Technical questions from a newbie

[tnFut]

Hi everyone,

I am a new member to the forum and new to 'professional' photography.

I have a question (not sure if posted to the right place; excuse me if not):

I have searched a lot to understand what is the 'focal length/distance', the 'object distance',
the 'aperture' etc. but I got a little confused. I found some calculators and formulas to compute,
for example, the 'ideal focal length' but I am not sure about the answers.

I am carrying out a project and I have to buy (professional?) equipment to take photos and videos
of aircrafts for analysis. The problem is that I am not sure about the ideal equipment. Given that I
will shoot mostly in daylight and the object will be at a distance of maximum 5km, what specifications
would meet my needs ('focal length', 'aperture' etc.) and why?

[A.M.D.A.]

Hi tnFut,

First of all – let me state that yours is a very complicated question to answer.

There are NO ideal aperture/shutter-speed settings for any given scene – the photographer must decide at the spur of the moment what will work best to achieve the photograph he/she has “formulated” in his/her mind.
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For example:

If you only have a lens whose maximum aperture is f/5.6, but the photographic situation calls for a very shallow depth-of-field, then this lens would not be ideal. You have to either change lenses or if there is no time to do so – try altering the focal length and distance from the subject.

#1. The longer the focal length – the less depth-of-field.
#2. The closer the lens is to the subject – the less depth-of-field.

#3. The shorter the focal length – the more depth-of-field.
#4. The more distance between lens and subject – the more depth-of-field.

In this example – the better choices to achieve the goal would be #1 and #2.

There are also many other factors to take into account before snapping the shutter, here is one:

~Perspective compression: For landscapes, the better choice in a lens would be wide-angle, since it seems to “push” everything farther away – thus giving an excellent sense of depth in the image.

For portraits, a large aperture and moderately long focal length are usually considered ideal – but not always, because as I already mentioned – all photographic situations differ and the photographer has to make his/her own judgement of what setting to use.

Sorry, but I can’t tell you what combination of ISO/aperture/shutter-speed/focal length to use, a certain combination could work beautifully in my backyard, but you may end up with an under-exposed, blurry picture.

From what you say that you will be photographing objects at a long distance away – it sounds like a good super-telephoto lens may well fit your needs. The EXACT focal length depends on the subject size.

You haven’t mentioned whether the aircraft will be flying as you shoot or whether they will be parked. This could mean a great difference in choice of gear.

Lastly, I have an entry in my PhotographyREVIEW.com blog dealing about finding the right camera. I am also nearly done another one for finding the perfect lens.

Photography is a field which requires A LOT of practicing, trial-and-error, patience, and willingess to learn. Don't expect outstanding results after one day of becoming interested in taking pictures.
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Hope you find this helpful, any more questions – please feel free to ask.

[tnFut]

Firstly, I want to thank you for taking the time to answer my question.

I understand that there is no 'ideal equipment' for 'general purposes' and I'm sorry for the wrong statement: when
I stated 'ideal equipment' I meant equipment which will fit my needs. I would like to find the best equipment
given my system limitations. To be more specific:

I want my system:
* to take photos and videos of flying aircrafts in daylight and at a distance of maximum 5km.
* to be able to zoom in and out accordingly (with autofocus function) so as the object length to occupy at maximum
half of the image length (I want to buy only one lens).
[Aircraft lengths vary from 15m to 75m.]

I don't expect the best output quality; I just want a typical photo or video. Depth-of-field doesn't matter.
I don't want to buy the perfect gear; I don't want to buy the wrong gear.

So to conclude, my question is this: what is the appropriate range of the focal length, of ISO, of aperture etc. (minimum
and maximum values)?

For example, what should be the minimum and maximum values if i would like to shoot similar photos like the images
below (found on internet):

[aperture: F/6,3/6,7/12,3 , focal length: 300/450mm ISO: 200/320, by reading the exif info]

Img.1:
http://www.freefoto.com/images/20/05...rcraft_web.jpg

Img.2:
http://images.businessweek.com/ss/08...rows_final.jpg

Img.3:
http://vaibhavsharma.com/photos/albu..._3_engines.jpg

Img.4 (maximum acceptable zoom):
http://www.freefoto.com/images/22/11...craft-_web.jpg



Thank you again for your time!

[Dylan8i]

why wouldn't you want the planes any larger than imag 4?



also post links to pictures that you have not taken yourself, as it is an infringment on the actua photographers rights.

and to conclude i don't think your going to find one lense can do all that. although maybe something like a 100-400l (canon) or 80-400 (nikon) might be around what your looking for.

although at 5km away even a 75m long plane is going to be tiny.

[A.M.D.A.]

I agree with Dylan.

Please remove the photos you posted here – unless you have permission from the owner. It is actually against the law to use someone else's work without permission.
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A long focal-length lens will be needed in order to fill the frame with distant aircraft.

Are you worried about obtaining perfect image quality? Because, for a far cheaper price you can buy a “super-zoom” compact digital camera. They won’t provide as much image quality as a D-SLR, but still are very good.

Olympus and Four-Thirds makes D-SLRS with better image quality than compacts, and can provide plenty of "reach", due to the 2x crop factor.

Another alternative is to buy a high-megapixel camera and medium-range lens – then crop the image in a computer software program. How much to crop will depend if you are planning to make printouts (and what size), and the focal length of the lens.

[tnFut]

Thank you for your replies.

I respect everyone's rights and I will remove the above images but I want your help
on how I could do this! There is no 'edit' or 'delete' button. I just wanted to show you
some examples (would be better if I had provided only the links).

I don't worry about perfect quality so I think the best solution is to buy a lens with
focal lengths in the above range and a high-megapixel camera in order to crop the
image.

[A.M.D.A.]

Thank you for your replies.

I respect everyone's rights and I will remove the above images but I want your help
on how I could do this! There is no 'edit' or 'delete' button. I just wanted to show you
some examples (would be better if I had provided only the links).

I don't worry about perfect quality so I think the best solution is to buy a lens with
focal lengths in the above range and a high-megapixel camera in order to crop the
image.

There is no EDIT/DELETE button because a member can only do so within 24h of the original posting. Within 24h, the EDIT button is next to the QUOTE at the end of your posts. After that time range, it will "disappear". You'll have to ask the forum Moderators or an Admin to remove the images.

Getting a high-megapixel camera and medium-range lens may be a good idea for you. Just keep in mind that the more you crop, the less your effective maximum output size will be. A 12-megapixel image can be cropped considerably and still have enough pixels left for an 8.5x11 inch printout. Of course, a 14.6 or 15 megapixel camera will offer far more versatility.

For only displaying photos on the web, 4mp+ is enough and gives plenty of cropping options.
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Also, here are some camera features you will be needing for this type of photography:

~AF speed: I know from personal experience that cameras/lenses with slower AF can be a nightmare to use when trying to take pictures of rapidly moving objects - such as aircraft. Fast AF is a must.
~High ISO low noise capapbility and/or a large max aperture lens: In order to "freeze" rapidly moving objects, a fast shutter-speed is needed. Fast shutter-speeds don't allow much time for light to strike the sensor, so either a high ISO number or a lens with a large aperture (e.g. f/2.8) will make life a lot easier.

D-SLRs and interchangeable lenses answer the previous, with some models being better than others.

[tnFut]

Thank you very much for your help!

[Loupey]

Based on what you've written so far, most dSLR's will suit your needs along with a zoom that takes you up to 400mm (300mm might work for the larger planes).

Don't worry about depth of field too much. The DOF at "infinity" is infinity. Just find the aperture that performs the best for a lens and keep it there. Then use the shutter speed and ISO to get the proper exposure.