How to improve quality

[abpho]

I would like to know how to improve on the overall quality and sharpness of my shots. Here is a 100% crop. Notice how the contrast is low, the detail in the hairs is low, here is a sort of halo around the hairs. The light source is a single flash unit fired through a styrofoam cup.

Taken with the Canon FD 20mm f/3.5 at f/3.5. 6.6:1 magnification.


If it the diffuser?
The lens?
The light source?

I get a few super sharp images that hold up to 100% viewing. Not something I care for. But a remarkable picture will hold up if scrutinized at that level.

CheerS!

[Chris S.]

My first thought would be to look for flare--in this case, either light hitting the front of the lens, or light reflecting off of some thing inside your bellows arrangment, or both. Flare can easily cause this sort of reduced contrast.

As a first step, I'd suggest looking at the front (subject-facing) surface of your lens while your flash is firing. If you see any light hitting it, try blocking this light. Does contrast improve?

As a second step, I'd suggest taking the camera off your rig and looking through your rig from the camera's viewpoint, while shining a bright light in through the lens. As you move the light around, can you see any shiny bits inside your rig? If so, you either want to cover them with a flocking material such as Protostar, or make a flare cut stop, or both.

This sort of thing is always interesting--I hope you'll share what you find out!

Cheers,

--Chris

[abpho]

Thanks Chris. The hardest part is not knowing what the picture will look like until after it is stacked. I get awesome results with my lenses all the way to #####. I think flash position, even if only by a few millimeters, is critical. I still have this subject. I will first try repositioning the flash. The should cover the first point in your recommendations. After that it is going to be a bit of work.

Cheers!

[Chris S.]

Thanks Chris. The hardest part is not knowing what the picture will look like until after it is stacked.

Yep! How many stacks have been redone because we learned things about the subject only after stacking? That said, I find it very useful to look at each subject under a low-powered stereo microscope before attempting to photograph it. This isn't necessarily predictive of what a stacked shot will look like at 50x or 100x, but is fairly predictive at lower magnifications. Such stereomicroscopes don't need to be expensive--I think I paid $150 USD for mine (used); but it's a great time saver, and is also an enormous help when cleaning sensors.

I think flash position, even if only by a few millimeters, is critical.

Agreed--which is why, for macro work, my investment in light positioning equipment is second only to my optics.

I will first try repositioning the flash. The should cover the first point in your recommendations. After that it is going to be a bit of work.

Don't worry--it's not as bad as it sounds. A while back, based on advice from this forum, I bought a piece of Protostar "flocked light trap material" to treat my rig--and what good advice it was. Since shipping was not inconsiderable, I decided to buy more than I needed just then, to avoid having to order more. It has turned out to be a tremendously useful studio supply. The stuff costs $0.50 USD per inch of a roll 30 inches wide. IIRC, I purchased about $40 worth, which might be a lifetime supply, as a little bit usually goes a long way. I can't count how many times I've reached for Protostar to treat a lens, tube, bellows, adapter, or whatever. Whenever I make changes to my rig, I shine a light through it and look for reflections. If I see any, out comes the Protostar material. Little bits and pieces of it are usually all it takes, and the increase in contrast is often astounding.

Good luck!

--Chris

[SONYNUT]

look inside bellows. extensions ect for reflections

[johan]

I was very pleasantly surprised with the increase in contrast & quality once I decided to try a hood over my reversed lens using just a spare endcap with the flat end cut off. My diffuser is relatively large (about a 120 degree arc over lens, protruding almost in front) and the cap seems to have dealt with this quite nicely.

Also, I can't tell from the image above (no exif data), but just to check, you're using the lowest ISO you can, right? Also, it looks as if there's very little information in the first 25% or so of the histo, might be worth comparing a shot that has 1/8 less light or so. Lenses are rarely at their best used wide open like this: I do though get a pleasing contrast hike on this image when I adjust levels in photoshop using 'Enhance Per Channel Contrast' & 'Snap Neutral Midtones' options, which might be worth a punt.

[seta666]

As others sugest my main problems with contrast have been reflections in tubes and bellows, it is a important part to fix
Also a lens hood when possible will help. Maybe your lens works best closed one stop but then difraction will become your new enemy
Regards

[DQE]

Would sending a very bright LED flashlight backwards, through the viewfinder and then out the camera's optics help the detective work re improving illumination, especially unwanted reflections, etc?

Just a late night thought, probably not so useful but I thought I would mention it just in case someone can make use of it in some way...

[enricosavazzi]

Would sending a very bright LED flashlight backwards, through the viewfinder and then out the camera's optics help the detective work re improving illumination, especially unwanted reflections, etc?

Just a late night thought, probably not so useful but I thought I would mention it just in case someone can make use of it in some way...

Probably not, flare is usually caused by light reflected/diffused multiple times within the optical system. By the time the light leaves the system in the opposite direction than the normal one, any flare will be visually swamped out by light following the main optical path.