8x Loupe Question

[seandavid]

I've got a Horseman 6x loupe, but sometimes I feel it's not quite enough for critical focusing (at least for my eyes).

I'm looking at this Schneider loupe, but the seller says he just used it for viewing slides. (Dumb?) Question... What's the difference between a loupe for viewing slides, and a ground-glass loupe? My Horseman is definitely longer than this one, which I find helpful.
For any of you that use 8x or greater loupes, what would you recommend (if not this one)?

Thank you.


161827

[JMO]

I can't explain the essential differences between loupes, except to say that I recently purchased a Peak 8-16x loupe from a seller on this Forum and have already found that the 8x magnification has been very useful for (as you say) critical focusing. Previously I had been relying on a 4x loupe. This Peak loupe is a (relatively expensive (https://www.bhphotovideo.com/c/product/40720-REG/Peak_1302044_8_16x_Zoom_Loupe.html)) gem adjustable to 8, 10, 12, 14 and 16x, and it is quite bright even at the higher magnifications. But I don't expect that I would use it as a "focusing" loupe with my 4x5 cameras at much higher than 10x magnification. ....

[Leigh]

The problem with high-power loupes is you see the texture of the ground glass, which obscures the subject.

IOW you gain nothing while losing the subject detail you want to concentrate on.

- Leigh

[Alan Gales]

Some loupes have interchangeable skirts (the part below the optics). Clear skirts are for viewing negatives or slides on a light table. Opaque skirts are for viewing a ground glass. That's all I know about it.

My loupe is a Toyo 3.6x if I remember correctly. I've never used anything stronger so I can't help you there.

[Doremus Scudder]

... What's the difference between a loupe for viewing slides, and a ground-glass loupe? My Horseman is definitely longer than this one, which I find helpful. For any of you that use 8x or greater loupes, what would you recommend (if not this one)?
Thank you.

A few things: as previously mentioned, many loupes designed for viewing non-back-lit things have clear skirts to let the light in. For ground-glass focusing, an opaque skirt is nice (especially if you're not using a dark cloth all the time), but not absolutely necessary.

The second thing is focus: loupes that work best for ground-glass focusing have adjustable length so you can find the exact right focal distance from your eye to the frosted surface of the ground glass where the image is formed. Loupes for viewing photos and even slides often have no adjustment and a focus set at the plane where the skirt ends. This is often not optimal for ground-glass viewing, since the frosted surface you need to focus on can be a couple of glass thicknesses away from the end of the skirt. It seems (but I'm not sure from the photo) that the Schneider loupe you are considering has an adjustable eyepiece. I'd check that out, though. If so, it would be perfectly suited to ground-glass viewing.

As for overall length, it's a function of the design of the loupe. If you find longer is better for you (e.g., you need a longer loupe because you use a focusing hood, etc.) then look for an 8x-10x loupe with a long barrel.

Finally, the question arises: what power loupe is right for you? Many feel that higher-power loupes in the 8x and above range are too strong; they see too much of the grit of the ground glass and cannot focus on the image well due to that. Personally, however, I like loupes in the 8x-10x range for fine focusing. I find I feel better about getting the small details really in focus. If 6x seems too weak for you, then you'll likely prefer 8x or stronger too.

An aside: I mentioned the need to have an adjustable loupe so you can set it at the right focus for your eye-to-ground-glass distance. One way around this is to simply use a loupe without a skirt attached, or even a higher-powered magnifying glass, and, while focusing, move it around to find the right distance for best focusing. This has the advantage of allowing you to tilt the loupe for better viewing in the corners or when extreme movements are applied. Years ago, I arrived in Venice without my loupe or my reading glasses. A friendly optician sold me a nice pair of reading glasses, but had no loupe. He did, however, have a small 8x collapsible magnifying glass with an aspheric lens (like the one Sherlock uses in "Sherlock"). I found this really liberating; no worries about the skirt, no extra piece of equipment bobbing around on a string around my neck, just an easily pocketable, smaller-than-a-matchbox-size case that I don't even notice in my pants or jacket pocket. I still use this magnifier for the majority of my work.

Best,

Doremus

[seandavid]

Thank you very much, everyone. So much great info here. Doremus, thanks for your lengthy response.

Much appreciated!

[Pfsor]

I've got a Horseman 6x loupe, but sometimes I feel it's not quite enough for critical focusing (at least for my eyes).

I'm looking at this Schneider loupe, but the seller says he just used it for viewing slides. (Dumb?) Question... What's the difference between a loupe for viewing slides, and a ground-glass loupe? My Horseman is definitely longer than this one, which I find helpful.
For any of you that use 8x or greater loupes, what would you recommend (if not this one)?

Thank you.


