paul_ong1

March 15, 2011

Q G de B and Neil,

Thanks for the information. I am still trying to get my head around the answers. I do realize that many film lens have problems when use for digital capture, particularly at the edge with wide angle lenses. The main problem frequently discussed is CA.

Here is what I think I know so far. The RB67 C 50mm is ok at the edge when I focus it specifically for the location, but when the center is in focus, then the edge is soft. I attribute this to lens curvature.

What I don't understand why film should be less affect since there is more of a chance that some part of the emulsion will fall outside the depth of focus.

One additional factor may be that film is not flat. In fact, Zeiss reports that "film curvature can be a major influence as a source of unsharpness." (Source: http://www.dantestella.com/zeiss/rollfilm.html.) Is the C 50mm designed to compensation for this, thus purposefully adding in some offsetting field curvature? Or, allowing the floating lens to play that role. The cited source suggests that Zeiss uses aberration correction to address the film curvature.

Anyway, does anyone have any scanned film using the C 50mm to compare the center and edge? It would be good if we can see some empirical examples.

March 11, 2011

Hi,

Thanks for pointing out that the digital sensor is the source of some of the problems. I think it accounts for the chromatic aberration at the edge, which is a common problem when using legacy film lenses with a digital back.I believe that the type of CA in the example is lateral and can be corrected by Photoshop.

Is my interpretation of the CA problem sound right?

The more I think about it, the more I believe that I am experience field curvature. As I noted, the edge is soft in the panorama image, that is when I concentrated on focusing at the center without paying much attention to the edge, particularly without carefully setting the floating lens. The perspective control photographs shows me that the lens is capable of being relatively sharp at the edge by carefully focusing.

Why is film less susceptible to field curvature?

In a previous thread, it was suggested that I try to reach a compromise by going with a smaller aperture (f/11), which introduces some diffraction in the center but less softness at the edge. I will give that a try the next time I am in the field.

I guess the final question that I still have in mind is what are people's experience with the floating lens when focusing at distant objects. Some say that it does not matter much.

March 10, 2011

Sorry, was in a hurry to get out of the house and catch the van pool. Below are the links to the descriptions and photos (large): For comparison of f/4.5 and f/8 at the center: http://www.flickr.com/photos/9476880@N02/5514494333/ http://farm6.static.flickr.com/5052/5514494333_c3ecdeb295_o.jpg For the panorama with the soft edge: /> http://farm6.static.flickr.com/5217/5515058610_f32df05aa8_o.jpg The edge is not bad if one works with the floating front element, and this can be seen in the shots illustrating perspective control (description on the photo page) /> http://farm6.static.flickr.com/5254/5514486361_9526e3bf61_o.jpg However, the edge does suffer from chromatic aberration, as can be seen in the another set of shots illustrating perspective control (but satellite dishes on top of the buildings are fairly sharp): /> http://farm6.static.flickr.com/5257/5514487101_a3ea7e065f_o.jpg

All shot on tripod. Captured digitally so no scanning.

March 10, 2011

Hi,

I recently got a Mamiya RB67 C 50mm lens, and last weekend I used it on my Mamiya-Toyo-Sony hybrid camera. The center is relatively sharp (usable is a good term), but the performance at the edge is mixed. In a panorama photo, the edge is definitely soft, but when I did my perspective control photos, the convergence-corrected photos taken at the edge of the image circle are fairly sharp (although suffer from chromatic aberration).

I think I got these result because I was not paying as much attention to the floating lens in the panorama photo but was much more careful with the PC shots. Some had mentioned that for long distances, adjusting the floating lens has little or no effect. But, I have gotten the mixed results.

I will go out again to experiment with the focusing when I have time, but does anyone have any advice or suggestion about how to get the most out of the lens?

You can see the photos discussed above at

http://www.flickr.com/photos/9476880@N02/

You might want to access the original size to better look at the sharpness.

Thanks.

March 9, 2011

Kent, yes, it is should relatively easy to attach the D300 onto the Shen Hao. You can do that with the product you listed. There are cheaper versions on ebay, but they do not have shift movements. If your intent is perspective control, than shifting the front standard may be sufficient. Be sure that the D300's focal plane is aligned with the lens when there is no intended technical movement. I have notice that even a slight misalignment in the DSLR adapter throws off the focus plane. I use shims between the adapter and lens board to make fine alignments.

