Issue with T5i view finder when shooting stars.

patsies62 wrote:

Hi everyone,

This is my first time posting here so I apologize if this is in the wrong sub forum or in the wrong format.

I have a canon t5i and it has been pretty solid for roughly 4 years. I want to get into Astrophotography and with that I started to take pictures of the stars a week ago to get practice on focusing on them. Everything was going fine I could see Vega clear as day and could focus it. I took one really noisy picture shooting at ISO 3200 for at 45 seconds and after that my view finder stopped working. I couldn't see Vega or anything in the view finder and when I went to take a photo it was pitch black. I took down my camera equipment and brought the camera inside and in bright light the camera seemed to be fine and I could take a normal photo. On the photos I took after the noisy photo and on the all black photo I took outside I noticed a lot of hot pixels or dead pixels on them that were not there before my very noisy photo. I ran the sensor cleaner in the cameras settings to hopefully fix the issue with the view finder after discovering these pixel issues. Friday night I went to take more photos. I turned the camera on and to my surprise I could see Vega again. I had to shut my camera off and wait about 30 minutes before I could take photos and when I went to turn the camera on again I couldn't see Vega anymore. It's like my lens cap is over the camera. Flash forward to last night and once again I couldn't see in the view finder but this time I could take photos unlike the prior night a week or so.

If anyone has any information as to what might be going on with my camera I would really appreciate any advice.

Thank you very much, Pat

PS: Here is a link to some of the photos I took last night: https://drive.google.com/drive/folders/1VJ1T-SBkFtOfURAwI5g3cEzRJiuYjfgu?usp=sharing
The first photo you can really notice all the hot/dead pixels.

Presumably you're referring to the eye-level viewfinder - you weren't using live view (in which case you'd be looking at the image, before taking it, via the LCD monitor), I assume?

I wonder if what you are running up against is long exposure noise reduction? Take a look in your menu system, in the third tab with a camera icon - note there is an entry called long exposure noise reduction. If you go into this, does it say either Auto or Enable? If so, that could be what you're seeing. There is also a Disable option, which could bypass this problem if this is what's causing it, but at the expense of even noisier results.

Most digitals have this option (sometimes under different names). It's a process called dark-frame subtraction. On long exposures (over 1 second long in the case of your model), this function can be used to help cut down the hot and stuck pixels that are more likely to build up during a long exposure as the sensor heats up. A second exposure (but with the shutter closed, so that it's blank) follows the actual exposure. Because the mirror is up, the viewfinder is blocked by it. The purpose is that in that second exposure, the only bright points will be the hot pixels, so the camera notes where they are and blanks them out on the real image it just took. On "Enable" this will always happen for long exposures - on "Auto", it will only happen if the camera thinks there are hot pixels in the real image - but it could mistake stars for these and trigger it. In any case, if it runs this process, that second exposure IS ALWAYS THE SAME LENGTH as the first, real one - so 45 seconds again in your example. Do you think this is maybe what you were experiencing when the viewfinder image disappeared? It would feel like forever if you weren't prepared for it to happen.

I breifly read some of the comments but I need to clarify one major mistake I made in this post.

1) I am talking about live view not the view finder... Sorry for the stupid silly confusion...

2) As far as the lens settings and what I was shooting at this is the information

Lens: 70-200MM f/4 L
Focal Length : 200MM
ISO: 1600
Shutter speed varied from 30-45 seconds.

I was using a skyguider pro and trying to verify it was tracking well and that I was indeed aligned with Polaris so I tried a few shots at 45 seconds and I increased the ISO to 3200 a shot a few shots at a shutter of 5-10 seconds. I finally shot a shot of 45 seconds at ISO 3200 and I got my the live view to stop working. The screen went totally dark.

This is a link to the first batch of photos I took of the stars when the live view was working.  I am very new to astrophotograhpy and I was really just trying to work on getting my stars sharp.  The stars are still out of focus but with the live view working and me being able to see the stars I had a much easier time focusing and they look a lot better rather than me just guessing the focus point and taking shots..  My only concern is I might have over heated the sensor when I took the image of ISO 3200 at 45 seconds.
https://drive.google.com/drive/folders/1aoob9MJCvGwzW-HJ-nWBaLCCvc7-QpvH?usp=sharing
Thank for all the replies so far.

Lemming51 wrote:

patsies62 wrote:

I briefly read some of the comments but I need to clarify one major mistake I made in this post.

1) I am talking about live view not the view finder... Sorry for the stupid silly confusion...

2) As far as the lens settings and what I was shooting at this is the information

Lens: 70-200MM f/4 L
Focal Length : 200MM
ISO: 1600
Shutter speed varied from 30-45 seconds.

I was using a skyguider pro and trying to verify it was tracking well and that I was indeed aligned with Polaris so I tried a few shots at 45 seconds and I increased the ISO to 3200 a shot a few shots at a shutter of 5-10 seconds. I finally shot a shot of 45 seconds at ISO 3200 and I got my the live view to stop working. The screen went totally dark. ...

+ 1 to Helen's response. It sounds to me that you have Long Exposure Noise Reduction enabled. pp. 127-128 of the 700D/T5i instruction manual. Whether using the viewfinder or live view it takes a 2nd exposure with the shutter curtains closed for the same length of time as your initial exposure. Shooting with the viewfinder, it remains dark because the mirror is up. Shooting with live view the monitor is completely black because the 2nd noise reduction exposure is with the shutter curtains closed.

Thanks - that saved me a long, waffly sequel (my style, unfortunately!!) adding that it could still be Long Exposure NR in live view too.  The OP's fear of overheating probably needn't be too much of a concern to them - long exposures do generate more heat (and hot pixels), but the camera would probably cut out to protect itself from damage (which is I suppose another potential reason for the live view cutting off, actually).