A900 crop vs. A700

Specifically for the discussion of the A-mount DSLR range
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harvey
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Re: A900 crop vs. A700

Unread post by harvey »

Argonaut wrote:I'm surprised that nobody has mentioned the alternative to wide angle shooting with an a900 and some expensive w/a glass - stitching. Stitching software (I'm not talking what comes with every camera these days) is sophisticated enough to make seamless panoramas and landscapes. I use PTAssembler, but there are others too. For less than $100 and a KM5, I can make a gigapixel landscape with the FOV of your choice.

You can do a 360 degree panorama for $100? No tripod? No panorama head?

Even stitchnig handheld images for a landscape is still a fair amount of effort.

But yes, stitching is an option with any kit.

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Re: A900 crop vs. A700

Unread post by bakubo »

harvey wrote:You can do a 360 degree panorama for $100? No tripod? No panorama head?

Even stitchnig handheld images for a landscape is still a fair amount of effort.


Yes, using a tripod is better, but I have done several panoramas handheld and they were very easy to stitch. Here are three (after each one is a link to a somewhat larger version):

Image

http://www.bakubo.com/panoramas/bryce_canyon_pano.jpg

Image

http://www.bakubo.com/panoramas/vancouver_false_creek_pano.jpg

Image

http://www.bakubo.com/panoramas/austin_capital_pano.jpg
Last edited by bakubo on Sat Aug 01, 2009 8:17 pm, edited 1 time in total.
harvey
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Re: A900 crop vs. A700

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Sonolta wrote:... [DxO comparison figure]...

I'm not familiar with DxOMark IQ methodology. How do they derive the SNR numbers, specifically how are they averaged across the pixels?
I could not find this information on their website.

Harvey
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Re: A900 crop vs. A700

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Update, no pix yet. The light today meant that my test shots were taken on a very strong Slik professional tripod with no column extension, camera located indoors, subject outside. The exposure was 1/30th approx (varied a bit, 1/20th-1/40th) at f/8 ISO 200. Because it had tested out as very sharp, and for other reasons (to see its coverage on full frame, and then to shoot a set comparing SSS with OS, I used the Sigma new 18-250mm OS at 250mm. I used the A900, A700 and A380 as all three operate with the Remote Commander. I did not use mirror lockup. SSS was off, so was lens OS, of course.

Disaster! The Alpha 900 at 1/40th, with a 250mm lens, was incapable of taking a single sharp picture on the tripod. The mirror jolt blurred every shot. The Alpha 700 was just a little better, but no shot was really sharp. The sharpest results by far came from the A380 with its tiny, light body and very quiet mirror/shutter action. They were still not as needed. I then tested the A380 hand-held, with OS, SSS and no stabilisation. Without - useless, three frames three lost shots. With SSS, one almost usable, two poor. With Sigma OS, one nearly 'good', two as good as the best SSS.

But I do not have the comparisons I needed, and I can now see that the A900 has a really serious problem around 1/30-1/60th which probably affects handheld pix as well. The mirror jolt creates a double image, not a smooth blur.

The surprise is the A380. it looks as if marginal handholding may actually be better due to the lack of any substantial mirror slap.

Will return to this later. Have just had to take an hour out to produce the new Alpha 850 page on the website, now that we all know it will be a full frame 24 megapixel exactly the same as the A900 in every respect except the shooting speed and viewfinder.

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Re: A900 crop vs. A700

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David Kilpatrick wrote:All well argued Don. I agree. I would not use my A900 for wildlife or sports, the A700 has higher true resolution - but I would very much like micro AF tuning to improve it with some lenses!

One thing we are omitting to say is that the A700 and A900 make an amazingly good team, they are so similar in most ways to handle. But if the truth is told, the old D7D and the A900 have much in common and every time I go into the studio and use the D7D I am reminded just how far ahead of its time it was despite being released in 2004 (it was designed for release in 2002 but never got there). I also think the A900 is or was ahead of its time, and simultaneously 'behind the times' - I doubt that any camera will again be made with the same richness of control interface access the A900 possesses.

It's far too financially tempting to stick it all into menus...

David

I'm off on another photo safari next Spring. I may swap one of my A700s and the SAL1118 for an A900...unless something more interesting turns up ;-)
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Re: A900 crop vs. A700

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Thanks for the DXO info.