If you want a really inexpensive option and have a workshop, then you can make your own adapter. I went through three versions for my Toyo. First with some PVC pipes, which I like because it allows for easy rotation of any angle. Second uses a reverse macro mount with with two short extension tubes. Because of the pentaprism housing and hand grip, you will need to make sure that there is enough space between the adapter board and the camera. The positive thing about this approach is that the camera is well secured, although can only be rotated in 90 degree increments. The third and last iteration is with the Sony NEX. Using a Nikon DSLR limits room for technical movement because of the long flange-to-focal-plane distance and the additional distance to clear the DSLR. It is possible to get the NEX sensor really close to the adapter, leaving more room for technical movement. I have the NEX 5, and you can get even closer with the NEX 3. Plus, live-view focusing is a real plus.

Because your sensor will be 60+ cm behind the mounting board, you will have problems using shorter LF lenses. When using the Nikon DSLR adapter, I can use my 90mm Schneider, but extremely limited camera movement. Using MF retro-focus lenses solves this problem, and the Mamiya RB67 has one of the longest register distance. I have two approaches to mounting Mamiya lenses. The first is to strip off the lens mount and external barrels, leaving only the lens cells and aperture housing, which I then mount on a custom made lens board. This really reduces the weight, but I only do this with broken lenses. The second approach is a customized lens board with a Mamiya lens mount taken from a broken RB67. This allows me to mount intact Mamiya lenses, but that is a heavy configuration.

I should note and acknowledge that I found many of the basic ideas on the web, which is a great place to share information and knowledge. Many of the refinements are new. I have documented some of my iterations of the LF-MF-digital hybrid, but unfortunately not every change, particularly the middle stages. You can see my initial effort and current effort at:

http://www.flickr.com/photos/9476880@N02/sets/72157621949266496/

Good luck, and look forward to seeing your results.

March 9, 2011

Joseph, thanks for the tip on the 6x9 Shen Hao. I will do some investigation.

Steve and Ellis, thanks for the info, and never knew about Canham. Looks interesting, but my goal is to move to a smaller than 4x5 platform.

Drew, will have to find a copy View Camera Magazine. Will be interested in reading about their approach, but for this project, my preference is to not do much work in terms of adding movements to a camera. I will focus on an adapter for the digital camera and modified lens board for different lenses. Agree with both you and Keven, so I have started checking things out.

Bob and David, the more I learn about the Linhof, the more I crave it, but my wife would kill me.

David, my main intent is to have more portability than my current Toyo-Mamiya-Sony hybrid. I use that when I need full movements, but it is really hard to setup far from my car. Hence, my search for a smaller and lighter body. I have the 2x3 Century and Crown Graphic on my list.

March 8, 2011

Frank, the smaller Graphics is on my list. Thanks.

March 8, 2011

Kevin,

Ideally, cheap and good, or at least the best I can do within my intended budget. Know that is hard, but I have been fairly luck with my 4x5 for previous projects. Toyo 45G, Cambo SCX and Horseman (not sure which model, but the one just before LE), each around $200 or less, and ended up with the Toyo because it came with extras. Not the absolute best but certainly more than sufficient for me. I just have to take my time and search ebay and craigslist over a couple of months. The advice helps me zero in on a set of possible options to search rather than randomly looking. Always willing to learn from others.

Now, to your specific question. I am willing to spend up to $250. Because of what I am doing, I am willing to purchase broken or "as is" camera, so long as it has the basic functions I need for the project.

March 8, 2011

Jenny,

Thanks for the advice. Had a look at the Technika, and impressive. Unfortunately the price at ebay for a used one is more than I would like to pay. I will, however, leave it on my list of search items.Will spend the next couple of months checking ebay and craigslist for possibilities.

For you and others, are there any possible cameras that fit my needs from the traditional MF makers? Hasselblad has the FlexBody CP, but that is way beyond my budget. The other option is a macro bellows with technical movements. Nikon has such a device, but I want something that I can mount and use MF lenses. Any suggestions.

Perhaps a picture of my current project will help people understand my goals. I have a Sony NEX on a Toyo 45G body using Mamiya RB67 lenses. I want to find a smaller, lighter alternative to the Toyo but still have technical movements.

Thanks.

March 8, 2011

David, thank you very much. Your first post really got me started by searching for Crown Graphic, which then led me to a number of other possibilities. Also, you are right about the project part. Would like to keep cost down. For my last project using a 4x5, I started with the Toyo 45G, then bought a Cambo SCX, and finally a Horseman LE. I eventually went back to the Toyo. Good thing that I was able to resell what I did not need. Hopefully, I will be wiser in selecting a camera for the new project.

