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Esprit finder scope for guiding?


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Has anyone used their Esprit series finder scope for guiding? If so, how did you fair? Secure enough in the shoe? Adapters needed to fit the guide camera? Reason I ask is I'm considering this as opposed to my OAG. I have started using filter offsets to capture data one filter after another without refocusing each time. So every filter change invokes a small movement with the focuser and my OAG is picking this up and I get a little spike in PHD with this. So far it hasn't caused a major issue but its a slight annoyance all the same. Those spikes you see are about one minute apart every filter change and focuser movement.

 

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9 minutes ago, vlaiv said:

Maybe image with single filter for longer than one exposure?

That was how I 'traditionally' done it but fed up of gathering half the data needed each season due to weather! It's not even an issue to be honest, but I'm just wondering if the Esprit 9x50 has been used as a guidescope as I've got one in the box doing nothing.

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I guess it can certainly be used - but I'd use it only in cases where I would not worry too much about flex - meaning short exposures and "loose" guiding requirements - short focal length scopes and low resolution work / wide field.

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What size esprit is it David? 

What program are you running for capture?  If you dither then you can set a settle down time before it stars it's capture again, sure it shouldn't be starting a exposure and still running a focus run at the same time?

Not sure that you would be able to use a 1.25 in the finder, seems thinner than that on my 80

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18 minutes ago, newbie alert said:

What size esprit is it David? 

What program are you running for capture?  If you dither then you can set a settle down time before it stars it's capture again, sure it shouldn't be starting a exposure and still running a focus run at the same time?

Not sure that you would be able to use a 1.25 in the finder, seems thinner than that on my 80

It's the Esprit 100 and using NINA. I'm not focusing. It's using a predefined autofocus step size (offset) for each filter. For example, I shoot a 60s Lum sub. The filyerwheel then changes to Red and the focuser moves 25 steps to account for the different focus position. During all this, PHD is guiding away merrily with the OAG but the focus movement is picked up as either a sudden star movement and/or the star profile changes size due to either moving in or out! I could add a 10s settle time after any focuser movement so it settles before imaging again but these 10s add up with each filter change and autofocus would take much longer as well. It goes against the idea of using the filter offsets to gather as much data as possible in a session! Anyway, I've looked at the Esprit finder and it's essentially a slightly shorter 9x50 than the normal one you get with a 200p for example so I've ordered one of those C adapters that let's you add a guide camera to the end. I'm hoping it's short enough where I can install a helical focuser and still get focus. If its 180mm focal length, it should work.

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Here's a better example of what I'm taking about. Those spikes are my filter changes and subsequent focuser movement at minute intervals. So clearly this method of using filter offsets is problematic for an OAG unless your willing to compromise with long settle times. I digress though, this thread was started to see if anyone used the Esprit 9x50. Hopefully I will be able to demonstrate that with use of the adapter.

 

 

Screenshot 2022-10-09 201417.jpg

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7 minutes ago, R26 oldtimer said:

I think that the main reason for sequential filter capture is to get even gradient across filters. But since your subs are so short, you could go for 10xsubs (10min total) before changing filter.

Perhaps for others, but for me I'm trying to gather a full data set each session. Also, if I done something like that, it's 6 autofocus routines and hour, so say 12 mins per hour, or 1 full hour of autofocusing per 5 hour session! It all adds up! 

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I see, even thou you're not doing a full blown autofocus run it still sounds like it needs a settle time, one for the filter to change and 2 for the autofocuser to move it's offset distance..  are you doing a full loop of filters?  

Nina is flexible enough to do say 10 exposures of red, 10x blue etc, or run a auto focus on temp change( if you have temperature reading)  or if you're using the sequencer it can check to HFR in the background after every sub and if it changes do a autofocus

Seems abit OTT to just use the offsets every sub to maximise capture but lose out on focus as the temp drops off, or am I reading that bit wrong

Anyway, don't think there's much to gain from using a oag on a esprit 100, but if it works then great..if you do go for the finder as a guider the biggest hurdle would be the adapter but I'd think you would have the same situation as the filterwheel is still going to change and the focuser move unless you add a few secs delay between subs

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9 hours ago, newbie alert said:

I see, even thou you're not doing a full blown autofocus run it still sounds like it needs a settle time, one for the filter to change and 2 for the autofocuser to move it's offset distance..  are you doing a full loop of filters?  

