Panda2 Posted June 2, 2018 Share #1 Posted June 2, 2018 Advertisement (gone after registration) Hi, is the 21 SEM supposed to have a high level of astigmatism? I took a few night pictures yesterday and all the small lights have a (sagittal?) tail attached to it across the frame (see attached, M10, f3.4 wide open). I'm quite surprised at this as my copy is otherwise edge-to-edge sharp and renders amazingly during the day, just shockingly unusable during the night - even when stopped down a bit, which is a bit disappointing for this highly corrected ASPH. lens. If this is the norm, would anyone be able to suggest a wide angle lens (<28mm) with relatively less astigmatism? Thanks. 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/285207-21-sem-astigmatism-at-night/?do=findComment&comment=3530015'>More sharing options...
Advertisement Posted June 2, 2018 Posted June 2, 2018 Hi Panda2, Take a look here 21 SEM astigmatism at night?. I'm sure you'll find what you were looking for!
adan Posted June 2, 2018 Share #2 Posted June 2, 2018 (edited) Looks to me far more like a fingerprint or other smudge on the front or back elements (or filter, if used). The ridge-lines of a fingerprint (or streaks, if the print in smudged in an incomplete attempt at cleaning) will give that type of linear smearing. I don't have the 21 SEM, but I cannot imagine it is supposed to do that, or that extremely, normally. https://goo.gl/images/mz6kv3 It is possible you just got a bad copy - including perhaps an internal fingerprint from the assembler. Edited June 2, 2018 by adan 2 Link to post Share on other sites More sharing options...
Panda2 Posted June 2, 2018 Author Share #3 Posted June 2, 2018 (edited) Looks to me far more like a fingerprint or other smudge on the front or back elements (or filter, if used). The ridge-lines of a fingerprint (or streaks, if the print in smudged in an incomplete attempt at cleaning) will give that type of linear smearing. I don't have the 21 SEM, but I cannot imagine it is supposed to do that, or that extremely, normally. https://goo.gl/images/mz6kv3 It is possible you just got a bad copy - including perhaps an internal fingerprint from the assembler. Thanks for the reply. Yes I assumed it was the filter so I removed it (a B+W clear filter) for this shot, but there may be a faint mark on the front element. I'll give it a good clean and try again to see if I can repeat this problem. I hope you're right! Here're some previous pics with the SEM on my flickr https://goo.gl/Ld7jLN Edited June 2, 2018 by Panda2 Link to post Share on other sites More sharing options...
onasj Posted June 2, 2018 Share #4 Posted June 2, 2018 The first copy of the 21 SEM I received was decentered and I saw odd radial coma distortion but mostly in one quadrant (upper left). I agree with Adan that the uniform distribution of the coma-like artifacts across your field implies something else like debris on an element. In any case the 21 SEM should definitely not look like that, even shot wide open at night. I used the first copy to shoot the Vegas night time skyline and other than the upper right quadrant, coma was well controlled. Link to post Share on other sites More sharing options...
Exodies Posted June 2, 2018 Share #5 Posted June 2, 2018 I don't see it with my copy. The lights are squares on the floor. 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! Incidentally the architect who designed this should have been drug into the street and shot. Walking over it at night is horrid. You are so dazzled you can't see anything. Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! Incidentally the architect who designed this should have been drug into the street and shot. Walking over it at night is horrid. You are so dazzled you can't see anything. ' data-webShareUrl='https://www.l-camera-forum.com/topic/285207-21-sem-astigmatism-at-night/?do=findComment&comment=3530224'>More sharing options...
Panda2 Posted June 2, 2018 Author Share #6 Posted June 2, 2018 Thanks guys for the response. I've given it a good clean today and went out to take a test shot at the same place (though I did not wait until the same time, which was very late). No dramatic astigmatism anywhere! So the faint fingerprint smudge was the culprit in the end, just as adan said. I'm very relieved now that my Super-Elmar is super once again :-) 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! 4 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/285207-21-sem-astigmatism-at-night/?do=findComment&comment=3530404'>More sharing options...
adan Posted June 2, 2018 Share #7 Posted June 2, 2018 Advertisement (gone after registration) So that must be about No. 1 Poultry Street? Link to post Share on other sites More sharing options...
Panda2 Posted June 2, 2018 Author Share #8 Posted June 2, 2018 So that must be about No. 1 Poultry Street? Good eye. The patterned building on the right is No.1 Poultry. Incidentally, the (very) short section of the street there is just called Poultry (without the word street), bit peculiar. Link to post Share on other sites More sharing options...
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