Photoclubalpha

I purchased this lens about 2 weeks ago and I was wondering does anyone else use this lens? When capturing pic's at long range photo's show a bright spot in the middle and the whole picture seems to have a blue tint but closer shots do not show this abnormality . Any ideas what could be the issue as I have adjusted the shutter speed and changed filters but it is still pronounced in long distance shots.???

Any info would be helpful as im contemplating returning it.

Muzics wrote:I purchased this lens about 2 weeks ago and I was wondering does anyone else use this lens? When capturing pic's at long range photo's show a bright spot in the middle and the whole picture seems to have a blue tint but closer shots do not show this abnormality . Any ideas what could be the issue as I have adjusted the shutter speed and changed filters but it is still pronounced in long distance shots.???

Any info would be helpful as im contemplating returning it.

I purchased an AF Reflex 500 nearly 12 months ago, if this is the same animal, and have not noted the problem you indicate, it’s a nice lens. I took some good long shots at a wedding last year - good for candids, the lens looking so modest does not attract attention like my Sigma 50-500 would. Besides that latter is just too cumbersome for such an occasion.

A few questions

What camera body are you using it on?

What do you call long distance?

What were the lighting conditions, i.e. sun position andangle, sky clear blue/scattered cloud/overcast.

I'll try and match your conditions and see what happens.

What camera body are you using it on? A700

What do you call long distance? Max range 500 mm plus

What were the lighting conditions, i.e. sun position andangle==Midday sun shooting with sun to the left , sky clear blue===sky is clear and blue
Happens mostly on bright days each time i shot with it on sunny days i get this ring in the center of the photo thats brighter than the rest of the picture.
The camera is ok as i have shot the same photo with the 75-300mm with no overexposure in the center as with the 500
See pictures at http://www.jpgmag.com/people/Muzics to see the surfing pictures that i took i had to edit the pictures but you can still tell they also have a pronounced blue hue.

Thanks

If you cannot see it I can send a photo

The 500mm f8 has quite strong vignetting - light in the centre, dark at the edges. It really shows if you increase JPEG contrast, use less exposure, shoot sea, sky or flat lighting low contrast subjects. Most mirror lenses are like this.

David

Thanks Dave for the info
I do like the lens it takes good pictures ill just have to do as you suggested by using it to take low constrast shots and curb the long shots. Any good long range telephoto lens i should take a look at


Thanks again

Yes, the Sigma 170-500mm zoom is pretty affordable, and the Tamron 200-500mm zoom not bad. One of the best solutions is the Sigma 100-300mm f4 zoom, which is fairly large but very high quality for closer range sports and action, plus the dedicated Sigma 2X converter. This makes a 200-600mm f8 (same effective aperture as your mirrorlens) with closer focusing than you would expect from a 200-600mm, and autofocus still works.

David

The so-called 'hot spot'---brighter center, darker corners---of most catadioptric lenses looks like vignetting but technically is a different thing ... although the effect in the image is the same eventually. The degree of the hot spot from the same lens can vary; some shot are almost free from it, others show it quite accentuated. As far as I can tell the reason is stray light inside the lens barrel; the best counter-measure is a long lens hood. The original lens hood is ridiculously short. A plain tube made from black cardboard paper helps a lot.

The vignetting filter of Camera Raw or Photoshop can take care of the vignetting caused by the hot spot---with images from an APS-C format camera, try Amount +20 .. +30, Center 15. If in doubt, better err towards under-correction.

Generally, images from catadioptric lenses are a little low in contrast. When processing raw images shot with the AF Reflex 500 mm in Camera Raw, go to the Curves tab and select the curve for Strong Contrast (rather than the default curve which is Medium Contrast).

When compensating for the lens' shortcomings properly then a very sharp, clean image free of chromatic aberrations will emerge. The lens is not bad, it's just 'special.' The images do require some post-processing, that's true, but on the other hand there's no way to get longer telephoto reach at an affordable price in a smaller package. And with auto-focus, too! A small and light mirror lens in your bag will always yield better results than a huge and heavy apo telephoto lens in your closet.

By the way, the filter drawer from the AF Apo G telephoto lenses fits the slot in the AF Reflex 500 mm's barrel just perfectly ... including the integrated polarizer unit.

-- Olaf

01af wrote:The vignetting filter of Camera Raw or Photoshop can take care of the vignetting caused by the hot spot---with images from an APS-C format camera, try Amount +20 .. +30, Center 15. If in doubt, better err towards under-correction.

When compensating for the lens' shortcomings properly then a very sharp, clean image free of chromatic aberrations will emerge. The lens is not bad, it's just 'special.' The images do require some post-processing, that's true, but on the other hand there's no way to get longer telephoto reach at an affordable price in a smaller package. And with auto-focus, too! A small and light mirror lens in your bag will always yield better results than a huge and heavy apo telephoto lens in your closet.

By the way, the filter drawer from the AF Apo G telephoto lenses fits the slot in the AF Reflex 500 mm's barrel just perfectly ... including the integrated polarizer unit.

-- Olaf

Thank you for that.

There is also a vignetting control tool in Lightroom and it is straightforward to enhance the contrast.

I agree on the lenses benefits, especially the light weight but perhaps the Bigma (Sigma 50-500mm) is a better choice for airborne aircraft.

Now, where can I get a polarizing filter for this beast?

Also I wonder if a polarizer would have a minimizing effect on that ‘vignetting’?

Sorry Muzics, I have not yet had an opportunity to test this lens in similar lighting conditions to your shots (Combination of weather and having to grapple with a Norton Internet Security install not resetting the subscription date – the one for the previous stuck like glue! Considering a migration to Kaspersky!) although one shot with it last year, an ground-to-air shot of a Tiger Moth on a landing approach showed it markedly. I was not behind the camera, Dynax7D, at the time being in the front cockpit of the Tiger and was unsure as to why the ‘vignetting’ had occurred.

I borrowed a mates Minolta version and found the same vignetting. Yes it is small and light but I'm not that impressed.
I have my own Sigma 170-500 (pre DG) which is actually quite good but the focus is very slow. I usually use it hand held (aviation) but have used it on a monopod when on the Farne Islands (puffins). I thought the 500 mirror would be good at that but I'm not impressed, I prefer the adjustable focal range.
I am desperately hoping that Sony bring out a 80-400 or 100-400 lens as this would be ideal for me. Sigma have just anounced a 120-400 with HSM so my interest is currently there.

Mike

Some sample images from the 170-500
http://i19.photobucket.com/albums/b184/ ... opper2.jpg
http://i19.photobucket.com/albums/b184/ ... CT0175.jpg
http://i19.photobucket.com/albums/b184/ ... T0122i.jpg

All thanks for the information I decided to keep the lens but made a barrel for it to keep the light out and what a difference. Also i purchased the SAL 200G F28 lens which works very well also and is lighting fast in comparison, however the 500 does have its place in my arsenal.

thanks again for the info