Anyone out there using this lens and would be willing to share their thoughts…
For the last few weeks I'd been thinking about getting a 23HR. I decided to purchase a preowned copy from Sean at Camera West in California and it arrived two days ago. So I'm hoping that the experiences of someone who just got the lens will help. There are also a few questions that I'm hoping people with more 23HR and Tech Cam experience will answer.
Here we go…
When I get a new lens I like to take test shots to get a sense for how it will work best for my needs. My goal for this test was to check for edge to edge sharpness at different f-stops and LCC. The recommended working f-stop range for the 23HR is 5.6-8 so I took shots at 5.6, 8, and 11. The images were all taken
without the center filter–my plans are to get a center filter for this lens, but I do not have one yet. All of the images were taken with a Cambo WRS 1600 using the standard lens board, not the one with tilt/swing.
Here are JPEG files to show you what the raw and lcc files at f8 with no camera adjustments and about 12mm of camera fall look like. The specs list that 11 is the max recommended vertical adjustment. The center of the building was about 40 feet away and the flag was about 20 feet away.
Here is what the images look like after processing. The LCC was corrected in Phocus and exported as a 16-bit tiff. Then I did the lens corrections using ALPA's Photoshop plugin and some exposure/color adjustments/sharpening in Photoshop as well.
Even without the center filter Phocus's Scene Calibration (LCC) cleaned up these images pretty well.
Here are 100% crops at the left, center, and right. These are from the images that were taken with no shift/rise/fall. I used live view at 100% with a Hoodman loupe to focus each shot. The Windsor High School sign in the center of the frame was the point of focus and I refocused the camera for each f-stop change. You can see from the above images that the left side of the building is a little closer and the right side is a little further from the center of the frame.
f5.6
f8
f11
On all three images the center sharpness is basically the same. After sharpening, the edge sharpness for the f5.6 and f8 shots is very close as well, but the f8 is a little better in the RAW file. The edge sharpness at f11 is significantly better. I didn't try f16 because I thought that lens diffraction was going to be an issue at f11, but it seems to be fine.
Here are a couple of questions for people that have more experience with this lens, and technical cameras/lenses in general:
- Are the results from this test in regards to edge to edge sharpness at different f-stops about the same as your experiences with this lens?
- In general, if your goal is to get edge to edge sharpness do you focus at the center of the frame or the edges of the frame?
- For a shot like this with different layers, would you focus at the furthest thing away that you want in focus or what's in the middle? Or would you take three shots–one for the closest, middle, and furthest then see which one gives you the best results?
This post about adjusting infinity focus for Alpa lenses is very interesting and leads me to ask one more question:
One of my Alpa lenses isn't focusing at infinity when set at infinity, and I'd like to adjust it. Shimming won't help; it's focusing slightly closer than infinity, so shimming would only make it focus even closer. And my adapter is already nicely shimmed for my other lens. I've seen past...
www.getdpi.com
- I'm using Cambo WRS and focusing with live view. If the infinity focus is not adjusted properly could that affect edge to edge sharpness, even though I'm able to focus on the sign like I wanted to?
You can see JPEG files of the full sized images here if you are interested:
https://ln2.sync.com/dl/f6e6ce050/idp7zvgc-cpa7qdec-zgvytpqy-bnsrwdki
Warren