Wide lenses, huge shifts, and Fresnels

[Ed Richards]

This is not a question for landscape photographers.:-) I am talking about when the light from the lens is really off axis, such as when you have your 90mm shifted 2 inches, or your 110/120 shifted 4 inches on 4x5. This seems to defeat wide Fresnels, which are otherwise great for head on shots with wide lenses. Do things like Maxwell screens help in this situtation? Is there a Maxwell screen users out there who uses extreme wide angle movements?

[Bjorn Nilsson]

The absolutely best solution for wide angle (which is the same as "steep angle") is to use a specially designed fresnel which is stronger than the universal fresnel. I don't use e.g. the Super Angulon 47XL, but even without any shift, the corners should suffer from the same problems which you describe.

//Björn

[Nathan Potter]

The only way I handle extreme off axis ray situations is to use a tilting loupe. Even that is a poor solution since the best focus on the GG occurs along a single line within the depth of focus of the loupe. But still it's the best solution I've found when you need to go beyond the widest angle fresnel. I don't think a 4 inch shift and a corner view will be handled by the widest Maxwell screen. My 110 SSXL with a 4 inch shift on 4X5 is a near impossible situation due to light falloff and less than stellar sharpness at the corners.

Nate Potter, Austin TX.

[jb7]

Nathan is right-
a tilting loupe, or at least, a tilted one, is the only way I can do it with 47xl, and the 72xl with movements-
and that's on a standard Arca fresnel-

[VictoriaPerelet]

On bright sunny day outside it's not big problem - you can deal with it.

In studio or dim lighted places, another story:

On Sinar(P2/F2) I use bino viewer (which has mirror angle control adjustement) + standard fresnel. It won't cover whole image at once with 72mmXL + center filter or Nikkor 65mm with movements, but at any given angle I can see part of image and varying angle covers whole image.

In studio sometimes I also use MF digital back for focusing & exposure (and then load film holder:))

I have Linhof TK for field, and on that thing using wides is royal pain cause there's no bino viewer, neither can it take sliding digital back holders. Tilting loupe & luck is all that you can count on. Overall it's up to your camera/accessories design and time you have for framing & focusing. I do quite a lot of portraiture and time is limited.

[Ed Richards]

Thanks for info on tilting loupes! I have been thinking about one, but did not want to spend the money without a report that they helped.

Bjorn - While the WA fresnels work better head on, they actually make things worse off axis. I had to pull mine on my Ebony because I just could not see what I was doing way off axis. I think they end up being more directional, which means when you get them out of their planned orientation, they do not help.

[rdenney]

With my standard Maxwell screen, I can see into the corners of my 47mm Super Angulon using a straight-on loupe. That lens needs a dark cloth and maybe even a little time under it to let the eyes open up a bit, if you want to see into the corners.

That lens is more limiting in terms of viewing than longer lenses with more extreme movements. (My 47 is not an XL and I use it for 6x12, where it is at its limits.)

I am able to compose a 65mm f/5.6 Super Angulon on 4x5 easily with the Maxwell screen, right into the corners of its coverage.

Rick "who'll experiment with a 90/5.6 Super Angulon with huge shifts and report back" Denney

[Ed Richards]

Hey Rick! Let us know about the 90mm. I have no trouble with my 65mm Nikon, but then all I can get is about 1/4 shift and it is f4 lens.:-)

[rdenney]

Okay, I just played a little bit with the 90/5.6 Super Angulon. Eyballing it, I'd say I have three inches of shift, right to the edges of coverage. Using a tilted loupe, I could easily focus on interior light sources in rather dark conditions, right at the edge of coverage, with no dark cloth. I measured a lamp that was in the view with my Pentax Spotmeter, and it was EV 5-1/3. With the shift removed and the camera pointed right at the lamp, it measured about 7-1/2. The lamp itself measured 15. The lens was wide open at f/5.6, which, of course, exacerbates the off-axis falloff. I would have needed a laser pointer to focus it at f/22.