Sonolta wrote:If you need more detailed info then what they provide on their website then you may need to contact DxO directly.

I have just done so.
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Re: A900 crop vs. A700

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David Kilpatrick wrote:Disaster! The Alpha 900 at 1/40th, with a 250 mm lens, was incapable of taking a single sharp picture on the tripod. The mirror jolt blurred every shot.

Huh!? "Incapable"? What do you think mirror lock-up and mirror pre-fire are for? Hint: The A900 has both. So has the A700. And it actually works. I have taken hundreds of tripod shots with the A900 and haven't lost a single one to mirror slap.


David Kilpatrick wrote:The sharpest results by far came from the A380 with its tiny, light body and very quiet mirror/shutter action. They were still not as needed.

So if I understand correctly, the A380's mirror jolt is substantially less than the A900's but still not completely absent. But it has neither mirror lock-up nor mirror pre-fire. So unlike the A900/A700, the A380 really is incapable of taking sharp pictures from atop a tripod at moderately slow shutter speeds.

As I keep saying: a toy.


David Kilpatrick wrote:... I can now see that the A900 has a really serious problem around 1/30 - 1/60th ... which probably affects handheld pix as well. The mirror jolt creates a double image, not a smooth blur.

The A900 has a problem!? :shock: You're screwing up the facts. Actually it's the A200 - A380 series bodies which are having a problem, as they don't feature mirror pre-fire at all. And yes indeed, it does look like a double image rather than a smooth blur. For example, the Minolta SR-T 303b with a 600 mm lens on a big tripod at 1/15 s or 1/30 s did exactly the same. As a matter of fact, basically all 35-mm single-lens reflex cameras of the last four or five decades do that, to varying degrees (depending on the camera's weight, the lens' focal length, and the tripod's sturdiness). By the way, try it in portrait orientation---then it will come out even worse. That's why mirror lock-up is an essential feature for any SLR camera ... even at entry-level.

You don't want to tell us you never came across this phenomenon before!?

-- Olaf
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Re: A900 crop vs. A700

Unread post by Greg Beetham »

Yep APS-C format has the advantage over FF in telephoto and macro, I've been saying that for years too anyone who cared to listen, BUT you can make FF equal or better than APS-C (in telephoto) if you want.....basically (as Don is saying) it's just a question of 'how big is your wallet' ? (it will need to be very big) :mrgreen:
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Re: A900 crop vs. A700

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Greg Beetham wrote:Yep APS-C format has the advantage over FF in telephoto and macro, I've been saying that for years too anyone who cared to listen, BUT you can make FF equal or better than APS-C (in telephoto) if you want.....basically (as Don is saying) it's just a question of 'how big is your wallet' ? (it will need to be very big) :mrgreen:
Greg


Besides the considerable additional money there are other issues that are important to some people:

    1. size
    2. weight
    3. fewer choices to get a particular fov (For example, how many ways can you get 450mm on the A700? How many on the A900?)
    4. A900 uses the full image circle so quality of corners is more important and more difficult to get. A700 uses the better central part of the image circle.
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Re: A900 crop vs. A700

Unread post by Greg Beetham »

bakubo wrote:
Besides the considerable additional money there are other issues that are important to some people:

1. size
2. weight
3. fewer choices to get a particular fov (For example, how many ways can you get 450mm on the A700? How many on the A900?)
4. A900 uses the full image circle so quality of corners is more important and more difficult to get. A700 uses the better central part of the image circle.


Extamundo Henry, the above points are just part of the aforementioned APS-C advantage.
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Re: A900 crop vs. A700

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01af wrote:You don't want to tell us you never came across this phenomenon before!?

-- Olaf


Of course I have, and tested it often enough in the past. It's the difference which is surprising, between the A900 and A380. I am not especially worried about the result as I generally don't combine a tripod with 1/30th or thereabouts, and if I do, I will use the 2sec mirror up (or longer on models which offer it). But there are occasions when I use a tripod while holding the camera, for real-time shooting, and mirror up is not an option.

