SnapperJ Posted October 2, 2007 Share #1 Posted October 2, 2007 Advertisement (gone after registration) Can you produce sharp pictures wide open when focusing on a person at about 20 feet away? If you can would you be good enough to tell me the type of 90mm lens you are using and if possible post a picture. I am asking is this because I have a 75mm Lux which when used wide open focusing on a person at about 15 feet distance produces good results, not great but exceptabe with a little bit of trial and error adjustment of focusing. I am wondering if I would get better results with a 90mm. Why a 90 and not a 75 Cron or other because I wish to try and keep the boken close to that of my 75 Lux, but have better sharpness. A 90 being a longer focal length may have a similar boken to my 75 Lux. I know that boken is individual to each lens and that I will not get exactly the same as my Lux, but I would like to see what boken a 90mm lens wide open will produce. Thanks for your help. Link to post Share on other sites More sharing options...
Advertisement Posted October 2, 2007 Posted October 2, 2007 Hi SnapperJ, Take a look here 90mm wide open. I'm sure you'll find what you were looking for!
carstenw Posted October 2, 2007 Share #2 Posted October 2, 2007 Have you tried the 75 Lux at f/2? Otherwise the 90 Cron pre-Asph might give what you want. Link to post Share on other sites More sharing options...
SnapperJ Posted October 2, 2007 Author Share #3 Posted October 2, 2007 Have you tried the 75 Lux at f/2? Otherwise the 90 Cron pre-Asph might give what you want. Yes I have, but still get a problem focusing have to use a bit of trial and error. Link to post Share on other sites More sharing options...
carstenw Posted October 2, 2007 Share #4 Posted October 2, 2007 Ah, you mean sharp due to focusing issues? I thought you were commenting on the lens qualities. A 90 will be harder to focus correctly, not easier. I suspect there is something about your lens or camera which isn't correctly adjusted. I don't have any issues with my 75 Lux. See Guy's long thread about the 75 Lux vs. Noctilux for lots of examples. Link to post Share on other sites More sharing options...
Eoin Posted October 2, 2007 Share #5 Posted October 2, 2007 The 90 Summicron pre asph is very much like the 75 Lux, slightly softer but still reasonably sharp at f:/2, This lens comes into it's own about f:/4 and really is razor sharp by f:/5.6. The problem as I see it is the 90 has less depth of focus at the same given aperture and distance compared to the 75. Why you are trying to take images of people at f:/1.4 @ 20 feet is however another question that needs to be answered. But for your info a 90mm at 20 feet @ f:/2 has the same DOF as the 75 at 20 feet @ f/:1.4 which is about 1.4 feet of focus depth. It should be enough to render the subject sharp but one must take into consideration the fingerprint of the lens which by it's nature is softer at this aperture. The 75 Summicron however while having a maximum aperture of f:/2 will give about 2 feet of DOF at the same distance but by it's design and optical formula is razor sharp and practically at full resolution at that aperture. I don't understand what your trying to achieve or what your criteria are but for me I'd be using the 75's at about 10-12 feet at apertures of 2.8 to 4 for head and shoulder type portraits. the closer distance will tend to obliterate the background and give smoother bokeh than the wider aperture. For full length portrait I'd be using a 50mm focal length and again a little closer. However YMMV Link to post Share on other sites More sharing options...
SnapperJ Posted October 2, 2007 Author Share #6 Posted October 2, 2007 Ah, you mean sharp due to focusing issues? Yes. I think you may be right. At about 15 to 20 feet at f1.4 the focus seems to be off! I will have a look at Guy's thread. - Thanks Link to post Share on other sites More sharing options...
SnapperJ Posted October 2, 2007 Author Share #7 Posted October 2, 2007 Advertisement (gone after registration) I don't understand what your trying to achieve or what your criteria are but for me I'd be using the 75's at about 10-12 feet at apertures of 2.8 to 4 for head and shoulder type portraits. the closer distance will tend to obliterate the background and give smoother bokeh than the wider aperture. For full length portrait I'd be using a 50mm focal length and again a little closer. However YMMV This is the type of picture I have been doing using the Lux at f1.4. Link to post Share on other sites More sharing options...
lars_bergquist Posted October 2, 2007 Share #8 Posted October 2, 2007 Note that the 75mm Summilux at f:1.4 and a 90mm Summicron at f:2 have practically the same depth of field. So there should be no great difference in the ease of focusing. The old man from the Age of Guess Focusing Link to post Share on other sites More sharing options...
