Dull photos / Dim User

Hello all.

Help!

As a newbie to the Pentax forum (bought my first Pentax just 3 days ago - a K20D with Pentax 18-250 lens), I was wondering if anyone could throw light upon my dull photos - pardon the pun!

I'm still very much finding my way around the camera, but noticed it was taking very underexposed images last night, indoors, in auto on the mode dial, when pointing and focusing on light-sources. For example, when taking a photo of a corner table-lamp of maybe 10 small 5 watt halogen bulbs this would result in a very dim image, although not so with my Sony A200. However, the K20D gives perfectly acceptable photos in the same room (same low-light conditions), when taking a photo but NOT pointing directly at any light source.

Sorry to be so dim, but I've had only about 1/2 hour per day to experiment so far. Any advice in providing a shortcut to the answer would be very much welcomed and appreciated.

Thanks.

Alan.

If you think about what happens when you include a bright light in a scene, you are adding lots of light that falls on the metering system. So the camera reduces the exposure accordingly.

The answer is to dial in exposure compensation when including bright lights or sky. Maybe 0.5 to 1 srop for starters, more if needed.

At least with a digital camera you can see the resukt straight away.

I think both George and myself routinely dial in + 0.7 exposure compensation to almost all images.

Let the histogram be your guide and use the 'expose to the right' rule. That is, the bulk of the histogram 'hump' should be as close to the right hand side as possible without clipping highlights. By doing so, you'll expose shadows more correctly and you can reduce the exposure if necessary in post processing.

I'm guessing you are still shooting JPG, when you've 'matured' into Pentax DSLR photography, you'll switch to RAW and find out how much better it as for compensating for incorrectly exposed images.

Is there any information you'd recommend on how to correctly use histogram information.

I looked at it once and didn't have a clue as to what it meant

The histogram effectively shows how much of each colour (luminance) exists in the photo.

The scale runs from black on the left to white on the right and all colours of the spectrum in between represented by their grey level.

EDIT: Matt's correction below shows that my understanding of the histogram is partly incorrect. The following paragraph is therefore inaccurate but I've left it in, otherwise Matt's correction is meaningless.

If a spike reaches the top of the graph anywhere along it's length it means that colour is clipped, meaning it has a higher intensity than the camera can capture. These spikes will most typically occur at the extreme left (black) or right (white) of the graph.

I find that the best histogram image for exposure accuracy, and which offers the best chance of getting it right in post processing (PP), is to have most of the white 'hump' of the histogram closer to the right, rather than to the middle, and certainly not the left.

If the bulk of the white hump is closer to the left, the image is under exposed and shadow detail will probably be lost. If it's not lost, you'll find yourself increasing the exposure in PP, only to suffer from noise in the shadows.

Better to have a slightly over exposed image where you can decrease the exposure in PP, than an underexposed image that needs an increase in exposure during PP.

For a more complete and illustrated explanation, see this.

Hope that helps.

Thanks, John & Peter.

I will have a 'play' this afternoon during lunch-break at work. I'm still very unaquainted with the Pentax Menu systems & the K20D's buttons, and that's where my great frustration lies.

Having owned my little Sony A200 for 6 months, I'm able to alter the EV easily, albeit, I never had to.

I had read, and seen on YouTube, that the K20D under-exposed a little, so the dull photos last night came as no great surprise. I did wake once or twice though during the night wondering if this was a gremlin within my camera only. I feel a bit more reassured now thanks.

Hopefully, I'll track down how to increase the EV during lunch today.

Many thanks.

Alan.

EV compensation is adjusted very easily on the K20D. Press the button on the back that is above and left of the AF button. It has a + and - symbol on it. At the same time, turn the front e-dial and check your setting in the lcd monitor on the top plate.

Hi, Peter.

It's interesting what you say about the histogram levels. I was introduced to the 'theory of' recently during my short OU course, and have picked up info from various other sources too.

