Using a 10X loup for focusing aid, is it too much?

[clark_king1]

I am currently usin g a 10x loup. Is this too much to use as a focusing aid on the 4x5 GG? I use a fresnel lens and the concentric circles are apparent when viewing a composition using this loup, but besides the annoying lines are there any other reasons that I should be using a lower power loupe. It seems to me that the higher the power the more critical the focus/sharpness. Any opinions?

 

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Thank you

 

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Clark

[matthew_runde]

<a name="1">I think that it's quite subjective.</a> Plus, there are

many different types of equipment (screens, Fresnels, loupes, lenses)

that may change the ease of focusing. Then there are many different

situations that can affect the ease of focusing (forest, urban, low

light, rain, no sleep, your socks being chewed off by weasels).

 

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I think that it's important for you to be able to focus the camera in

a way that's quick and easy for you. To that end, I think that you

should experiment a bit and see for yourself whether or not a

different loupe would make it easier <i>for you</i>.

[thilo_schmid]

Clark,

 

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for 10x loupes, use a Bosscreen for perfect vision. 10x loupes are

useful for macro work. For "normal" photography, a 4x loupe will be

sufficient. It gives you the vision of a 20x16" print and DOF on a

well stopped down lens will do the rest.

 

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Regards,

[upscan]

Clark: Good question. That depends on several factors most important

of which is the texture of your GG. On a fine GG 4X5 I do not think

it is too much, rather, it is best. On a fine 8X10 it is not too much

either but you might want to opt for one that gives you a wider

field. If the GG is coarse, yes, the ideal should be at around 6X on

4X5. Some people prefer their 4X loupes on 8x10.

[michael_briggs2]

I've used a variety of loupes and magnifiers on a variety of screens

on 4x5 cameras. My conclusion is that about X4 or X5 is the best

magnification. Because of the grain of most ground glass, higher

magnification doesn't reveal much additional detail and in fact can be

harder to use because the view is dimmer. The only viewing screen I

have used on which higher power was commonly useful was a Bosscreen,

however, I don't recommend this screen for general use because mine

self-destructed under moderately elevated temperatures.

 

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If you use a X4 loupe to judge at what aperture something is in focus,

it is a good idea to stop down about one more stop than seems

necessary from observing with the loupe. Alternatively, use the

techniques described on "A large format photography homepage".

[pete_andrews]

Unless you're absolutely sure that your screen is in perfect

register, and you also use precision filmholders, lke the $inar, then

IMHO there is no point in ultra-critical focusing. A small bow in your

film, or a worn filmholder, will easily negate that extra close

scrutiny of the screen.<br>A register error of just the thickness of a

sheet of film can put your focus out by <i>metres</i> at mid subject

distances with a moderate wideangle lens.<br>LF photography, in most

cases, ain't precision photography, I'm afraid.

[george_jiri_loun]

While it is true what Pete says, it is also true that when these

elements of imprecision are present, the loup with less magnification

(4x) can add even one more additional cause of the imprecision...

That's why it is not irrelevant if you strive for a higher

magnification loup.

[brian_ellis3]

With a plain ground glass, or a Bosscreen, 10x should be fine though

personally I don't see a need for anything more than 4x. But with a

Fresnel, Beattie, or any other similar "bright screen," I think 10x

is unnecessary overkill for the reason you've discovered - those

lines aren't just annoying, in my experience they actually make it

more difficult to properly focus.

[david_haynes]

Hi Clark,

 

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As others have noted, it's really a personal preference issue, IMO. However, I'll

throw out another alternative to a loupe that I've found to work great. For my

8x10 (Deardorff) work, I've been using a pair of jewelers flip-up glasses, the

kind with an adjustable headband.

 

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This thing has various accessory pairs of lenses that snap in with different

magnification powers. I use the ones that focus at 5 inches, although they have

lenses that'll focus down to about 3 inches.

 

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For me, this method is far superior to using a loupe for three major reasons:

 

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1. When composing an image, I can flip up the lenses (like a welder's helmet)

and it helps keep the dark cloth from sagging, allowing for easier composition.

2, It allows me to "see" an area about 4x5 inches all at once, so adjusting focus

for a tilt to bring near and far planes into focus is much easier. I can also easily

see all the way into the corners.

3. Because of its design, both hands are free, allowing me to use my left hand

to gather the bottom of the dark cloth while focusing with the right.

 

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I did a year-long 8x10 project in 2000 and used this set-up for every shot and

found it to be much, much faster working than with a traditional loupe. And

BTW, the entire unit including lenses is about a third the price of a decent

Schneider or Rodenstock 4x loupe.

 

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Hope this is of some help. Good Shooting!

[upscan]

Pete: Yes, the filmholders are a source of variations, sometimes even

significant variations. The problem I see with allowing known,

controllable deviations to creep into any system is that if 'Murphy'

would have his (or her) way, (he ..or she...often does) the

variations can be additive, making something bad but tolerable into

something not tolelable. Big problems can result from little ones,

which in isolation would be nothing to worry about. Sinar allows

0.0005" into the design of their holders to allow for film bow. The

assumption being I suppose that film never lays perfectly flat

against the septum. Another practical argument can be that without

seemingly great concern about such technicalities, great

photographers have made great photographs. Pete I hear what you are

saying.