Kevin, good suggestion to look at the best. This will help me evaluate the various alternatives in terms of what features are present or missing. I am a big fan of Linhof, although never owned one. I did own a Cambo briefly and really appreciate the fine mechanical details. I am flexible in terms of make and country of origin. Will probably take me a couple of months before landing a camera.

Friedemann, thanks for useful information. The Plaubel Peco Junior looks like a beauty, and I am open to both a folding and smaller rail, with the operative word being smaller (and lighter). I have been using my current rig, but it is really hard to take into the field.

March 7, 2011

Hi,

I am looking for a smallish, light-weight technical view camera for a future project. I have completed a project where I have added a digital camera to the back of a Toyo 45G using Mamiya RB67 lenses. I have done this to learn technical control. The system works well, but it is large, cumbersome and heavy. (See link below if interested in seeing the setup.)

So, I am now looking to do something similar with a field camera. One possibility is the Horseman VH-R, a medium-format camera that has technical movements, removable back, and no internal mirror mechanism. However, I read on another forum that there may be alternatives to the VH-R.

I am starting to do some of my own search, but any assistance would be appreciated. Does anyone have any suggestions?

Thanks.

March 7, 2011

Hi,

A post in another forum introduced me to the Horseman VH-R MF camera. What I really like about that camera is the technical movements, removable back, and the LACK of a mirror mechanism. This is ideal for a future project I have in mind.

So, my question is "are there other MF cameras like the Horseman VH-R"? Again, I am looking for something with technical movements (tilt/swing and rise/shift), removable back and no internal mirror.

Thanks.

March 6, 2011

Maris,

Thank you very much. Very useful information. I did have some time yesterday to try out the 50mm C lens mounted on a Toyo 45G and a Sony NEX 5 to capture images. I worked around f/8, and was able to take shots across the entire image circle. My initial impressions are that at this aperture size the center is sharp but the edges are very soft and suffer from noticeable CA. A quick comparison to previous shots indicates that the 90mm KL is sharper across its image circle and less CA, but that was shot with a different digital camera (Nikon D70). I will have to play with higher f-stop values and the floating element on the 50mm C, but your advice is a very good starting point.

Kevin,

Hope to post some of my initial shots with the 50mm C next weekend. I want to go back out again today if I can find some time. For now, you can see what the rig looks like at:

I am happier with this configuration than with my earlier efforts. Must say that live-view focusing is a major plus for this type of work.

March 5, 2011

Kevin,

Thanks for the comment. My goal is to create a 24mmx72mm image using the Mamiya RB67 lens on the Toyo 4x5. My understanding ins that the C 50mm is good for 6x9. I have done something similar with a Mamiya RB67 KL 90mm, which turned out to be acceptable. You can see that image (very large) at:

Hope to go out later today to test the C 50mm, which I hope will focus fine at infinity (just like the 90mm is able to do on my rig).

March 4, 2011

Christoph, Thanks. It is mainly an inexpensive device for me to learn technical controls. I have new configuration, replacing the Nikon D70 with a Sony NEX 5, which has live-view focusing with zoom. I am planning to do some panoramas because I can move the back standard without moving the lens. Here is a link to the rig: http://www.flickr.com/photos/9476880@N02/sets/72157621949266496/

March 4, 2011

Hi, I just got a RB67 C 50mm, which I will use on my modified Toyo 4x5 with a ASP-C digital camera. I searched the site and read a few threads but could not find an answer. When I have time, I will do some systematic comparison of various f-stops. But for now, I have very limited time, and I just want to go out and take some shots. So, from your experience, what is the sharpest f-stop for this lens? Thanks.

February 24, 2011

Thanks everyone for the very useful info. Now I know why the 50mm produces such poor images when used as the rear lens. I will try attaching my enlarger lenses (Schneider Componon-S 50mm and 80mm) on my Nikon 105mm and 200mm (AIS). Became intrigued by the 10x Nikon CF N Plan Achro microscope objective lens, so went to ebay to take a look. No cheap ones now, but will keep looking.

February 24, 2011

Juri,

What I see on my adapter is 43mm but don't know the thread pitch. You should be able to get the exact dimensions from the Schneider web site. Look for their PDF product booklet. I got a 43mm to 52mm step up ring from ebay, fairly inexpensive if I recall correctly. You then can use that on any reverse 52mm adapter, again from ebay. You may need additional adapters, depending on your tube or bellows. I have a Asahi bellows, so I used other adapters to get to the 52mm. I also reverse the aperture control handle to make it stick out the back. You might consider making a lens hood for the back lens barrel of the enlarger lens with black construction paper. Helps cut any flare.

