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Tamron SP 350/5.6 DIY reapair or send it to a Professional?
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PostPosted: Mon Sep 29, 2014 1:35 am    Post subject: Tamron SP 350/5.6 DIY reapair or send it to a Professional? Reply with quote
This is my Tamron SP350/5.6 front glass,you can see the cloudy dirt around the edges.



These are two sample images taken with it,it does not seem as sharp as the SP500.Am I deceiving myself thinking there is something wrong? And I just need to practice more? There is no tripod mount on this lens so all is hand held or braced against a wall for support.





PostPosted: Mon Sep 29, 2014 5:33 am    Post subject: Reply with quote
Nope, cannot be caused by that. The impact might be the ever so slight loss in contrast, but that woudl be all. Misadjusted optics I guess it is (most likely the secondary mirror.


PostPosted: Mon Sep 29, 2014 5:53 am    Post subject: Reply with quote
Thanks Klaus
Groan I was hoping for something simple....it may have to go for a professional service down the track wen the funds are there. Sad


PostPosted: Mon Sep 29, 2014 6:29 am    Post subject: Reply with quote
I agrees with Klaus. Small amount of haze or dust only cause loss in contrast but little lost in sharpness.

It seems there is nothing wrong in the photos you posted if they are 100% crop. When focus to close distance, the contrast and sharpness will drops like the other mirror lenses. It is best if you can upload a RAW file of the second photo so I can check it for you at my computer.


PostPosted: Mon Sep 29, 2014 6:48 am    Post subject: Reply with quote
Embarassed I don't have the raw file,I deleted it only recently. I can take a few more shots tomorrow and upload the raw files from those images.


PostPosted: Mon Sep 29, 2014 6:58 am    Post subject: Reply with quote
OK. You can send me the links via PM if you don't want to post it here.


PostPosted: Mon Sep 29, 2014 7:22 am    Post subject: Reply with quote
The above images are only resized not cropped...if that's what you mean by 100% cropped?


PostPosted: Mon Sep 29, 2014 7:30 am    Post subject: Reply with quote
If resized is applied, it is not a crop anymore. See here: http://www.juzaphoto.com/article.php?l=en&article=9 .


PostPosted: Mon Sep 29, 2014 2:54 pm    Post subject: Reply with quote
Hi mo
I concur with preceding comments that's not going to cause any noticeable image degradation TBH.
Take a tripod mounted (or bean bag/sand bag works well) pic or two using 2 secs timer of eg a brick wall at medium distance, something with lots of detail and micro contrast. If you have good live view (Kr and later models) then that's the most accurate way of checking focus. One trick is to take a pic of eg a wall at a bit of an angle so that there will be part of the centre pic in perfect focus.
Use jpg + raw so we can have a look at both. If you have another longer focal length lens eg 300mm/200mm then take the same pics with that too at its best f stop ie f8, f11 for comparison.
Those pics above didn't look too bad but being resized means they don't really tell us the score. Pics from my dodgy 55BB looked Ok resized.


PostPosted: Mon Sep 29, 2014 9:07 pm    Post subject: Reply with quote
Mo,
You can get the front retaining ring off using a set of calipers, using the set of tongs used for measuring inside diameters. I paid $30US for a set of digital calipers from a local tool supply store.
This will allow you to get the front corrector plate off and cleaned, but probably will not fix your sharpness unless the corrector plate was seated wrong.

John


PostPosted: Mon Sep 29, 2014 9:21 pm    Post subject: Reply with quote
I think I see camera shake in last photo.

Using the crude rule of one divided by the focal length for minimum shutter speed to prevent camera shake, 1/200 sec is not fast enough for 350mm lens. Wink


PostPosted: Mon Sep 29, 2014 11:24 pm    Post subject: Reply with quote
Thanks guys,I have plenty to work with,strangely enough I don't have an unpainted brick wall to shoot.. Laughing I will find something.


