Cambo Groundglass and Loupe

[Don Libby]

Yesterday I published a blog on working with the Cambo Groundglass/loupe which includes a video of actual usage. Video is here

Today I thought I'd add a couple images of the components themselves.

This images shows the Groundglass and loupe attached to the WRS. My right eye is my dominant shooting eye so you'll notice the Cambo tags are upside-down. The rubber eye cup is huge and sturdy which makes sense since Cambo originally designed this for video.

This image shows it from the other side.

This shows the Groundglass set into the WRS, Notice the notches on at the four corners? This is where the loupe can travel around to check the scene for focus.

This is a view of the loupe as it attaches to the Groundglass. The 4-small screw looking things are the magnates that hold the loupe to the Groundglass and also allow for travel in the 4-corners.

This Groundglass/loupe isn't mine yet. I had asked Dave Gallagher while we were in Carmel if I could borrow it for my work in Death Valley which he said yes, so long as I give it a review as well. The review is done and I'm surprised that I like it as much as I do. So much that I'll be trying to buy this set and not send it back to him.

First time I used the Groundglass was at Pfieffer Beach

The second time at Mono Lake

There's many options we have to shoot and with a Cambo WRS however this is the closest I've ever found that puts the user using what I call as a medium format manual technical rangefinder camera system. I've now used this at Pfeiffer Beach, Mono Lake, Devil's Golf Course, The Racetrack and at Badwater. In each instance I found using this to be super easy and superior to anything I'd done previously. The one item that ties all this together is the plate cover. Having the ability to remove the back and plate adapter together and place a protective cover of the sensor is something that's been needed for years. Well done Cambo and many thanks to Dave Gallagher to let me try it out.

Devil's Golf Course

Racetrack...

And at Badwater

At Pfeiffer Beach I took less than 5-images to get what I wanted. The major problem was re-learning how to see/think upside-down. Again at Mono Lake the high winds and very low temps made me work that much faster and I ended up taking far less that I normally would and still ended up with great files. Devils Golf Course was much like those before in that I sat down composed the shot checked the focus and waited until everyone left me alone to get this one. The Racetrack was interesting and the sample here is a 2-shot pano. Finally the shot from Badwater is the result of 3-shot vertical pano which I was able to clearly see in the loupe prior to shooting them.

Hope this helps anyone who might be considering Cambos Groundglass/loupe.

Don

 

[kdphotography]

Nice review, Don.

What I like is having focusing/composing options, especially with the IQ series MFDBs. Depending on conditions and/or personal preferences, you can choose among focus mask, live view, tethering, and the new ground glass loupe option.

ken

 

[Don Libby]

It really is all about choices. If I'm shooting in a fast moving circumstances where I just the right amount of time to set the camera up and shoot then I'd go "old school". I'm thinking of very quick fading light or an unusual cloud formation or both. Old school is set focus, f/stop, turn the back on and capture as many as I can.

If on the other hand I feel I have more time then it's a choice between live view and groundglass. Personally after using both I'd choose groundglass if I feel I have the little extra time needed. In practice I'd bet the actual act of thinking this through is longer than switching to the groundglass. Besides I need to remember live view also need a filter to work. I could of gone either way with the Pfeiffer Beach shot; while the light/color was fast moving I set the shot up using the groundglass then used a 10-stop for the waves.

The third circumstances is when I have all the time I need and really need to ensure critical focus. Hands down I'd use the groundglass.

The only time I see myself not wanting to use the groundglass is if I'm in an environment where I fear for the safety of my back while switching. (You'll notice the back can be removed and replaced while keeping it within an inch of the body and using your body as a shield.)

Just my 2¢

 

[jlm]

couple of things:

what is the magnification of the loupe? how much of the GG can you see without shifting? is there a fresnel in the GG so brightness is even?

alo did you compare exact focus of an image vs. what was supposed to be an exact focus in the gg?

you must have dipped up and down six times in the video, going back and forth to your bag. for your height, that's considerable movement!

