Suggested DSLR shutter speed and ISO for imaging the ISS with a C5

Celestron C5 SC XLT spotting scope DSLR ISS
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Rick Evans avatar
Rick Evans avatar

I would like to try and image the ISS tonight with my Celestron C5 scope (5 inch F10) and my Canon 60D DSLR. I would be at about 1250mm focal length and F10. I have been practicing manual alt/az tracking at this focal length and seem to be able to do it well enough. I have tried movie mode in the past and it doesn’t seem to give me a good result and I have had better luck using continuous capture mode in the drive settings which generates a series of still photos as you hold the shutter down. That is my plan for tonight.

I’m not sure what shutter speed would work best and am not sure which ISO to use. I am also not sure if I should use a thread on 1.5x or 2x barlow either, but thought that for tonight maybe I would not use a barlow.

Any suggestions especially from those who have tried something similar? I’ve previously tried various long telephoto lenses recently with DSLRs and also with astrocams and the best I’ve done so far is to be able to recognize the main ISS components but they have not been aesthetic, particularly sharp, or detailed.

Rick

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Tony Gondola avatar
Tony Gondola avatar

I’m assuming you’ll be tracking manually and letting the ISS zip through the frame as you take a quick burst of exposures. Working that way you want a high ISO and very fast shutter speed. Technically the ISS is an object in bright sunlight so something close to a daylight exposure should be right. Holding the shutter button in burst mode isn’t the best idea though as you will introduce a lot of vibration. If you can dig up an electronic release you’ll be much better off. Then you can place the field of view just ahead of the station and start the burst just as it enters the frame. I would not use the Barlow. Doing this with your setup and hardware is going to be difficult so don’t be surprised if it takes a lot of attempts. Good luck!

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Rick Evans avatar
Rick Evans avatar

Setting my shutter speed to 1/6400 and my ISO to 6400 as well gives a nice result in broad daylight of trees on a distant ridge some miles away using a 1.5x thread-on barlow on the camera. I am pretty sure that I can track at least briefly at 2000mm FL and from past results I suspect that for any real detail to appear on the ISS then this sort of focal length appears necessary. If I can follow the ISS across the sky and get a couple of hundred frames of it then I’ll be happy, even if it is out of the FOV on the vast majority of total frames captured. I’ve become pretty good at weeding out the frames that miss the subject. Anyway, it is worth a try and if it doesn’t work then I’ll just plod along with subsequent passes, weather permitting.

I can try test images of Jupiter and Venus at twilight using these settings and adjust if necessary.

Update: On Venus a shutter speed of 1/2000 and an ISO of 4000 seemed to work best. Unfortunately, just as I’d made this adjustment and the ISS appeared and I began to track it with the setup…. the camera nosepiece came out of the telescope back and into my hands… so much for the two little thumbscrews Celestron provides on the visual back of their spotting scope… Oh well… I’ll have another chance at imaging the ISS after the next few days of rain. There is another pass later tonight but it is too low in the sky at 17 degrees.

This is what I ended up with so far. 1/400 sec at ISO 6400.

ISS-5-12-26-2209EDT-90mmF11-FL990mm-Canon60D-400th-6400iso-fr2401.jpg

Rick

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Tony Gondola avatar
Tony Gondola avatar

I honestly don’t know how to respond to the image you posted except to say, that’s not the ISS.

Rick Evans avatar
Rick Evans avatar

I am too early in my attempts to image the ISS to really know what it looks like and it is more than likely that AI sharpening with Topaz created a lot of artifact giving the false impression of structure that isn’t really there in reality. I hope that as I do more of this I will be able to tell when that is happening. Here is an earlier imaging attempt I made with and without the Topaz AI sharpening. That attempt used the same camera but a Canon supertelephoto lens with a couple of extenders on it.

Rick

Without Topaz Sharpening:

ISS-2026-05-10--Canon400mmF7o8-Canon6D-250thsec-ISO400-fr7928-final.jpg

With Topaz Sharpening:

ISS-2026-05-10--Canon400mmF7o8-Canon6D-250thsec-ISO400-fr7928-final-1.jpg

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V avatar
V avatar

I recommend taking a video instead, with a camera that does not interpolate/bin. (planetary cameras are great for this!) Then, using autostakkert or a similar program you can create a high quality video. (which you can then take a frame from)

Topaz is also a generative sharpening software, so I would not use it for any astrophotography purposes, as it creates “things” that are simply not there. Stick to using wavelet sharpening or other non-degrading methods, and be more conservative with your processing intensity, as you are clipping your dark and light points significantly for no gain to actual image data.

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