Looking at the Maxwell screen straight on, the brightness of the lamp (shifted to the edge of coverage) dropped three or four stops compared to viewing it with a tilted loupe.

So, the Maxwell screen is quite usable at the extreme of the 90, but a tilting loupe is still necessary.

Rick "whose loupe is too bulky" Denney

[Struan Gray]

If you are doing a lot of work with a roughly constant front movement (for example, taking architecture shots with a roughly constant large amount of front rise) you can cut an off-centre section from a larger fresnel.

Say you are working in 4x5 with two inches of front rise. Mentally imagine you have an 8x10 back on the camera with some kind of reducer that puts the 4x5 film in the right place. What you want is to cut out the section of an 8x10 Fresnel that corresponds to where your 4x5 film is.

Don't get hung up on the 8x10 size: the real problem is that the optic axis of your lens is not aligned with the optic axis of your Fresnel. Cutting an outer section of a larger Fresnel lets you align the axes again. The only problem is knowing which section to cut, and that's why you need a roughly constant set of movements (unless you want to carry a whole bunch of Fresnels for different cases).

Of course, good large Fresnels are expensive, but a whole page magnifier gives enough offset for 4x5 to provide a useful composing tool - just pop it out when you want to fine-focus.

[Doremus Scudder]

Tilting loupe for me equals turning my 8x loupe around and viewing through the barrel end. Sure, you have to make sure you hold the loupe at precisely the right distance from the ground glass, but you can position it at any angle to the ground glass in order to get maximum illumination. I now use the loupe this way more than the intended way, i.e., with the barrel flat against the ground glass.

I find that tilting the loupe to the proper angle helps with regular ground glass as well as with Fresnel lenses to get the brightest image to focus with.

Best,

Doremus Scudder

[Ed Richards]

Rick,

Focusing on the light? If I had lights to focus on, I could use my reading glasses.:-)(Seriously, I will stick a light into the scene when I can, but that does not work with big spaces.)

Doremus,

Good idea, but my loupe does not work very well that way - is one of the those long ones, like a little telescope. I should try my light table loupe that way.

[Mike1234]

Rick mentioned using a laser pointer which would substitute as an included light source but this will only work on fairly near objects and I don't know how much help it would be in bright daylight. I don't have the practical experience with that.

I had considered using one of those tiny crypton bulb units with a flexible shaft to place in the photo but that's usually impractical. A laser pointer is a much better and more refined idea.

Speaking of using laser pointers to provide a bright spot for focusing: Has anyone used a flexible arm mounted to the camera or tripod to hold it in place to free your hands during focusing? If so, what did you use?

[jb7]

I've started wearing a jewelers loupe on a lanyard-
the one you grip in your eye socket-
I bought a set to use for something else, but decided to give them a go for focusing-

It takes a bit of getting used to,
and makes you look a bit eccentric-
as if using a lf camera wasn't comical enough...

[Mike1234]

Regarding loupes: I'm going to try a really powerful set of reading glass in lieu of a loupe. Reading glasses up to +6 are easy to find on-line... and they're cheap. I'm thinking it will be easier to see just by moving my head around and it frees up my hand to make adjustments. If +6 isn't enough and I can't find +10 then I'll try jewelers' goggles.

[BetterSense]

Speaking of using laser pointers to provide a bright spot for focusing: Has anyone used a flexible arm mounted to the camera or tripod to hold it in place to free your hands during focusing? If so, what did you use?

I have a keychain-size laser pointer taped to the inside bed of my Speed Graphic. It makes an extremely handy focusing aid. It's very easy to put the spot on the subject and rack the focus until it's a small spot. Doing this I can shoot quickly when it is too dark to use a rangefinder well. It even helps in achieving fine focus for indoor still lifes and the like...putting the dot on the point of desired focus and then minimizing it with focus doesn't even require me to get out the loupe. It's much easier than straining trying to see the focus snap in on a smooth surface or convenient edge that may not be exactly at the desired focus point.

[pocketfulladoubles]

There is a special purpose Maxwell Wide-angle fresnel, but I think it pushes a grand and is only meant for very wide angle lenses. Never seen one. Don't know much about it, perhaps worth a call to Bill.

