Blurry stars/images

[Jjmorris90]

Hello



I have a 700d attached to a skywatcher 200p



when I take photos they always blur.



as I don’t have a tracked mount yet I can only do short manual exposures. Around 2 seconds.



could it be the vibration caused by the camera in such a short space of time blurring the image ?



ive attached a photo. You’ll see the stars in the background blurry

You may have to zoom on the image to see what I mean

 

[Leonard Migliore]

Hello

I have a 700d attached to a skywatcher 200p

when I take photos they always blur.

as I don’t have a tracked mount yet I can only do short manual exposures. Around 2 seconds.

could it be the vibration caused by the camera in such a short space of time blurring the image ?

ive attached a photo. You’ll see the stars in the background blurry

You may have to zoom on the image to see what I mean

How is the camera set up? Do you have the sensor at the prime focus or are there other optics in there?

Anyway, it looks like linear motion to me, caused by the rotation of the earth. Two seconds is a long time when you have a telescope.

Of course, a DSLR really shakes things up. Are you using a remote shutter and live view with an electronic first curtain? That helps a lot with camera vibration.

 

[Alice732]

Hello

I have a 700d attached to a skywatcher 200p

when I take photos they always blur.

as I don’t have a tracked mount yet I can only do short manual exposures. Around 2 seconds.

could it be the vibration caused by the camera in such a short space of time blurring the image ?

ive attached a photo. You’ll see the stars in the background blurry

You may have to zoom on the image to see what I mean

you mean all the stars are lines rather than dots?

 

[Jjmorris90]

Thanks for the reply

the camera is attached directly to the scope via a t ring adapter.



I can obtain focus without a “Barlow lens”

i have a shutter cable yes which I’ve been using. I think the fact that it is not tracked is the issue

 

[Jjmorris90]

Yeh they are like lines lol

 

[davev8]

Hello

I have a 700d attached to a skywatcher 200p

when I take photos they always blur.

as I don’t have a tracked mount yet I can only do short manual exposures. Around 2 seconds.

i think 2 seconds is too long for a 1200mm telescope on APS-c

if the 500 rule is used which is for FF which is 500 divided by the focal lengths to give you the length of exposure in seconds

well you have a APS-c so need to divide the 500 by 1.6 so 320 so you need to use the 320 rule for APS-c ..you have a 1200mm lens so 320 divided by 1200=0.26 seconds exposure

so your exposure is going to be 1/4 of a second for no movement ...if i remember at 1000mm on APS-c you can see the moon moving pretty fast in the vf

could it be the vibration caused by the camera in such a short space of time blurring the image ?

ive attached a photo. You’ll see the stars in the background blurry

You may have to zoom on the image to see what I mean

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Attention Dislexsic i mean dyslexic person... This post will have many although spell checked, spelling and grammatical errs ..its The best its going get so no need to tell me it is bad I know it is .....................................................................................................
the EOS M is not dead and wont be for a long time ....as long as you don't want a flagship camera with a VF...if that's the case it died sometime ago
My 5D IS a MK1 classic
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There is no argument for FF vs APS-c (or m43) with shallow DOF..as it's a law of physics and a very subjective personal thing if you want to make use of the shallow DOF only FF can offer
.....................................................................................................
If you wait for a camera that will tick all your boxes ....by then you will have more boxes to tick..... so the wait continues .....David Appleton

 

[swimswithtrout]

Motion blur from no tracking....at the VERY most, you can only expose for 0.2" without trailing. ( And forget the "Rule of 500". That was only good for course grain film/6Mp digital cameras. )

 

[davev8]

Motion blur from no tracking....at the VERY most, you can only expose for 0.2" without trailing. ( And forget the "Rule of 500".

well the 500 rule calculated 0.26 that's very close to your 0.2..nobody ever says the 500 rule is cast in stone but more of a guide or starting point also i believe the OPs 700D can only adjust the shutter speed in full stops in manual, the nearest to your recommendation is 1/4 of a sec or 0.25

so tell me how did you come to 0.2 we would all like to know

That was only good for course grain film/6Mp digital cameras. )

 

[Jjmorris90]

What if I track the stars ? Will this allow a longer exposure time

 

[Kazmarov]

The short answer to your question is "Yes" but then there are many caveats that impact the exposure time that would work best for a particular situation (location & sky conditions e.g. light levels, atmospherics etc), equipment (tracker/ mount, lens etc) & your objective (e.g. wide field, wide field so etc).

For untracked exposure length, Ian has a calculator & a discussion on some of the factors on his Lonely Speck site. There are others too but perhaps you would find other articles on the site helpful too.

 

[Tristimulus]

What if I track the stars ? Will this allow a longer exposure time

That is exactly what star trackers are for. Following stars from rise to set.