PostPosted: Tue Sep 30, 2014 1:03 am    Post subject: Reply with quote
I hope this works here are three raw images shot this morning. I did notice the "wobble" after you push the button that it may take longer than 2 secs to stop moving. Rolling Eyes I used a tripod and a kilo bag of lentils to try and dampen the wobble...not very effective.
Raw
1) https://app.box.com/s/cooay5lurmqu3svtbwv4
2)https://app.box.com/s/b7t6sd631vqg1kad39xs
3)https://app.box.com/s/vbmn544b2erda2fftdg8

JPGS
1)https://app.box.com/s/s6j36l7etyrmp80npzn6
2)https://app.box.com/s/s9o0m60n7q28et480xav
3)https://app.box.com/s/x7l86e1y7xeiiwg1bv8o


PostPosted: Tue Sep 30, 2014 4:01 am    Post subject: Reply with quote
#1 and #3 looks ok to me(a bit of under exposure). I assume the focus point is in the left of the fence. #2 looks ok too if you are focused at any of the circled part. This lens be less sharp within few meters and I think it works best from five meters and more.



Here is a 100% crop from the center part of a snapshot about ten meters away for your comparison. I covert use the default screen sharpen on Adobe Lightroom without further sharpen for screen. Bright sunlight is needed for maintain a high shutter speed.



PostPosted: Tue Sep 30, 2014 10:53 am    Post subject: Reply with quote
I was focusing on the white spot on the tap, image 2 ,and the top edge of the fence post, image 3,and finally probably more centre and right edge of the fence post, image 1.

I don't have a tripod mount on the lens so I had to use the cameras tripod mount. I did notice this lens "wobble" when viewing through the close up feature on the K-01,something I had not noticed before and certainly could cause motion blur. If these images fall into the normal range of how this lens performs, then its simply a case of getting to know how to handle this lens a little better.

Thanks for helping me Calvin I really appreciate it.


PostPosted: Tue Sep 30, 2014 9:19 pm    Post subject: Reply with quote
Those shots look pretty ok to me - I would expect #2 to be a bit sharper. ?OoF ? bit of shake/vibration
I suggested mid range ie 10-30m. As calvin says close focus isn't really a forte of the tamron mirrors IMO.

Try a sand bag eg ziplock filled with dirt. Set on 2 secs timer. Use a remote release.


PostPosted: Tue Sep 30, 2014 9:26 pm    Post subject: Reply with quote
Handhold is fine if crank up the iso to get a fast shutter speed, at least 1/350 sec, to freeze motion, such as camera shake. Wink


PostPosted: Tue Sep 30, 2014 9:58 pm    Post subject: Reply with quote
Sadly for the time being, I have to push the button I don't have the funds to buy the remote...it's now on the too get list. The ziplock bag and dirt are easier to obtain. Laughing Give me some time and I will see what I can do. I had the iso at 400 which I use for the SP500.


PostPosted: Wed Oct 01, 2014 3:09 am    Post subject: Reply with quote
Jupiter 200/4 at F8
https://app.box.com/s/dmrqjsvtt1idmr9mohq0 JPEG

https://app.box.com/s/mf2zev9bp0pzshccijdd DNG

Tamron 350/5.6
https://app.box.com/s/0evaaeceymmhr69nfi5z JPEG

https://app.box.com/s/a9zkvm8a671bzuvxehf8

Both taken at a greater distance than the other images,no tripod resting on a fence pole with a bag of dirt...I think I turned focus peaking off for these and the anti shake.Both at iso400...both focused on the piggies eyes.


PostPosted: Wed Oct 01, 2014 4:05 am    Post subject: Reply with quote
It look ok but I would expect better result if you nail the focus. Focusing this lens should be more easily than those 500mm mirrors. Have you use Liveview with zoom/enlarge when you focus?


PostPosted: Wed Oct 01, 2014 4:25 am    Post subject: Reply with quote
I do use the zoom in feature, and I have to say when there is full sun at my back it's hard to see anything.Until I get a shade, I just have to work with what I have....I do use focus peaking normally but even then there is a slight margin of unknown focus, depending on what lens you use.

I will take an image using the SP500, same subject and same distance and upload it here.It is so much easier to see the focus using this lens than the 350 Sad
JPEG SP500 https://app.box.com/s/6ft3klh9tvgjtixwu6jc
DNG SP500 https://app.box.com/s/lumo09oyjg62za2becfc

Last edited by mo on Wed Oct 01, 2014 4:39 am; edited 1 time in total


PostPosted: Wed Oct 01, 2014 4:39 am    Post subject: Reply with quote
I can barely see the screen of my NEX under direct sunlight too. If in doubt, I always perform a focus bracketing.