Let's just say that I would happily have fired a Hasselblad at 1/30th in this situation, but not with the equivalent of a 375mm lens on the front (600mm or thereabouts would be the Hasselblad equivalent). This is not a light tripod, it's the modern version of the Slik 67 which I still have an old one of as well. I have never thought of the A900 mirror action as particularly liable to produce vibration. It seems that it is.

Exposures at 1/25th are consistently better than those at 1/50th on the A900/tripod/no mirror lock combo. This indicates that there is a peak of vibration hitting at around 1/50th, which is maybe not a good thing.

98% of my photography is hand-held and using SSS, which would almost certainly have been better than a tripod in this case.

I'll have another go on Sunday, weather and light permitting. At least with the A700 and A900, mirror lock up can be used - but not with the A380 of course.

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Re: A900 crop vs. A700

Unread post by Greg Beetham »

Hmm I'm just wondering if the SSS being 'off' has relaxed the mounting of the sensor enough to record the mirror slap vibration. I wonder how it is with SSS turned 'on'.
Now if you had some benchrest sandbags David, you could eliminate any question of image 'pivot' movement getting into the mix....
Also that lens has some question marks over it as well with it's internal floating elements...
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Re: A900 crop vs. A700 Link to images

Unread post by sury »

This afternoon I took these shots. There are 12 images in the set. All are taken with Beercan at 210 except for four of them, which are at 135mm on A700 (Hoping to get equiv. of 210 for A900 comparo). All these shots were taken sequentially from approximately same location (within inches may be).

A900 in A mode, f8, f9, f10 and f11, beercan at 210mm
A700 in A mode, f8, f9, f10 and f11, beercan at 210mm
A700 in A mode, f8, f9, f10 and f11, beercan at 135mm.

No post processing, straight from the camera. Please let me know if I could take some other combo. I have couple of hours tomorrow to spare. As for long lenses, I have a Tamron 200-500, Sigma 70-300 APO and a Takuram 300/f4 with M42 (chipless) adapter.


http://www.flickr.com/photos/bigsur/sets/72157621916873046/


harvey wrote:Does anyone have comparisons of A900 cropped compared to A700 for same image view with the same lens (between 200mm and 450mm)?
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Re: A900 crop vs. A700

Unread post by sury »

Hmm. I can post the original size image at say f8 of both A900 and A700. I gave full permission on the images. I uploaded using flickr uploader. Let me check again.


Sonolta wrote:Sury - I don't see the all sizes tab. How do we get to the full size JPG's and/or Raw files? Did you forget to enable view all sizes or did you not upload the full size files?

-Sonolta
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Re: A900 crop vs. A700

Unread post by sury »

OK. Since I took them with A mode, the shutter speed could be different. I will take some shots on tripod tomorrow AM in M mode. I will also use Mirror lockup and use RAW+jpeg. Only converter I have is Sony IDC. I will use camera default. Now back to flickr on permissions issue.

With best regards,
Sury


Sonolta wrote:Sury - Thanks for taking the time to post those but what we are really looking for is a controlled test and full size images or 100% crops. To compare properly this test should be precisely done so that we can rule out extraneous influences like handshake blur, SSS etc. For instance I notice at least 1 of the 210 shots was taken at 1/160. I think we are looking for tripod shots precisely focused so we can get a real good look at what we are talking about here. The test does not have to be done exactly like the way this photographer did it but it should be at least something similar:

All of the photographs presented in this article were taken using my 17 pound studio tripod. I used manual focus to the exact same spot in each image. As an extra focus control measure I took three shots of each subject and re-focused in-between each shot. I examined the images and looked for the best focused shot. In truth, there was almost no difference in focus in the series of images. I have been successfully using manual focus on a variety of camera types for over 25 years.

I used manual exposure at 1/320 sec @ ISO 100 and F8 with the mirror locked up for all of the outdoor comparison images. All of the photos were shot in RAW. I used Capture One Pro to convert and save to 16 bit TIFF. I used Capture One's default settings except for using 'film extra shadow' and 'standard look' sharpening at 20. I used ETC's low sat profile for the 1Ds Mark II images. All of the full frame photos and thumbnails were saved as level 9 JPEG in Photoshop with the EXIF info intact. The thumbnail full resolution examples were cropped out of the original TIFF images.


http://www.sphoto.com/techinfo/dslrsens ... ensors.htm

Thanks.

-Sonolta
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