Could use some help diagnosing this problem

[bobwysiwyg]

Ignoring the manifest problems with this image (most of which I have figured out) there is one that has me stumped as to cause and future avoidance. I've circled the issue(s) and they seem to me to be latent images of the iris?? I was shooting TMax 100 with a 4x5 Shen Hao with a 90mm Super Angulon (new to me so wanted to try it) probably at f45 as I was trying for a very slow shutter speed. The sun was to my left and ever so slightly forward of the edge of the lens. Given the shape of the front element I was sure some light would strike the lens surface so I, at first, tried two Cokin lens shade modules but found it intruded on the image so I removed one and double checked that it was still shading the lens surface. Any thoughts or suggestions would be appreciated.

[Bob Salomon]

Internal flare bouncing off the diaphram. At f45 you were also grossly into diffraction with that lens. Use a quality, strong ND to get to a long exposure time. Heliiopn makes them up to 10 stops (4.0 density).
A proper compendium, not a lens hood, or a gobo or hat or black matte board would have prevented the flare. A multi coated version of the lens would have also helped.

[Joanna Carter]

Bob's right, get a proper compendium shade, or use sheets of black card. The snap-together lens hoods can allow light in between the sections if you are not careful.

I use a Lee hood with filter slots on the back. Even with such a high quality hood, I throw a lightweight black cloth over the filter holders, as light can catch on the edge of the filters and get in that way.

[bobwysiwyg]

Thanks all.

[jeroldharter]

I suspect that if you took the advice above, after seeing your results without the advice, that you would have skipped taking this picture. The compendium hoods are great, but with a 90mm lens you are limited to how much you can shield the lens and the flare is difficult to control. Sometimes moving the camera to a slightly different angle and using the maximum lens shading for the lens can solve the problem.

Sometimes switching to a longer focal length lens (which of course changes the image but perhaps for the better) will allow for more lens shading and allow you to get the shot. I mention that because sometimes people anticipate cropping in the darkroom but could do so in the camera instead with better results.

[Bob Salomon]

I suspect that if you took the advice above, after seeing your results without the advice, that you would have skipped taking this picture. The compendium hoods are great, but with a 90mm lens you are limited to how much you can shield the lens and the flare is difficult to control. Sometimes moving the camera to a slightly different angle and using the maximum lens shading for the lens can solve the problem.

Sometimes switching to a longer focal length lens (which of course changes the image but perhaps for the better) will allow for more lens shading and allow you to get the shot. I mention that because sometimes people anticipate cropping in the darkroom but could do so in the camera instead with better results.

Not true, a properly designed compendium can effectviely shield any lens. When it is properly adjusted it cuts out all stray light that is not directly imaging the scene. That is why good compendiums are adjustable for length as well as position and many have cropping masks to ensure that all stray light is blocked. What it can't control is a bright spectral coming directly into the lens. That is when you want good MC on the lens and any filters you are using.

[mandoman7]

Not true, a properly designed compendium can effectviely shield any lens. When it is properly adjusted it cuts out all stray light that is not directly imaging the scene. That is why good compendiums are adjustable for length as well as position and many have cropping masks to ensure that all stray light is blocked. What it can't control is a bright spectral coming directly into the lens. That is when you want good MC on the lens and any filters you are using.

This raises an interesting question: Just how much value is there to using a lens shade with significantly wide-angle lenses? The idea of limiting extraneous light makes sense when you're working with a lens that is selecting a small portion of what's in front of you. But when the lens is encompassing 75% of what's in front of you, how much difference does it make to exclude the remaining 25%? Particularly when there's a good chance of vignetting.

I have a 75mm for my 4x5 that will vignette when you put nearly anything in front and move slightly off center. It took a lot of wasted film for me to get to where I could let go of the shading priorities that one internalizes after reading a lot of articles. One begins to wonder just how productive the people are who write the articles and teach the courses.

For practical purposes, working in the field, I've found it more useful to develop a strong sense of where the light sources are and what their relationships are with each other and the subject. If you've shot with white backgrounds in a studio you know that flaring isn't something that's limited to light coming from outside the image area. The whole business of retaining contrast involves learning the characteristics (coatings) of your lenses and how the various light angles and specularity will affect the image. Its not just about adding a piece of equipment.

I wouldn't go into the field without my shade, and have found it to be a life saver with longer lenses in particular, as I love to shoot into the light. But with wides it seems to me to be most important to have multi coating and to check the front of the lens to see if any direct sunlight is getting in there.

[GPS]

Not true, a properly designed compendium can effectviely shield any lens. When it is properly adjusted it cuts out all stray light that is not directly imaging the scene. That is why good compendiums are adjustable for length as well as position and many have cropping masks to ensure that all stray light is blocked. What it can't control is a bright spectral coming directly into the lens. That is when you want good MC on the lens and any filters you are using.

Not true, unfortunately. No compendium and no lens shade can cut out all the stray light coming on the front lens surface. For that you would theoretically need a lens hood stretching right to the offending light source (and shading it) with the corresponding increase of its overall size. But a good compendium lens shade can cut out a lot of the offending light. The longer it is (with the corresponding increase in its dimension) the better its efficiency is as it makes the angle where the offending light can enter smaller and smaller (but never equal to zero).

[bobwysiwyg]

Thanks again all for the additional follow-on. Ordinarily, I wouldn't have used the 90mm, but wanted to try it. Guess I picked the wrong time/scene. But, on the other hand, it taught me quite a bit combined with this feedback. The 90mm is one of four lenses I have, and I have to say, none of them are modern or technically wonderful, but they are what they are and what I can afford at the moment. I will file away the feedback and pointers and pursue finding a better shade, or compendium. I know there is one for the Shen Hao specifically, but I have been stymied by the filter slot size which is much larger than those filters that I have and seemingly no one makes anything that size so I have some things to contemplate.

[Bob Salomon]

There is a big difference between a compendium for a view camera and a lens hood. A proper compendium can be adjusted for any movements done by the camera as well as adjust for length to accommodate all focal lengths and also adjust for the opening of the compendium to block extraneous light. Compendiums attach to the front standard, not the lens. A lens hood may or maynot be somewhat adjustable and attach directly to the lens. These can easily vignette with short lenses or back movements and are generally ineffective with a long lens if they are wide enogh for a short lens and will vignette with a short lens if they are made for a longer lens.