Loupe question

[Raffay]

Hello, I am using a 128mm enlarging lens to act as a loupe but with a 127mm lens on the camera I am still finding it difficult to focus on my subjects eye. I know 127mm is way too short for portraits but this is the only lens I have right now. I was looking at this loupe on freestyle photos that says 10x magnification. I wanted to know how magnification factor is calculated for example what magnification factor is my lens providing and whether this loupe from freestyle be a substantial increase in magnification - it is for almost 40 dollars.

Any help would be appreciated.

Cheers
Raffay

[vinny]

10x is too strong as you'll be viewing the grain of the ground glass. I prefer 6x from Peak.

[Ari]

I normally use a 5x Peak loupe, but switch to a 10x for wide-angle work; I find it harder to achieve precise focus with wides using only a 5x.
Vinny's right, though; at 10x, you get a lot of the GG grain.

[C. D. Keth]

I use an 8x. I don't think 10x is too strong if that's what you happen to have. It will work. 4x to 8x is kind of the sweet spot for most people.

[Raffay]

Thank you for your inputs, however, I want to know the comparison between what I am using and this one, so that I don't spend money on something that I already have. Where can you order this peak brand from?

Cheers
Raffay

[Doremus Scudder]

I use 8x or 10x. I like the extra magnification.

Best,

Doremus

[Michael W]

I've been using one of the Peak 5x magnifiers. About $14 from B&H. Good quality for a plastic magnifier and longer than most so I don't have to push my face up against the ground glass.

[vinny]

Sorry, i must be using a 4x. Where to find it? B&h, or any other online photography store. Try google.
http://www.peakoptics.com/index.php?...a8c59752dc32f2

[John Kasaian]

The cheap Agfa type 9x loupes (less than $8) do all right plus they'll multi task when louping your negatives. Upgrade to a nicer Toyo or Silvestri if you really want to spent the extra $$. My 2-cents anyway.

[Leonard Evens]

Some googling suggests that the formula for magnification is either
250/f or 250/f + 1
depending on how the loupe is used. Here f is the focal length measured in mm. (250 mm is the location of the unaided near point for normal eyes for young people.

250/127 is about 2. So you "loupe" is providing between two and three times magnification. This would be too little to see much detail for a wide angle lens or any lens used in closeups. You should try something with a magnification of 8 X to 10 X, but even 10 X will be hard to use because it will show surface detail on the gg, which may be difficult to distinuinguish from image detail.

Of course, you would have so much depth of field in such circumstances, that critical focusing my not be all that important.

You should look up advice about how to focus in closeups. Oftne, you should move the camera rather than hte lens. This is described elsewhere in the large format site.