PostPosted: Wed Oct 01, 2014 4:44 am    Post subject: Reply with quote
I will take it out for one more spin and see what happens,the sun has gone from my back and the subject is in better light. I may have to look into focus bracketing with this lens.


PostPosted: Wed Oct 01, 2014 11:56 am    Post subject: Reply with quote
I'm afraid I agree with Calvin, mo, focus not quite hit. A case of if at first you don't succeed...

This was a post I made on pentax forums 300mm+ lens club basically about the same issues

Quote:
For me a big part of the learning curve with the manual focus lenses has been tweaking and fine tuning the viewfinder. At the mo I am using a Tenpa 1.36x magnifier with a split prism screen taken from an old ME super (needed cutting down). I think most regulars on this thread would recommend a screen upgrade. This thread on the canon ees screen is well worth browsing - I have one but haven't got round to fitting it yet.
I didn't think theTenpa would work for me because I need extra diopter correction ( I really should try contacts...) but in fact these magnifiers typically have a -1 diopter built in so my VF is sharp to my eye. I was lucky with the Tenpa a dodgy ebay seller (now defunct) was auctioning them 1p start so i got one for ~ $12 equiv and IMO it's a good piece of kit - good image.
But the other fall back resource I am always using, particularly when the subjects are stationary enough to allow it, is live view. I was about to say it's the most accurate focussing tool on the camera but with a moments reflection I would have to qualify that depending on the contrast and illumination of the image at high magnification and how well you can see the screen in the ambient (sun)light. (I haven't tried a loupe yet - on the try it out list...). It's also a reliable reference that can help you identify if there are persistent front focus/back focus issues with either your technique or the camera.

And always hold on to: fast shutter speeds (up the ASA) - aim for 1 over double focal length ie 1/800+; stop down a bit if you can; every trick available to stabilise lens + camera, reduce shake and vibration: 2 secs mirror lock up; remote shutter release an essential piece of kit. I have no doubt that part of the reason ...x...for example gets such good results with the 500's etc is the top end gimbal mount and tripod he uses. I'm at the make and mend end of the scale - home made bean bag! But it works. "


I have a sense that you front focussed (ie focus is just in front of the pig) on both your shots. This can be caused by inaccurate diopter correction, or by inherent lack of callibration with the VF screen (shimming). The big advantage of live view is that neither of these things come into play. Ever seen a pic of old time photographers with a black cloth over their head (to see the image on a ground glass screen)?? But sure , you have strong sun down there in the antipodes, doesn't help.

Remotes: see
http://www.ebay.co.uk/itm/IR-Remote-Control-for-Pentax-K-x-k7-K20D-K100D-K200D-K110D-E0Xc-/161438407219?pt=UK_Photography_DigitalCamAccess_RL&hash=item25967a9a33
K5:
http://www.ebay.co.uk/itm/IR-Remote-Control-for-Pentax-Q-K10D-K100-K100D-K110-645D-K-5-K7-K-X-K-R-istDS2-A-/201181836839?pt=UK_Photography_DigitalCamAccess_RL&hash=item2ed75f3627
Dirt cheap but work fine. Buy a couple so that when you lose one or can't remember which pocket you put it in, just grab the other.

PS you can just post a centre crop of the jpg on a test pic like these thats the only part of the image of interest. Do you have faststone? (free image viewer/editor)

UPDATE pics look better when downloaded and viewed in an image viewer, in the browser I can't tell whats 100%.
Focus trick: include a piece of newsprint to act as a focus target in the set up, the higher the contrast the easier to see the focus. Also slant it at an angle - that will act as a diagnostic re front/back focus. A ruler/tape measure works good too.


PostPosted: Wed Oct 01, 2014 12:59 pm    Post subject: Reply with quote
Thanks for the tips,if the weather permits I shall have another go...if anything I am getting plenty of practice focusing.Thanks for the Ebay link I found a cheap K-01 remote,no viewfinder with the K-01 its the good ol back screen of death in bright light...lol
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