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Tamron SP 350/5.6 DIY reapair or send it to a Professional?
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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


PostPosted: Wed Oct 01, 2014 2:49 pm    Post subject: Reply with quote
For non-moving objects, I use two second timer on my camera to allow a relatively low shutter speed. This will help to eliminate the vibration of pressing the shutter. You may also set the camera in continuous shooting mode, press down the shutter button and pick the best photo afterward.


PostPosted: Wed Oct 01, 2014 3:16 pm    Post subject: Reply with quote
heres a few test pics on my 06B for comparison pentax K-r, 12 MPx, jpg's



Its not a very good set up, the lighting in particular is too dull, although I was trying to use a couple of reading spots to brighten up a bit. distance ws about 4-5m, depth of field is therefore about 3-4cm. 100% crop:



Here's one from outdoors, about 30m distance, DoF about 1m+:








UPDATE the sun came out so I retook the pics, and (below) tamron Nestor 400mm f6.9 for comparison. Left the previous pic posted because it illustrates the importance of lighting.





06B gives typical mirror shots: inherently dull contrast, and TBH I find that these lenses are tested by high pixel/high pixel density sensors. if you're using a 16MPx, then actually the pics you got may well be as good as you can get. RAW does better with more leeway to oomph the contrast and sharpen.


PostPosted: Wed Oct 01, 2014 4:32 pm    Post subject: Reply with quote
Mirror lenses need sufficient light to give good results. My 06B have good resolution, decent contrast and almost no CA. Here is an 100% crop of a fence roughly 70 meters away without any sharpen.


With a bit of sharpen, the result becomes pretty promising. It will be even better with the contrast and charity boosted.


PostPosted: Wed Oct 01, 2014 8:26 pm    Post subject: Reply with quote
mo wrote:
... I had the iso at 400 which I use for the SP500.


That may not be enough unless shutter speeds are 1/350 sec or faster -- 1/350 sec is faster than hand-hold shake. Your camera should go to iso 1600 no problem. Wink


PostPosted: Wed Oct 01, 2014 10:28 pm    Post subject: Reply with quote
It has been suggested that I boost my iso setting higher than I normally would. Your 06B images look about the same as mine so perhaps it is performing within the accepted range for this lens?


PostPosted: Thu Oct 02, 2014 1:21 am    Post subject: Reply with quote
I got a little bored so thought I would try the G1 with its VF and fine focus,amazing difference I do know this sample is spot on for focus. The VF makes a difference.I also remembered to bump the iso higher.

G1 iso 800 tripod and fine focus https://app.box.com/s/yhu9j1zwgfx00rjic8v6 JPEG,I have not shot with raw on the G1 as yet. this was using the Fotassy adapter M42-M4/3 which I note was a little loose...combined with the Orginal M42 Tamron adapter.


PostPosted: Thu Oct 02, 2014 2:01 am    Post subject: Reply with quote
Congrats! The photo look good to me. The M4/3 cameras are pretty good on testing the resolution limit of manual lens thanks to their high pixel density.

As visualopsins suggested, I think it is OK to boost ISO to 800 or 1600 under sun light to keep the shutter speed high. The noise will only visible in the dark area.


PostPosted: Thu Oct 02, 2014 3:33 am    Post subject: Reply with quote
Do you think I can conclude from these tests, that there is no fault with the lens, and it is within the normal range in the way it produces images?
I wish my K200D was still working so I could test it on a heavy bodied DSLR.


PostPosted: Thu Oct 02, 2014 4:09 am    Post subject: Reply with quote
I think the resolution and contrast is consistent with the result of my copy. It does not seems there is any fault from the samples you have posted.


PostPosted: Thu Oct 02, 2014 4:47 pm    Post subject: Reply with quote
Final test - my standard shot of the castle tower.



Crops:
1. off the card jpg



2. pp'ed from RAW




These crops comfortably stand comparison with the same subject shot with my other TP's including eg tamron 200-500mm. Under these conditions, and range the mirror is at its best IMO. And also IMO it's more the sensor on my K-r that's the limit rather than the lenses.

I've put a couple more pics in the mirror thread, manual focus lenses.
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