161827

I have been using this Schneider loupe (with its adjustable eyepiece) for at least 25 years. Was serving me well all that time. But then I'm not picky about loupes. And yes I was using it for critical viewing of slides too. No problem either.

[Bob Salomon]

I have been using this Schneider loupe (with its adjustable eyepiece) for at least 25 years. Was serving me well all that time. But then I'm not picky about loupes. And yes I was using it for critical viewing of slides too. No problem either.

Since slides have to be backlit to view them with a loupe your loupe, as shown, is excellent! However, as shown, it is impossible to properly view prints. For that you need the clear skirt. Do you also have it?

[Leigh]

Clear skirts are for viewing negatives or slides on a light table. Opaque skirts are for viewing a ground glass.
I agree about using opaque skirts for ground glass viewing.

However...
Those are also used for viewing negatives or slides on a light table, to eliminate ambient light on the film surface.

Transparent skirts are for viewing prints or other subjects printed on paper, meant to be viewed by incident light.

- Leigh

[Jac@stafford.net]

The problem with high-power loupes is you see the texture of the ground glass, which obscures the subject.

IOW you gain nothing while losing the subject detail you want to concentrate on.

- Leigh

I have the same experience.

[Pere Casals]

I agree about using opaque skirts for ground glass viewing.

However...
Those are also used for viewing negatives or slides on a light table, to eliminate ambient light on the film surface.

Transparent skirts are for viewing prints or other subjects printed on paper, meant to be viewed by incident light.

- Leigh


I have the same experience.

I also think the same.

Just I'd like to add that a particular GG may have a finer or coarser grain, so perhaps what is the ideal loupe it depends on the particular GG one uses, IMHO.


Anyway when stopping the lens it happens that the DOF at the film plane is better than when photographer is focussing with diafragm fully open.

IMHO a 4x Loupe is more than OK, and a 8x can be more convenient if we have a GG with very fine grain.

Also it depends a bit on the particular sight score one has. People with low sight score may prefer 8x instead 4x.

For sharp results the critical issue is the film plane vs GG plane perfect alignment, not the loupe, IMHO.

[Bob Salomon]

I also think the same.

Just I'd like to add that some GG may have a finer or coarser grain, so perhaps what is the ideal loupe depends on the particular GG one uses, IMHO.


Anyway when stopping the lens it happens that the DOF at the film plane is better than when photographer is focussing with diafragm fully open.

IMHO a 4x Loupe is more than OK, and a 8x can be more convenient if we have a GG with very fine grain.

Also it depends a bit on the particular sight score one has. People with low sight score may prefer 8x instead 4x.

For sharp results the critical issue is the film plane vs GG plane perfect alignment, not the loupe, IMHO.

Assuming the gg is in its proper position and that you are using a lens that does not shift focus as it is stopped down. Then you should always focus wide open and not depend on depth of field to focus!

[chassis]

I use a Peak 1975 scale loupe 7x and it works for me with a Toyo Field ground glass. I like this loupe because it is focus-able and has a nice reticle which is mostly useful for reflective (e.g. paper, prints) media. It is unshaded, which is needed for reflective media, and does not create problems when using with a dark cloth on the ground glass.

[Pere Casals]

Assuming the gg is in its proper position and that you are using a lens that does not shift focus as it is stopped down. Then you should always focus wide open and not depend on depth of field to focus!



Hello Bob,

I've found what you point with my 1964 Symmar 360 when converted to 620. I guess that modern lenses (including Symmar convertible when not converted) have much less focuss shift than DOF increase at film plane when stopping. I don't know if some modern (process) lenses are exeptions...

Regards

[Bob Salomon]

Hello Bob,

I've found what you point with my 1964 Symmar 360 when converted to 620. I guess that modern lenses (including Symmar convertible when not converted) have much less focuss shift than DOF increase at film plane when stopping. I don't know if some modern (process) lenses are exeptions...

Regards
The Imagon shifts focus as the aperture changes.Modern lenses like the Sironar N, Apo Sironar N, Apo Sironar S, Apo Sironar, Apo Sironar W, Apo Ronar, etc. do not shift focus as they are stopped down. Your lens example is a very old lens.

[Pere Casals]

The Imagon shifts focus as the aperture changes.Modern lenses like the Sironar N, Apo Sironar N, Apo Sironar S, Apo Sironar, Apo Sironar W, Apo Ronar, etc. do not shift focus as they are stopped down. Your lens example is a very old lens.

Interesting information, thanks. It makes a lot of sense that Imagon shifts focus, as it plays with (by design) uncorrected spherical aberration to be used with diffusion discs.

[Pfsor]

Since slides have to be backlit to view them with a loupe your loupe, as shown, is excellent! However, as shown, it is impossible to properly view prints. For that you need the clear skirt. Do you also have it?

No, I don't - as I only take slides, the skirt is not needed.