 

[swimswithtrout]

Motion blur from no tracking....at the VERY most, you can only expose for 0.2" without trailing. ( And forget the "Rule of 500".

well the 500 rule calculated 0.26 that's very close to your 0.2..nobody ever says the 500 rule is cast in stone but more of a guide or starting point also i believe the OPs 700D can only adjust the shutter speed in full stops in manual, the nearest to your recommendation is 1/4 of a sec or 0.25

so tell me how did you come to 0.2 we would all like to know

That was only good for course grain film/6Mp digital cameras. )

The 0.2" is the absolute max and will still exhibit 7 pixels of smearing if you pixel peep. To cut that in half, you're down to 0.1".

https://www.lonelyspeck.com/advanced-astrophotography-shutter-time-calculator/

 

[davev8]

Motion blur from no tracking....at the VERY most, you can only expose for 0.2" without trailing. ( And forget the "Rule of 500".

well the 500 rule calculated 0.26 that's very close to your 0.2..nobody ever says the 500 rule is cast in stone but more of a guide or starting point also i believe the OPs 700D can only adjust the shutter speed in full stops in manual, the nearest to your recommendation is 1/4 of a sec or 0.25

so tell me how did you come to 0.2 we would all like to know

That was only good for course grain film/6Mp digital cameras. )

The 0.2" is the absolute max and will still exhibit 7 pixels of smearing if you pixel peep. To cut that in half, you're down to 0.1".

https://www.lonelyspeck.com/advanced-astrophotography-shutter-time-calculator/

very useful link that you posted.. it seems 7 pixels is the default for the calculator

and it looks like its confirmed that the 1/4 of a sec shutter speed i recommended derived from the 500 rule is valid

here is a passage i cut and paste from it

For photographers that are just learning astrophotography, I’ve very often recommended using the 500 Rule (calculator) to calculate shutter time. My tutorials here and here recommend determining shutter speed based on this “500 Rule” concept. More of a guideline than a rule, the 500 Rule tells us a rough recommendation for limiting shutter time. Limiting the shutter time with the 500 Rule helps reduce star trailing while also allowing adequate light to enter the lens. The 500 Rule is simple: Take 500 and divide it by the focal length of your lens to determine your shutter time. For example, for a 20mm lens, we would want a shutter time of 25 seconds:

 

[3dpan]

Hello

I have a 700d attached to a skywatcher 200p

when I take photos they always blur.

as I don’t have a tracked mount yet I can only do short manual exposures. Around 2 seconds.

could it be the vibration caused by the camera in such a short space of time blurring the image ?

ive attached a photo. You’ll see the stars in the background blurry

You may have to zoom on the image to see what I mean

As has been mentioned you will need a much shorter exposure time with an un-tracked Skywatcher 200P.

Yes you can do longer exposures with the 200P if you have a tracking mount. But it is going to be fairly expensive, and you will need to pay attention to your Polar alignment, among other variables.
Trying to image with something as heavy, and slow, and with such a long focal length as the 200P is really jumping into the deep end, even with a tracking mount.

Better to start with just a wide angle/standard/short tele lens. The faster the better will reduce your exposure times. (eg f/2.8 or faster).

And with a very good tracking mount, and lenses f/2.8 or faster, you can do a lot of imaging with 2 minute exposures, and all without resorting to auto-guiding.

 

[Andy01]

I was under the impression that Rule of 200 was more appropriate for APS-C (Crop) cameras, Rule of 300 for "normal" resolution FF cameras, and something lower for higher resolution cameras (like Canon 5DS, R5 or 90D). Rule of 500 was for older film and low resolution digital cameras.

Using Rule of 200 for a 1200mm telescope, I would imagine that a shutter speed around 1/6th second may work reasonably well.

If this is correct, then the OP's 2 seconds is about 12 times too slow - a similar result could be expected using an untracked 180 second shutter speed for a FF with a 20mm lens.

I am not sure about a Canon 700D, but both my Canon 6D ii and M5 both have 1/10th, 1/8th, 1/6th, 1/5th and 1/4th shutter speeds available, so there are a few options in that range between the above-quoted 0.1" (1/10th) and 0.2" (1/5th).

Colin

 

[davev8]

I was under the impression that Rule of 200 was more appropriate for APS-C (Crop) cameras, Rule of 300 for "normal" resolution FF cameras, and something lower for higher resolution cameras (like Canon 5DS, R5 or 90D). Rule of 500 was for older film and low resolution digital cameras.

the rule of 500 (for FF so divide by 1.6 for canon APS-c) is still a valid starting point and a starting point is what any rule is ..the reason being is you are not only fighting against the movement but also high ISO so noise, so its going to be a compromise between the amount of noise that's acceptable and the amount of movement that is acceptable

Using Rule of 200 for a 1200mm telescope, I would imagine that a shutter speed around 1/6th second may work reasonably well.

If this is correct, then the OP's 2 seconds is about 12 times too slow - a similar result could be expected using an untracked 180 second shutter speed for a FF with a 20mm lens.

I am not sure about a Canon 700D, but both my Canon 6D ii and M5 both have 1/10th, 1/8th, 1/6th, 1/5th and 1/4th shutter speeds available, so there are a few options in that range between the above-quoted 0.1" (1/10th) and 0.2" (1/5th).

i know the earlier xxxD camera in manul only had shutter speeds and F stops adjusted in full stops only to differentiate them from the xxD line of body ..i don't know if its still the case with the 700D

Colin