighter, in a general sense, without losing the details? This photographer’s portraits are great, have a wider range. I think mine looks flat.
http://www.collodion.com/forum_posts.asp?TID=12106&title=two-portraits-from-this-week

3. #3 looks underexposed, but it has more contrast than the other two. Do I get more contrast if I underexpose a plate in general?

Thanks in advance!

1: those lines are related to the partial drying/coagulation of the collodion when flowing the plate. The collodion mix, particularly the ether & alcohol content is the primary determinant, and technique also influences it a bit.

2: your examples look fine, really, esp. #2. I don't think it gets much better than that. The type of fixer does influence the nature of the highlights a bit; e.g. rapid fixer tends to give fairly bright, metallic highlights.

3: the main determinant of contrast is the lighting of the scene. Other than that, yes, you can alter the contrast of the plate by either overexposing and underdeveloping to reduce contrast or the opposite for more contrast. There's only so much room to alter contrast though, you run into the limitations of the medium fairly fast.

As to the beautiful examples you see online: digital capture and post processing contribute a lot to the end result. Likewise, under what kind of loop lighting conditions you view your plates in real life also does a lot for how they look. As does varnishing!

Hi Koraks, Thank you for your comments!
I guess I need a lot of practice to be able to pour collodion nice and smoothly. I usually spill some collodion when I move the plate around, and especially when I pour the excess collodion into the drain bottle, hahaha.

I totally understand your comments on the beautiful examples. Even the scanned images of my plates seem to have more contrast than how they look in real. The way Ambrotype look really is largely affected by viewing environments.
I would like to try Tintype also in near future.