Luminous Landscape Forum

Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: Smoothjazz on April 24, 2015, 02:06:02 am

Title: Alpa Ground Glass Focusing
Post by: Smoothjazz on April 24, 2015, 02:06:02 am
I am considering an Alpa TC or STC with my IQ 180 back, and for focusing have thought that I may want to use the ground glass, and then remove it, and then put on the digital back to acquire images. Is anyone else doing this?
I have not been comfortable with Live View focusing, or focusing with tables/charts, or sliding backs; I am thinking this may be my best option now. Thanks for your input.

John
Title: Re: Alpa Ground Glass Focusing
Post by: dchew on April 24, 2015, 06:28:10 am
I have the ground glass with my STC and use an IQ180. However, I don't use the ground glass for critical focusing, I use it for framing. When stitching two images together, it is the only way to see the whole image before you shoot. Also, for me there is some compositional benefit to seeing the image upside down and backwards. I have three masks: 54x40, 76x54 and 90x40. Those last two represent a vertical stitch and a horizontal stitch 18mm each way. In my opinion a geared head like the Arca Swiss Cube or D4 makes this much easier since you can adjust in one direction at a time.

I have a Leica Disto for critical focusing. In general, if I am not using tilt and shooting at f/11 or smaller, I can use the GG:

If there is a single-distance subject at f/11 or larger, I will pull out the Disto and set the HPF ring. That is always accurate. If I am using tilt, I will try first using the GG. But often I cannot get sharp enough so I use a tilt calculator combined with the Disto. I keep trying manually first so I learn and improve. I have two loupes that I carry: the Alpa 3x (310.010.040), and a std Hoodman loupe. The Alpa is the better experience, especially when framing a stitched image and focusing but attaching and removing is a bit fiddly. The Hoodman is quick for a single 50x40 frame. I've tried using a 10x loupe for focusing, but I find it faster to just pull out the Disto and I have not found an acceptable method to shade the GG when using a bare loupe.

There are multiple ways to frame and focus these things. Live view, Disto, GG, Surface Pro 3, estimate, ... you just have to experiment and see which one fits your style and what you are willing to carry. Google Wayne Fox's technique for using the IQ180's live view w/ variable ND filter. Also Ken Doo's work on using a Surface Pro 3 running Capture One.

Dave
Title: Re: Alpa Ground Glass Focusing
Post by: Smoothjazz on April 24, 2015, 09:17:12 am
Thank you very much. I think your method makes the most sense for me. I agree that seeing the image in the ground glass just seems to be important for landscape type photography.
Title: Re: Alpa Ground Glass Focusing
Post by: epines on April 25, 2015, 01:30:57 pm
I use the Alpa GG as well. For critical focusing, you might try the Linhof Silvestri 12x loupe, available from Linhof Studio. Works very well. Don't be concerned about being unable to focus due to the prominence of the GG grain. It works great.

http://www.linhofstudio.com/products/Loupes

Dave Chew -- how do you make your masks?

thanks
ethan



Title: Re: Alpa Ground Glass Focusing
Post by: lowep on April 25, 2015, 03:45:25 pm
this is a reason why i stick with my old Contax 645  8)
Title: Re: Alpa Ground Glass Focusing
Post by: dchew on April 25, 2015, 09:20:39 pm
Quote from: epines on April 25, 2015, 01:30:57 pm

Dave Chew -- how do you make your masks?

thanks
ethan

When I ordered the GG I asked for 2 24x36 masks, knowing I would cut them to custom sizes, and the std 40x54. I tape them to a self-healing cutting mat and measure carefully then cut with a fresh blade. I practiced on some old transparency sheets I found.

The 40x90 was the tricky one because the window goes almost to the end of the mask. Here they are:

Title: Re: Alpa Ground Glass Focusing
Post by: sgilbert on April 25, 2015, 09:52:34 pm
ALPA used to offer downloadable GG overlays in various sizes/formats that could be printed on clear plastic and cut to fit the GG.  You could choose various sensor sizes, shifts, etc. 

They've now "improved" their website, and I can't find them anymore.  If you're interested, you could contact ALPA and ask about them.
Title: Re: Alpa Ground Glass Focusing
Post by: pemihan on April 26, 2015, 05:40:14 am
Here you go:
http://www.alpa.ch/_files/ALPA_Stiching_Masks.pdf
Title: Re: Alpa Ground Glass Focusing
Post by: sgilbert on April 26, 2015, 12:24:45 pm
Thanks, Peter.  I used a laser printer to print some of these, and it worked well.
Title: Re: Alpa Ground Glass Focusing
Post by: epines on April 28, 2015, 11:58:41 am
Steve -- can you recommend a clear plastic / acetate to print on?
Title: Re: Alpa Ground Glass Focusing
Post by: sgilbert on April 29, 2015, 10:59:15 am
I don't recall the brand, but they were like this:  http://www.amazon.com/C-Line-Transparency-Printers-Inches-60837/dp/B000FNBTBG

I thought I used Avery brand, but not sure.  Sorry
Title: Re: Alpa Ground Glass Focusing
Post by: Smoothjazz on May 04, 2015, 03:57:12 pm
A quick follow-up for those with tilt on their Alpa cameras; how important is the tilt for composing landscapes? The reason I ask is that I have the option of an Alpa lens in a long barrel mount, which would not allow for the tilt adapter, from what I understand.
I had personally thought that the tilt would be good to have, but now I am not so sure.