Conversion Help...

[dunlin]

Hi all
Can anyone help i was trying to work out how you know the magnification of telephoto lenses compared to binoculars..ie how close is a 500mm lens compared to 10 x magnification binos. and is there a formula you can use
( assuming the 500mm lens is on a full frame sensor)
cheers mark n ..............

[colincurry]

My Panasonic FZ30 has 12 x optical zoom that comes out at 420mm without any crop factor as provided by a DSLR.

Hope this helps.

Colin

[pressld2]

On a 35mm camera a 50mm lens is considered standard meaning it captures (almost) exactly what you see, neither magnifying nor reducing. The same is true for DSLRs with a full frame sensor. The magnification of a telephoto lens can be found by simply dividing its focal length by the 50mm standard. So a 100mm lens is 2x magnification, 200mm gives 4 and the 500mm from your original question gives 10x.

However this is only an approximation because of the "(almost)" in my first sentence. A true "standard" lens for a 35mm camera is actually closer to 55mm, meaning that 2x magnification requires 110mm, 4x magnification means a 220mm lens and so on. Using this slightly more accurate figure your 500mm lens gives 9.0909090909...x magnification.

Dave P.

[dunlin]

Many thanks for the info. I thought it was around 10 times but wasnt sure.
I am thinking of either going down the digiscoping route or buying a 500mm lens with a 1.4 converter. The latter option is going to cost a packet though so im trying to justify the cost.
With a 1.4 converter i should get around 14 times magnification i think ! but also the added advantage of capturing moving subjects like birds and other wildlife.
Thanks again for the help
..........mark n............

[Blackbrook Eye]

Your choise of equipment would much depend on what you want the pictures for, the difference between digiscoping and using a full frame dslr is truly astronomical, the very fact that you have asked this question, would lead me to believe that you are prepared to take photography seriously, in this case digiscoping is out of the question regardless of cost, however superb results can be achieved with lower spec SLRs without the need to get involved with full frame, which really is a second mortgage option, and totally over the top for even the most advanced amateur.

[HowlinWolf]

The diagonal of a format is normally considered the proxy for a standard lens. In 35mm terms (135 format), the frame dimensions are 36x24mm, giving a diagonal measurement of 43.3mm. The forthcoming Nikon D3 has a digital sensor that measures 36x23.9, so for all intents and purposes, is the same size. As Dave P points out, the 50mm lens is regarded as a standard lens in this case, although a 35mm lens could also be considered for the same title. Nit-picking, I know, but the usual zoom ratios are calculated from the more accepted, and usually much maligned (these days) 50mm "standard" lens.

As a matter of interest, a standard lens for 6x6 medium format is considered to be an 80mm lens, and the standard lens for 4x5 format would be in the region of 150mm.

HW

[dunlin]

Originally Posted by Blackbrook Eye

Your choise of equipment would much depend on what you want the pictures for, the difference between digiscoping and using a full frame dslr is truly astronomical, the very fact that you have asked this question, would lead me to believe that you are prepared to take photography seriously, in this case digiscoping is out of the question regardless of cost, however superb results can be achieved with lower spec SLRs without the need to get involved with full frame, which really is a second mortgage option, and totally over the top for even the most advanced amateur.

I know what you mean regards digiscoping, i tried it several years ago and was disappointed with the results.
I own a canon 5d and use the "L" series lenses . I am probably over critical when i look at my own pictures and the difference in quality is huge when you compare the two types of wildlife shots SLR/digiscoped images.
The only thing putting me off going down the slr route is the cost of the 500mm L series f4 the cheapest ive seen it at is ?3800.
The problem with digiscoping is poor quality images and the difficulty in taking pictures of moving subjects. As i said earlier i tried it once and ended up selling the equipment.
could do with a lottery win that would solve the problem.
THANKS for all your help
best regards
............mark n..............

[Hobjob]

Just to make things a little clearer

If you buy a dSLR that is not full frame then you
get a magnification factor from that too.

It is often referred to as the "crop factor" and
is commonly about 1.4 - 1.6.

That is a 400mm lens suddenly becomes 560 - 640mm
all for free
(well apart from some v small loss of pixels etc.)

[DaiTheDragon]

Sorry Hobjob but you are giving the wrong impression in your post. If you put a 400mm lens on a FF, 1.3, 1.4, or 1.6 size sensor you get exactly the same picture at exactly the same distance except that if you had a bird in the center the FF would have more space around the bird than a 1.6 sensor. In other words using a 1.6 sensor would look like a cropped version of a FF sensor.

Dai

[pressld2]

What you say is all completely true Dai, but there is another consideration...

Assuming that both the full frame and the 1.6 sensors are 10 megapixels then cropping the image from the FF to match the one from the 1.6 (to give you the same size bird) means you end up with a 6.25 megapixel image. Whereas the one from the 1.6 sensor is still 10 megapixels. So although in truth the smaller sensors do not really magnify anything, they just record a smaller area of the image that the lens can "see", in practical terms by cramming the pixels closer together on the sensor you do end up with an enlarged image at the same megapixel resolution. And as long as this isn't done at the expense of extra image noise (which it certainly isn't on the Nikon DSLRs) then I for one prefer it for wildlife photography. It's not so good for landscapes and wide angle work.

Dave P.

[eeyore]

Originally Posted by DaiTheDragon

Sorry Hobjob but you are giving the wrong impression in your post. If you put a 400mm lens on a FF, 1.3, 1.4, or 1.6 size sensor you get exactly the same picture at exactly the same distance except that if you had a bird in the center the FF would have more space around the bird than a 1.6 sensor. In other words using a 1.6 sensor would look like a cropped version of a FF sensor.

Dai

which is exactly the same result that you would get through having a longer le
ns as hobjob said (with the slight exception that a 500mm lens would give slightly less depth of field )

Nor is it exactly the same as a crop as the number of MP your sensor has comes into play - if the FF sensor has the same megapixelage as the 1:6 then cropping it to the same factor would leave you with a smaller file.

I know that technically it is a crop factor but the 35mm equivalent lens lengths are pretty widely accepted now , like it or not.