[Mike1234]

$1000?? :confused: :eek:

I don't think so... :rolleyes: :(

[pocketfulladoubles]

$1000?? :confused: :eek:

I don't think so... :rolleyes: :(

Exactly, especially when it won't work with normal to long lenses. But, I suppose if you're a pro getting paid to take such shots, then it's all relative.

[Mike1234]

Exactly, especially when it won't work with normal to long lenses. But, I suppose if you're a pro getting paid to take such shots, then it's all relative.

None of my relatives are worth $1000. ;)

[Ed Richards]

Might be cheaper to get an assistant with a flashlight.

[rdenney]

Rick,

Focusing on the light? If I had lights to focus on, I could use my reading glasses.:-)(Seriously, I will stick a light into the scene when I can, but that does not work with big spaces.)

I'll have to test again when I can have some daylight to work with. I was in my loft office last night, which at night is like a cave. It's fine for working on the computer, and I have task lights for other stuff, but the main general lighting comes from a skylight that seems to be mostly dark this time of year, especially when I'm at home.

That's why I made measurements. With the 90 at its limits, and at f/5.6, the scene was about 10 EV less on the screen than the actual thing being viewed. It was several EV brighter when viewed straight on with that lens. Outdoors, with a dark cloth, everything would have been much easier to see. Many parts of my office measure under EV 3 directly--no focus screen is going to show much of that.

Rick "who just ordered a Silvestri 6x tilting loupe" Denney

[Ed Richards]

> Many parts of my office measure under EV 3 directly--no focus screen is going to show much of that.

Most of the church interiors I shoot are in the 3-5 EV range, and some of my Katrina and fort stuff was 3 EV or less. I could still see some, so the Ebony and Sinar screens were not doing too badly. I think Sinar has the best arrangment for a Fresnel - it clips on the back with a little frame. You can be in the field and just pop it out to see if the GG works better without it. I suppose you could even have a separate WA Fresnel and pop that in when you needed it.

[rdenney]

Most of the church interiors I shoot are in the 3-5 EV range, and some of my Katrina and fort stuff was 3 EV or less. I could still see some, so the Ebony and Sinar screens were not doing too badly. I think Sinar has the best arrangment for a Fresnel - it clips on the back with a little frame. You can be in the field and just pop it out to see if the GG works better without it. I suppose you could even have a separate WA Fresnel and pop that in when you needed it.

Well, if the Sinar Fresnel worked at all for you, then the Maxwell will work much better. I can't get the Sinar Fresnel to work at all at such shallow angles--it gives double images, displaced images, ghosting, and all manner of distortion. I went with the Maxwell screen because the Sinar Fresnel was basically unusable for 65 and 47mm lenses, even for 6x12.

I just played with it again, and was able to aim it at my computer monitors. From diagonally across the room, I was able to focus on the computer monitors with a tilted loupe at the extremes of the 90/5.6 Super Angulon. Even through the Maxwell screen at that shallow an angle, I could focus clearly on what was displayed on the screen, without a dark cloth.

In this case, I measured about a 6-stop difference between the subject and the image on the focus screen.

I don't think it would have been possible to see details at EV3 or less, though, without a laser pointer or some other aid. I can see the objects, but not well enough to focus on them. This is with a 3" shift and the camera tilted back at a severe angle to put the monitors and keyboard right at the edge of coverage. This does put the image where it is most advantageous with the Fresnel. The keyboard is about EV3, lit only by the glow of the monitors, and I can see it but not focus on it.

I can't compare it directly to the Sinar Fresnel because I don't have a standard ground glass in the frame.

Rick "whose laser pointer is, um, rather brighter than those in the stores" Denney

[shadowleaves]

This is not a question for landscape photographers.:-) I am talking about when the light from the lens is really off axis, such as when you have your 90mm shifted 2 inches, or your 110/120 shifted 4 inches on 4x5. This seems to defeat wide Fresnels, which are otherwise great for head on shots with wide lenses. Do things like Maxwell screens help in this situtation? Is there a Maxwell screen users out there who uses extreme wide angle movements?