Eoin Posted October 2, 2007 Share #9 Posted October 2, 2007 I see now what your after, but you need to consider the limited depth of focus which in essence is 17 inches at f:/1.4 at 20 feet anything outside that will appear softer. Again it's difficult to tell from a web image where the point of focus is, I'd suspect the father with his 2 kids yet the cobble lock paving behind seems sharper. It could be a trick of the light with the shadow. Have you tried a 1.25x Magnifier to aid focusing?. Link to post Share on other sites More sharing options...
marknorton Posted October 2, 2007 Share #10 Posted October 2, 2007 I agree, you definitely need the magnifier for focussing a 75 and a 90, I find it useful too on a 50. Link to post Share on other sites More sharing options...
SnapperJ Posted October 2, 2007 Author Share #11 Posted October 2, 2007 I see now what your after, but you need to consider the limited depth of focus which in essence is 17 inches at f:/1.4 at 20 feet anything outside that will appear softer. Again it's difficult to tell from a web image where the point of focus is, I'd suspect the father with his 2 kids yet the cobble lock paving behind seems sharper. It could be a trick of the light with the shadow. Have you tried a 1.25x Magnifier to aid focusing?. Thanks, I have a 1.25x Magnifier which is a great help. I did focus on the 2 kids but out of about 4 pictures only one was sharp as I had to focus slightly off the subject. I was hoping that the out of focus areas would be more out of focus than they are. That is why I am thinking about a 90mm lens. Link to post Share on other sites More sharing options...
Eoin Posted October 2, 2007 Share #12 Posted October 2, 2007 ....I was hoping that the out of focus areas would be more out of focus than they are. That is why I am thinking about a 90mm lens. No you need to go the other way, get much closer to the subject with a wider angle of view lens, say a 28 or 35mm and open that up to max aperture, then you'll wipe the background Link to post Share on other sites More sharing options...
huwge Posted October 2, 2007 Share #13 Posted October 2, 2007 I think you might want to run some tests on the lens to check that you don't need the lens shimming. To me it seems the focus point is at least a foot behind where you say that you focused. I would try some tests shots using a tripod and delayed release of fixed objects where it is clear that you are in focus from the viewfinder perspective. I had something similar with my 50 lux asph which once corrected now performs fabulously. That said, at slow shutter speeds the 75 lux is very unforgiving of the slightest camera shake. Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted October 2, 2007 Share #14 Posted October 2, 2007 I know this is the 90 mm APO Asph at F2 and about 20 ft. But looking for one that may show more bokeh this one is a little tough to see. Looks to me your focus is behind the man and also a 1.25 magnifier is extremely helpful Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/34807-90mm-wide-open/?do=findComment&comment=367577'>More sharing options...
SnapperJ Posted October 2, 2007 Author Share #15 Posted October 2, 2007 I know this is the 90 mm APO Asph at F2 and about 20 ft. That's a very sharp image and with a shallow depth of field. Thanks Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted October 2, 2007 Share #16 Posted October 2, 2007 The 90mm is a very sharp lens wide open so really your image should have nailed that guy standing with ease. As long as the shutter speed is high enough you should be getting tack sharp images. yours looks like it is backfocusing a little , might be worth a test to see where you are at with the M8 and your lenses. Link to post Share on other sites More sharing options...
SnapperJ Posted October 2, 2007 Author Share #17 Posted October 2, 2007 This was taken with my 75 Lux, no problems with focusing at all, bat at 15 to 20feet it seems to focus behind the point on which I have focused! Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted October 2, 2007 Share #18 Posted October 2, 2007 I shot this of my daughter the other day for her High School senior ad but i was really pushing the shutter speed issue here a 75 lux wide open but my shutter is a touch to low 1/30 of a second handheld is really tough, it is very close to the edge of being out but it is working okay here , would have loved to been shooting at 1/90 and i should have bumped the ISO up . But i did want a soft look for her Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/34807-90mm-wide-open/?do=findComment&comment=367617'>More sharing options...
carstenw Posted October 2, 2007 Share #19 Posted October 2, 2007 ... the 75 Lux has a narrow depth of field wide open, as we know. Do you know whether your M8 may have a near-far imbalance in the rangefinder adjustment? Do you have other super-narrow DOF lenses? It is unlikely that a lens focuses correctly at one distance but incorrectly at another (but not impossible). Link to post Share on other sites More sharing options...
SnapperJ Posted October 2, 2007 Author Share #20 Posted October 2, 2007 ... Do you know whether your M8 may have a near-far imbalance in the rangefinder adjustment? Do you have other super-narrow DOF lenses? It is unlikely that a lens focuses correctly at one distance but incorrectly at another (but not impossible). My M8 seems to be ok with my other lenses. I have a 50mm Cron which produces sharp pictures at any distance. Link to post Share on other sites More sharing options...
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