 

[Don Libby]

John, the loupe is 3x. While I can see everything keeping the loupe centered there is slight light falloff at the edges; moving the loupe around helps. Guess this answers the fresnel question...

Regarding focus. I've focused using the GG/Loupe then after taking the shot checked with the FM on the back. I'm just now reviewing the images on a 30" monitor. So far I'm impressed.

I wanted to keep the video going throughout the entire shot and yes I had to dip into the camera bag several times. I feel the more I get used to a proper workflow the less dipping.

Don


Double checking facts. Cambo advertizes the WDS-619 as a "Groundglass/Fresnel Frame..." They also advertize a "spare Ground Glass" which is used on the 619. My guess is that if the current glass is somehow unacceptable a replacement can be had.

 

[stephengilbert]

Don,

I see that the tripod isn't too high for you. Were you standing on a box?

Steve

 

[Don Libby]

Don,

I see that the tripod isn't too high for you. Were you standing on a box?

Steve

Steve, actually it is a little too tall; I've learned that lowering the legs by 6" works great. It also opens flat which is what I used at the Racetrack.

Don

 

[neil]

Don,

3x seems to be a relative low magnification for a loupe. Do you find that magnification to be enough to judge critical focus?

My eyes may be getting old. I have to use at least 6x or I seem to be just moving the focus backwards and forwards and never hitting the critical focus.

Neil

 

[Don Libby]

Neil - fair question(s). I can only report on what work well for me. One thing I omitted to say was that I've been wearing tri-focal glasses for the better part of 10 years and they can at times in a huge PIA when doing close in focusing.

A couple things here - the groundglass appears to me to be better than the one I used to have several years ago. I can't do a side by side test however I believe this one is much brighter. I remember having to open the lens all the way in order to see and this one I don't have to do it.

The viewfinder/loupe - is much much much better than the flexible one I had from years before. The old one leaked light where it was attached and it generally sucked when you tried to move the loupe around. The new viewfinder/loupe has none of these failings which may account for the thoughts of a better groundglass viewing.

I tried this out for the first time on the beach at sunset at Pfeiffer and was able to see good enough for a couple captures; the second time I used it was in the bright light of Death Valley and had no problems or concerns. Bottom line here is this combination works for me and maybe you should contact your dealer for a demo.

The third aspect of this is the ability to protect your back now with a cover plate attached to the mounting plate. Without this cover I don't care how good the groundglass/loupe is it would still be lacking.

One last thought on the 3x. I used to do a bit of long range rifle shooting (500 to 1500 yards). I thought the higher the magnification the better but found 10x was the best. Here with the groundglass I'd like to see a variable power 3x5, just a thought....

Don

 

[Don Libby]

One more thought -

Anyone in or near Arizona who would like to see this first hand let me know as I'll share it with you either here in Tucson or if we meet somewhere else. I'll be in Monument Valley in April for full moon then June shooting in New Mexico and Wyoming (Taos, Devils' Tower, Jackson Hole).

Ken and I are in the early stages of a short shooting spree in Napa Valley this Fall.

I do plan on buying this from Dave just as soon as I can get a hold of him.

Don

 

[torger]

If the loupe is used for focusing (and not just framing or general inspection) my experience is that higher magnification indeed is better. The magnification should be so high that one clearly sees the ground glass grain, only then one will maximize the use of the ground glass. One might think that once grain is barely seen there is no further gain to magnify more, but my experience is that it does become more easy to see nuances in the contrast of the image that is formed on the grain with further magnification.

On my Linhof Techno I use a 20x jewellery loupe (which I've made a custom base for to match the ground glass+fresnel thickness) for critical focusing. The field of view is tiny, I only see a small spot with it but that's enough for focusing, and for overview I use a low magnification loupe or more often (=almost always) no loupe at all.

I've done some formal testing, and with a 6x-10x loupe I make occassional focusing errors which I don't do with the 20x.