Nina is flexible enough to do say 10 exposures of red, 10x blue etc, or run a auto focus on temp change( if you have temperature reading)  or if you're using the sequencer it can check to HFR in the background after every sub and if it changes do a autofocus

Seems abit OTT to just use the offsets every sub to maximise capture but lose out on focus as the temp drops off, or am I reading that bit wrong

Anyway, don't think there's much to gain from using a oag on a esprit 100, but if it works then great..if you do go for the finder as a guider the biggest hurdle would be the adapter but I'd think you would have the same situation as the filterwheel is still going to change and the focuser move unless you add a few secs delay between subs

I already have NINA set to focus if temp changes by 2° and star HFR increases by 5%. Also a refocus every 30 mins anyway using the L filter which usually only takes less than 2 mins. So far it has worked very well and even if I only gather an hour or 2 of subs, I have a full even set of data across all filters. 

I do prefer the OAG but I would prefer nice smooth guiding even more. The idea of changing back to guidescope is it will become fully independent of any movement by the focuser which is causing the issues you can see above. I should have the adapter from FLO tomorrow so will find out if the Esprit finder is OK to use.

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20 hours ago, david_taurus83 said:

Perhaps for others, but for me I'm trying to gather a full data set each session. Also, if I done something like that, it's 6 autofocus routines and hour, so say 12 mins per hour, or 1 full hour of autofocusing per 5 hour session! It all adds up! 

Forgive me, I don't want to sound pertinacious but, you could take 10x1min subs in R, use filter offsets, take another 10x1min subs in G, filter offsets again and 10x1min in B.

This way you will only refocus 6 times (using filter offsets) per hour, instead of 60 and have a full set of RGB every half an hour.

The reason for being so persistent is because I recently moved from a guidescope to an oag. Had a decent 70mm guidescope and an imx290 cam with small pixels. Although phd2 calculates centroid on subpixel scale it's not as accurate as calculating it on a bigger pixel scale. Flexure creeped from almost everything (finder shoe - finder rings - plastic tipped finder screws), but my phd2 graph looked very good. Moving to oag and after fettling for hours to make it work (you 've got one so you know all about it), my phd2 graph turned a little worst, but my star shapes got a lot better.

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On 10/10/2022 at 17:08, R26 oldtimer said:

Forgive me, I don't want to sound pertinacious but, you could take 10x1min subs in R, use filter offsets, take another 10x1min subs in G, filter offsets again and 10x1min in B.

This way you will only refocus 6 times (using filter offsets) per hour, instead of 60 and have a full set of RGB every half an hour.

The reason for being so persistent is because I recently moved from a guidescope to an oag. Had a decent 70mm guidescope and an imx290 cam with small pixels. Although phd2 calculates centroid on subpixel scale it's not as accurate as calculating it on a bigger pixel scale. Flexure creeped from almost everything (finder shoe - finder rings - plastic tipped finder screws), but my phd2 graph looked very good. Moving to oag and after fettling for hours to make it work (you 've got one so you know all about it), my phd2 graph turned a little worst, but my star shapes got a lot better.

A completely valid point and makes perfect sense, however it still doesn't remove the spikes from guiding without a long settle time and it would mildly bug me that it's not an even capture! I realise I'm trying to fix a problem that isn't there but I do want to put my 6D on there soon so a guidescope is needed anyway. 

To answer my original question, yes, the Esprit finder can be converted to a guidescope. You need the M51 to C adapter from FLO, the ZWO M42(T2) to C adapter and a helical focuser. I happened to have most of these bits in my astro parts box so only needed to purchase the M51 adapter. The spacer between the guidescope and focuser is optional also. I prefer to have the camera inserted almost fully into the focuser body as opposed to sticking half out.

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