What is "sharp?"

[brian vega]

I was just reading through a post about being rejected. The gentleman

stated that he looked at his slides with a magnifying glass and

projected them. I understand his error here. Bob Atkins made a good

point many of us newbies don't know what sharp is.

 

So my question: What is sharp and how do you tell?

 

When I look at my slides (with a loupe)sometimes I can't tell for sure

if they are sharp? I think my probably is not knowing what to look for

Is sharp when edges stand out, when they are well defined? I am able

to tell when slides are absolute losers. I've had plently of practice.

 

My next question: Does anyone want to send me two slides of the same

subjet, one that is "sharp" and one that is just slightly off?

 

Thanks, BV

[kent_chai]

Good question!

 

As a beginner I am interested to know too.

[marcus_hawkins]

What is sharp? Sharp is looking through a high magnification loupe and having a smile creep across your face as the smallest details of your subject sing from the the film.

 

One technique I often use to double-check sharpness is to rotate the tranny and look at it again - if it's a vertical portrait, turn it so it's horizontal and vice versa. That way I'm looking purely at the sharpness and not being swayed by the image at all. The prime area to scrutinise is the space around the eyes of your subject (if it has eyes!). You'll soon be able to tell if the image is truly tack sharp - there should by no softness around the eyelids. I've found it's also much easier to get used to 'spotting' sharpness if you start out examining portraits of birds taken on bright days - just see how much detail you can pick out in the feathering in your processed film. Pull out your best images and come back to them a couple of days later - it's amazing what you miss on your initial tranny trawl.

 

One more 'tip' - look at your trannies raw and clean, not through plastic sleeves.

[scott_fairbairn]

To tell if a slide is sharp you will need two things. A High magnification loupe,I personally use a 10x. It must have good enough optics to begin with or else it is less than useless. The second thing you need is a sharp slide! Unless you can get a sharp slide it is impossible to know what truly sharp is. To get this you need good optics, tripod,cable release, stationary subject with fine detail,sharp fine grained film like Velvia.(birds, if you can get one that is still , are perfect)Basically what you want to do is eliminate operator error from the equation. Using flash on a subject is a good way to get rid of vibrations,movements. At ten times mag, you should be able to pick out fine details, edges should be sharp, there should be no softness to it. (kinda like looking through a window with binoculars) Macro lenses are good for testing your ability to see sharpness because they have great optics and the use of flash eliminates problems with camera shake. I hope I answered your question!

[scott_fairbairn]

Sorry I forgot to mention one thing. You cannot tell if a slide is sharp by projecting via slide projector or scanning into the computer. The best way IMO, is my previous answer.

[pete_parker]

Scott's post is right on. I can fully attest to the quality of a loupe making all the difference in the world. When I really became serious about photography, I bougnt a 35 dollar square 8x loupe. I used this for quite a while unti a friend told me about having the opportunity to use a high quality loupe made by the same manufacturer. I went ahead and bought a Schneider 8x and then went through my files. What I saw made me sick. I had to re-edit my entire file and reject much of what I had saved. Had I went ahead and bought a high quality loupe in the first place, re-editing and rejecting much of the work I done wouldn't have been necessary. If your work looks sharp through a high quality loupe, you're on your way to sucess. Good luck, Pete.

[carlos_co]

Hold on, hold on, lets not get carried too far. From my experience, even crappy $8 Samigon 8x loupes can be used to evaluate slides properly. You do not necessarily need a >$100 loupe. The key is to judge ONLY the center of the viewing field presented by the loupe. So you have to keep moving the loupe which makes it rather difficult. The more expensive a loupe is, the larger the region of the viewing field that will be sharp and undistorted. This makes it easier to judge slides for sharpness. An excellent 8x loupe that I've been using recently is the Mamiya Pro Cabin 8x which is only half the price of a Schneider 8x - check out the regular photo.net forum.

[pete_parker]

I have to totally disagree with you Carlos. I was using a Peak square 8x and was extremely critical in my editing process. When I bought the high end loupe I was astounded what had passed my scrutiny with the Peak. I not saying Peak doesn't make good loupes. Their 7x anastigmatic is supposed to be very good. What I am saying is that you cannot make and adequate determination of image quality with a cheap loupe if your image acceptance standards are very high. I only say this guided by many years of experience and shooting with high end optics. This is starting to be a good thread. I hope more of you watching these posts give your opinion in this issue. What we are talking about here is very critical for anyone getting seriously involved in Nature Photography. Pete

[carlos_co]

Your right, Pete, and I'm just quibbling around as usual. I agree that you need a high quality loupe to judge your slides properly. If I only had my $8 Samigon 8x to judge my slides, I'd think they are all sharp. Now that you have seen what sharp is using your Schneider, go back and use your old Peak 8x. What looked sharp before, won't look sharp anymore. Do this a few times, then switch the order around. Judge using the Peak 8x first, then double check with the Schneider. After a while, you'll find that you can judge sharpness with the cheap Peak 8x as well! It is very difficult, yet crucial, to have your eye in the right place when using high magnification low quality loupes. After a while, you get a headache, then everything starts looking good. Another problem is if you have a non-focusing loupe and your vision cannot compensate - then everything looks bad.