So to anyone using ground glass for focusing I would recommend to at least try a high quality 20x jewellery loupe, these cost only about $40.

 

[Don Libby]

Okay - paid for the groundglass/loupe and thought I'd add one last series of photos showing the groundglass/loupe in place, open for close checking and a shot of the groundglass itself. This series was taken this afternoon in the shade of our front courtyard.

Don

 

[neil]

Thanks, threads like this are very helpful to us beginners.

I still have not perfected ground glass focus technique. I make focus errors often. There seems to be a small band of in focus. The focus has to be on the near part of the band or I miss the image focus.

Is there a fresnel screen behind the ground glass screen? I cannot quite make it out from the picture.

Interesting there are hinges which means you can move the loupe out of the way and put a higher magnification loupe there. This device is well thought out.

Also Interesting idea to try a very high magnification loupe. I searched I see that silvestri is bringing out a 12 times loupe which can get into the corners. Will try this when available.

Neil

 

[jlm]

if you go too high in mag, the glass grain becomes a problem

 

[kdphotography]

The Cambo loupe is 3x; Schneider makes a 6x which might work when needed...

 

[Don Libby]

Just finished re-reading what I wrote so far and see I omitted one item (the cause was too much cold medicine or maybe not enough)....

The second image sort of shows a knob right in front of the eye piece. That's the diopter adjustment. The first thing I did was adjust the loupe to suite my glasses which is the reason so far I haven't had a problem with focus issues.

You could on the other hand swing the loupe out of the way and after spending an extra $100 or so use a 6x or more loupe to double check focus; remembering there's a point of diminishing returns on the power as you'll soon be getting the too much of the actual groundglasss.

Don

The older I get the harder it is to shake a damn cold....

 

[torger]

I disagree with the assumption that if you see grain you have reached the point of diminishing returns. I think the very reason that ground glass has got so poor reputation concerning focus precision is that people use too low magnification on the loupes. The secret of good focusing precision on the ground glass is high magnification and being concentrated every time to do the absolute best you can.

I have done some formal testing, look at the "focus precision test" section towards the end of this review:
Review: Linhof Techno

I did improve my focusing precision when going from a 10x to 20x loupe. The thing is that with larger magnification it is easier to see the small nuances in contrast-difference in the formed image, even if you see the grain.

The attached image shows a good simulation of what I see through my 20x loupe on the Linhof Techno standard ground glass (it's based on an actual macro photo of the ground glass). I e you see grain, but not too bad, and the gain is that you without effort can see the fine nuances in contrast of the image so it is easier to nail the focus.

However, if you do experience that your focusing precision is good enough with whatever loupe you use, then it's fine of course. There is a degree of skill and eyesight to it too which makes the choice personal.

 

[neil]

For the diopter adjustment how do you know that you have adjusted to match your eyesight. This seems to be absolutely critical to get right. Do you adjust with the unit detached from camera and until the grain on ground glass looks sharp.

I agree that being able to add a cover to the digital back while its attached to mounting frame is very important. Could be the deciding factor to buy this camera. (I am wondering if Linhif techno might also have a cover. )

I noticed Linhif studio started to sell a 12 x silvestri loupe with special 1cm square bottom which can slide into corners. Looks interesting.

Neil

 

[alajuela]

Hi Don
I got the Ground Glass from Dave at CI - used it over the weekend. Like it. Especially good when very bright out and Live View is difficult.
Have you tried this tripod apron. I think it is very good for the tech, when you need 3 hands to change the back or the lens.
Manfrotto 166 Tripod Utility Apron166 B&H Photo Video

I used a cheap one I got in China, but ordered this one as it seems more study and we don't want any mistakes

Best

Phil

 

[tjv]

I agree with Torger in that I went from a 8x to 12x magnification loupe and found a marked difference in accuracy. The new 12x Loupe from Linhof Studio is very, very good and has a small, square base to get right into the corners. Plus there's very low distortion.