Question about proper exposure with a manual lens

[Novelectro]

Hi All,

First post so hopefully I am in the right place. I'm still learning a lot and am pretty new - but I figured this question wasn't completely basic, so here goes.

I'm into nightsky photography and I recently picked up a Rokinon 16mm f2.0 lens for my canon 70d. It appears that it's one of the best nightsky lenses for aps-c cameras and I'm really excited to use it. It's a manual lens and so understand my I need to adjust focus and aperture via the lens itself and not my camera.

What I'm confused about right now is that my camera doesn't seem to tell me the appropriate exposure at all prior to taking a picture. Basically if I set my shutter speed to what my camera says is zero/in the middle/ perfectly exposed - the photo image when I view it is significantly underexposed. In order for me to expose properly where the histogram is in the middle - I actually need to take the picture at somewhere around +2 or +3. This doesn't seem right to me, but then again I'm still very much a novice.

I bought the lens used, so most importantly I want to make sure that I didn't get hosed by a faulty lens (or maybe there is even something wrong with my camera? But I don't seem to have this problem with my kit lens).

Thanks in advance to anyone who has some suggestions!

 

[runnah]

sounds like something going on with your camera. I have a few manual Rokinon lenses for my video camera and since they are manual there is no lens to camera communication.

What metering mode are you in? Does it only happen for night photography?

 

[Novelectro]

I'm on center weighted average but tried another mode as well and didn't seem to make a difference. I just switched back to my kit lens and that still appears to be measuring alright. If I'm in the middle then the histogram on the taken picture looks roughly where it should be.

I haven't taken any night shots yet. This is just taking the first few test shots in my kitchen and wondering why I need to get it to +3 to get an appropriately exposed photo.

 

[jcdeboever]

I don't have a Canon but the older Pre- AI, AI, and AIS glass will not meter on my Nikon D3300. I go by the sunny 16 rule. In your case with nighttime stuff, a notepad may be in order. Mobile light meter app may be useful as well.

Sent from my XT1254 using Tapatalk

 

[gsgary]

It should work in manual and aperture priority exposure mode

 

[Novelectro]

I don't have a Canon but the older Pre- AI, AI, and AIS glass will not meter on my Nikon D3300. I go by the sunny 16 rule. In your case with nighttime stuff, a notepad may be in order. Mobile light meter app may be useful as well.

Sent from my XT1254 using Tapatalk

Thanks for the suggestion. While I don't really want to give up and accept that the only conclusion is a workaround (at least until I get the impression that my issue is known and accepted by many), do you have any recommendations for an app? I tried downloading "myLightmeter" but it doesn't work very well. Seems to be like 4 or 5 clicks underexposed.

Man this is frustrating. Just wanted to hit the ground running with the lens.

 

[jcdeboever]

I have used light meter and it is generally spot on when comparing to digital. One thing to keep in mind though, if you have auto ISO set in camera, this may throw things off as light changes rapidly and this may be why your stuff isn't right.

Sent from my XT1254 using Tapatalk

 

[Novelectro]

It should work in manual and aperture priority exposure mode

Good point about Aperture priority. Just tried that and it appears to be much closer. Still not perfect and maybe a touch underexposed but that's probably just me nitpicking (I still don't know enough to say whether or not something "should" or "shouldn't" be anything. I'm basically 3 months into learning photography from YouTube and Google).

Manual is very clearly off though. Like not even close and I definitely don't plan on using Aperture priority for the bulk of what I want to do with this lens.

 

[Novelectro]

I have used light meter and it is generally spot on when comparing to digital. One thing to keep in mind though, if you have auto ISO set in camera, this may throw things off as light changes rapidly and this may be why your stuff isn't right.

Sent from my XT1254 using Tapatalk

Nope I'm set to 100. Now I'm really wondering what's going on.

 

[gsgary]

It should work in manual and aperture priority exposure mode

Good point about Aperture priority. Just tried that and it appears to be much closer. Still not perfect and maybe a touch underexposed but that's probably just me nitpicking (I still don't know enough to say whether or not something "should" or "shouldn't" be anything. I'm basically 3 months into learning photography from YouTube and Google).

Manual is very clearly off though. Like not even close and I definitely don't plan on using Aperture priority for the bulk of what I want to do with this lens.

Manual should be closer than aperture priority if you are reading the meter properly you can't just go by the meter you have to learn to evaluate the scene

Sent from my SM-G903F using Tapatalk

 

[jcdeboever]

I have used light meter and it is generally spot on when comparing to digital. One thing to keep in mind though, if you have auto ISO set in camera, this may throw things off as light changes rapidly and this may be why your stuff isn't right.

Sent from my XT1254 using Tapatalk

Nope I'm set to 100. Now I'm really wondering what's going on.

Have you tried a total reset? I once was having issues similar to that and I apparently changed something in the menu and couldn't figure out. Reset and was back on track. Now I am totally familiar with the menu and developed pretty good pre-check skills.

Sent from my XT1254 using Tapatalk

 

[jcdeboever]

I have used light meter and it is generally spot on when comparing to digital. One thing to keep in mind though, if you have auto ISO set in camera, this may throw things off as light changes rapidly and this may be why your stuff isn't right.

Sent from my XT1254 using Tapatalk

Nope I'm set to 100. Now I'm really wondering what's going on.

I'm not familiar with that app, some are apparently better than others. Relax, you'll get er sorted. gsgary is familiar with your Canon stuff.

Sent from my XT1254 using Tapatalk

 

[Novelectro]

I just tested something...looking at the same subject with the same focus and making no changes at all, set to aperture priority and the camera selected 40 as the shutter speed and I took a picture. It was slightly underexposed but definitely right in the ballpark.

Immediately after I switched to manual, the camera was set to 250 shutter speed and indicated that it was exposed correctly (of course it was very dark).

 

[Novelectro]

A total reset doesn't sound like a bad idea. I'll figure out how to do that and report back.

It should work in manual and aperture priority exposure mode

Good point about Aperture priority. Just tried that and it appears to be much closer. Still not perfect and maybe a touch underexposed but that's probably just me nitpicking (I still don't know enough to say whether or not something "should" or "shouldn't" be anything. I'm basically 3 months into learning photography from YouTube and Google).

Manual is very clearly off though. Like not even close and I definitely don't plan on using Aperture priority for the bulk of what I want to do with this lens.

Manual should be closer than aperture priority if you are reading the meter properly you can't just go by the meter you have to learn to evaluate the scene

Sent from my SM-G903F using Tapatalk

I'm sure you are right about that. But you're saying that there could be a discrepancy as large as what I'm indicating? That seems far fetched but maybe not.

 

[wfooshee]

That lens does not communicate electronically with the camera, and metering must be done stopped down. If you can't do stopped-down metering with your camera, then you have some arithmetic to do. Meter at f:2, which is wide open, then adjust your reading for what you want to set your aperture to. If you want f:8, for example, then whatever it meters for your shutter speed when it's wide open, you need to lengthen by 4 stops, since f:8 is four stops under f:2.