Maxwell has a special wide-angle fresnel. ask him.

[Mike1234]

Doesn't that one cost something like $1000??

[Ed Richards]

I never had much trouble with the 65mm on 4x5 because there is not much room for movements. It could be a bigger problem with 6x12, no question. Tell me more about focusing on the laser pointer. How far away will that work before the pointer image is so small on the GG that you cannot tell when it is in focus?

[Robert Hughes]

Focusing with a laser pointer is just like focusing on any bright spot in your range of focus: find a "pretty good" focus, then rock the focus settings back & forth until you've found the center point between two equally out-of-focus settings. Interestingly, that's also how I tune a guitar, except I'm going for pitch...

[rdenney]

How far away will that work before the pointer image is so small on the GG that you cannot tell when it is in focus?

When I find that distance, I'll let you know.

Actually, I haven't yet tried it with the Maxwell screen, which I just installed a couple of months ago. I suppose I ought to experiment before depending on it.

Rick "who doesn't use it for really distant stuff" Denney

[Ed Richards]

With wide lenses, I suppose far away would never be more than about 200 feet. That would effectively be infinity.

[Ivan J. Eberle]

I have a heck of a time with focusing the corners of my GG with the Nikon 90mm SW f/8. Got to give the laser pointer suggestion a shot before I invest $300 in a Maxwell.

I'm most interested in finding one that has a locking "on" switch and compact enough to fit inside the body of my Super Graphic and my Meridians (might also use the Focuspot port of the Kalart on the 45CE).

Rick, are you using green lasers instead of the stationery store red ones?

[Ed Richards]

Ivan,

Unless size of the lens is very important, you could probably turn you f8 into an f4.5 Nikon 90mm for a lot less than 300, maybe even a trade with someone. The f4.5 is a LOT easier to focus, both because of the reduced DOF and more light.

[Brian Ellis]

One of the downsides of Fresnels is the need to keep your head centered. One of the Deardorff guys (actually I think it was a brother-in-law of one of the Deardorffs) wrote a little booklet about that and other problems inherent in Fresnels. I no longer have the booklet so I can't explain the reasons but I've certainly experienced the problem.

Maxwell screens do help in the situation you describe, at least mine did although I doubt that I ever shifted my 80mm lens that much. I move the tripod first before resorting to shifts in order to keep the lens and film centered as much as possible. But in normal use with the 80mm I saw virtually no light fall-off at all on the edges and corners, much better than the Fresnels that were OE on my Ebonys, Tachiharas, etc.

[rdenney]

Rick, are you using green lasers instead of the stationery store red ones?

Yes, I have a green one that is 50 milliwatts (maybe that's microwatts). It is bright enough to use for point out stars--it creates a sharp line through even slight atmospheric haze for hundreds of feet. I don't do that much photography in dark places, so I have only used it once or twice and don't have the experience to judge how far away it will work. Bought from some dubious internet source by my father who was tickled to find something to give me for my birthday that he knew I would not already have.

I can't conduct that experiment in my office. I have to go out into the real world, and it's cold!

Rick "a wuss" Denney

[jan staller]

This thread was interesting to me, but I wish to know if the Maxwell would be the preferred screen to replace my standard screen in an 8x10 Sinar. I have used it with a
250mm Fuji and a 165 Super Angulon. I can't see much outside of about a 6" circle with the 165 and have not used it much at all for that reason. I use a fresnel and Boscreen on my Cambo Wide DS 4x5, taking off the fresnel when using the 150mm, but using it for shorter lenses. I might consider the Boscreen for the 8x10 but worry about the wax melting, since it sits in the back seat of the car. I do location work. What is the best and brightest screen replacement? Is there such a product available as a tilting loupe? I haven't seen one. I use a Toyo. Thanks to all.

