Photoclubalpha

Today...surprise, suprise,a big box arrived with all lenses and the A700, of course. The report sheet said they ahad djusted the A700 to function with the 70-200 by software.
That might be the software that was mentioned as a potential V5, but I'm not sure.
I think, the lens is oké-ish now.

I would like to ask you guys to have a look at the crops from the test chart.
I also did the normal 'cerial box tests', but they do not tell me more then the ones I'm showing here.

I will post them two by two, 70-100 mm F2.8 and 135-200 mm F/2.8.

Here are the fist two.

70 mm


100 mm


next the 135mm en 200 mm

Is that on a computer monitor or printed out on paper?

135 mm




200mm

KevinBarrett wrote:Is that on a computer monitor or printed out on paper?

100% crop of a paper print.....but I had to reduce the size to fit them on the page.

It looks just fine to me.

David

David, thanks for looking at it.
Yes, it does. Though wide open I still see a slight tendency to FF at 200 mm, and surprisingly 135 mm is now slightly BF'sed.
But from thereon there is good improvement in terms of focus accuracy.

One weird thing though. They said they adjusted the lens by software only. I'm not sure if they touched the hardware, but now my Tamrons look less sharp wide open.

Anyway with the focus being more or less right, I should be able to judge the quality of the lens. Sofar, it hasn't convinced me much, but I will give a couple of runs to make my final judgement. If it doesn't impress me afterall, I will sell it.

lock

Do remember that the 70-200mm, though excellent, is not pin-sharp wide open - just the same way the Nikon is not, the Canon is not, ditto Tamron and Sigma. The f/2.8 result looks about the same sharpness as a 50mm f/1.4 stopped down to f/1.6 - not as soft as a 50mm wide open. Just closing down to f/3.2 or f/3.5 makes a big difference and the lens is at its most accurate for resolution and focus around f/4 to f/5.6 (for close-ups, use smaller settings - f/11 if possible).

I don't know how the tables are programmed, or reprogrammed, for the 70-200mm and why this should have any effect on the Tamron (shorter) lenses.

Most subjects you shoot will be three-dimensional and not many will demand wide aperture or close focusing distances. Before making any decisions, use the lens on normal subjects at typical working settings and see how it does.

David

David Kilpatrick wrote:Do remember that the 70-200mm, though excellent, is not pin-sharp wide open - just the same way the Nikon is not, the Canon is not, ditto Tamron and Sigma. David

I'd say the Tamron 70-200 beats the Sony, particularly at 200 mm. If it wasn't because of noisy AF-mechanism, I probably would have bought the Tamron.

David Kilpatrick wrote: Just closing down to f/3.2 or f/3.5 makes a big difference and the lens is at its most accurate for resolution and focus around f/4 to f/5.6 (for close-ups, use smaller settings - f/11 if possible).

I bought it as one of the three fastest zooms to use it in low light, indoor sports. So I prefer good sharpness at 200 mm, though indeed, in most cases the pictures will not be closeups. In most cases the distance will be between 30 to 60 feet. But the sharpness and resolution should provide enough detail to allow some cropping to frame out the subjects. That's when I will judge the lens.

lock

Back to the real world I quickly found out things were still 'weird'. A couple of faces, whend focussing on the eyes cause sharp noses but blurry eyes at 200 mm. At the lower end of the range 100 mm and downward, the hair was sharp but the eyes were out of focus again. I thought of user errors, until I tested it with the tape on the fence and a tripod:

100 mm F/2.8:


200 mm:



Grrrrr. Same old story....FF at the high end, BF at the low end. Or is it just me ?

BTw, I've got a number of other examples with identical results. 70 mm as awfull.

I think both areas to each side of the white tape are higher contrast than the white tape itself and is catching the attention of the focus? couple that with shallow DOF and something you don't intend to focus on is going to be sharp

That would be an exceptable explanation, if it wasn't for the fact that in 5 pictures on a row at 200 mm, and refocusing each time a picture was taken, it comes up with FF. At 100 mm ( and at 135 and at 70 mm) it picks it up with BFin a total of nine out nine...
Surely with two rivaling more contrast parts it might pick either two ?

In the next excpamples you ca nsee what happens with F/2.8, distance about 10 feet. Focus is set on the left end of the knife, angle from tripod mounted A700 to the knife about is 45 degrees, and pictured are cropped to show the effect.

70 mm:



200 mm:



At 100 mm the BF is less prominent but clearly visable. At 135 mm it is about oké. Then at 200 mm (see picture) it reverses to FF.
Every picture has been reproduced three times after complete refocus, with identical result at each focal length. I could reproduce the same effect with the tape pictures five resp. three time on a row as well.

lock

lock

Did you use manual or auto-focus?

Cheers,

Do you know anyone else that has a a700 (or any model Alpha)?

If you try the lens on another body and it works fine, then aleast you know the problem is with your a700.

Cheers, Stephen

stevecim wrote:Did you use manual or auto-focus?

Cheers,

It was the AFadjustment...they said they did.

stevecim wrote:Do you know anyone else that has a a700 (or any model Alpha)?

If you try the lens on another body and it works fine, then aleast you know the problem is with your a700.

Cheers, Stephen

That's easier said then done. Sony users are quite a minoritiy over here, A700 users in particular. But I might give a try .