[bobatkins]

What you need is experience as much as a good loupe. Having seen a sharp slide helps a lot! Take your best lens (preferably not a zoom), stop it down to f8 or f11, put some Velevia in your camera and take some shots with your camera on a tripod and focus carefully. These can be your reference slides. Now open up to full aperture and stop down to f22. These are your <em>slightly</em> less sharp shots. If your focus was good, you should be able to see the difference.

<p>

The advice about using a good loupe and not projection is sound. With enough experience you can tell if a slide is sharp with a crummy

4x loupe, or even via projection. However you are looking for subtle effects and without experience you'll never be able to do it.

<p>

Basic rule - if you have any doubt about whether it's sharp or not, it isn't.

[pat_byrnes1]

What about color neg film? What about b/w neg film? Do any of the

"rules" change when evaluating these?

[clivecc]

Regarding Loupes: I use the Peak 8x and, although not so good on the edges, it is good enough for me in the center. What I mainly use the loupe for is to check for camera shake (blurr or ghosting of the whole subject) , and "sharpness" of the subject by moving the loupe around over the slide. "Sharpness" for me is how close you can get to "laboritory results" (images can only be as crisp as the glass allows) for that particular lens in the field. Some lenses have better resolving power/sharpness than others. This is quite a controversial subject but most often more money buys more sharpness and better optics. How well you have been able to maintain the "sharpness" in the eyes (where appl.), overall sharpness of the subject and how pleasing is the backround blurr (if the apperture is closed down too far it may cause overall sharpness of the subject to be ok but distracting backround or cause camera shake or blurring of moving subject from slow shutter speed).

 

I guess everything in this game is a tradeoff: as you gain by changing something you usually lose in another area. The trick is to minimise the losses. As they say: "practice makes perfect".

[nature-photography]

Bob brings up a good point, experience with sharp slides really helps out. If you have never seen a sharp image, then it is going to be difficult to edit your images. A good sharp subject with a nice out-of-focus background should practically jump off the slide at you. It should "pop" as a lot of photographers call it. Images that lack critical sharpness will kind of blend at the edges.

 

Another way to evaluate them is to have enlargements made. Images that are "less sharp" will really be noticeable.

 

A good quality loupe is also key, the more expensive loupes really do make a difference. It is a great one time investment towards one of the most crucial parts of your photography. Loupes that are only sharp in the center drive me nuts, I want be able to look at the entire image at one time.

[pete_parker]

I guess talking to the people that make their living by looking through a loupe might help put this issue into a better perspective. I would be interested to hear what the magazine editors use for their critical sharpness determination. I know that some editors use a 4x for initial editing. I am assuming that they also use an 8x or 10x for really determining how crisp an image is. Perhaps someone knows an editor or has had enough experience with editors to be aware of the types of loupes used by these people to determine if a submission meets their criteria. Pete

[bobatkins]

Again, with experience, the type of loupe doesn't matter. Most of the time I can pick out soft shots with a 4x loupe, but I also use a 10x if I really want a critical look at a particular area of the slide. If you don't know what you're looking for, even a 10x might not help you. I think most phoot editors will use a 4x or 5x loupe, because you can see the full frame. Not many (any?) 10x loupes will give you a full frame view.

 

For a standard slightly "soft" slide, anything shot wide open (f5.6) at 300mm with a consumer 75/100-300 zoom will be a good example. With luck it won't be too bad, but placed against a shot at f5.6 with a good 300/4 or 300/2.8 prime, it will look soft. The same "soft" or probably even "softer") image will be obtained from any long telephoto consumer zoom shot wide open at the long end (80-400, 135-400, 200-400, from Sigma, Tamron, Tokina etc. plus any 28-300 or 28-300).

[john_macpherson]

Brian - something that seems to have been missed thus far and which

CANNOT be overlooked in the context of this thread (IMHO) is that the

loupe is near the end of the process of picture taking.