[rdenney]

This thread was interesting to me, but I wish to know if the Maxwell would be the preferred screen to replace my standard screen in an 8x10 Sinar. I have used it with a
250mm Fuji and a 165 Super Angulon. I can't see much outside of about a 6" circle with the 165 and have not used it much at all for that reason. I use a fresnel and Boscreen on my Cambo Wide DS 4x5, taking off the fresnel when using the 150mm, but using it for shorter lenses. I might consider the Boscreen for the 8x10 but worry about the wax melting, since it sits in the back seat of the car. I do location work. What is the best and brightest screen replacement? Is there such a product available as a tilting loupe? I haven't seen one. I use a Toyo. Thanks to all.

This thread will be relevant:

http://www.largeformatphotography.info/forum/showthread.php?t=52905

BosScreen is no longer in business, so you'd have to buy a used one.

On the subject of the tilting loupe, yes, there is a tilting 6x loupe made by Silvestri, and of quite good quality at first appearance. My only beef with it is the tilting base is metal, and I'm going to cover mine with something soft to avoid scratching my screen. A search on B&H Photo's website will turn up the Silvestri--that's who I bought mine from just a week or so ago.

Rick "noting that the Maxwell screen is still 100% usable with a 6x loupe" Denney

[Ed Richards]

Just got my Silverstri - does a much better job with rise than my straight on magnifier. What it needs is some adhesive backed pad for the plate, but something that would slide, not stick like rubber. Anyone have some teflon mailing labels?

[jan staller]

Just fitted an 11.0" X 11.0", 13.8" Focal Length Fresnel from Edmund to my Sinar F 8x10 which I am unfortunately using in the field. The difference is incredible when framing and focusing the 250mm Fuji, and my cursory look though the 165mm Super Angulon was also significant. Until that time, I could barely see anything more than the center of the ground glass. Some posts have mentioned that Fresnels are not good for wide angle, but the installation of the Fresnel makes all the difference. I am also using a cambo wide DS 4x5 using the Boscreen and the Fresnel. Typically I use the 72mm
Super Angulon and a center filter. With that I take off the filter to focus, and when using the 150mm Symmar, I take off the Fresnel to focus since it makes it easier to focus. The Fresnel for this camera is ancient and I have no idea of the focal length. Any comments or recommendations on either of these set ups? Specifically, I wonder if any improvement can be expected from a replacement screen for the Sinar 8x10,
and what about a replacement screen for the Cambo? Lately, I have struggled to focus this camera in the field on rainy days. Direct replies would be welcome. thank you.

[Ivan J. Eberle]

Unless size of the lens is very important, you could probably turn you f8 into an f4.5 Nikon 90mm for a lot less than 300, maybe even a trade with someone. The f4.5 is a LOT easier to focus, both because of the reduced DOF and more light.

I tote my gear pretty far afield in dusty wilderness areas, and got the Nikkor 90mm f/8 SW in no small part because it fits inside my Meridian 45B with the bed folded up. I do like the idea of a Grandagon XL for the color consistency with my other Caltar II-Ns (perhaps a 75mm is next). I would've sooner but for not having yet solved this focusing and viewing problem-- because I'm still chafing at the prospect of spending as much or more than I've spent on many very fine used lenses on a Maxwell screen, essentially a piece of plastic. (I've nearly talked myself into it, just need to set aside an afternoon for the phone call :-)

[Robert Hughes]

One of the downsides of Fresnels is the need to keep your head centered.
Quote of the Day! :D

[Michael Rosenberg]

I use wide angle lenses a lot when photographing interiors of abandoned buildings or in cathedrals/churches. I could not have done without my Maxwell screen. I still have trouble focusing in very dark interiors, and in trying to see if I have stopped down enough. I bought a 75 mW green laser to aid in focusing, and it is a real winner. As some have pointed out the switch has to be depressed to keep on; I resorted to using a rubber bumper (found at hardware store and used to prevent frames from scratching walls etc) attached to something like a paper clamp - hits the button just right. To attach it to the camera I got a Kensington document holder from Office Depot (http://www.officedepot.com/a/products/272627/Kensington-FlexClip-Copyholder/. Cheap too at $10.

Mike