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09-17-2011, 10:50 PM   #1
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second opinion on pics from these lenses?

I was hoping a couple of people could give an opinion on these pics from different lenses (actually the 2 that are nearly the same focal distance are diffrent lenses but the one that is much wider is the same as one wider). I'm not really looing for nitpicking or what is wrong with them, just a brief they are about the same quality, one is slightly worse (if so which one), one is a lot worse etc. Of course any additional or deeper opinions are welcome but I am really wondering if one is very much better or about the same (I'll explain later why).

lens_test Photo Gallery by Richard Homeyer at pbase.com

09-17-2011, 10:56 PM   #2
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Last one seems a tiny tad sharper, which could be down to your focussing. Apart from that there is not much between them I would say.

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09-18-2011, 05:27 AM   #3
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I'd suggest you use a different target, maybe a sheet of newsprint taped to a wall? As it stands I tend to agree with Prieni, but none of them are steller.
09-18-2011, 06:03 AM   #4
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QuoteOriginally posted by JohnX Quote
I'd suggest you use a different target, maybe a sheet of newsprint taped to a wall? As it stands I tend to agree with Prieni, but none of them are steller.
Not stellar as in a bad lens or just not a great lens?
Anyway I was more interested in the difference but I got a couple more shots coming.

09-18-2011, 06:13 AM   #5
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Here is a test with newsprint. Again I am primarily wondering if there is a big difference in quality between the two lenses. I'll post what they are shortly.
lens_test_2 Photo Gallery by Richard Homeyer at pbase.com
09-18-2011, 06:30 AM   #6
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On the newsprint, the one on the left appears to be a bit sharper, but it also has more barrel distortion.
09-18-2011, 07:06 AM   #7
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Let us know what 2 lenses those are so we know which two lenses not to buy






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09-18-2011, 07:21 AM   #8
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I botched that one a little too (tired and have a headache). look at the right edge to judge barrel distortion as the left edge of the page is actually curved (the tape grabbed and folded the page a little). I do see some barrel distortion on the right edge myself but not as bad. I was a bit surprised to hear someone say the left was sharper.

So I guess I'll let everyone in on the secrete and hopefully no one will be too mad about the deception.

There is a question that gets asked on various forums often and the stock answer is just plain and simple, don't do it. I am referring to front mount converters. On rare occasion you hear a voice of reason that says it depends on the quality of the glass but the standard answer is usually it will ruin the picture. I understand that any added glass will cost image quality, but people use macro attachments all the time as well as rear mount converters. There are front mount converters that cost hundreds of dollars so I am skeptical about claims that they will horribly destroy the picture. I also know from experience with point and shoot cameras and many front mount converters that they can sometimes cause minimal quality loss. Fyi I have a cabinet full of front mount teleconverters from my prosumer days including some very expensive ones but very few wide converters.

I just wanted an honest second opinion about a lens I just got but knew if I mentioned it was front mount I might get some stock don't do it answers (it's kind of hard not to think that way when that's what everyone says). I couldn't see and major lose in quality but wanted a second opinion.

The first lens was a vivitar 35-70mm 2.8-3.8. The wide converter is a panasonic (no magnification or model number on the lens). It seems to be about 0.7x. Seeing as panasonic teleconverters sell for 200-300$ new for most, I took my chances (7$ shipped for it and a panasonic teleconverter with original leather soft cases). There seems to be little to no light loss using it. In the first test, the first shot is the vivitar full wide, wide open aperture and the wide converter. The second is mid range with the wide converter, and the third is without the converter (tried to match the focal distance). The first shot should be about 24.5mm 2.8.

The second tests (the ones with news print) are with a pentax 28-80mm power zoom (I originally used the vivitar as it is the only fast wide zoom I have and the purpose was to get a fast lens a little wider and stay fast). First with and the second without.

Thanks for the opinions. Had I been more awake I might have thought to try some fast primes that have better glass than the vivitar (fast wide zooms are expensive so it's the best I have so far). I'll try that a little later today (right now my 4 year old is standing next to me and has said are you done yet daddy aproxamatly 50 times while I try to type on a remote with a cel phone size keyboard).