<P>

Now ok I will accept that not everyone can afford Canon L or Nikon ED

or Pentax whatever lenses, but these manufacturers "consumer" grade

lenses are able to take perfectly acceptable pictures. As are the

better models of Tokina, Sigma etc etc. Sharp and contrasty enough

to satisfy most folks in average circumstances.

<P>

It is well worth checking that your AF system is working as it should

(for the AF people amongst us), and for the manual focus folks - Do

you need an eyepiece correction lens? Is your eyesight as good as you

think? If too many slides on your light table are crap then you MIGHT

need to consider having an eyesight test and fitting the appropriate

correction dioptre.

<P>

As for loupes? I just bought a Pentax 5.5X, which I never ever see

mentioned in the posts on loupes. It has to be the bargain of the

century. It is huge, and sharp enough for me. But hey, is my eyesight

defective! Hell no, I cna tpye staright enouhg.

<

[mark_daigle]

OK, so the general concensus is that a top quality loupe is required to judge sharpness. So my question is which Schneider loupe do you all recommend. I was at B+H's website today, and they have a few different ones listed. Is this the one I should get?

1. Schneider 8x Magnifier (080-39643)

With strap.

Item # SCL8X....174.00

 

Thanks

--Mark

[ShunCheung]

For 35mm film, the Schneider 4x loupe is the "industry standard" that a lot of editors use. I have one of those as well as a Schneider 10x loupe. The extra power in the 10x loupe makes it even easier to spot anything that is slightly unsharp. However, the 4x gives you the full-frame view.

[ken_dunn]

Send me your address and I will send you a slide of some flowers in which one is sharp and the other is a little off due to DOF problems. It is a 2 1/4 slide so it should stand as a good reference.

[lanierb]

I wanted to add that, while they do help, I don't think you actually *need* a high magnification loupe to tell what's sharp. I can tell the difference between my best and worst lenses (and my worst lens is a Tamron 300/2.8!) even in perfect conditions with just an NPC 5.5x loupe, and I can certainly see camera shake and focus errors. I can also easily see the grain on Velvia at that magnification. I think you can do pretty discerning editing with just one loupe and I think many photo editors even just use a 4x. If you don't know if your pictures are sharp chances are you probably just haven't looked very carefully, and you definitely haven't enlarged them!

[clivecc]

I agree with Lanier that if you know what your looking for you don't need to spend a lot of money on a loupe. My Peak 8x ($35-00) is good enough to separate the wheat from the chaff but I would not buy anything less than this. This loupe gives me enough discernment to go just about anywhere with a 35mm slide!

[roger_s._przybys]

If you are not ready to sink a couple hundred dollars in a high quality loupe, use a good quality 50mm lens reversed. I do this regularly with my Cannon EOS lens and it is very sharp edge to edge. Just be real careful not to get skin oils or dirt on the electronic contacts. A high quality loupe is still the best answer, but if you don't have one available this might be an interim solution.

[bobatkins]

My standard 4/5x loupe is an old Pentax 50/1.8 lens. Just as good as anything I've seen selling for $100+ and I think I paid $10 for it. My standard 10x is a "Focus Achromatic Loupe" from Edmunds Scientific. It's plenty good enough to show if a slide is sharp and is actually quite good. The field is limited, but if I want full frame I use the 4/5x lens! I just don't see spending $200 or so on a loupe, but others do I guess. You certainly don't need to spend that much to see if your slides are sharp. I can tell a sharp slide from a soft slide using a $5 Agfa 8x plastic loupe. The edge quality isn't very good and I would recommend it, but it's OK in the center and good enough to tell if the image is sharp.

[john_macpherson]

A small but important point I feel should be made here. Yes a cheap

loupe is usable, and with practise you should be able to discern the

difference between sharp and unsharp slides. However, long term use of

cheap loupes is a recipe for eye strain and headaches. You might start

the editing process able to discern the subtle differences between

images but fortyfive minutes into the session and your eyes will start

to complain, and your ability becomes a little impaired. Try sorting

through lots of rolls of Velvia using a $200 loupe and then try the

$10 model and you will not only see the difference, but feel it. Given

that your eyesight is the basis for your photography, and you are all

happy to spend the bucks on ED or L lenses, I dont see why you should

damage yourself, and your editing ability, by buying junk loupes. A

good loupe that allows focusing saves a lot of work for your eyes =

less strain and pain. Just my five cents worth - without a headache!

<P

[alan___1]

IMO, you don't need an expensive loupe to determine sharpness. A good 10X loupe from Peak would do the job just as well. I have used "branded" and "no-brand" loupes and with both types, I can still tell if a slide is sharp or not. It is a question of what to look out for. In the case of animals, look for the fine hairs on the eyes, ears, etc. But don't confuse sharpness with DOF.