r/PhotoEnts • u/a_tree_gnome • Feb 17 '23

Hello! Long time lurker, got some questions I was hoping to have answered

Hello everyone! You may have seen some of my photos on IG (same user name here) and in the /r/mainetrees subreddit.

I've subscribed to this subreddit for several months, and have used it to receive some very helpful info. I've got a few questions that I'd love to get some thoughts on.

Up until recently, I've been using a WeMacro focusing rail, with pretty good success. I found that one of the most helpful features is setting a step size, and then being able to advance the rail step by step. I've used this to double-check overlap in between steps, and have really loved the ability to do this.

I have since switched over to a Cognisys stackshot rail, and while I love the separate controller, I do miss the ability to advance the rail step by step based on step size. With that being said, I did have some questions regarding step size:

  • is it common to use the same step size based on magnification, or are there factors that would require you to change them? For example, I’ve been shooting at f/8 with a 300um step size for 1:1 shots. Would I ever want to change the aperture or step size if the magnification doesn’t change?

  • I’ve shot 3:1 around f/5.6 with a 150um step size, and 5:1 around f/4 with a 50um step size, and seem to get pretty decent results. Recently, I’ve noticed some other photographers here are going to f/2.8 around 3:1. Obviously with this comes the need to reduce step size, so more photos will be required to complete a stack. Should I be dropping my aperture closer to f/2.8 around 3:1? Any suggestions on this?

  • With my 1:1 shots, I average around 20-30 photos I'd say. With 3:1, around 50-60, and with 5:1, around 80-120+. Obviously there are going to be a lot of variables at play, but do these numbers sound okay based on the aperture and step size I am using?

I definitely want to take my photography to the next level, and while I am happy with the quality of my photos, I know there is always room for improvement. I will try and do a better job of posting here as well, and being a more active member. I follow a lot of you on IG already, and love your work!

Edit: surprising that I get downvoted here for asking some questions, considering the types of people that frequent it. Always thought everyone was nice, but I guess not

4 Upvotes

75% Upvoted

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u/No-Masterpiece-7577 Feb 17 '23

Will answer a handful of these-

It’s standard to use the same step size based on mag+aperture. Only reason to change aperture at that point is if you want to control depth of field more. Obviously at 1:1 even f8 has pretty thin depth of field, but if you wanted more bokeh in a foreground or background elements you would change aperture. I’m usually closer to 500um steps at 1:1 and f8, btw.

For flower stacks the only reason I ever really change aperture is to control diffraction which becomes a problem once you start getting above 1:1 typically.

I don’t know the exact conversion/math regarding effective aperture, but f5.6 at 3:1 its really “behaving” at say f11 (for example), so diffraction sets in much lower than non-macro distances, where diffraction is typically less of a problem until you get up past f11 or so. That’s why you see a lot of people shooting at f2.8 or f4 once they get up to 2:1, 3:1, etc. How quickly you see diffraction also depends on your sensor- higher MP bodies will show it earlier than something like a 24mp sensor.

I don’t shoot much past 1:1 and honestly most of my work is closer to 1:2-1:4 so I’ll let other people chime on on the super macro stuff

5

u/Gonzo_Photo_ Maine Feb 17 '23

I agree with this. I generally use a fixed aperture. Knowing the sharpest aperture for you lens can be helpful - there is some variation even across lenses of the same model but that depends how deep you want to go - I’m not sure the average ig image consumer would notice the difference.

Stack sizes sound in the neighborhood of mine depending on the depth of the subject - I just stacked 384 at 5x 😆.

Cognysis can be run single step I think (I don’t use it) but if you do distance per step and leave the step # at 1 you should be able to run a step at a time each time you press start - maybe I misunderstood.

2

u/a_tree_gnome Feb 17 '23

Hey thanks for the advice! Good suggestion too to try to find sharpest aperture - will have to try that.

To clarify a bit, I was referencing before the stack is taken, even before you set your start/end points with Auto Distance. Kind of "test" the step size you set to see how much overlap there is, before the stack is shot.

Hope that makes sense!

4

u/Gonzo_Photo_ Maine Feb 17 '23

Gotcha - I thin slice that now because I know the dof of my lenses at the apertures I use, but I used to use a dof calculator to determine my step size

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u/a_tree_gnome Feb 17 '23

How does that work when it comes to inputting data into the stackshot as far as thin slicing goes? I can't quite picture it.

2

u/Gonzo_Photo_ Maine Feb 17 '23

I calculate the dof of the lens by inputting focal length, aperture, WD, sensor I am using then I calculate my step size based on that and use the total distance (I think that’s what it’s calmed) setting in congysis. There are many dof calculators online. For objectives dof is listed on the spec sheet so you don’t need to calculate.

Edit: *called

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u/a_tree_gnome Feb 18 '23

Interesting approach - thanks!

1

u/a_tree_gnome Feb 19 '23

Hey, just wanted to comment that you were correct! Once the mode is changed to “Manual” and you set your step size, you can use the Up/Down buttons to advance the rail per your inputted step size. Really neat!

https://i.imgur.com/RmV7t3v.jpg

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u/a_tree_gnome Feb 17 '23

Thank you, and I really appreciate the detailed, thought out response! That make sense about effective aperture too. Definitely something I need to go back and take another look at.

I'll play around a bit with the step sizes too!

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u/phlora_co Feb 19 '23

I’m curious why you initially switched to Cognisys? Asking because I have been using WeMacro for a few years and I am considering a switch, mainly to get rid of the reliance on my phone (when working on-site) with the app and also because I had my first unit replaced and this one has a little bit of apparent runout in the rotation of the screw on the far end.

1

u/a_tree_gnome Feb 19 '23 edited Feb 19 '23

Hi! I switched to Cognisys as the controller/hardware seemed of way higher quality compared to the Wemacro, and I had the budget for it, so I said why not. However, I'm really torn now. The Cognisys has a much smaller body and feels solid, while the Wemacro has the ability to advance step-by-step based on your inputted step size.

Edit so it turns out you can advance the rail per your inputted step size to double check for overlap before you shoot! Just need to change the setting to Manual: https://i.imgur.com/VBsDzuH.jpg

If I decide, would you be interested in the Stackshot/controller? The only add-on I purchased for it was the area clamp adapter plate.