09-18-2011, 08:43 AM   #9
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Hopefully someone will be nice enough to give an opinion on these even if a bad one (just mentioning a front mount converter can be a thread killer sometimes).

First 2 shots are a 50mm 2.0 prime. next 2 are the prime with the camera at the same spot with the wide converter. I didn't like the focus on these so their is a third at the end. third set of 2 are with the camera moved closer to get the same focal distance as the lens alone (lens and converter). The last pic is a re shoot as mentioned. My eyes are not what they used to be ( I guess I need glasses) so any opinions would be appreciated. I notice a little loss of quality but not much. Are others seeing the same?

50mm_plus_pan Photo Gallery by Richard Homeyer at pbase.com
09-18-2011, 08:43 AM   #10
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I didn't notice anything in the first set (post #1 link). With the second set (newsprint in post #5), there's a highlight in the upper left that looks like a short line in the first shot (like motion blur) and a point in the second. I'm not sure whether it is motion blur. To me, the corners of the first shot look pretty bad but the centers are OK.
09-18-2011, 08:56 AM   #11
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With the 50mm set (post #9), I can sort them quickly by center sharpness. OK to good: 5582, 5583, 5586 5588. Bad: 5584, 5585, 5587. The center sharpness declines generally in the higher file numbers. Corners still look bad with the converter shots.
09-18-2011, 09:26 AM   #12
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With the 50mm set, I think the 3 bad ones were focus issues (shouldn't have been motion blur as I used a tripod and 2 second timer on everything). My eyesite is just barely past what the camera diopter adjustment can adjust for.
So on the 4 you said were ok to good, 5582 and 5583 were with the lens only. 5586 and 5588 were with the converter? Would you say that the converter is harming picture quality to a very great extent? As far as corner sharpness, it is only 49mm mount so I'm thinking it might be creating an artificial aperture restriction (lens is too small, if I stopped it down some it would go away but that would defeat the purpose of a fast wide lens). I have a 49mm 3 element macro lens that does the same thing. I didn't even know what size it was when I bought it but it was 7$ shipped for 2 lenses (the leather cases are probably worth that) so I gambled.

On the first set I'm thinking average lens on a generic picture, so it does not show much harm (could also be 2.8 is working better than 2.0 since the lens is small). Until I get a better fast wide zoom (I want a 28-90 f2.8 constant or similar but they seem to be uncommon and expensive so I'll have to look for a while), I use the vivitar. I'll have to try it with the converter next time I go out and do some real shooting.
I have bigger wide angle lenses that seem to work even better, but its like hanging a brick on the front (focus won't turn smooth) so it defeats the purpose. Fyi, this is an LBA thing, its not important if they work or not but it would be nice if they would. Eventually I will get something better for a fast wide zoom.
09-18-2011, 05:44 PM   #13
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Is the vivitar really that bad?

QuoteOriginally posted by joe.penn Quote
Let us know what 2 lenses those are so we know which two lenses not to buy






----
Do you think the vivitar is really that bad (without the converter)? I'm still new to manual focus lenses and many have little or no use yet (it's going to take some time to use them all and get a feel for which do a better job). Is the vivitar really that bad (keep in mind 15$ manual focus Cary lens)? I knew some were much better but I had thought this one was usable quality. Perhaps I liked it because its the fastest zoom I have and it was the only lens I had fast enough to get the job done (can not remember for sure). I have been looking for a better one but wanted a 2.8 constant and a little wider range if possible but that seems a rare one to find.

Edit: you know, with a little more testing, the vivitar is not looking so good on paper to me either but I did notice something. When the camera says it's in focus it doesn't look in focus to me (and comments on a few shots would seem to confirm that). I really need to get a diopter adjustment attachment for my camera.

I'm not sure if anyone is still paying attention to this thread now that it is known its a front converter, but could someone comment on these 2 shots? first is with a different wide angle and second is just the vivitar 35-70mm. One important note is on the second one (lens only), according to the camera the shot was NOT in focus. As best as my eyes could tell it was.

http://www.pbase.com/richardh/viv_oly

Last edited by ripit; 09-18-2011 at 06:24 PM.
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