An external monitor is useful because LV stays on, and the view is larger. The camera's LCD screen turns off after a few seconds to save power. You don't have to buy a Marshall monitor, which is a specialized device mainly for video. Any HDMI capable monitor would work.

I hear that Sony is discontinuing the NEX 3, so you might soon be able to pick up one at a good price.

I have more information on other macro setups at the site below. Making specialized devices is a hobby.

http://www.flickr.com/photos/9476880@N02/sets/72157625831487247/

Have fun.

February 23, 2011

Hi,

Been concentrating on macro photography recently. In a previous post regarding effective f-stop, I asked a followup question that seem to have gotten lost. So, here it is again.

What is your favorite two Nikon lenses when stacking?

I have tried my 24mm on the 50mm and it was terrible. I tried the 50mm on the 105mm and that is much better. I have to wait for some step-up and step-down adapters to try other combinations. So for now, hopefully I can get some insights and suggestions from you.

Thank you.

February 23, 2011

Hi,

Interesting thread. I have been using the 80mm Schneider, reverse mounted. Not sure what you consider to be sharp, but I am relatively happy with the results. I normally shoot Nikon, but I have switched to the Sony NEX for tabletop macros. No mirror vibration as someone else mentioned, and LV focusing is fantastic. I try to keep the lens wide open or only one stop down because at high magnification, the effective f-stop is quite small.

You can see some of the macro shots with the 80mm at the following web site. Would be interested to hear if you think that they are sharp or not. Perhaps I am too easily satisfied.

http://www.flickr.com/photos/9476880@N02/sets/72157625808528681/

February 12, 2011

Joseph and Bjorn, many thanks for your explanations. I have learned much, and I will try to do some of my own testing.

Wonder if you can give me some starting point regarding some of your preferred combination of stacked lenses. I try not to spend too much time "reinventing the wheel." (Bjorn, I have used your incredibly useful web site as a guide to help me select and buy lenses over the last few years.)

February 11, 2011

Hi,

Again, thank you for the information and discussion. There is certainly lots to digest. For example, I do accept that it is possible to have an entrance pupil larger than the front lens. However, I wonder about the light gathering ability of two lenses of the same focal length and identical maximizing entrance pupil but (significantly) different front lens element sizes. Would the light gathering ability be identical? Won't the one with the larger front lens have more potential? I just do not know enough about lens design.

But back to my main concern, which is about where to set the nominal f-stop to avoid diffraction. Say that I am using a reversed lens (nominally a f/2.8) that after accounting for magnification (of say 2x), the effective maximum effective f-stop is about f/8. Does that mean that I will start experiencing diffraction if I close it down a step or two? What if the optimal (sharpest) setting for that lens is a nominal f/5.6? Is there, then, a trade off between moving to the "sweet" stop and introducing diffraction?

Thanks in advance.

(Edit, additional comments). I realized that the formula I used to calculate an effective f-stop is nominal f-stop times (1+magnification) squared. I notice that some people use nominal f-stop times (1+magnification). Not sure which is correct, but the concern about diffraction remains the same. If the effective f-stop is f/8, does closing the lens down introduce difrraction?

February 11, 2011

Thanks everyone. I think I am starting to understand in terms of light equivalent. Good for setting exposure, but not a major issue with behind-the-lens metering.

I guess I should have stated that my main interest in knowing the f-stop is avoiding diffraction, and also aiming for optimal aperture opening for sharpness. Of course, I could test, but too many lens options and magnifications with extension tube(s) or bellows. So a general rule of thumb is helpful.

So, when I estimate the equivalent f-stop to account for magnification and other factors (e.g., light lost from reversing a lens not designed for that), how is that calculated f-stop related to the general rule of avoiding small settings (f/11 and smaller) or to what is consider the optimal f-stop (generally one or two stops down from wide open)?

I am asking because it seems like diffraction sets in earlier if I just look at the nominal f-stop setting.

February 11, 2011

Hi, I am trying to figure out the change in effective or initial f-stop when reversing a lens for macro photography. For both my Nikon 28mm f/2.8 and Nikon 50mm f/1.4, the rear element is smaller than the front element, so I assume that there is less light gathering ability. I know that the f-stop needs to be estimated taking into account the magnification. What I want to know is what is the initial max f-stop value on a reversed lens. Thanks.

February 5, 2011

Bjorn, thanks. Sorry, I missed your post when I was writing my response. I will give your suggestion a try.

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