Somewhere admidst all this info, I'd learned about the K20D's tendancy to under-expose, but how this wasn't too bad as detail could always be rescued in the digital darkroom. The opposite, i.e. burned out highlights, once gone were gone for good!

So, your recommendations on just where to pitch the histogram levels are very much appreciated, Peter. Actually, it's the customisation of the Pentax that I'm really looking forward to. Just got to figure out those buttons asap!!!

Best wishes.

Alan.

Wonderful! Revelation!!
I guess I should read the manual too.

Many thanks.

Alan.

Just to correct Peter's histogram explanation...

It doesn't matter how high the histogram graph is - that just shows there's lots of pixels at that particular intensity. What matters is where the "hump" (or "humps") sit.

The areas to watch are the extreme left and extreme right
Ideally you don't want anything touching the far left or the far right - that means information has been lost as either too dark or too bright (respectively). However, in practice this isn't always possible.

Cameras have a certain "dynamic range" - the variance of dark to light they can handle. The human eye has a phenomenal dynamic range (in part backed up by the brain's ability to seamlessly join dark and bright regions while adjusting the eye to compensate). Cameras have limited range - they cannot, for example, record direct sunlight at the same time as pitch black! (Photographers will often use filters, multiple exposures, even "HDR" photography to capture wide dynamic range situations.)

In the OP's original situation, pointing the camera directly at the light source is essentially saying to the metering system "The light source is important - please record it for me". Consequently, the rest of the image has to plunge into darkness (because the range of bright to dark is outside the range) - the camera is trying not to "clip" the part of the image you are saying is important.

When looking at the histogram you have to also take into account the subject - for example, when taking images of stained-glass windows, or subjects that are mainly black, or mainly white - you need to use some discernment when interpreting the histogram

The Pentax dSLRs have a couple of things that help in those situations:
First, there is the "AE-L" button. You point the camera more towards the lighting level you wish to be "normal", and press AE-L. Then, when you reframe with the light source more in the frame the camera will "ignore" it - taking the original reading.

Secondly, you can use "M" mode. Again, here you can carefully examine the range of light levels and use your brain (!) to work out the "correct" exposure - based on what you want shown in the image.

Thirdly, there is the exposure compensation.

Don't forget that the metering system aims for mid-grey. So, if you are taking a shot of a black cat against a black wall you will have to adjust the exposure to make it underexpose by 1 or 2 stops (otherwise you'll have a grey cat against a grey wall!). Conversely, taking a shot of a white tree in a snow covered hill will need over-exposing by 1 or 2 stops (otherwise, again, you'll have a grey tree against a grey hill!).

As John mentioned, the beauty of digital is its immediacy. You can always check straight away and adjust. Additionally, you have some latitude when you get back to the PC - you can adjust exposure somewhat there (especially when you use RAW to shoot).

Hope that explains things a bit better!!
Matt

Wonderful information!
Sorry Alan for hijacking your thread, but when Peter mentioned the histogram I just had to ask.

It's certainly given me food for thought and I will start using it next time I get my camera out.
It wasn't so scary after all

Father Ted I read this and it helped a bit

link

Your mileage may vary as they say

Mike

Thanks for the correction Matt. I'm still learning . . I just wonder if I'll remember it next week . . .

John/Peter...I tried this over the lunch-break; works beautifully thanks. Although, not available when mode dial is turned to Green: Page 100 of the manual.

Matt, Using the AE-L button as advised worked a treat. Very many thanks.
Also, thanks for reminding this newbie about how the metering systems aims for mid-grey. On my recent OU course, the experiment was to take photos of two sheets of paper: one all white and the other all black.
The results (as I remember) were mid-grey tones.

Father Ted...you haven't highjacked my thread...simply, the more the merrier!

Very many thanks to all; really enjoyed my learning this lunch-time.
Also learned how to get the focus point back from the peripheral points...darn, how did that happen?!

Alan.

Green mode is for people who should have bought a compact camera

If you set the focus point to centre spot only (using the big dial to the right of the screen), like most of us here, you won't have that problem again.